Polyurethane-based elastomer foams comprising adhesion promoters suitable for battery potting

Abstract

The invention provides a reaction system for producing polyurethane-based elastomer foam. The reaction system comprises a component A, a component B and a component C, wherein the component A is an isocyanate component containing a hard block prepolymer; and component B) an isocyanate reactive component comprising: a polyol; a first chain extender and a second chain extender different from the first chain extender, wherein the first and second chain extender are each an aliphatic diol having 2 to 6 carbon atoms; one or more adhesion promoters; a foaming agent; optionally, a surfactant; and optionally a catalyst.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims priority to U.S. Patent Application No. 63 / 537,623, filed September 11, 2023. The application is incorporated herein by reference. TECHNICAL FIELD

[0003] The present invention relates to a reaction system for producing a polyurethane-based elastomeric foam. The present invention also relates to a method of producing a polyurethane-based elastomeric foam, a polyurethane-based elastomeric foam, a method of potting a battery pack, a potted battery pack, and the use of the reaction system or the polyurethane-based elastomeric foam in battery potting. The polyurethane-based elastomeric foam is particularly suitable for use as a potting material for battery packs designed for use in automobiles, such as electric vehicles. BACKGROUND

[0004] Polyurethane-based elastomeric foams have a variety of uses. One use is as a battery potting material (or battery encapsulation material). Battery potting is the process of partially or completely filling a battery pack or a mold containing a cell with a material, thereby at least partially encapsulating or surrounding the cell with the material. The purpose of battery potting is generally to protect the cell, by, for example, providing resistance to mechanical impact and vibration, forming a seal against moisture, solvents, and corrosion agents, and assisting in electrical insulation and heat dissipation.

[0005] Battery potting is particularly important for battery packs used in electric vehicles (EVs), where many cells are contained that need protection from harsh conditions such as large temperature gradients, mechanical impact, vibration, and moisture. Therefore, the battery potting material must have good mechanical properties, particularly tensile properties (such as tensile strength, modulus (also known as Young’s modulus), and elongation at break), over a large temperature range in order to effectively function in an electric vehicle, while being lightweight and easy to process. Additionally, the battery potting material must also sufficiently adhere to the cell under wet conditions. If the adhesion of the battery potting material is poor, the performance of the battery potting material naturally decreases.

[0006] However, battery potting materials of the prior art can be too brittle when providing stable properties over the required temperature range, or can not provide the required elongation over the required temperature range. The inability to exhibit the required tensile properties over the required temperature range limits the effectiveness of battery potting materials of the prior art as battery potting materials, particularly in electric vehicles.

[0007] For example, polysiloxane (silicone) materials can be used as battery potting materials. However, the modulus of silicone polymers is generally lower than the effective modulus required for use in electric vehicles. Additionally, silicones are expensive and are generally more difficult to process than alternatives such as polyurethane-based elastomers.

[0008] With the growing demand for electric vehicles, the need for novel, high-efficiency battery potting materials is also increasing. Consequently, there is a growing demand for polyurethane-based elastomer foams that offer improved tensile properties (such as tensile strength, modulus, and elongation at break) and provide an ideal balance of tensile and chemical properties for use as battery potting materials in electric vehicles. There is also a need for battery potting materials that can effectively bond to the surface of the battery cell.

[0009] Therefore, there is a need for a polyurethane-based elastomer foam that can be used as a battery potting material, possessing an ideal balance of tensile properties (such as tensile strength, modulus, and elongation at break) and chemical properties suitable for battery potting materials, particularly for electric vehicles. There is also a demand for battery potting materials that can effectively bond to the surface of the battery cell.

[0010] This invention addresses the aforementioned problems and needs. Summary of the Invention

[0011] In a first aspect, a reaction system for producing polyurethane-based elastomer foams is provided, the reaction system comprising: component A) an isocyanate component containing a rigid block prepolymer; and component B) an isocyanate reactive component comprising: a polyol; a first chain extender and a second chain extender different from the first chain extender, wherein each of the first and second chain extenders is an aliphatic diol having 2-6 carbon atoms; one or more adhesion promoters; a foaming agent; an optional surfactant; and an optional catalyst.

[0012] The inventors have surprisingly discovered that the above-described reaction system can be used to produce polyurethane-based elastomer foams with an ideal performance balance for use as battery potting materials. Specifically, the polyurethane-based elastomer foams obtained from the reaction system exhibit high tensile strength and high elongation at break, while also possessing a high (Young's) modulus, and interestingly retain these beneficial tensile properties over a wide temperature range. Particularly surprising is the relatively high elongation at break and relatively high modulus of the foam over a wide temperature range. Polyurethane-based elastomer foams with this combination of tensile properties are an excellent choice for battery potting materials, particularly for battery encapsulation in electric vehicles. This is because the foam possesses high strength, high strain capacity, and sufficient rigidity to protect the encapsulated battery cells from the harsh conditions experienced in electric vehicles, such as significant vibration, mechanical shock, and extreme temperatures. It is difficult to design a reaction system for polyurethane-based elastomer foams that can produce foams with high tensile strength, high elongation at break, and high modulus. Until now, at least one tensile property has been insufficient for use as a battery potting material over the wide operating temperature range required for effective use, particularly in electric vehicles. It is particularly difficult to design reaction systems for obtaining polyurethane-based elastomer foams with relatively high elongation at break and relatively high modulus.

[0013] In addition, the foam obtained from the reaction system has excellent adhesion to the battery cell containing a nickel-plated steel battery cell casing, so the foam can be effectively bonded to the surface of the battery cell.

[0014] Furthermore, the polyurethane-based elastomer foam obtained from the reaction system is lightweight and the reaction system is easy to process, making the foam an ideal choice for battery potting materials.

[0015] In one embodiment, the hard block prepolymer can be formed by the reaction of an isocyanate composition with one or more isocyanate reactive compounds with a molar mass of less than 500 g / mol.

[0016] In one implementation, the hard block prepolymer may be an MDI-based prepolymer.

[0017] In one implementation, the NCO% of the hard block prepolymer can be about 15-30%.

[0018] In one embodiment, the average functionality of the hard block prepolymer can be about 1.7-2.3.

[0019] In one embodiment, the isocyanate component may further comprise a polyisocyanate compound different from the hard block prepolymer. The polyisocyanate compound may be polymerized MDI.

[0020] In one embodiment, the NCO% of the polyisocyanate compound can be about 25-40%.

[0021] In one embodiment, the average functionality of the polyisocyanate compound can be about 2.4-3.0.

[0022] In one embodiment, the weight ratio of the hard block prepolymer to the polyisocyanate compound in the isocyanate component can be from 70:30 to 90:10.

[0023] In one embodiment, the average functionality of the isocyanate component may be about 1.8-2.4.

[0024] In one implementation, the polyol may be a polyether polyol.

[0025] In one embodiment, the hydroxyl value of the polyol can range from about 10 to 180 mg KOH / g.

[0026] In one embodiment, the weight-average molecular weight of the polyol can be in the range of about 1000-7500 g / mol.

[0027] In one embodiment, the average functionality of the polyol can be about 2.0-3.0.

[0028] In one embodiment, the first and second chain extenders may each be straight-chain aliphatic diols, and are preferably independently selected from any one of monoethylene glycol (MEG), diethylene glycol (DEG), 1,3-propanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, 3-chloro-1,2-propanediol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol, 2-ethyl-1,4-butanediol, 1,5-pentanediol, 1,3-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol, 1,6-hexanediol, 1,2-hexanediol, and dipropylene glycol.

[0029] In one embodiment, the molar mass of each of the first and second chain extenders can be about 60-110 g / mol, wherein the molar mass of the first chain extender is less than the molar mass of the second chain extender.

[0030] In one embodiment, the first chain extender may be monoethylene glycol (MEG). In one embodiment, the second chain extender may be diethylene glycol (DEG).

[0031] In one embodiment, the sum of the OH equivalents of the first chain extender and the second chain extender may account for more than 85% of the total stoichiometric OH equivalent (excluding water) of component B.

[0032] In one embodiment, one or more adhesion promoters may be independently selected from phosphoric acid or derivatives thereof, acid-functional polyesters, polyester alkylammonium salts, acid-functional acrylics, epoxy resins, siloxanes, and silanes.

[0033] In one embodiment, one or more adhesion promoters may be independently selected from acid-functional polyesters and polyester alkylammonium salts.

[0034] In one embodiment, one of the one or more adhesion promoters may be a polyester alkylammonium salt with an acid value of about 10-50 mg KOH / g and an amine value of about 10-50 mg KOH / g.

[0035] In one embodiment, one or more adhesion promoters may consist of a first adhesion promoter and a second adhesion promoter different from the first adhesion promoter.

[0036] In one embodiment, the first adhesion promoter may be a polyester alkylammonium salt with an acid value of about 10-50 mg KOH / g and an amine value of about 10-50 mg KOH / g, and the second adhesion promoter may be an acid-functionalized polyester.

[0037] In one embodiment, based on the total weight of component B, the first adhesion promoter may be present in component B in an amount of about 1-6 wt%, and the second adhesion promoter may be present in component B in an amount of about 1-6 wt%.

[0038] In one embodiment, the polyol may be present in component B in an amount of about 65-90 wt%, based on the total weight of component B.

[0039] In one embodiment, the first chain extender may be present in component B in an amount of about 5-15 wt%, based on the total weight of component B.

[0040] In one embodiment, the second chain extender may be present in component B in an amount of about 4-10 wt%, based on the total weight of component B.

[0041] In one embodiment, components A and B are present in the reaction system in a certain amount, such that when components A and B are mixed, the isocyanate index is about 75-150.

[0042] In one embodiment, the tensile strength of the polyurethane-based elastomer foam at 23°C can be at least about 3.0 MPa. In one embodiment, the % elongation at break of the polyurethane-based elastomer foam at 23°C can be at least about 50%. In one embodiment, the modulus of the polyurethane-based elastomer foam at 23°C (measured at a strain rate of 12 mm / min and determined in a strain interval of 0.1-2%) can be at least about 30 MPa.

[0043] In one embodiment, the storage modulus (MPa) of the polyurethane-based elastomer foam at -35°C / the storage modulus (MPa) at 100°C can be about 10-150.

[0044] In one embodiment, the tanδ of the polyurethane-based elastomer foam can be less than about 0.5 in a temperature range of -60°C to 200°C.

[0045] In a second aspect, a method for producing polyurethane-based elastomer foam is provided, the method comprising: mixing component A with component B as defined in the reaction system described herein to form a reactive mixture; and curing the reactive mixture to form a polyurethane-based elastomer foam.

[0046] In a third aspect, polyurethane-based elastomer foams that can be obtained by the methods for producing polyurethane-based elastomer foams described herein are provided.

[0047] In a fourth aspect, a method for potting a battery pack comprising a plurality of cells is provided, the method comprising: mixing component A with component B as defined in the reaction system described herein to form a reactive mixture; placing the reactive mixture around the plurality of cells; and curing the reactive mixture to at least partially encapsulate the plurality of cells with a polyurethane-based elastomer foam.

[0048] In a fifth aspect, a potted battery pack is provided that can be obtained by the potting battery pack method described herein.

[0049] In the sixth aspect, the use of the reaction system or polyurethane-based elastomer foam as defined herein is provided for at least partially encapsulating multiple cells within a battery pack with polyurethane-based elastomer foam.

[0050] The above embodiments should not be construed as limiting or otherwise narrowing the scope of any other inventive concepts provided herein. While several embodiments have been disclosed, other embodiments will become apparent to those skilled in the art from the following description. Therefore, this description should be considered descriptive rather than restrictive. Detailed Implementation

[0051] This invention relates to a reaction system for producing polyurethane-based elastomer foams, the reaction system comprising: component A) an isocyanate component containing a rigid block prepolymer; and component B) an isocyanate reactive component comprising: a polyol; a first chain extender and a second chain extender different from the first chain extender, wherein the first and second chain extenders are each aliphatic diols having 2-6 carbon atoms; one or more adhesion promoters; a blowing agent; an optional surfactant; and an optional catalyst. Thus, the reaction system comprises two separate components (component A and component B) that are only mixed when a reactive mixture is formed.

[0052] The reaction system is used to produce polyurethane-based elastomer foam, which is particularly suitable as a battery encapsulation material for electric vehicles. This is because the mechanical (including tensile) and chemical properties of the polyurethane-based elastomer foam obtained through the reaction system are ideally suited for use as a battery encapsulation material. Specifically, the polyurethane-based elastomer foam has an excellent balance of tensile properties (such as tensile strength, modulus, and elongation at break), and therefore effectively protects the encapsulated battery cells even under the harsh conditions exposed to electric vehicles, such as large temperature gradients, mechanical shock, vibration, and humidity. Furthermore, the polyurethane-based elastomer foam has excellent adhesive and cohesive properties, thus allowing the foam to adhere fully to the surface of the battery cell.

[0053] [Component A]

[0054] Component A is an isocyanate component comprising a hard block prepolymer. In the context of this invention, "hard block prepolymer" refers to a prepolymer formed by the reaction of an isocyanate composition with one or more isocyanate reactive compounds with a molar mass less than 500 g / mol. When forming the prepolymer, an isocyanate reactive compound with a molar mass greater than 500 g / mol may be additionally used, provided that the weight ratio of one or more isocyanate reactive compounds with a molar mass less than 500 g / mol to that with a molar mass greater than 500 g / mol is 90:10 or less, such as 95:5 or 99:1. Preferably, no additional isocyanate reactive compound with a molar mass greater than 500 g / mol is used when forming the hard block prepolymer. The hard block prepolymer is isocyanate-terminated. "Hard block" refers to the properties imparted to the obtained polyurethane-based elastomer foam by the prepolymer, because the prepolymer provides rigid segments to the foam.

[0055] The one or more isocyanate reactive compounds used to prepare the hard block prepolymer, with a molar mass of less than 500 g / mol, can be a single compound or a mixture of different compounds. Each isocyanate reactive compound has at least two active hydrogen atoms in its molecule and is capable of reacting with the isocyanate compound. The one or more isocyanate reactive compounds may each have a molar mass of less than 400 g / mol, less than 300 g / mol, or less than 200 g / mol. The low molar mass of the one or more isocyanate reactive compounds indicates the attainment of a hard block prepolymer.

[0056] The isocyanate reactive compound with a molar mass less than 500 g / mol can be any isocyanate reactive compound known in the prior art suitable for use in this invention. The isocyanate reactive compound can be a chain extender or a mixture of chain extenders. One or more isocyanate reactive compounds preferably contain at least two, preferably three, chain extenders. The isocyanate reactive compound can be any one or more selected from: polyols such as ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, methylpentanediol, 1,6-hexanediol, dipropylene glycol, and tripropylene glycol.

[0057] The isocyanate composition for preparing hard block prepolymers may comprise a single polyisocyanate compound or a mixture of different polyisocyanate compounds. The isocyanate composition may comprise any polyisocyanate compound known in the art suitable for use in this invention. Polyisocyanate compounds typically have the structure R-(NCO). x Where x is at least 2 and R is an aromatic group, an alicyclic group, an aliphatic group, or a combination thereof. The polyisocyanate compound may include any one or more selected from: hexamethylene diisocyanate, isophorone diisocyanate, methylene dicyclohexyl diisocyanate, cyclohexane diisocyanate, toluene diisocyanate (TDI), naphthalene diisocyanate, tetramethylxylene diisocyanate, phenylene diisocyanate, toluidine diisocyanate, and diphenylmethane diisocyanate (also known as methylene diphenyl diisocyanate, MDI). Any isomer of the said polyisocyanate compound may be used. For example, when referring to MDI, at least isomers 2,4 are indicated. -MDI, 4,4 -MDI or combinations thereof. The isocyanate composition preferably includes MDI and / or its derivatives, and the isocyanate composition more preferably includes 4,4 -MDI and 2,4 -MDI. Hard block prepolymers are preferably MDI-based prepolymers.

[0058] Other components, such as stabilizers, can be present in hard block prepolymers. For example, modified MDI (such as urea-ketimine modified MDI) can be added to the prepolymer to improve its liquid stability.

[0059] Commercially available hard block prepolymer compounds suitable for use in this invention include those sold by Huntsman Corporation under the trade names SUPRASEC® and RUBINATE®. A particularly preferred hard block prepolymer for use in this invention is SUPRASEC® 2021.

[0060] Methods for preparing hard block prepolymers are known in the art. The relative amounts of the isocyanate composition and the isocyanate reactive compound depend on their equivalent weights and the desired NCO%, which can be readily determined by those skilled in the art.

[0061] The NCO% of hard block prepolymers can be about 15-30%, or about 17-28%, or about 19-27%, or about 20-26%, or about 21-25%. As used herein, NCO% refers to the isocyanate content and can be calculated according to ISO 14896:2009.

[0062] The average functionality of hard block prepolymers can be about 1.7–2.3, or about 1.8–2.2, or about 1.9–2.1. As used herein, “average functionality” refers to the number-average functionality commonly used in the art. The average functionality of isocyanate compounds or compositions refers to the average number of NCO groups per molecule. Similarly, the average functionality of polyol compounds or compositions refers to the average number of OH groups per molecule.

[0063] In a preferred embodiment, the hard block prepolymer is formed by a reaction between substances including MDI, preferably 4,4 -MDI and 2,4 - An isocyanate composition of a mixture of MDI; and at least two chain extenders, each with a molar mass of less than 500 g / mol, optionally wherein the NCO% of the hard block prepolymer may be about 20-26%, and the average functionality of the hard block prepolymer may be about 1.8-2.2.

[0064] The isocyanate component may contain only the hard block prepolymer, or it may contain additional isocyanate compounds. In one embodiment, the isocyanate component also contains a polyisocyanate compound that is different from the hard block prepolymer.

[0065] The polyisocyanate compound can be a polymerized isocyanate compound, and is preferably a polymerized MDI. Commercially available polymeric MDI compounds suitable for use in this invention are those sold by Huntsman Corporation under the trade names SUPRASEC® and RUBINATE®. A particularly preferred polymeric MDI for use in this invention is SUPRASEC® 5025.

[0066] The NCO% of polyisocyanate compounds can be about 25-40%, or about 26-38%, or about 26-37%, or about 26-36%, or about 27-35%, or about 28-34%, or about 29-33%.

[0067] The average functionality of polyisocyanate compounds can be about 2.4-3.0, about 2.5-2.9, or about 2.6-2.8.

[0068] In a preferred embodiment, the polyisocyanate compound is polymerized MDI, wherein the polymerized MDI has an NCO% of about 28-34% and an average functionality of about 2.5-2.9.

[0069] In the isocyanate component, the weight ratio of the hard block prepolymer to the polyisocyanate compound (when present) can be 65:35 to 95:5, 70:30 to 90:10, or 75:25 to 85:15. This weight ratio imparts excellent mechanical properties to the elastomeric foam.

[0070] The viscosity of the isocyanate component at 25°C can be approximately 400-1600 mPa·s, or approximately 500-1500 mPa·s, or approximately 600-1400 mPa·s. Viscosity can be measured at 25°C using a Brookfield DV-II viscometer.

[0071] The average functionality of the isocyanate component can be about 1.8-2.4, or about 1.9-2.3, or about 1.9-2.2.

[0072] Component A and component B can exist in a certain amount in the reaction system, so that when component A and component B are mixed, the isocyanate index is about 75-150, or about 80-140, or about 85-140, or about 90-130, or about 95-125, or about 95-120, or about 95-115.

[0073] As used in this article, the isocyanate index refers to the ratio of isocyanate groups (NCO groups) to reactive hydrogen atoms of isocyanates present in a composition or formulation:

[0074] ([NCO] / [Active Hydrogen]) 100

[0075] In other words, the isocyanate index expresses the percentage of isocyanate used in the composition relative to the amount of isocyanate theoretically required to react with the amount of reactive hydrogen of the isocyanate used in the composition. It should be noted that the isocyanate index used herein is considered from the perspective of the actual polymerization process for preparing materials comprising both isocyanate components and isocyanate reactive components. In calculating the isocyanate index, any isocyanate groups consumed in the initial steps of preparing modified polyisocyanates (including isocyanate derivatives referred to in the art as prepolymers) or any active hydrogen consumed in the initial steps (e.g., those reacting with isocyanates to produce modified polyols or polyamines) are not considered. Only free isocyanate groups and free isocyanate reactive hydrogen (including, if applied, those from water) present in the actual polymerization stage are considered.

[0076] [Component B]

[0077] Component B is an isocyanate reactive component comprising: a polyol; a first chain extender and a second chain extender different from the first chain extender, wherein the first and second chain extenders are each aliphatic diols having 2-6 carbon atoms; one or more adhesion promoters; a foaming agent; an optional surfactant; and an optional catalyst.

[0078] [Polyols]

[0079] The isocyanate reactive component comprises a polyol. Based on the total weight of component B, the amount of polyol present in component B can be about 50-90 wt%. Preferably, based on the total weight of component B, the amount of polyol present in component B can be about 55-90 wt%, about 60-90 wt%, about 60-85 wt%, or about 65-85 wt%.

[0080] The polyol may be selected from polyether polyols (referred to herein as "polyether polyols") having at least two hydroxyl groups, polyester polyols, or polyether-polyester polyols. Polyether polyols are preferred.

[0081] Polyether polyols can be prepared by adding an epoxide to an initiator, wherein each molecule of the initiator may contain 2-8 active hydrogen atoms. In some embodiments, the initiator may include diols, glycerol, trimethylolpropane, triethanolamine, pentaerythritol, sorbitol, sucrose, ethylenediamine, ethanolamine, diethanolamine, aniline, toluenediamine (e.g., 2,4 and 2,6 toluenediamine), polymethylene polyphenylene polyamine, N-alkylphenylene diamine, o-chloroaniline, p-aminoaniline, diaminonaphthalene, or combinations thereof. Suitable epoxides that can be used to prepare polyether polyols include ethylene oxide (EO), propylene oxide (PO), butane oxide, or combinations thereof. In a preferred embodiment, glycerol is used as the initiator in the preparation of the polyol, and EO and PO are used as the epoxides.

[0082] When the epoxide used to form the polyether polyol is EO and / or PO, the polyether polyol may contain PO, EO, or a combination of PO and EO groups or portions in its polymeric structure. These PO and EO units are randomly arranged throughout the polymeric structure or arranged as block portions. In some embodiments, the EO content of the polyol may be 0-100 wt% (e.g., 5-20 wt%) based on the total weight of the polyol. In some embodiments, the PO content of the polyol may be 100-0 wt% (e.g., 95-80 wt%) based on the total weight of the polyol. Therefore, in some embodiments, the EO content of the polyol may be 5-20 wt%, while the PO content may be 80-95 wt%. Additionally, in some embodiments, the EO and / or PO units may be located at the ends of the polyol's polymeric structure or within the internal regions of the polyol's polymeric backbone structure. Suitable polyether polyols include poly(oxyethylene-oxypropylene) glycols and triols obtained by sequentially adding PO and EO to di- or trifunctional initiators known in the art.

[0083] The commercially available polyether polyols suitable for use in this invention are those sold by Huntsman Corporation under the trade name DALTOCEL®. A particularly preferred polyether polyol for use in this invention is DALTOCEL® F499.

[0084] Other suitable polyols that can be used in this invention include Mannich polyols with a nominal hydroxyl functionality of at least 2 and each molecule having at least one secondary or tertiary amine nitrogen atom. In some embodiments, the Mannich polyol is a condensation of an aromatic compound, an aldehyde, and an alkanolamine. For example, Mannich condensates can be generated by condensing phenol and / or alkylphenol with formaldehyde and one or more of monoethanolamine, diethanolamine, and diisopropanolamine. In some embodiments, the Mannich condensate comprises the reaction product of phenol or nonylphenol with formaldehyde and diethanolamine. The Mannich condensates of this invention can be prepared by any known method. In some embodiments, the Mannich condensate is used as an initiator for alkoxylation. Any epoxide (e.g., those mentioned above) can be used to alkoxylate one or more Mannich condensates. When polymerization is complete, the Mannich polyol contains primary and / or secondary hydroxyl groups bonded to an aliphatic carbon atom.

[0085] The weight-average molecular weight of polyols can be approximately 1000-7500 g / mol, or approximately 2000-7000 g / mol, or approximately 3000-6500 g / mol, or approximately 3500-6000 g / mol, or approximately 4000-6000 g / mol, or approximately 4500-5500 g / mol, or approximately 4700-5300 g / mol. The weight-average molecular weight used in this article was measured by gel permeation chromatography (GPC).

[0086] The hydroxyl value of polyols can be approximately 10-180 mg KOH / g, or approximately 10-150 mg KOH / g, or approximately 10-125 mg KOH / g, or approximately 10-100 mg KOH / g, or approximately 15-90 mg KOH / g, or approximately 20-80 mg KOH / g, or approximately 20-70 mg KOH / g, or approximately 20-60 mg KOH / g, or approximately 20-50 mg KOH / g. The hydroxyl value of polyols can be measured using ASTM-D4274-21.

[0087] The average functionality of polyols can be about 2.0-3.0, or about 2.1-2.9, or about 2.2-2.8, or about 2.3-2.7, or about 2.4-2.6.

[0088] The purpose of polyols is to impart flexibility to polyurethane-based elastomer foams, which is necessary to prevent cracking and / or breakage. Flexibility is also needed to impart toughness to the foam.

[0089] In a preferred embodiment, the polyol is a polyether polyol with a weight-average molecular weight of about 4000-6000 g / mol, a hydroxyl value of about 20-50 mg KOH / g, and an average functionality of about 2.0-3.0.

[0090] Other polyols may be present in component B. Component B may contain only one type of polyol, such as the polyether polyol mentioned above.

[0091] [Chain Growth Agent]

[0092] Component B contains a first chain extender and a second chain extender, which is different from the first chain extender. The chain extender reacts with the isocyanate component to form rigid segments in the polyurethane-based elastomer foam. The purpose of the chain extender is to impart stiffness and tensile strength to the foam.

[0093] The first and second chain extenders are each aliphatic diols having 2-6 carbon atoms. Preferably, the first and second chain extenders are each aliphatic diols having 2-5 carbon atoms, more preferably having 2-4 carbon atoms.

[0094] In one embodiment, the molar mass of each of the first and second chain extenders is about 60-200 g / mol, or about 60-150 g / mol, or about 60-140 g / mol, or about 60-130 g / mol, or about 60-120 g / mol, or about 60-110 g / mol. Preferably, the molar mass of the first chain extender is less than the molar mass of the second chain extender.

[0095] In one embodiment, the first and second chain extenders are each straight-chain aliphatic diols, and preferably independently selected from any of the following: monoethylene glycol (MEG), diethylene glycol (DEG), 1,3-propanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, 3-chloro-1,2-propanediol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol, 2-ethyl-1,4-butanediol, 1,5-pentanediol, 1,3-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol, 1,6-hexanediol, 1,2-hexanediol, and dipropylene glycol.

[0096] In a preferred embodiment, the first chain extender is monoethylene glycol (MEG), and / or the second chain extender is diethylene glycol (DEG). In a particularly preferred embodiment, the first chain extender is monoethylene glycol (MEG) and the second chain extender is diethylene glycol (DEG).

[0097] In one embodiment, the sum of the OH equivalents of the first chain extender and the second chain extender accounts for more than 85%, or more than 87%, or more than 89% of the total stoichiometric OH equivalent (excluding water) of component B.

[0098] In one embodiment, the first chain extender is present in component B in an amount of about 3-17 wt%, or 4-16 wt%, or 5-15 wt%, or 6-14 wt%, or 7-13 wt%, or 8-12 wt%, or 9-11 wt%, based on the total weight of component B.

[0099] In one embodiment, the second chain extender is present in component B in an amount of about 2-12 wt%, or 3-11 wt%, or 4-10 wt%, or 5-9 wt%, or 6-8 wt%, based on the total weight of component B.

[0100] In one embodiment, in component B, the weight ratio of the first chain extender to the second chain extender is 10:2 to 10:9, or 10:5 to 10:9, or 10:6 to 10:8.

[0101] In a preferred embodiment, the first chain extender is MEG and the second chain extender is DEG, wherein the first chain extender is present in component B at an amount of about 5-15 wt% and the second chain extender is present in component B at an amount of about 4-10 wt% based on the total weight of component B.

[0102] Adhesion accelerator

[0103] Component B contains one or more adhesion promoters. Adding adhesion promoters to component B is more advantageous than primering foam / cells or other objects to be encapsulated because it reduces the likelihood of improper primer deposition and / or eliminates the need for additional steps (i.e., primer steps).

[0104] The role of adhesion promoters is to improve the adhesion of polyurethane-based elastomer foam to the battery cell or other objects it wraps or encapsulates.

[0105] The inventors have surprisingly discovered that the reactive mixture described herein exhibits excellent mechanical properties and excellent adhesion to battery cells when used as a battery potting material in electric vehicles, making the foam particularly suitable for use as a battery potting material.

[0106] Component B may contain one, two, three, four, or five adhesion promoters. Preferably, component B includes two different adhesion promoters.

[0107] Any adhesion promoter known in the art can be used in this invention, particularly any known adhesion promoter that bonds well to nickel-plated steel can be used for battery potting. Examples of suitable adhesion promoters include, but are not limited to, phosphoric acid or derivatives thereof, acid-functionalized polyesters, polyester alkylammonium salts, acid-functionalized acrylics, epoxy resins, siloxanes, and silanes. Adhesion promoters are preferably selected from polyester alkylammonium salts and acid-functionalized polyesters. Preferably, the polyester alkylammonium salt has an acid value of about 10-50 mg KOH / g or about 20-40 mg KOH / g, and an amine value of about 10-50 mg KOH / g or about 20-40 mg KOH / g. The amine value can be determined according to ASTM D 2074-07, and the acid value can be determined according to ASTM D 7253-16. Commercially available adhesion promoters particularly useful in this invention include BYK-4509 (a polyester alkylammonium salt available from BYK) and TEGO® Addbond LP 1611 (an acid-functionalized polyester available from Evonik).

[0108] In a preferred embodiment, component B comprises a first adhesion promoter and a second adhesion promoter, wherein the first adhesion promoter is a polyester alkylammonium salt with an acid value of about 10-50 mg KOH / g and an amine value of about 10-50 mg KOH / g; and the second adhesion promoter is an acid-functionalized polyester. One or more adhesion promoters may consist of a first adhesion promoter and a second adhesion promoter different from the first adhesion promoter.

[0109] In one embodiment, based on the total weight of component B, the total amount of one or more adhesion promoters present in component B is about 1-15 wt%, or 1-12 wt%, or 1-10 wt%, or 2-8 wt%.

[0110] In one embodiment, when only one adhesion promoter is present in component B, the amount of the adhesion promoter in component B is about 1-6 wt%, or 1-5 wt%, or 2-4 wt%, based on the total weight of component B. In another embodiment, when only two adhesion promoters (a first adhesion promoter and a second adhesion promoter) are present in component B, the amount of the first adhesion promoter in component B is about 1-6 wt%, or 1-5 wt%, or 2-4 wt%, and the amount of the second adhesion promoter in component B is about 1-6 wt%, or 1-5 wt%, or 2-4 wt%, based on the total weight of component B. These amounts of adhesion promoters ensure good adhesive performance without significantly adversely affecting the mechanical properties of the foam.

[0111] [Foaming Agent]

[0112] Component B contains a foaming agent. One or more foaming agents may be present.

[0113] Both physical and chemical foaming agents are applicable to this invention.

[0114] Any physical blowing agent known in the art can be used as a blowing agent. For example, suitable blowing agent compounds include hydrocarbons, hydrochlorofluorocarbons, hydrofluorocarbons, hydrohaloolefins, or combinations thereof.

[0115] Examples of applicable hydrocarbon blowing agents include lower aliphatic or cyclic, straight-chain or branched hydrocarbons (e.g., alkanes, alkenes and cycloalkanes, preferably those having 4-8 carbon atoms). Specific examples of suitable blowing agent compounds include n-butane, isobutane, 2,3-dimethylbutane, cyclobutane, n-pentane, isopentane, industrial-grade pentane mixtures, cyclopentane, methylcyclopentane, neopentane, n-hexane, isohexane, n-heptane, isoheptane, cyclohexane, methylcyclohexane, 1-pentene, 2-methylbutene, 3-methylbutene, 1-hexene, or combinations thereof.

[0116] Suitable examples of hydrochlorofluorocarbons include 1-chloro-1,2-difluoroethane, 1-chloro-2,2-difluoroethane, 1-chloro-1,1-difluoroethane, 1,1-dichloro-1-fluoroethane, monochlorodifluoromethane, or combinations thereof.

[0117] Suitable examples of hydrofluorocarbons include 1,1,1,2-tetrafluoroethane (HFC 134a), 1,1,2,2-tetrafluoroethane, trifluoromethane, heptafluoropropane, 1,1,1-trifluoroethane, 1,1,2-trifluoroethane, 1,1,1,2,2-pentafluoropropane, 1,1,1,3-tetrafluoropropane, 1,1,1,3,3-pentafluoropropane (HFC 245fa), 1,1,3,3,3-pentafluoropropane, 1,1,1,3,3-pentafluoro-n-butane (HFC 365mfc), 1,1,1,4,4,4-hexafluoro-n-butane, 1,1,1,2,3,3,3-heptafluoropropane (HFC 227ea) or combinations thereof.

[0118] Suitable examples of hydrohalogenated olefins include trans-1-chloro-3,3,3-fluoropropene (HFO 1233zd), trans-1,3,3,3-tetrafluoropropene (HFO 1234ze), cis- and trans-1,1,1,4,4,4-hexafluoro-2-butene (HFO 1336mzz), or combinations thereof.

[0119] Chemical blowing agents, such as water, monocarboxylic acids (e.g., formic acid), and polycarboxylic acids, can also be used as the sole blowing agent. Alternatively, these chemical blowing agents can be combined with the aforementioned physical blowing agents as co-blowing agents.

[0120] In a preferred embodiment, the blowing agent is water. Water reacts with isocyanate to form gaseous CO2, thereby imparting a polyurethane foam structure.

[0121] In one embodiment, based on the total weight of component B, the amount of foaming agent present in component B is less than about 1 wt%, or about 0.1-0.9 wt%, or about 0.1-0.8 wt%, or about 0.1-0.7 wt%, or about 0.1-0.6 wt%, or about 0.1-0.5 wt%.

[0122] [Additives in component B]

[0123] The application of surfactants in component B helps control the cell structure of the final foam product. Therefore, component B may contain surfactants. Component B may contain two or more surfactants. Any surfactant known in the art can be used in component B. Suitable surfactants include silicone surfactants and non-silicone surfactants. In a preferred embodiment, the surfactant comprises one or two silicone surfactants. Suitable silicone surfactants include polyether polydimethylsiloxane copolymers. Commercially available silicone surfactants suitable for this invention include TEGOSTAB® B 1048 (available from Evonik) and VORASURF® DC198 (available from DOWChemical Co.).

[0124] In one embodiment, the surfactant is present in component B in an amount less than about 2 wt%, or about 0.1-2 wt%, or about 0.5-1.9 wt%, or about 0.5-1.8 wt%, or about 0.5-1.7 wt%, or about 0.5-1.6 wt%, or about 0.5-1.5 wt%, based on the total weight of component B.

[0125] To improve the curing of the reactive mixture formed when components A and B are mixed, component B may contain a catalyst. Preferably, a catalyst with delayed action is included. This allows the reactive mixture to fill the battery pack and effectively encapsulate the cells before curing. Suitable catalysts include blocked tertiary amine catalysts (such as DABCO® 8154 available from Evonik), blocked formic acid catalysts (such as JEFFCAT® ZF-54 available from Huntsman Corporation), and tertiary amine foaming catalysts (such as POLYCAT® SA 5 available from Evonik). One or more catalysts may be applied to component B.

[0126] In one embodiment, the catalyst is present in component B in an amount less than about 1 wt%, or about 0.1-0.9 wt%, or about 0.1-0.8 wt%, or about 0.1-0.7 wt%, or about 0.1-0.6 wt%, or about 0.1-0.5 wt%, based on the total weight of component B.

[0127] Other additives, such as antioxidants, crosslinking agents, or pigments, may be present in component B.

[0128] The following are some exemplary reaction systems of the present invention.

[0129] In one embodiment, the reaction system for producing polyurethane-based elastomer foam comprises: component A) an isocyanate component containing a rigid block prepolymer, wherein the rigid block prepolymer is formed by the reaction between an isocyanate composition containing MDI and one or more isocyanate reactive compounds with a molar mass of less than 500 g / mol; and component B) an isocyanate reactive component comprising: a polyether polyol; a first chain extender and a second chain extender different from the first chain extender, wherein the first and second chain extenders are each aliphatic diols having 2-6 carbon atoms; one or more adhesion promoters; a foaming agent; an optional surfactant; and an optional catalyst.

[0130] In one embodiment, the reaction system for producing polyurethane-based elastomer foam comprises: component A) an isocyanate component containing a rigid block prepolymer, wherein the rigid block prepolymer is formed by the reaction between an isocyanate composition containing MDI and one or more isocyanate reactive compounds with a molar mass of less than 500 g / mol; and component B) an isocyanate reactive component comprising: a polyether polyol; a first chain extender and a second chain extender different from the first chain extender, wherein the first and second chain extenders are each aliphatic diols having 2-6 carbon atoms; one or more adhesion promoters, wherein the one or more adhesion promoters are independently selected from acid-functional polyesters and polyester alkylammonium salts; a blowing agent; an optional surfactant; and an optional catalyst.

[0131] In one embodiment, the reaction system for producing polyurethane-based elastomer foam comprises: component A) an isocyanate component containing a rigid block prepolymer, wherein the rigid block prepolymer is formed by the reaction of an isocyanate composition containing MDI and one or more isocyanate reactive compounds with a molar mass of less than 500 g / mol; and component B) an isocyanate reactive component comprising: a polyether polyol; a first chain extender and a second chain extender different from the first chain extender, wherein the first and second chain extenders are each aliphatic diols having 2-6 carbon atoms; a first adhesion promoter and a second adhesion promoter different from the first adhesion promoter, wherein the first adhesion promoter is a polyester alkylammonium salt with an acid value of about 10-50 mg KOH / g and an amine value of about 10-50 mg KOH / g, and the second adhesion promoter is an acid-functionalized polyester; a blowing agent; an optional surfactant; and an optional catalyst.

[0132] In one embodiment, the reaction system for producing polyurethane-based elastomer foam comprises: component A) an isocyanate component containing a rigid block prepolymer, wherein the rigid block prepolymer is formed by the reaction of an isocyanate composition containing MDI and one or more isocyanate reactive compounds with a molar mass of less than 500 g / mol; and component B) an isocyanate reactive component comprising: a polyether polyol; a first chain extender and a second chain extender different from the first chain extender, wherein the first and second chain extenders are each aliphatic diols having 2-6 carbon atoms; a first adhesion promoter and a second adhesion promoter different from the first adhesion promoter, wherein the first adhesion promoter is a polyester alkylammonium salt with an acid value of about 10-50 mg KOH / g and an amine value of about 10-50 mg KOH / g, and the second adhesion promoter is an acid-functionalized polyester, wherein the first adhesion promoter is present in component B in an amount of about 1-6 wt% and the second adhesion promoter is present in component B in an amount of about 1-6 wt% based on the total weight of component B; a blowing agent; an optional surfactant; and an optional catalyst.

[0133] In one embodiment, the reaction system for producing polyurethane-based elastomer foam comprises: component A) an isocyanate component containing a rigid block prepolymer and polymeric MDI, wherein the rigid block prepolymer is formed by the reaction between an MDI-containing isocyanate composition and one or more isocyanate reactive compounds with a molar mass less than 500 g / mol; and component B) an isocyanate reactive component comprising: a polyether polyol; a first chain extender and a second chain extender different from the first chain extender, wherein the first and second chain extenders are each aliphatic diols having 2-6 carbon atoms; one or more adhesion promoters; a foaming agent; an optional surfactant; and an optional catalyst.

[0134] In one embodiment, the reaction system for producing polyurethane-based elastomer foam comprises: component A) an isocyanate component containing a rigid block prepolymer, wherein the rigid block prepolymer is formed by the reaction between an isocyanate composition containing MDI and one or more isocyanate reactive compounds with a molar mass of less than 500 g / mol; and component B) an isocyanate reactive component comprising: a polyether polyol; a first chain extender (which is MEG) and a second chain extender (which is DEG); one or more adhesion promoters; a blowing agent; an optional surfactant; and an optional catalyst.

[0135] In one embodiment, the reaction system for producing polyurethane-based elastomer foam comprises: component A) an isocyanate component containing a rigid block prepolymer, wherein the rigid block prepolymer is formed by the reaction of an isocyanate composition containing MDI and at least two isocyanate reactive compounds with a molar mass of less than about 500 g / mol; and component B) an isocyanate reactive component comprising: a polyether polyol with a weight-average molecular weight of about 1000-7500 g / mol; a first chain extender (which is MEG) and a second chain extender (which is DEG); one or more adhesion promoters; a blowing agent; an optional surfactant; and an optional catalyst.

[0136] In one embodiment, a reaction system for producing a polyurethane-based elastomer foam having a tensile strength of at least about 3.0 MPa at 23°C, an elongation at break of at least about 50% at 23°C, and a modulus (12 mm / min, 0.1-2% strain) of at least about 30 MPa at 23°C comprises: component A) an isocyanate component containing a rigid block prepolymer; and component B) an isocyanate reactive component comprising: a polyol; a first chain extender and a second chain extender different from the first chain extender, wherein the first and second chain extenders are each aliphatic diols having 2-6 carbon atoms; one or more adhesion promoters; a blowing agent; an optional surfactant; and an optional catalyst.

[0137] [Methods for producing polyurethane-based elastomer foam]

[0138] The present invention provides a method for producing polyurethane-based elastomer foam, the method comprising: mixing component A and component B as defined in the reaction system to form a reactive mixture; and curing the reactive mixture to form a polyurethane-based elastomer foam.

[0139] Methods for mixing component A and component B are known in the art and include mechanical mixing.

[0140] The method may further include placing the reactive mixture into a mold and then curing the mixture. If a mold is used, the polyurethane-based elastomer foam formed by curing the reactive mixture can then be demolded.

[0141] To aid curing, the reactive mixture can be heated to temperatures above room temperature, such as approximately 30-100°C, 30-50°C, or 35-45°C. Alternatively, if the reactive mixture is to be cured in a mold, the mold can be preheated to approximately 30-100°C, 30-50°C, or 35-45°C. However, it is not necessary to heat the reactive mixture to cure it.

[0142] [Polyurethane-based elastomer foam]

[0143] The above reaction system can be used to obtain polyurethane-based elastomer foam in the above method.

[0144] The tensile properties of the polyurethane-based elastomer foam prepared according to the present invention are the reason why the foam is particularly suitable as a battery potting material (especially in electric vehicles).

[0145] In one embodiment, the polyurethane-based elastomer foam has a tensile strength of at least about 2.0 MPa, or at least about 2.5 MPa, or at least about 3.0 MPa, or at least about 3.1 MPa, or at least about 3.2 MPa, or about 3.0–10 MPa, or about 3.0–5.0 MPa, or about 3.1–5.0 MPa, or about 3.2–5.0 MPa at 23°C. Tensile strength refers to the maximum tensile stress that a test sample can withstand during a tensile test. Tensile strength primarily measures the foam's resistance to tensile forces. Therefore, higher tensile strength is generally beneficial for battery potting materials in electric vehicles.

[0146] In one embodiment, the polyurethane-based elastomer foam has a % elongation at break of at 23°C of at least about 40%, or at least about 45%, or at least about 50%, or at least about 55%, or at least about 60%, or about 50-90%, or about 55-90%, or about 60-90%. Elongation at break primarily measures the flexibility of the foam, which is related to its resistance to fracture or cracking under stress. Therefore, a higher elongation at break is generally beneficial for battery potting materials in electric vehicles.

[0147] The tensile strength and elongation at break of polyurethane-based elastomer foams were measured according to ISO 1798:2008 using Class 1A samples and a test speed of 12 mm / min. That is, the travel speed of the electric clamp specified in the test standard has been adjusted to 12 mm / min.

[0148] In one embodiment, the modulus (12 mm / min, 0.1-2% strain) of the polyurethane-based elastomer foam at 23°C is at least about 20 MPa, or at least about 25 MPa, or at least about 30 MPa, or at least about 32 MPa, or at least about 34 MPa, or at least about 36 MPa, or at least about 38 MPa, or at least about 40 MPa, or about 30-80 MPa, or about 35-80 MPa, or about 40-80 MPa. The term "(12 mm / min, 0.1-2% strain)" refers to the modulus measured at a strain rate of 12 mm / min over a 0.1-2% strain interval. Modulus, also known as Young's modulus, is a measure of elasticity. Generally, a higher modulus is beneficial for battery potting materials in electric vehicles.

[0149] Modulus refers to the ratio of the stress difference to the corresponding strain difference at 0.1% and 2% strain. Stress is the ratio of the measured force to the initial cross-sectional area of ​​the tensile specimen. Strain is measured using a tensile tester (clamp-on or video tensile tester) that records the length change of the constant cross-sectional portion at the center of the tensile specimen during the gauge mark test. Strain is the ratio of the measured length between gauge marks to the initial length between these gauge marks (at the start of the test).

[0150] In a preferred embodiment, the polyurethane-based elastomer foam has a tensile strength of at least about 3 MPa at 23°C, an elongation at break of at least about 50% at 23°C, and a modulus (12 mm / min, 0.1-2% strain) of at least about 30 MPa at 23°C. Polyurethane-based elastomer foams with this combination of tensile properties are excellent battery potting materials. This is because the foam possesses high strength, high strain capacity, and sufficient rigidity, thus protecting the encapsulated battery cells from the harsh conditions experienced in electric vehicles, such as severe vibration, mechanical shock, and extreme temperatures. The inventors have surprisingly discovered that the above-described combination of tensile properties can be obtained by preparing polyurethane-based elastomer foams using the reactive mixtures described herein.

[0151] In one embodiment, the storage modulus (MPa) of the polyurethane-based elastomer foam at -35°C / the storage modulus (MPa) at 100°C is about 10-150, or about 20-100, or about 20-75, or about 30-60, or about 40-50. Surprisingly, the polyurethane-based elastomer foam of the present invention has a storage modulus of about 10-150 at both -35°C and 100°C, as this indicates that its mechanical properties (including tensile properties) are very stable over a wide temperature range.

[0152] In one embodiment, the polyurethane-based elastomer foam has a tanδ of less than about 0.5, or less than about 0.4, or less than about 0.35 over a temperature range of -60°C to 200°C. tanδ is the ratio of loss modulus to storage modulus. It is essentially a measure of the energy dissipation of the foam.

[0153] The storage modulus and tanδ of the foam were measured using a TA Q800 DMA machine with a double cantilever clamp via dynamic mechanical analysis (DMA). The sample dimensions were 80 mm long, approximately 10 mm wide, and approximately 5 mm thick. The measurement amplitude was 5 µm, and the frequency was 1 Hz. The sample was scanned at a rate of 3 °C / min over a temperature range of -60 °C to 200 °C.

[0154] In one embodiment, the density of the polyurethane-based elastomer foam is at least about 200 kg / m³. 3 or at least about 300 kg / m 3 or at least about 350 kg / m 3 or at least approximately 380 kg / m 3 or at least about 400 kg / m 3 or approximately 200-1000 kg / m 3 or approximately 300-800 kg / m 3 or approximately 350-600 kg / m 3 or approximately 350-500 kg / m 3 .

[0155] The reactive mixtures disclosed herein can form polyurethane-based elastomer foams with the aforementioned tensile properties.

[0156] [A potting method for a battery pack containing multiple cells and a potted battery pack]

[0157] The present invention provides a method for encapsulating a battery pack comprising multiple battery cells, the method comprising: mixing component A and component B as defined in the reaction system described herein to form a reactive mixture; placing the reactive mixture around the multiple battery cells; and curing the reactive mixture to at least partially encapsulate the multiple battery cells with a polyurethane-based elastomer foam.

[0158] A battery pack contains multiple cells that can be configured in various ways. For electric vehicles, for example, it is important to protect the multiple cells in the battery pack by applying a potting material. Here, the battery potting material is a polyurethane-based elastomer foam.

[0159] The reactive mixture can be placed around multiple cells using any method known in the art to obtain a potted battery pack, and the method will not be discussed in detail here.

[0160] Polyurethane-based elastomer foams can completely or substantially completely encapsulate multiple battery cells.

[0161] The curing process can be aided by heating the reactive mixture or preheating the mold inside the battery pack to a temperature of, for example, about 30-50°C.

[0162] The encapsulated battery pack can be obtained using the methods described above.

[0163] [Applications of reaction systems or polyurethane-based elastomer foams in battery potting]

[0164] This invention also provides the use of the reaction system described herein or the polyurethane-based elastomer foam described herein for at least partially encapsulating multiple battery cells within a battery pack. The polyurethane-based elastomer foam can completely or substantially completely encapsulate multiple battery cells.

[0165] Example

[0166] The present invention will now be described in more detail with reference to the embodiments. The present invention is not limited to the following embodiments.

[0167] Example 1

[0168] Components A and B are formed as shown in the table below:

[0169]

[0170] SUPRASEC® 2021 is a hard block prepolymer with an NCO% of 23.2 and an average functionality of 2.0.

[0171] SUPRASEC® 5025 is a polymeric MDI with an NCO% of 31.0 and an average functionality of 2.7.

[0172]

[0173] DALTOCEL® F499 is a polyether polyol (based on glycerol, EO and PO) with a hydroxyl value of 35 mg KOH / g, a molecular weight of approximately 5000 and a functionality of 2.5.

[0174] TEGOSTAB® B 1048 and VORASURF® DC198 are silicone surfactants.

[0175] JEFFCAT® ZF-54 is a closed-type formic acid foaming catalyst.

[0176] POLYCAT®SA 5 is a tertiary amine gel catalyst.

[0177] MEG and DEG are chain extenders.

[0178] Water is the foaming agent.

[0179] BYK-4509 is an adhesion promoter.

[0180] Components A and B are then mixed in a 1:1 weight ratio and placed into a preheated mold (at 40°C) to obtain a polyurethane-based elastomer foam (density 400 kg / m³). 3 The tensile properties of the resulting foam at 23°C are as follows:

[0181]

[0182] Tensile strength and elongation at break were measured as described above according to ISO 1798:2008. Modulus was measured as described above.

[0183] The above results demonstrate that the resulting foam and the reaction system are excellent choices for battery potting materials (especially in electric vehicles) due to their high tensile strength, high elongation at break, and high modulus. Furthermore, the foam exhibits excellent adhesion to its contact surfaces due to the addition of an adhesion promoter, and surprisingly, the addition of the adhesion promoter does not significantly affect the tensile properties of the foam.

[0184] Example 2

[0185] Components A and B are formed as shown in the table below:

[0186]

[0187] SUPRASEC® 2021 is a hard block prepolymer with an NCO% of 23.2 and an average functionality of 2.0.

[0188] SUPRASEC® 5025 is a polymeric MDI with an NCO% of 31.0 and an average functionality of 2.7.

[0189]

[0190] DALTOCEL® F499 is a polyether polyol (based on glycerol, EO and PO) with a hydroxyl value of 35 mg KOH / g, a molecular weight of approximately 5000 and a functionality of 2.5.

[0191] TEGOSTAB® B 1048, TEGOSTAB® B 8745 LF2, and VORASURF® DC198 are silicone surfactants.

[0192] JEFFCAT® ZF-54 is a closed-type formic acid foaming catalyst.

[0193] POLYCAT®SA 5 is a tertiary amine gel catalyst.

[0194] MEG and DEG are chain extenders.

[0195] Water is the foaming agent.

[0196] BYK-4509 is an adhesion promoter.

[0197] TEGO® Addbond LP 1611 is an adhesion promoter.

[0198] Components A and B are then mixed in a 1:1 weight ratio and placed into a preheated mold (at 40°C) to obtain a polyurethane-based elastomer foam (density 400 kg / m³). 3 The tensile properties of the resulting foam at 23°C are as follows:

[0199]

[0200] Tensile strength and elongation at break were measured as described above according to ISO 1798:2008. Modulus was measured as described above.

[0201] The above results demonstrate that the resulting foam and the reaction system are excellent choices for battery potting materials, especially in electric vehicles, due to their high tensile strength, high elongation at break, and high modulus.

[0202] Furthermore, due to the addition of two different adhesion promoters, the foam exhibits excellent adhesion properties, and surprisingly, the addition of both adhesion promoters did not significantly affect the tensile properties of the foam. In Example 2, when adhered to a nickel surface, the foam exhibited complete cohesive failure and maintained excellent adhesion properties even after aging for 10 days in a humid environment at 40°C and 100% relative humidity, meaning that the adhesion properties of the foam are ideal for battery potting.

[0203] The inventors were surprised to find that the reaction system disclosed herein can yield polyurethane-based elastomer foams with an ideal performance balance for use as battery potting materials (especially in electric vehicles).

[0204] All ranges described herein are exemplary in nature and include any and all values ​​therein. The terms “substantially,” “about,” and “approximately” used herein are interchangeable and refer to a measurement value including the stated measurement value as well as any measurement value reasonably close to the stated measurement value. A measurement value reasonably close to the stated measurement value deviates from the stated measurement value by a reasonably small amount, as understood and readily determined by one of ordinary skill in the art. Such deviation may be due to measurement error, differences in the scale of measuring and / or manufacturing equipment, human error in reading and / or setting the measurement value, fine-tuning of performance and / or structural parameters to take into account measurement differences related to other components, specific implementation scenarios, and imprecise adjustments and / or manipulations of the object by humans or machines. If it is determined that the value of such a reasonably small deviation is not readily determined by one of ordinary skill in the art, the terms “about” and “approximately” may be understood as plus or minus 10% of the stated value.

[0205] Throughout the specification and claims, unless the context clearly indicates otherwise, the terms have the meanings explicitly defined herein.

[0206] The terms "in one embodiment," "in one embodiment," and "in some embodiments" used herein do not necessarily refer to the same embodiment, although they may refer to the same embodiment. Similarly, the terms "in another embodiment" and "in some other embodiments" used herein do not necessarily refer to different embodiments, although they may refer to different embodiments. All embodiments of this invention are combinable.

[0207] The terms “comprising” and “including” mean, but are not limited to, other features that may be present. These terms may also mean “consisting of” or “substantially composed of”.

[0208] All references and test methods cited in this article are incorporated herein by reference in their entirety.

Claims

1. A reaction system for producing polyurethane-based elastomer foam, said reaction system comprising: Component A) Isocyanate component containing hard block prepolymer; and Component B) Isocyanate reactive component, which includes: Polyols; A first chain extender and a second chain extender different from the first chain extender, wherein each of the first and second chain extenders is an aliphatic diol having 2-6 carbon atoms; One or more adhesion promoters; Foaming agent; Optional surfactants; and Optional catalyst.

2. The reaction system of claim 1, wherein the hard block prepolymer is formed by the reaction of an isocyanate composition with one or more isocyanate reactive compounds with a molar mass of less than 500 g / mol.

3. The reaction system according to claim 1 or 2, wherein the hard block prepolymer is an MDI-based prepolymer.

4. The reaction system according to claim 1 or 2, wherein the NCO% of the hard block prepolymer is about 15-30%.

5. The reaction system according to any one of the preceding claims, wherein the average functionality of the hard block prepolymer is about 1.7-2.

3.

6. The reaction system according to any one of the preceding claims, wherein the isocyanate component further comprises a polyisocyanate compound different from the hard block prepolymer.

7. The reaction system of claim 6, wherein the polyisocyanate compound is polymerized MDI.

8. The reaction system of claim 6 or 7, wherein the NCO% of the polyisocyanate compound is about 25-40%.

9. The reaction system according to any one of claims 6-8, wherein the average functionality of the polyisocyanate compound is about 2.4-3.

0.

10. The reaction system according to any one of claims 6-9, wherein the weight ratio of the hard block prepolymer to the polyisocyanate compound in the isocyanate component is from 70:30 to 90:

10.

11. The reaction system according to any one of the preceding claims, wherein the polyol is a polyether polyol.

12. The reaction system according to any one of the preceding claims, wherein the hydroxyl value of the polyol is about 10-180 mgKOH / g.

13. The reaction system according to any one of the preceding claims, wherein the weight-average molecular weight of the polyol is about 1000-7500 g / mol.

14. The reaction system according to any one of the preceding claims, wherein the average functionality of the polyol is about 2.0-3.

0.

15. The reaction system according to any one of the preceding claims, wherein the first and second chain extenders are each straight-chain aliphatic diols, and preferably independently selected from any one of monoethylene glycol (MEG), diethylene glycol (DEG), 1,3-propanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, 3-chloro-1,2-propanediol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol, 2-ethyl-1,4-butanediol, 1,5-pentanediol, 1,3-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentanediol, 1,6-hexanediol, 1,2-hexanediol, and dipropylene glycol.

16. The reaction system according to any one of the preceding claims, wherein the first chain extender is monoethylene glycol (MEG), and / or wherein the second chain extender is diethylene glycol (DEG).

17. The reaction system according to any one of the preceding claims, wherein the one or more adhesion promoters are independently selected from phosphoric acid or derivatives thereof, acid-functional polyesters, polyester alkylammonium salts, acid-functional acrylic acids, epoxy resins, siloxanes and silanes.

18. The reaction system according to any one of the preceding claims, wherein the one or more adhesion promoters are independently selected from acid-functional polyesters and polyester alkylammonium salts.

19. The reaction system according to any one of the preceding claims, wherein the one or more adhesion promoters are polyester alkylammonium salts with an acid value of about 10-50 mg KOH / g and an amine value of about 10-50 mg KOH / g.

20. The reaction system according to any one of the preceding claims, wherein the one or more adhesion promoters comprises a first adhesion promoter and a second adhesion promoter different from the first adhesion promoter.

21. The reaction system of claim 20, wherein the first adhesion promoter is a polyester alkylammonium salt with an acid value of about 10-50 mg KOH / g and an amine value of about 10-50 mg KOH / g, and the second adhesion promoter is an acid-functionalized polyester.

22. The reaction system of claim 20 or 21, wherein, based on the total weight of component B, the first adhesion promoter is present in component B in an amount of about 1-6 wt%, and the second adhesion promoter is present in component B in an amount of about 1-6 wt%.

23. The reaction system according to any one of the preceding claims, wherein the polyurethane-based elastomer foam has a tensile strength of at least about 3.0 MPa at 23°C.

24. The reaction system according to any one of the preceding claims, wherein the polyurethane-based elastomer foam has a % elongation at break of at least about 50% at 23°C.

25. The reaction system according to any one of the preceding claims, wherein the modulus of the polyurethane-based elastomer foam at 23°C (12 mm / min, 0.1-2% strain) is at least about 30 MPa.

26. A method for producing polyurethane-based elastomer foam, the method comprising: As defined in the reaction system of any one of claims 1-25, component A is mixed with component B to form a reactive mixture; and The reactive mixture is cured to form a polyurethane-based elastomer foam.

27. A polyurethane-based elastomer foam that can be obtained by the method defined in claim 26.

28. A method for potting a battery pack comprising multiple cells, the method comprising: As defined in the reaction system of any one of claims 1-25, component A is mixed with component B to form a reactive mixture; The reactive mixture is placed around the plurality of battery cells; and The reactive mixture is cured to at least partially encapsulate the plurality of battery cells with a polyurethane-based elastomer foam.

29. A potted battery pack that can be obtained by the method defined in claim 28.

30. Use of the reaction system as defined in any one of claims 1-25 or the polyurethane-based elastomer foam as defined in claim 27 for at least partially encapsulating a plurality of cells within a battery pack using the polyurethane-based elastomer foam.

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