Low viscosity polyurethane potting agent composition

Abstract

In some embodiments, a polyurethane composition may include the reaction product of: an isocyanate component including one or more isocyanate compounds; and an isocyanate reactive component comprising: one or more polyether polyols, one or more aliphatic polyols; and one or more hollow particles present in at least one of the isocyanate component, the isocyanate reactive component, or the third component. In some embodiments, a method can include preparing the polyurethane composition by combining the isocyanate component and the isocyanate reactive component to form a mixture; and reacting the mixture to form the polyurethane composition. In one embodiment, a method may include preparing a composite article including disposing a polyurethane composition on a substrate and curing the composition to produce the composite article including the polyurethane article on the substrate.

Description

Technical Field

[0001] Embodiments relate to low viscosity polyurethane compositions, methods of making the same, and applications utilizing the same. Background Art

[0002] Electric vehicles (EVs) operate using battery packs, and the individual battery cells are arranged in different patterns along with cooling mechanism related components and other nearby parts. The battery geometry and form can be cylindrical, rectangular / prismatic and / or pouch-shaped. In order to connect these battery cells together with the surrounding components, materials similar to potting agents can be used with different chemistries, including silicones, polyurethanes, etc. The main purpose of the potting agent and / or encapsulant in the battery is to provide isolation between the battery cells during use (minimizing the impact of thermal events, including cascading damage between adjacent battery cells), and in some cases, to enhance the strength of the battery assembly so that it can withstand stress and deformation as a structural element of the vehicle. In some applications, polyurethane-based foams are also used as potting agents to reduce weight, thereby improving efficiency and handling. However, there is usually a trade-off with the durability and heat resistance of such materials. Summary of the Invention

[0003] In one aspect, embodiments disclosed herein include a polyurethane composition comprising the reaction product of an isocyanate component comprising one or more isocyanate compounds; and an isocyanate-reactive component comprising: one or more polyether polyols, one or more aliphatic polyols; and one or more hollow particles present in at least one of the isocyanate component, the isocyanate-reactive component, or a third component.

[0004] In another aspect, embodiments disclosed herein include preparing a polyurethane composition by combining an isocyanate component and an isocyanate-reactive component to form a mixture; and reacting the mixture to form the polyurethane composition. The method may also include preparing a composite article, comprising disposing the polyurethane composition on a substrate and curing the composition to produce a composite article comprising the polyurethane article on the substrate. DETAILED DESCRIPTION

[0005] Embodiments relate to polyurethane (PU) compositions for potting agents and electronic materials that have low viscosity to increase flow and penetration during application and reduce expansion or foaming. The PU compositions can also produce high-strength, low-density, and low-thermal-conductivity materials upon curing. Specifically, the developed PU applications can exhibit reduced density without the need for incorporation of chemical or physical blowing agents. Methods disclosed herein also include preparing and applying the PU compositions, particularly as potting agents, encapsulants, or thermal barriers in electronic devices and / or automotive applications.

[0006] The PU compositions disclosed herein generally comprise a product obtained by combining a two-component curable composition: an isocyanate component ("A-side") and an isocyanate-reactive component ("B-side"). During application, the isocyanate and isocyanate-reactive components are mixed, initiating a curing reaction and forming a polyurethane article or material. The PU composition may also include one or more hollow particles added to the isocyanate and / or isocyanate-reactive component (or as a third component added during mixing) to reduce the overall composition density and modify various mechanical properties.

[0007] The polyurethane compositions disclosed herein may include an isocyanate component containing one or more isocyanate compounds, such as polymeric isocyanates, aromatic isocyanates, or carbodiimide-modified isocyanates. The isocyanate compound may be a monomer, an oligomer, a prepolymer, or the like. The isocyanate component may include, for example, one or more isocyanate and / or polyisocyanate compounds. The isocyanate component may include an isocyanate compound having a nominal functionality greater than 1.5, greater than 2.0, or in the range of 1.5 to 4. The polyurethane composition may include, by weight percentage (wt %), an isocyanate component in the range of 15 wt % to 80 wt %, 20 wt % to 80 wt %, or 25 wt % to 80 wt %.

[0008] The isocyanate component can include an isocyanate compound with a number-average molecular weight of 150 g / mol to 750 g / mol. In some cases, the number-average molecular weight of the isocyanate compound can be a low value of 150 g / mol, 200 g / mol, 250 g / mol or 300 g / mol to a high value of 350 g / mol, 400 g / mol, 450 g / mol, 500 g / mol or 750 g / mol. The number-average molecular weight values ​​reported herein are determined by end group analysis, gel permeation chromatography and additives known in the art. The isocyanate compound can be monomeric and / or polymeric, as known in the art.

[0009] In some cases, the isocyanate component can include an isocyanate compound having an isocyanate content of 10 wt % or more, 20 wt % or more, or 30 wt % or more, or within a range of 10 wt % to 50 wt %.

[0010] The isocyanate component may include one or more of aliphatic polyisocyanates, alicyclic polyisocyanates, araliphatic polyisocyanates, aromatic polyisocyanates, etc. Examples of isocyanates include, but are not limited to, polymethylene polyphenyl isocyanate; toluene 2,4- / 2,6-diisocyanate (TDI); methylene diphenyl diisocyanate (MDI, including isomers thereof); polymeric and prepolymeric MDI; triisocyanatononane (TIN); naphthyl diisocyanate (NDI); 4,4'-diisocyanatodicyclohexyl-methane; 3-isocyanatomethyl-3,3,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate, IPDI); tetramethylene diisocyanate; hexamethylene diisocyanate (HDI); ); 2-methyl-pentamethylene diisocyanate; 2,2,4-trimethylhexamethylene diisocyanate (THDI); dodecamethylene diisocyanate; 1,4-diisocyanatocyclohexane; 4,4'-diisocyanato-3,3'-dimethyl-dicyclohexylmethane; 4,4'-diisocyanato-2,2-dicyclohexylpropane; 3-isocyanatomethyl-1-methyl-1-isocyanatocyclohexane (MCI); 1,3-diisooctylcyano-4-methylcyclohexane; 1,3-diisocyanato-2-methylcyclohexane; and combinations thereof. In addition to the isocyanates mentioned above, modified or partially modified polyisocyanates including uretdione, isocyanurate, carbodiimide, uretonimine, allophanate or biuret structures and combinations thereof may be utilized. For example, the isocyanate compound may include carbodiimide-modified MDI.

[0011] The isocyanate component may include isocyanate prepolymers obtained by reacting an isocyanate-reactive compound with a molar excess of a polyisocyanate compound or a polymeric isocyanate compound under conditions that do not result in gelation or curing, and these isocyanate prepolymers may have a relatively high average isocyanate equivalent weight of >400 g / eq. The formation of isocyanate prepolymers is known in the art and may include reacting (1) at least one isocyanate compound and (2) at least one polyol compound. The isocyanate prepolymer may be described by an isocyanate index, which is defined as the ratio of isocyanate groups to isocyanate-reactive groups (such as OH groups) multiplied by 100. The isocyanate prepolymers disclosed herein may have an isocyanate index in the range of 30 to 400, 40 to 300, or 40 to 200, which is defined as the equivalent weight of isocyanate divided by the total equivalent weight of isocyanate-reactive hydrogen-containing materials, multiplied by 100.

[0012] Examples of commercial isocyanates include, but are not limited to, VORANATE TM 、PAPI TM 、VORATRON TM 、VORAFORCE TM and ISONATETM Polyisocyanates of the invention are available from The Dow Chemical Company.

[0013] The isocyanate-reactive component may include a polyol blend comprising one or more polyether polyols, polyester polyols, aliphatic polyols, a polyol crosslinker, and hollow particles, as well as other additives such as catalysts, surfactants, etc. The polyurethane composition may include, by weight percentage (wt%), an isocyanate-reactive component in an amount ranging from 20 wt% to 85 wt%, from 20 wt% to 80 wt%, or from 25 wt% to 80 wt%.

[0014] Isocyanate reactive components may include one or more polyether glycols, which are prepared by adding an alkylene oxide such as propylene oxide and / or ethylene oxide to a polyhydroxy-functional starting compound in the presence of a catalyst known in the art. Polyether glycols may be prepared by a starting compound and one or more alkylene oxides (e.g., ethylene oxide, propylene oxide, and / or butylene oxide). Starting compounds may include, but are not limited to, molecules having 1 to 8 hydroxyl groups per molecule, such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, 1,4-butylene glycol, 1,6-hexanediol, triethanolamine, diethanolamine, diisopropanolamine, bisphenol A, glycerol, diglycerol, triglycerol, trimethylolpropane, di(trimethylolpropane), pentaerythritol, dipentaerythritol, tripentaerythritol, sugars and sugar alcohols such as sucrose and sorbitol, etc. It should be understood that for the purposes of the present invention only, the polyether polyol may also be a blend of any of these polyether polyols with one or more starting compounds, and the polyether polyol may also be one or more starting compounds themselves. The polyether polyol may also include polyols reacted with polyethers formed from copolymers of alkylene oxides, including block copolymers and polyethers "capped" with hydroxyethyl and / or hydroxypropyl oligomers or polymers.

[0015] The polyether polyols may have a hydroxyl functionality ranging from 1 to 8 or from 1.5 to 7. The polyether polyols may have a hydroxyl equivalent weight, defined as the weight average molecular weight of the polyol divided by the average number of hydroxyl groups of the molecules, or the average hydroxyl functionality, ranging from 30 Da to 4000 Da or from 30 Da to 3000 Da.

[0016] The isocyanate-reactive component can include at least one polyether polyol present in a weight percent (wt %) of 40 wt % to 95 wt %, 45 wt % to 95 wt %, or 50 wt % to 90 wt %.

[0017] The isocyanate-reactive component may include one or more polyester polyols produced by the reaction of one or more carboxylic acid diacids with a polyol having an OH functionality of 2 to 4. Suitable carboxylic acids may include aromatic diacids or anhydrides such as phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, methyl esters of phthalic acid, isophthalic acid, or terephthalic acid, dimethyl terephthalate, trimellitic anhydride, pyromellitic dianhydride, or mixtures thereof; and C4 to C12 aliphatic diacids. Suitable polyols for forming polyesters include one or more alkylene glycols or polyalkylene glycols having a hydroxyl functionality of 2 to 4, such as ethylene glycol, 1,2- or 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, glycerol, and the like. Examples of polyester polyols include polyesters of phthalic anhydride and diethylene glycol, and polyesters of C4 to C12 diacids (such as succinic acid or adipic acid) and diethylene glycol.

[0018] The polyester polyol may have an average hydroxyl number (OH value) in the range of 100 mg KOH / g to 500 mg KOH / g, 150 mg KOH / g to 450 mg KOH / g, or 200 mg KOH / g to 450 mg KOH / g as determined according to ASTM D4274-21. The isocyanate-reactive component may include one or more polyester polyols in an amount, by weight percentage (wt%), in the range of 10 wt% to 40 wt%, 15 wt% to 35 wt%, or 15 wt% to 30 wt%.

[0019] The isocyanate reactive component can comprise one or more aliphatic polyols with at least two reactive hydroxyl groups.Aliphatic polyols comprise natural and synthetic polyester polyol derivatives, comprise the product generated by the reaction of polyols with one or more hydroxy fatty acids having 10 to 20 carbon atoms, the hydroxy fatty acids comprising hydroxydecanoic acid, hydroxylauric acid, hydroxymyristic acid, hydroxypalmitic acid, hydroxyheptadecanoic acid, hydroxystearic acid, hydroxyeicosanoic acid, ricinoleic acid etc.For example, aliphatic polyols comprise triglycerides containing a part of hydroxy fatty acids, such as castor oil or its derivatives, and / or the polyols made from natural oils such as soybean oil, cashew nut shell liquid (i.e. CNSL) of epoxidation or hydroformylation.Aliphatic polyols can have a hydroxyl equivalent in the range of 30Da to 2500Da or 30Da to 2000Da.

[0020] The isocyanate-reactive component may include, by weight percentage (wt %), 2 wt % to 25 wt %, 5 wt % to 25 wt %, or 5 wt % to 20 wt % of one or more aliphatic polyols.

[0021] The isocyanate-reactive component may include one or more polyol crosslinking agents having a hydroxyl functionality of at least 3 and a weight average molecular weight of 800 g / mol or less. Suitable polyol crosslinking agents may include glycerol, diglycerol, triglycerol, trimethylolpropane, di(trimethylolpropane), pentaerythritol, dipentaerythritol, tripentaerythritol, sorbitol, derivatives such as alkoxylates, or combinations thereof.

[0022] The isocyanate-reactive component may include, by weight percentage (wt %), 1 wt % to 15 wt %, 1 wt % to 10 wt %, or 1 wt % to 5 wt % of one or more polyol crosslinkers.

[0023] The isocyanate reactive component may include one or more silicone polyols (e.g., diols, triols, polyols) having at least two reactive hydroxyl groups. The silicone polyol may include siloxane linkages (Si-O-Si) within its backbone and, in some cases, may also include divalent alkyl groups separating the siloxane units. The silicone polyol may have the general formula HO-R 1 -Si(R 2 )2-[O-Si(R 2 )2] n -R 1 -OH, where each R 1 is independently a linking group having 0 to 18 carbon atoms; each R 2 is independently a group having 2 to 18 carbon atoms, such as an alkyl or hydroxyalkyl group; and wherein n is 10 to 20.

[0024] The isocyanate-reactive component may include one or more silicone polyols in an amount by weight (wt %) ranging from 10 wt % to 40 wt %, from 15 wt % to 35 wt %, or from 15 wt % to 30 wt %.

[0025] The isocyanate reactive component may include one or more catalysts for enhancing polyurethane polymerization to generate a PU composition. The catalyst may be used alone or as a catalyst package comprising a variety of catalysts, such as a gelling catalyst, a foaming catalyst, and a trimerization catalyst. Gelling and foaming catalysts may be distinguished by their tendency to favor urethane (gelling) reactions in the case of a gelling catalyst or to favor urea (foaming) reactions in the case of a foaming catalyst. Trimerization catalysts may be used to promote the isocyanate formation reaction in the composition. The catalyst package may also be added to the reaction mixture of isocyanate and isocyanate reactive composition as a separate stream.

[0026] Gelling catalysts include organometallic compounds, cyclic tertiary amines and / or long chain amines (e.g., containing several nitrogen atoms) and combinations thereof. Organometallic compounds include organotin compounds such as tin (II) salts of organic carboxylic acids, for example, tin (II) diacetate, tin (II) dioctoate, tin (II) diethylhexanoate, and tin (II) dilaurate, and dialkyltin (IV) salts of organic carboxylic acids, for example, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate, and dioctyltin diacetate. Bismuth salts of organic carboxylic acids may also be used as gelling catalysts, such as bismuth octoate. Cyclic tertiary amines and / or long chain amines include dimethylbenzylamine, triethylenediamine, and combinations thereof. Examples of commercially available gelling catalysts are Evonik® from Evonik. 8. 33-LV and T-12, and other commercially available gelling catalysts.

[0027] The blowing catalyst may include bis-(2-dimethylaminoethyl) ether, pentamethyldiethylenetriamine, triethylamine, tributylamine, N,N-dimethylaminopropylamine, dimethylethanolamine, N,N,N',N'-tetramethylethylenediamine, and combinations thereof. Examples of commercially available blowing catalysts are available from Evonik 5, and other commercially available blowing catalysts.

[0028] The trimerization catalyst may include any such catalyst known in the art. Examples of trimerization catalysts include N,N',N"-tris(3-dimethylaminopropyl)hexahydro-s-triazine; N,N-dimethylcyclohexylamine; 1,3,5-tris(N,N-dimethylaminopropyl)-s-hexahydrotriazine; [2,4,6-tris(dimethylaminomethyl)phenol]; potassium acetate, potassium octoate; tetraalkylammonium hydroxides such as tetramethylammonium hydroxide; alkali metal hydroxides such as sodium hydroxide; alkali metal alkoxides such as sodium methoxide and potassium isopropoxide; and alkali metal salts of long chain fatty acids having from 10 to 20 carbon atoms, and combinations thereof, and the like. Some commercially available trimerization catalysts include, for example, each from Evonik Corporation TMR-2 TMR-20, TMR-30, TMR-7, K 2097; KI 5, 41 and 46, and other commercially available trimerization catalysts.

[0029] The catalyst may include a "latent catalyst" or "delayed catalyst," which is defined as a catalyst compound having low catalytic activity or being relatively inactive at ambient temperature and which becomes more catalytically active upon heating, for example, by dissociation, decoordination, ring opening, ionization, or tautomerism, to achieve catalysis of at least one of the chemical reactions involved in making the PU foam. The ambient temperature may be in the range of 15° C. to 35° C., with room temperature typically being about 23° C.

[0030] In terms of their function in the foaming process, latent / delayed catalysts can be gelling, foaming and / or trimerization type catalysts. Latent catalysts are generally a subgroup of tertiary amine gelling catalysts (e.g., delayed action tertiary amines based on 1,8-diazabicyclo[5.4.0]undec-7-ene), which include acid salts, phenolates or complexes of tertiary amine catalysts, wherein the acid or phenol is generally a carboxylic acid or phenolic material, but is not limited to, such as formic acid, acetic acid, propionic acid, 2-ethylhexanoic acid, phenoxyacetic acid, gluconic acid, tartaric acid, citric acid, phenol, nonylphenol, diisopropylphenol, etc.; and mixtures thereof. Some commercially available latent catalysts include, for example, phenols from Evonik TMR-30, SA2LE, SA-1 / 10 and 8154; NIAX from Momentive TM A-107, NIAX TM C-31 and NIAX TM C-225; and JEFFCAT from Huntsman Corporation TM ZF-54, JEFFCAT TM LED-204; and mixtures thereof.

[0031] The catalyst or catalyst package may be present in the PU composition in a weight percent (wt %) ranging from 0.1 wt % to 10 wt %, or from 1 wt % to 7 wt %. In some cases, the catalyst package may be added to the isocyanate-reactive component in an amount sufficient to provide a mixture having the above-recited corresponding weight percents.

[0032] The polyurethane composition may include one or more hollow particles, which can modify physical properties, introduce void volume, and reduce overall density. Hollow particles and mixtures can be added to one or more of the isocyanate component and / or the isocyanate-reactive component, or added as a third component during the combination of the isocyanate component and the isocyanate-reactive component. In some cases, hollow particles can be added to multiple components to enhance viscosity matching and promote uniform mixing.

[0033] The hollow particles may include hollow shell particles or porous aerogels composed of glass, ceramic, silica, etc. The hollow particles may have different shapes and geometries, such as spherical, hemispherical, tubular, elongated, rectangular, elliptical, etc. The hollow particles may have a density in the range of 0.05 g / mL to 0.8 g / mL or 0.10 g / mL to 0.6 g / mL.

[0034] In some cases, the surface of the hollow particles can be modified to mediate interactions between the particles and the surrounding matrix and / or polymer phase, such as by adjusting the hydrophobicity or hydrophilicity. Surface modification can include covalent and ionic attachment chemistries to attach functional groups such as alkyl chains, siloxanes, hydroxyl groups, amines, thiols, isocyanates, epoxies, acrylates, aromatic compounds, etc. For example, surface modification can include the use of silane chemistries, including organosilanes, such as those having the formula: R (4-n) Si(OR 2 ) n , wherein R is an alkyl group or a substituted alkyl group having 1 to 20 carbon atoms (for example, substituted with the above-mentioned functional groups), and n is an integer from 2 to 4. Examples of organosilanes include dimethoxydimethylsilane, dimethoxydiethylsilane, diethoxydimethylsilane; trimethoxymethylsilane, trimethoxyethylsilane, trimethoxypropylsilane, triethoxymethylsilane, triethoxyethylsilane, aminopropyltriethoxysilane, (3-glycidoxypropyl)trimethoxysilane, methacryloxypropyltrimethoxysilane, and vinyltriethoxysilane.

[0035] In some cases, the hollow particles may include glass particles having a density in a range of 0.1 g / mL to 0.6 g / mL and having an organosilane (eg, epoxy silane) surface modification.

[0036] The polyurethane composition can include, by weight percentage (wt %), one or more hollow particles in a range of 0.5 wt % to 90 wt %, 1 wt % to 85 wt %, or 1 wt % to 70 wt %.

[0037] The polyurethane composition may contain one or more flame retardants (also referred to as FR or FR additives) to improve flame retardancy. Suitable flame retardants may specifically include, for example, carbon black, hydrated aluminum hydroxide and silicates such as wollastonite, platinum and platinum compounds, carbonates such as calcium carbonate, red phosphorus, sodium citrate, etc. Alternatively, the flame retardant may be at least one of halogen-based flame retardants such as decabromodiphenyl ether, octabromodiphenyl ether, hexabromocyclododecane, decabromodiphenyl ether, diphenoxybenzene, ethylenebis-tetrabromophthalimide, pentabromoethylbenzene, pentabromobenzyl acrylate, tribromophenylmaleimide, tetrabromobisphenol A, bis-(tribromophenoxy)ethane, bis-(pentabromophenoxy)ethane, polydibromophenyl ether, tribromophenyl allyl ether, bis-dibromopropyl ether, tetrabromophthalic anhydride, dibromoneopentyl glycol, dibromoethyldibromocyclohexane, pentabromodiphenyl ether, tribromostyrene, pentabromochlorocyclohexane, tetrabromoxylene, hexabromocyclododecane, brominated polystyrene, tetradecabromodiphenoxybenzene, trifluoropropylene, and PVC. Alternatively, the flame retardant may be at least one of a phosphorus-based flame retardant such as (2,3-dibromopropyl)-phosphate, phosphorus, cyclic phosphate, triaryl phosphate, bis-melamine pentate, pentaerythritol bicyclic phosphate, dimethyl methyl phosphate, phosphine oxide diol, triphenyl phosphate, tris(2-chloroethyl) phosphate, trichloropropyl phosphate, triethyl phosphate, phosphates such as tricresyl phosphate, trixyl phosphate, isodecyl diphenyl phosphate, ethylhexyl diphenyl phosphate, isopropylated triphenyl phosphate, tert-butylated triphenyl phosphate, isobutylated triphenyl phosphate, and mixtures thereof. Alternatively, phosphate salts of various amines such as ammonium polyphosphate, trioctyl phosphate, tributyl phosphate or tributoxyethyl phosphate, and alkyl phosphate oligomers. Other flame retardants can include melamine and derivatives such as melamine salts, guanidine, dicyandiamide, ammonium sulfamate, aluminum oxide trihydrate, and magnesium hydroxide. FR additives can also include copolymer polyols such as polyisocyanate polyaddition (PIPA) polyols or polyurea polyols, which are made by reacting low equivalent weight polyols (e.g., hydroxyl equivalent weight up to 80) or polyamines with polyisocyanates in the presence of a base polyol continuous phase (e.g., a homopolymer or copolymer of propylene oxide and / or ethylene oxide having a hydroxyl equivalent weight of at least 200).

[0038] The amount of flame retardant can vary depending on factors such as the flame retardant selected and the intended use of the polyurethane composition to achieve a UL-94 vertical burning performance of V2 or better, more preferably V1 or better, and most preferably V0. Flame retardants and mixtures can be added to one or more of the isocyanate component and / or the isocyanate-reactive component. The amount of flame retardant in the polyurethane composition can depend on the specific flame retardant (if any) employed and can generally range from up to 60 weight percent, or from 5 weight percent to 60 weight percent, based on the total weight of the polyurethane composition.

[0039] The PU composition can include one or more silicone or organic defoamers in an amount ranging from 0.05 wt% to 5 wt%, 0.1 wt% to 1.5 wt%, or 0.1 wt% to 1 wt% based on the weight percentage (wt%) of the polyurethane composition.

[0040] The polyurethane composition may include one or more fillers, including glass fiber, fiber, carbon fiber, silica, CaCO 3 , kaolin, talc, alumina, alumina trihydrate (ATH), and the like. The one or more fillers may be added in a weight percentage (wt %) ranging from 0 wt % to 25 wt %, or from 1 wt % to 20 wt % of the composition. In some cases, the filler may be added to the isocyanate component and / or the isocyanate-reactive component in an amount sufficient to provide a mixture having the above corresponding weight percentages.

[0041] The isocyanate-reactive component may also include one or more additives, including blowing agents, surfactants, crosslinking agents, plasticizers, smoke suppressants, fragrances, enhancers, dyes, colorants, pigments, preservatives, odor masking agents, physical blowing agents, chemical blowing agents, flame retardants, internal mold release agents, biocides, antioxidants, UV stabilizers, antistatic agents, thixotropic agents, adhesion promoters, cell openers, and the like. When reacted in the presence of an amine catalyst and an isocyanate, an additive amount of epoxy resin may also be used to increase the thermoset glass transition temperature. Examples include DER383 and DER354 from Olin Corporation.

[0042] While the formulation components have been disclosed individually, it is contemplated that any of the above concentration ranges and nested subranges therein may be utilized to include, exclude, or combine component elements (e.g., isocyanates or compounds in the isocyanate-reactive component) in any manner or subcombination.

[0043] The PU composition disclosed herein may have flame retardancy according to the UL 94 standard, with vertical burning at 5 mm being V2 or better, or V1 or better.

[0044] The PU composition can have a thermal conductivity suitable for the intended application. In some cases, such as automotive applications, the thermal conductivity can be less than or equal to 0.2 W / mK, while for other applications, the thermal conductivity can be higher, such as less than or equal to 0.5 W / mK, 0.4 W / mK, or 0.3 W / mK.

[0045] The PU composition can have a density of less than 1 g / mL, or in a range of 0.3 g / mL to 1.2 g / mL, or 0.3 g / mL to 1.0 g / mL according to ASTM D3574-17 Test A.

[0046] The PU composition may have a viscosity of less than 1500 cP at 6 seconds, less than 2500 cP at 2 minutes, and less than 3500 cP at 5 minutes upon mixing the components.

[0047] While the formulation components and properties have been disclosed individually, it is contemplated that any of the above concentration ranges and subranges nested therein may be utilized to include, exclude, or combine component elements (e.g., isocyanates or compounds in an isocyanate-reactive component) in any manner or subcombination. Furthermore, the formulation properties described may similarly be achieved by various combinations of the described components within the described ranges.

[0048] The PU composition can generally be formed by combining an isocyanate component and an isocyanate-reactive component (and optionally a third component comprising, for example, hollow particles) to form a mixture by a suitable method (e.g., static mixing, dynamic mixing, dynamic and static mixing, rapid mixing, low-pressure mixing, overhead mixing with an impeller or paint mixer, impingement mixing, etc.), and reacting the mixture to form a PU article. The PU composition can be used in any suitable method for developing articles and composites, including molding, injection, vacuum infusion, and the like. The method can include applying the PU composition to a substrate by dispensing or coating using: spin coating, brush coating; drop coating; spray coating; dip coating; roller coating; flow coating; slot coating; gravure coating; Mayer rod coating; and the like. In some cases, the method can include combining an isocyanate component and an isocyanate-reactive component to form a mixture, applying the mixture to a substrate, and reacting the mixture to form a polyurethane article or composite (e.g., a coating, encapsulant, potting agent). The PU composition can be formed by dispensing, injecting and / or spraying into and / or over one or more specific locations of a battery pack or module using suitable methods for battery pack / module assembly to achieve complete (or partial) encapsulation of the battery cells.

[0049] The method may include preparing a polyurethane composition by the following steps: combining an isocyanate component and an isocyanate-reactive component to form a mixture; and reacting the mixture to form a polyurethane composition. The composite article may be prepared by the following method: disposing the composition on a substrate and curing the composition to produce a composite article comprising a polyurethane article on the substrate. In some cases, the substrate may define at least one gap, and the arrangement may include placing the composition in the at least one gap so that the polyurethane article is present in the gap in the composite article. For example, the substrate may include a battery cell, surface or component, and the composite article may include a battery pack and / or module. However, the composition polyurethane article can be used in other end-use applications, including as a potting agent or encapsulant in end uses other than battery packs, such as for circuits, and for purposes other than potting agents and / or encapsulants.

[0050] The PU compositions disclosed herein can be used as potting agents or thermal barriers for electrical, battery pack and / or module related applications. Potting agents can coat, encapsulate (completely or partially) and / or protect electrical connections from damaging environmental influences such as heat, cold, flame, weather elements, dust (e.g., sand or dirt particles), physical shock or vibration, or other destructive factors. The amount of potting agent used can range from a minimum amount sufficient to coat and protect the electrical connections to a maximum amount sufficient to fill gaps in battery cells, junction boxes, etc. and include this maximum amount. The PU compositions can also be used in stationary energy storage applications in private and commercial environments. The PU compositions can be formulated to meet the constraints of automotive and mobile solutions (e.g., EVs), but can be modified outside of these constraints for use in other related electrical and stationary energy storage applications. For example, stationary storage applications can be formulated with higher density / weight (>1 g / mL) and higher thermal conductivity (e.g., >0.2 W / mK), where considerations of total weight and lack of external cooling are not driving factors.

[0051] Example

[0052] The following examples are provided to illustrate embodiments of the present invention and are not intended to limit the scope of the invention.Table 1 provides the materials used in the following examples.

[0053]

[0054]

[0055] Example 1: Properties of polyurethane compositions

[0056] In this example, the physical properties of samples of the present invention comprising a polyurethane composition were tested and compared to a comparative example that did not contain hollow particles. The sample formulations are shown in Table 2 (comparative) and Table 3 (inventive).

[0057] According to the formulation requirements (polyol, additives, and catalyst), all the isocyanate-reactive components from Tables 2 and 3 were weighed on an analytical balance and mixed using a DAC 600.1FVZ-K high-speed mixer until dispersed. Pre-blended batches were used within 2 hours of mixing, and if used on the day of coating, they were pre-mixed to avoid phase separation. When hollow particles were included, they were added to the isocyanate-reactive components and mixed at high speed before use in the formulation.

[0058] The corresponding isocyanate components were then added to the isocyanate reactive components in appropriate ratios, mixed at high speed, and placed in a rectangular metal mold at room temperature (20°C to 25°C). The metal mold dimensions were 19 cm long and 12.5 cm wide (2 mm thick for mechanical properties, and the 12.5 mm thick samples were further cut into 5 mm thick and 0.5 inch wide for UL-94 vertical burning tests to measure flame retardancy (FR). The cured molded plaques of the PU potting material samples were then tested to determine the mechanical properties of the potting agent.

[0059] After demoulding, measure the dimensions of the rectangular potting agent sample with a measuring instrument and weigh it on a weighing balance. Calculate the density of the sample as the weight of the sample / (length * width * height).

[0060] All potting compound samples were demolded after 30 to 60 minutes and post-cured at 60°C for 1 hour before testing for mechanical and thermal properties to ensure the cure was similar to that used in EV batteries. Some potting compound samples were observed to crack and / or shatter and / or break during demolding or during stamping of the samples into dog-bone shapes and were classified as "untestable" due to their brittle nature.

[0061]

[0062]

[0063] The sample formulations were then tested for various physical characteristics (1) to (13), as listed below. The test results for each formulation are shown in Tables 4 and 5.

[0064] UL 94 Vertical Flame Test (1): The 12.7 mm thick potting material prepared in the metal mold was then cut into 5 mm thick, 0.5 inch and ≥ 10 cm dimensions using the procedure described above. The prepared potting compound samples (potting compound only) were tested using the standard UL 94 vertical flame protocol and the performance was classified into the appropriate categories - V0 (optimum and expected performance), V1, V2, and Fail (Failure means that the potting compound sample burned all the way to the fixture during and / or after the flame exposure).

[0065] Thermal Conductivity (2): Thermal conductivity of 2 mm thick pre-cured potting compound samples was measured using a Hot Disk ABTPS2500S instrument with a Kapton insulated 5465F1 sensor, using an isotropic (standard) module at 50 mW heating power, a 5 second measurement time, and standard analysis according to ISO 22007-2. 2 mm thick potting compound plaques were prepared for testing using the procedure described above.

[0066] Density (3): Calculated as the density (i.e., weight / volume) of the cured potting agent plate sample according to ASTM D3574-17 Test A. The weight of the plate is measured in grams and the height of the plate is measured in cm. The width and thickness of the plate are 12.5 cm and 0.2 cm, respectively. The density of the potting agent sample (in g / cm 3 (unit): weight of potting agent sample*1000 / (height*12.5*0.2).

[0067] Viscosity (4-6): The fluidity of the potting material in the actual composite battery assembly was quantified using the measurement results of the polyol + isocyanate reactive viscosity on the AREG G2 from TA Instruments. A 50 mm cone-plate geometry made of stainless steel was used. The pre-blended polyol side (with or without pre-mixed bubbles according to the recipe) was placed in a high-speed mixer cup (maximum 20 cups) and the appropriate amount and type of isocyanate (according to the recipe in Table 4) was added thereto. The formulation was mixed at 2100 rpm for 8 to 10 seconds and the appropriate amount of liquid was poured (within 3 to 4 seconds after mixing was completed) onto the AREGG2 rheometer plate and the gap was set to 2 mm (wipe off the excess with a q tip) and the measurement was started as soon as possible (within 3 to 5 seconds after adding to the plate). The measurement temperature was set to 25°C + / - 2°C, the oscillation strain was 5%, and the angular frequency was 10 rad / sec. The measurement lasted for a minimum of 5 minutes. The reaction viscosities at the first data point (t=6 seconds), 2 minutes, and 5 minutes are reported in Tables 4 and 5.

[0068] Elastic modulus (7), ultimate tensile strength (8), and elongation at break (9): For the cured potting agent plate samples prepared using the procedure described above, the elastic modulus (E), elongation at break (%), and ultimate tensile strength (MPa) were obtained on an MTS machine using the ASTM D1708 standard. Microtensile samples were punched into dog-bone shapes from plates molded in 2 mm thick metal molds. "N / A" samples (C1-C2) could not be tested because they broke during cutting of the samples into 2 mm thick dog-bone shapes due to their inherent brittleness.

[0069] Shear modulus at -30°C (10), 25°C (11), 50°C (12) and 60°C (13): Shear modulus in torsion mode (Physical Features (10) to (13)) was obtained by dynamic mechanical analysis (DMA) using ASTM D5279-21 on an Advanced Rheology Extension System (ARES-G2) from TA Instruments equipped with liquid nitrogen environment control and torsion rectangular fixtures. 2 mm thick rectangular specimens were cut from potting agent plates prepared in metal molds (A and B) according to the procedure described above and cut to dimensions of 45 mm long and 12.8 mm wide. The sample length was axially aligned with the torsion axis and the DMA experiments were performed in torsion mode. The temperature was increased from -70°C to 150°C at a ramp rate of 3°C / min. The test frequency was 1 Hz, the torsional strain was 0.05%, an axial tension of 0.098 N was applied to keep the sample taut, and the data collection interval was 30 seconds / point. The output of the characterization is the storage modulus (G') in shear mode over a range of temperatures.

[0070]

[0071]

[0072]

[0073] *"Calculated" for Sample 16 means that since Isocyanate-3 was not mixed (as with all other Examples), the value was extrapolated from the viscosity-time curve measured using the rheometer (procedure described previously) and the reverse intercept was calculated accordingly.

[0074] The potting agent formulations provided in Tables 4 and 5 were prepared without chemical or physical blowing agents, so no foaming occurred. For C1 and C2, the non-foaming liquid cured into a PU elastomer, but both failed the UL 94 fire resistance (FR) test. For C3 and C6, when using a 5mm thick potting agent, providing a FR additive resulted in a V2 rating for C3 and a V0 rating for C6 in the UL 94 vertical burning test, but the thermal conductivity values ​​increased to 0.22 and 0.27, respectively. Samples C1-C3 and C6 had a density of >1g / mL and a thermal conductivity of more than 0.2W / mK. Samples C4 and C5 incorporated hollow particles, and those samples exhibited lower thermal conductivity (<0.2W / mK) and density, however, the potting agent failed in the UL-94 vertical burning test and had a high viscosity when mixed (>10,000cP and >8,000cP after 5 minutes, respectively). Therefore, C1-C6 are considered unsuitable for EV battery potting / encapsulant applications.

[0075] In contrast, the examples of the present invention combining polyols, liquid FR additives, and hollow particles achieved the desired performance parameters. For samples I1-I6, all exhibited UL-94 V0 performance, along with low viscosity values, high mechanical strength, and softening points above 60°C that meet the flow requirements for potting material applications. I1-I6 also demonstrate that isocyanate types 1, 2, and 3 can be used alone (or in combination) to achieve potting agent properties (1) to (14) with the desired properties in I1-I6.

[0076] While the foregoing is directed to illustrative embodiments, other and further embodiments may be devised without departing from the basic scope of the invention, which is defined by the claims that follow.

Claims

1. A polyurethane composition comprising the reaction product of: an isocyanate component comprising one or more isocyanate compounds; and An isocyanate-reactive component, the isocyanate-reactive component comprising: one or more polyether polyols, one or more aliphatic polyols; and One or more hollow particles are present in at least one of the isocyanate component, the isocyanate-reactive component, or a third component.

2. The composition according to claim 1, further comprising a FR additive, wherein the weight percentage of the FR additive in the composition is in the range of 5 wt% to 60 wt%.

3. The composition of claim 1, further comprising a polyol crosslinking agent.

4. The composition of any one of claims 1 to 3, wherein the polyurethane composition has a density in the range of 0.3 g / mL to 1 g / mL according to ASTM D3574-17.

5. The composition according to any one of claims 1 to 4, wherein the hollow particles are present in a weight percentage (wt%) in the range of 1 wt% to 70 wt% of the polyurethane composition.

6. The composition of any one of claims 1 to 5, wherein the polyurethane composition has a UL94 vertical burning performance of at least V2.

7. The composition according to any one of claims 1 to 6, wherein the polyurethane composition has a viscosity of less than 3500 cP 5 minutes after mixing at 25°C or higher.

8. The composition of any one of claims 1 to 7, wherein the polyurethane composition has a viscosity of less than 1500 cP 6 seconds after mixing at 25°C or higher.

9. An article or composite material prepared from the polyurethane composition according to any one of claims 1 to 8.

10. A method for preparing the polyurethane composition according to claim 1, the method comprising: combining the isocyanate component and the isocyanate-reactive component to form a mixture; as well as The mixture is reacted to form the polyurethane composition.

11. A method for preparing a composite material product, the method comprising: providing the composition according to any one of claims 1 to 8 on a substrate, and The composition is cured to produce the composite article comprising a polyurethane article on the substrate.

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