Polyurethane composition, polyurethane article, and methods of preparing polyurethane composition and composite article

Abstract

The multilayer composition may include: at least one first layer containing a thermosetting resin; and a second layer disposed on the at least one first layer and containing the following reaction products: an isocyanate component containing one or more isocyanate compounds; and an isocyanate reactive component containing: 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. The method may include preparing the multilayer composition by depositing at least one thermosetting resin layer on a substrate; and disposing a second layer on the at least one thermosetting resin layer.

Description

Technical Field

[0001] The examples relate to low-viscosity polyurethane compositions, their preparation methods, and their applications. Prior Technology

[0002] Electric vehicles (EVs) operate using battery packs, with individual batteries configured in various ways along with cooling mechanisms and other nearby components. Battery pack geometries and forms can be cylindrical, rectangular / prismatic, and / or pouch-shaped. To connect these batteries together with surrounding components, potting materials and various chemicals, including polysiloxane, polyurethane, and similar materials, can be used. The primary objective of potting and / or encapsulation materials in battery packs is to provide isolation between battery cells during use (minimizing the effects of thermal events, including cascading damage to adjacent cells) and, in some cases, to strengthen the battery pack assembly to withstand the stresses and deformations experienced when used as a structural component of a vehicle. Polyurethane-based foams are also used as potting materials in some applications to reduce weight and improve efficiency and disposal. However, a trade-off often exists between the durability and heat resistance of such materials. Summary of the Invention

[0003] In one embodiment, the embodiments disclosed herein include a multilayer composition comprising: at least one first layer containing a thermosetting resin; and a second layer disposed on the at least one first layer and containing the following reaction products: an isocyanate component containing one or more isocyanate compounds; and an isocyanate reactive component containing: 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.

[0004] In one embodiment, the embodiments disclosed herein include a method for preparing a multilayer composition, comprising depositing at least one thermosetting resin layer on a substrate; and disposing a second layer on the at least one thermosetting resin layer, the second layer containing the following reaction products: an isocyanate component containing one or more isocyanate compounds; an isocyanate reactive component containing 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. Simple Explanation of the Diagram

[0005] none Implementation

[0006] The examples relate to polyurethane (PU) compositions for potting and electronic materials that have low viscosity to increase flow and penetration during application and reduce expansion or foaming. 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 incorporation of chemical or physical foaming agents. The methods disclosed herein also include the preparation and application of PU compositions, particularly as potting or encapsulating materials or thermal barriers in electronic and / or automotive applications.

[0007] Besides being used as a single material, the PU compositions disclosed herein can be used as part of multilayer compositions with other compatible thermosetting materials. Specifically, some thermosetting materials used in potting materials and thermal management applications (e.g., battery packs) can foam or expand, resulting in variations in surface area and layer thickness due to the natural distribution of voids or phases throughout the material. Unreliable placement and lack of thickness control of foamable thermosetting materials can lead to inadequate coverage and poor performance. For example, even with FR-grade potting materials, incomplete installation of potting materials on battery pack cells can create a risk of thermal events and fires. Irregular layer coverage of functional components can also cause problems. If the potting material layer is too thick, vents and other components may not allow accumulated gas to escape, increasing the risk of explosion.

[0008] The PU composition disclosed herein is self-leveling and can be applied with consistent layer coverage and thickness without over-expansion or under-expansion issues. In some cases, the self-leveling PU composition disclosed herein can be used as a capping layer in a multilayer configuration with foamed PU to produce a leveled finished surface for thermal management applications, such as capping thermosetting potting materials dispersed between battery pack assemblies. The self-leveling composition can cap the surface of the battery pack and form a uniform layer of 0.1 to 7 mm thickness above the height of the battery pack. In one application, a first layer containing a low-density foamed potting material (e.g., 0.65 g / mL or less, or 0.5 g / mL or less) covers or encapsulates about 1% to 70% of the height of the battery pack cells, while a second layer (capping layer) containing the PU composition disclosed herein covers the remaining height of the battery pack cells, providing a uniform and level surface. This configuration allows for the incorporation of low-density / weight materials to achieve lightweighting, improved fuel economy, increased range (measured in miles or km), and enhanced thermal management properties for functionality and safety.

[0009] The PU compositions disclosed herein typically comprise products derived from a combination of two-component curable compositions: an isocyanate component (“A side”) and an isocyanate reactive component (“B side”). During application, the isocyanate and the isocyanate reactive component are mixed, initiating a curing reaction and forming a polyurethane article or material. PU compositions may also include one or more hollow particles added to the isocyanate and / or the isocyanate reactive component (or as a third component added during mixing) to reduce the overall composition density and modulate various mechanical properties.

[0010] The polyurethane compositions disclosed herein may include isocyanate components containing one or more isocyanate compounds, such as polymeric isocyanates, aromatic isocyanates, or isocyanates modified with carbodiimide. The isocyanate compounds may be monomers, oligomers, prepolymers, and the like. The isocyanate components may include, for example, one or more isocyanate and / or polyisocyanate compounds. The isocyanate components may include isocyanate compounds having a nominal functionality greater than 1.5, greater than 2.0, or in the range of 1.5 to 4. The polyurethane compositions may include isocyanate components in weight percentages (wt%) ranging from 15 wt% to 80 wt%, 20 wt% to 80 wt%, or 25 wt% to 80 wt%.

[0011] The isocyanate component may include isocyanate compounds having a number average molecular weight of 150 g / mol to 750 g / mol. In some cases, the isocyanate compound may have a number average molecular weight from a low value of 150 g / mol, 200 g / mol, 250 g / mol, or 300 g / mol to an upper 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 were determined by end-group analysis, gel permeation chromatography, and other methods known in the art. The isocyanate compound may be a monomer and / or a polymer, as known in the art.

[0012] In some cases, the isocyanate component may include an isocyanate compound having an isocyanate content of 10% or more, 20% or more, or 30% or more, or in the range of 10% to 50% by weight.

[0013] The isocyanate component may include one or more of aliphatic polyisocyanates, cycloaliphatic polyisocyanates, aryliphatic polyisocyanates, aromatic polyisocyanates, and their analogues. Examples of isocyanates include, but are not limited to, polymethylene polyphenyl isocyanate; toluene 2,4- / 2,6-diisocyanate (TDI); methylene diphenyl diisocyanate (MDI, including its isomers); polymeric and prepolymerized 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-diisocyanocyclohexane; 4,4'-diisocyano-3,3'-dimethyl-dicyclohexylmethane; 4,4'-diisocyano-2,2-dicyclohexylpropane; 3-isocyanomethyl-1-methyl-1-isocyanocyclohexane (MCI); 1,3-diisooctylcyano-4-methylcyclohexane; 1,3-diisocyano-2-methylcyclohexane; and combinations thereof. In addition to the isocyanates mentioned above, modified or partially modified polyisocyanates including urea diketone, isocyanurate, carbodiimide, urea-imide, ureocarbamate, or biuret structures, and combinations thereof, can be used. For example, isocyanate compounds may include MDI modified with carbodiimide.

[0014] Isocyanate compounds may include isocyanate prepolymers produced by reacting isocyanate reactive compounds with a molar excess of an isocyanate compound or a polymeric isocyanate compound under conditions that do not lead to gelation or curing, such isocyanate prepolymers may have a high average isocyanate equivalent of >400 g / eq. The formation of isocyanate prepolymers is known in the art and may include reacting (1) at least one isocyanate compound with (2) at least one polyol compound. Isocyanate prepolymers may be described by an isocyanate index, 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 defined as the isocyanate equivalent divided by the total isocyanate reactive hydrogen-containing material equivalent, multiplied by 100, in the range of 30 to 400, 40 to 300, or 40 to 200.

[0015] Examples of commercial isocyanates include, but are not limited to, polyisocyanates under the trademarks VORANATE™, PAPI™, VORATRON™, VORAFORCE™, and ISONATE™, all of which are available from The Dow Chemical Company.

[0016] The isocyanate reactive component may include a polyol blend containing one or more polyether polyols, polyester polyols, aliphatic polyols, polyol crosslinking agents, hollow particles, and other additives such as catalysts, surfactants, and the like. The polyurethane composition may include the isocyanate reactive component in the range of 20 wt% to 85 wt%, 20 wt% to 80 wt%, or 25 wt% to 80 wt%.

[0017] The isocyanate reactive component may include one or more polyether polyols prepared by polyaddition of 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. The polyether polyol may be prepared from a starting compound and one or more alkylene oxides, such as ethylene oxide, propylene oxide, and / or butane oxide. The starting compound may include, but is 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-butanediol, 1,6-hexanediol, triethanolamine, diethanolamine, diisopropanolamine, bisphenol A, glycerol, diglycerol, triglycerol, trimethylolpropane, di(trimethylolpropane)neopentyl tertrol, dineopentyl tertrol, trineopentyl tertrol, sugars and sugar alcohols such as sucrose and sorbitol, and the like. It should be understood that, for the purposes of this invention only, polyether polyols may also be blends of any of these polyether polyols with one or more starting compounds, and polyether polyols may themselves be one or more starting compounds. Polyether polyols may also include polyols reacted with polyethers formed from copolymers of epoxides, including block copolymers and polyethers "capped" with hydroxyethyl and / or hydroxypropyl oligomers or polymers.

[0018] Polyether polyols may have hydroxyl functionality in the range of 1 to 8, or 1.5 to 7. Polyether polyols may have hydroxyl equivalent, defined as the weight average molecular weight of the polyol divided by the average number of hydroxyl groups or average hydroxyl functionality of the molecules, in the range of 30 Da to 4000 Da, or 30 Da to 3000 Da.

[0019] The isocyanate reactive component may include at least one polyether polyol, which is present in an amount of 40 wt% to 95 wt%, 45 wt% to 95 wt%, or 50 wt% to 90 wt% by weight percentage (wt%).

[0020] The isocyanate reactive component may include one or more polyester polyols, which are generated by the reaction of one or more carboxylic diacids with a polyol having 2 to 4 OH functionalities. Suitable carboxylic acids may include aromatic diacids or anhydrides, such as phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, methyl phthalate, dimethyl terephthalate, trimellitic anhydride, phenylpyridine 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 2 to 4 hydroxyl functionalities, such as ethylene glycol, 1,2- or 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, glycerol, and the like. Exemplary 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.

[0021] The polyester polyol may have an average number of hydroxyl groups (OH groups) in the range of 100 mg KOH / g to 500 mg KOH / g, 150 mg KOH / g to 450 mg KOH / g, or 150 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 the range of 10 wt% to 40 wt%, 15 wt% to 35 wt%, or 15 wt% to 30 wt%.

[0022] The isocyanate reactive component may include one or more aliphatic polyols having at least two reactive hydroxyl groups. Aliphatic polyols include natural and synthetic polyester polyol derivatives, including products arising from the reaction of polyols with one or more hydroxy fatty acids having 10 to 20 carbon atoms, including hydroxydecanoic acid, hydroxylauric acid, hydroxymyristic acid, hydroxypalmitic acid, hydroxyheptadecanoic acid, hydroxystearic acid, hydroxyeicosanoic acid, ricinoleic acid, and their analogues. For example, aliphatic polyols include triglycerides containing a certain proportion of hydroxy fatty acids, such as castor oil or its derivatives; and / or polyols produced from epoxidized or hydromethanized natural oils, such as soybean oil and cashew nut shell extract (i.e., CNSL). Aliphatic polyols may have a hydroxyl equivalent in the range of 30 Da to 2500 Da, or 30 Da to 2000 Da.

[0023] The isocyanate reactive component may include one or more aliphatic polyols, in weight percentages (wt%) ranging from 2 wt% to 25 wt%, 5 wt% to 25 wt%, or 5 wt% to 20 wt%.

[0024] The isocyanate reactive component may include one or more polyol crosslinking agents having at least 3 hydroxyl functional groups and a weight average molecular weight of 800 g / mol or less. Suitable polyol crosslinking agents may include glycerol, diglycerol, triglycerol, trimethylolpropane, di(trimethylolpropane), neopentyl tertrol, dinepentyl tertrol, trinepentyl tertrol, sorbitol, derivatives such as alkoxylates, or combinations thereof.

[0025] The isocyanate reactive component may include one or more polyol crosslinking agents, in weight percentages (wt%) ranging from 1 wt% to 15 wt%, 1 wt% to 10 wt%, or 1 wt% to 5 wt%.

[0026] The isocyanate reactive component may include one or more polysiloxane polyols (e.g., diols, triols, polyols) having at least two reactive hydroxyl groups. The polysiloxane polyol may include siloxane bonds (Si-O-Si) within its main chain, and in some cases may further include divalent alkyl-separated siloxane units. The polysiloxane polyol may have the general formula HO-R1-Si(R2)2-[O-Si(R2)2]nR1-OH, wherein each R1 is independently a bonding group having 0 to 18 carbon atoms; each R2 is independently a group having 2 to 18 carbon atoms, such as alkyl or hydroxyalkyl; and wherein n is 10 to 20.

[0027] The isocyanate reactive component may include one or more polysiloxane polyols in the range of 10 wt% to 40 wt%, 15 wt% to 35 wt%, or 15 wt% to 30 wt%.

[0028] The isocyanate reactive component may include one or more catalysts for enhancing polyurethane polymerization to produce the PU composition. The catalyst may be used alone or as a catalyst encapsulation containing multiple catalysts, such as gelling catalysts, foaming catalysts, and trimerizing catalysts. Gelation catalysts and foaming catalysts can be distinguished by their tendency to favor urethane (gelling) reactions (in the case of a gelling catalyst) or urea (foaming) reactions (in the case of a foaming catalyst). Trimerizing catalysts can be used to promote isocyanate formation reactions in the composition. Alternatively, the catalyst encapsulation can be added as a separate stream to the reaction mixture of the isocyanate and the isocyanate reactive component.

[0029] Gelation catalysts include organometallic compounds, such as cyclic tertiary amines and / or long-chain amines containing several nitrogen atoms, and combinations thereof. Organometallic compounds include organotin compounds, such as tin(II) salts of organic carboxylic acids, such as tin(II) diacetate, tin(II) dioctanoate, tin(II) diethylhexanoate, and tin(II) dilaurate, and dialkyltin(IV) salts of organic carboxylic acids, such as dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate, and dioctyltin diacetate. Bismuth salts of organic carboxylic acids can also be used as gelation catalysts, such as bismuth octanoate. Cyclic tertiary amines and / or long-chain amines include dimethylbenzylamine, triethyldiamine, and combinations thereof. Examples of commercially available gelation catalysts are Evonik's POLYCAT® 8, DABCO® 33-LV, and DABCO® T-12, as well as other commercially available gelation catalysts.

[0030] Foaming catalysts 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 foaming catalysts include Evonik's POLYCAT® 5, and other commercially available foaming catalysts.

[0031] Trimerizing catalysts may include any such catalysts known in the art. Examples of trimerizing catalysts include N,N',N"-tris(3-dimethylaminopropyl)hexahydro-S-triol; N,N-dimethylcyclohexylamine; 1,3,5-tris(N,N-dimethylaminopropyl)-S-hexahydrotriol; [2,4,6-tris(dimethylaminomethyl)phenol]; potassium acetate, potassium octanoate; 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 10 to 20 carbon atoms, and combinations thereof. Some commercially available trimerizing catalysts include, for example, DABCO®TMR-2, DABCO®TMR-20, DABCO®TMR-30, DABCO®TMR-7, DABCO®K 2097; DABCO®K15, POLYCAT ®41 and POLYCAT ®46, respectively, are from Evonik, as well as other commercially available trimer catalysts.

[0032] Catalysts may include "latent catalysts" or "delayed catalysts," defined as catalytic compounds that have low or relatively inactive catalytic activity at ambient temperature, but become more catalytically active upon heating, such as through dissociation, decoupling, ring-opening, ionization, or tautomerism, to catalyze at least one of the chemical reactions involved in the manufacture of PU foam. Ambient temperature can range from 15°C to 35°C, with room temperature typically around 23°C.

[0033] In terms of its function in the foaming process, a latent / delayed catalyst can be a gelling, foaming, and / or trimerizing type catalyst. A latent catalyst is typically a subset of tertiary amine gelling catalysts (e.g., a delayed-action tertiary amine based on 1,8-diazabicyclo[5.4.0]undec-7-ene), including acid salts, phenol salts, or complexes of tertiary amine catalysts, wherein the acid or phenol is typically a carboxylic acid or phenolic substance, but not limited to, formic acid, acetic acid, propionic acid, 2-ethylhexanoic acid, phenoxyacetic acid, gluconic acid, tartaric acid, citric acid, phenol, nonylphenol, diisopropylphenol, and their analogues; and mixtures thereof. Some commercially available latent catalysts available include, for example, DABCO® TMR-30, POLYCAT® SA2 LE, POLYCAT® SA-1 / 10, and DABCO® 8154 from Evonik; NIAX® A-107, NIAX® C-31, and NIAX® C-225 from Momentive; and JEFFCAT® ZF-54 and JEFFCAT® LED-204 from Huntsman Corporation; and mixtures thereof.

[0034] The catalyst or catalyst encapsulation may be present in the PU composition at a weight percentage (wt%) ranging from 0.1 wt% to 10 wt%, or from 1 wt% to 7 wt%. In some cases, a sufficient amount of catalyst encapsulation may be added to the isocyanate reactive component to provide a mixture having the above corresponding weight percentages.

[0035] Polyurethane compositions may include one or more hollow particles, which can modulate physical properties, introduce void volume, and reduce overall density. Hollow particles and mixtures may 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 may be added to multiple components to increase viscosity matching and promote homogeneous mixing.

[0036] Hollow particles can include hollow-shell particles or porous aerogels constructed from glass, ceramics, silicon dioxide, and the like. Hollow particles can have different shapes and geometries, such as spheres, hemispheres, tubular, elongated, rectangular, elliptical, and the like. Hollow particles can have densities ranging from 0.05 g / mL to 0.8 g / mL, or from 0.10 g / mL to 0.6 g / mL. Hollow particles can have particle sizes and distributions ranging from 1 to 350 micrometers, or from 1 to 300 micrometers, or from 1 to 250 micrometers.

[0037] In some cases, the surface of hollow particles can be modified to mediate interactions between the particles and the surrounding matrix and / or polymer phase, such as by adjusting hydrophobicity or hydrophilicity. Surface modification can include covalent and ionic bonding chemistry reactions to attach functional groups, such as alkyl chains, siloxanes, hydroxyl groups, amines, thiols, isocyanates, epoxy groups, acrylates, aromatics, and the like. For example, surface modification can include the use of silane chemicals, including organosilanes, such as silane chemicals having the following formula: R(4-n)Si(OR2)n, where R is an alkyl or substituted alkyl group having 1 to 20 carbon atoms (e.g., substituted with the above functional group), 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.

[0038] In some cases, hollow particles may include glass particles having a density in the range of 0.1 g / mL to 0.6 g / mL and having an organosilanes (e.g., epoxy silanes) surface modified.

[0039] The polyurethane composition may include one or more hollow particles in the range of 0.5 wt% to 35 wt%, 1 wt% to 25 wt%, or 1 wt% to 20 wt%.

[0040] Polyurethane compositions may include one or more flame retardants (also known as FR or FR additives) to improve flame resistance. Suitable flame retardants may include, in particular, carbon black, hydrated aluminum hydroxide, and silicates such as wollastonite, platinum and platinum compounds, carbonates such as calcium carbonate, red phosphorus, sodium citrate, and the like. Alternatively, the flame retardant may be at least one of the following: halogen-based flame retardants, such as decabromodiphenyl oxide, octabromodiphenyl oxide, hexabromocyclododecane, decabromobiphenyl oxide, diphenoxybenzene, ethyl bis-tetrabromophthalimide, pentabromoethylbenzene, pentabromobenzene acrylate, tribromophenyl maleic anhydride, tetrabromobisphenyl A, bis-(tribromophenoxy)ethane, bis-(pentabromophenoxy)ethane, polydibromophenyl oxide, tribromophenyl allyl ether, bis-dibromopropyl ether, tetrabromophthalic anhydride, dibromoneopentyl glycol, dibromoethyldibromocyclohexane, pentabromodiphenyl ether, tribromostyrene, pentabromochlorocyclohexane, tetrabromoxylene, hexabromocyclododecane, brominated polystyrene, tetradecylbromodiphenoxybenzene, trifluoropropylene, and PVC. Alternatively, the flame retardant may be at least one of the following: phosphorus-based flame retardants, such as (2,3-dibromopropyl)-phosphate, phosphorus, cyclic phosphates, triaryl phosphates, bis-melaminium pentate, neopentyltetrol bicyclic phosphate, dimethyl methyl phosphate, phosphine oxide diol, triphenyl phosphate, trichloroethyl phosphate, trichloropropyl phosphate, triethyl phosphate; phosphate esters, such as tricresyl phosphate, tridimethyl phosphate, isodecyl diphenyl phosphate, ethylhexyl diphenyl phosphate, isopropylated triphenyl phosphate, tributylated triphenyl phosphate, isobutylated triphenyl phosphate; and mixtures thereof. Alternatively, phosphates of various amines, such as ammonium polyphosphate, trioctyl phosphate, tributyl phosphate, or tributyloxyethyl phosphate, and alkyl phosphate oligomers. Other flame retardants may include melamine and its derivatives, such as melamine salts, guanidine, dicyandiamine, ammonium aminosulfonate, alumina trihydrate, and magnesium hydroxide. FR additives may also include copolymer polyols, such as polyisocyanate addition (PIPA) polyols or polyurea polyols, which are manufactured by reacting a low-equivalent polyol (e.g., with a hydroxyl equivalent of up to 80) or a polyamine with a polyisocyanate 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 of at least 200).

[0041] The amount of flame retardant may vary depending on factors such as the selected flame retardant and the intended use of the polyurethane composition to achieve UL-94 vertical burn performance of V2 or better, better V1 or better, and best V0. Multiple flame retardants and mixtures may 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 may vary depending on the specific flame retardant used (if present) and is generally in the range of up to 60 wt% or from 5 wt% to 60 wt% of the total weight of the polyurethane composition.

[0042] The PU composition may include one or more polysiloxane or organic defoamers added in amounts ranging from 0.05 wt% to 5 wt%, 0.1 wt% to 1.5 wt%, or 0.1 wt% to 1 wt% of the polyurethane composition by weight percentage (wt%).

[0043] The polyurethane composition may include one or more fillers, including glass fiber, fiber, carbon fiber, silica, CaCO3, kaolin, talc, alumina, alumina trihydrate (ATH), and the like. One or more fillers may be added in amounts ranging from 0 wt% to 25 wt%, or from 1 wt% to 20 wt%, based on the weight percentage (wt%) of the composition. In some cases, sufficient amounts of filler may be added to the isocyanate component and / or the isocyanate reactive component to provide a mixture having the corresponding weight percentages described above.

[0044] The isocyanate reactive component may also contain one or more additives, including foaming agents, surfactants, crosslinking agents, plasticizers, smoke suppressants, fragrances, reinforcing agents, dyes, colorants, pigments, preservatives, masking agents, physical foaming agents, chemical foaming agents, flame retardants, internal mold release agents, biodegradants, antioxidants, UV stabilizers, antistatic agents, thixotropic agents, tackifiers, cell openers, and similar additives. When reacting in the presence of an amine catalyst and isocyanate, epoxy resins in additive amounts may also be used to enhance the thermosetting glass transition temperature. Examples include DER383 and DER354 from Olin Corporation.

[0045] Although individual formulation components have been disclosed, it is anticipated that component elements (e.g., isocyanates or compounds in isocyanate reactive components) may be included, excluded, or combined in any manner or sub-combination using any of the concentration ranges and nested sub-ranges described herein.

[0046] The PU composition disclosed in this article may be flame retardant, with a vertical flammability of 5 mm, V2 or better, or V1 or better, according to UL 94 standard.

[0047] PU compositions can have thermal conductivity suitable for the desired application. In some cases, such as automotive applications, thermal conductivity can be less than or equal to 0.2 W / mK, while in other applications, 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.

[0048] The PU composition may have a density according to ASTM D3574-17 Test A in the range of less than 1 g / mL, or 0.2 g / mL to 2.0 g / mL, or 0.3 g / mL to 1.5 g / mL, or 0.6 g / mL to 1.5 g / mL, or 0.65 g / mL to 1.5 g / mL, or 0.7 g / mL to 1.5 g / mL.

[0049] The PU composition can 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 when the components are mixed.

[0050] While the components and properties of formulations have been individually disclosed, it is anticipated that component elements (e.g., compounds in isocyanates or isocyanate reactive components) can be included, excluded, or combined in any manner or sub-combination using any of the concentration ranges and nested sub-ranges described above. Furthermore, the properties of the formulations can be similarly achieved through various combinations of the components within the ranges.

[0051] PU compositions are typically formed by combining an isocyanate component with an isocyanate reactive component (and optionally a third component containing, for example, hollow particles) to form a mixture using suitable methods (e.g., static mixing, dynamic mixing, dynamic and static mixing, rapid mixing, low-pressure mixing, top mixing using an impeller or paint mixer, impact mixing, and others), and by reacting the mixture to form a PU article. PU compositions can be used in any process suitable for developing articles and composites, including molding, injection molding, vacuum infusion, and similar processes. Methods may include applying the PU composition to a substrate by dispensing or coating using spin coating, brush coating; drip coating; spray coating; dip coating; roller coating; flow coating; slot coating; gravure printing coating; Meyer bar coating; and similar methods. In some cases, methods may 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, encapsulating material, potting compound). The PU composition can be formed by dispensing, injecting, and / or spraying onto one or more specific locations in and / or on top of the battery pack or module using a suitable battery pack / module assembly process to achieve complete (or partial) encapsulation of the battery cells.

[0052] Methods may 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. A composite article may be prepared by placing the composition on a substrate and curing the composition to produce a composite article containing a polyurethane article on the substrate. In some cases, the substrate may define at least one gap, and placement may include placing the composition in at least one gap such that the polyurethane article is present within the gap in the composite article. For example, the substrate may include (multiple) battery cells, surfaces, or components, and the composite article may include battery packs and / or modules. However, the composition polyurethane article may be used in other end-use applications, including as an end-use besides battery packs, such as for use as a potting or encapsulating material in circuits, and for purposes other than potting and / or encapsulating materials.

[0053] The PU compositions disclosed herein can be used as potting materials or thermal barriers for electrical, battery pack, and / or module-related applications. The potting materials can coat, encapsulate (fully or partially), and / or protect electrical connections against harsh environments such as heat, cold, fire, weather elements, ash (e.g., sand or dirt particles), physical shock or vibration, or other harsh elements. The amount of potting material used can range from a minimum sufficient to coat and protect electrical connections to a maximum sufficient to fill voids in battery packs, junction boxes, and the like. 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 mobility solutions (e.g., EVs), but can be modified beyond those constraints for 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), without considering issues related to total weight and the absence of external cooling.

[0054] The PU composition disclosed herein may include a multilayer composition comprising a first layer of thermosetting resin, wherein a second layer (or capping layer) is disposed on the first layer of thermosetting resin and comprises the PU composition disclosed herein. The multilayer composition may also include a capping layer disposed on two or more lower layers. In some cases, the multilayer composition may include a first layer (or multiple layers) comprising a volume percentage (vol%) of the multilayer composition ranging from 1 vol% to 70 vol%, or from 1 vol% to 30 vol%, wherein the remaining volume is the PU composition disclosed herein. In some cases, the first thermosetting resin layer (or multiple layers) may be deposited on a substrate, such as between battery cells in a battery pack assembly, and subsequently a second layer comprising the PU composition according to the disclosure is added thereto.

[0055] The PU composition in the first layer (or one of several first layers) used to contact the substrate may include thermosetting resins, such as polyurethanes, including polyurethanes prepared using any of the above components and additives, and may include foamed PU compositions containing one or more blowing agents, epoxides, phenolic resins, polyesters, polyamides, polysiloxanes, and the like, or combinations thereof. Blowing agents may include water and aqueous fluids; chemical blowing agents, such as hydrocarbons, hydrofluoroolefins, hydrofluorocarbons, acids, volatile organic compounds, and the like; and physical blowing agents, including gases such as nitrogen, air, carbon dioxide, and the like. The blowing agent may be added to the isocyanate reactive component in weight percentages (wt%) ranging from 0.1 wt% to 7 wt%, or from 0.1 wt% to 4 wt%. Sufficient amounts of blowing agent may be added to the isocyanate component and / or added during mixing to provide a mixture having the above-mentioned corresponding weight percentages.

[0056] The first layer (or one of the first layers) may or may not be assessed for fire retardancy or flame retardancy during UL-94 vertical or horizontal flammability tests with a thickness of ≤10 mm. The first layer (or one of the first layers) may have a thermal conductivity value of less than 0.25 W / mK or less than 0.30 W / mK according to ISO 22007-2. The first layer (or one of the first layers) may be flexible or rigid, depending on the composition described above, and have a modulus of elasticity (E') in the range of 5 to 1000 MPa according to ASTM D638-03. In some cases, the thermosetting resin has a thermal conductivity value of less than 0.25 W / mK and a modulus of elasticity in the range of 5 to 1000 MPa.

[0057] While the components and properties of formulations have been individually disclosed, it is anticipated that component elements (e.g., compounds in isocyanates or isocyanate reactive components) can be included, excluded, or combined in any manner or sub-combination using any of the concentration ranges and nested sub-ranges described above. Furthermore, the properties of the formulations can be similarly achieved through various combinations of the components within the ranges.

[0058] The numerical ranges disclosed herein include all values ​​from the lower to the higher values, and include both the lower and higher values ​​and all values ​​in between. Unless otherwise stated, implied from the context, or customary in the art, all parts and percentages are by weight. Unless otherwise specified, all standardized test methods utilize current standards as of the date of this disclosure. Example

[0059] The following examples are provided to illustrate embodiments of the invention and are not intended to limit its scope. Table 1 provides the materials used in the following examples. Table 1: Materials used in the examples Components describe source Polyol-1 Propoxylated glycerol with an OH equivalent of 85 g / mol Dow Polyol-2 Propane-oxylated bifunctional polypropylene glycol with an OH equivalent of 510 Da Dow Polyol-3 glycerin Millipore Sigma Polyol-4 Naturally sourced aliphatic polyols with an OH equivalent of 330 g / mol Acme-Hardesty Co. Catalyst-1 Tertiary amines based on 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). Evonik Catalyst-2 A mixture of 33 wt.% triethylenediamine dissolved in 67 wt.% dipropylene glycol. Evonik Catalyst-3 N,N,N',N'',N''Pentamethyldiethyltriamine TCI America Additive-1 Dehumidifying paste based on castor oil and molecular sieve powder Dow Additive-2 Defoaming / anti-foaming compounds based on polysiloxane Momentive FR Additives Trichloropropyl phosphate ICL-IP Hollow Particle-1 Glass bulb with a density of approximately 0.22 g / mL 3M Hollow Particle-2 Glass bulbs with a density of approximately 0.2 g / mL and surface-modified with epoxy silane. 3M Isocyanate-1 MDI modified with carbodiimide and containing approximately 29% NCO by weight Dow Isocyanate-2 Polymer MDI with a nominal functionality of 2.3 and an NCO content of 32% by weight Dow Isocyanate-3 Polymer MDI with a nominal functionality of 2.7 and an NCO content of approximately 31% by weight Dow Example 1: Properties of polyurethane compositions

[0060] In this example, the physical properties of the sample of the present invention containing a polyurethane composition were tested relative to a comparative example without hollow particles. The sample formulations are shown in Table 2 (Comparative) and Table 3 (Invention).

[0061] According to the formulation requirements, all inclusions (polyols, additives, and catalysts) from the isocyanate reactive components listed in Tables 2 and 3 were weighed on an analytical balance and mixed using a DAC 600.1 FVZ-K rapid mixer until dispersed. The pre-blended batch was used within 2 hours of mixing, and if used on layer days, it was pre-mixed to prevent phase separation. When included, hollow particles were added to the isocyanate reactive components and rapidly mixed before being used in the formulation.

[0062] The corresponding isocyanate component was then added to the isocyanate reactive component at an appropriate ratio, rapidly mixed, 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; the 12.5 mm thick sample was further cut for flame retardancy (FR) performance measurement, cut into 5 mm thick pieces with a 0.5-inch width for UL-94 vertical burning tests). Subsequently, cured molded sheets of the PU potting material were tested to determine the mechanical properties of the potting material.

[0063] After demolding, measure the dimensions of the rectangular potting material sample with a ruler and weigh it on a weighing balance. Calculate the sample density as the sample weight divided by (length * width * height).

[0064] After 30 to 60 minutes, all potting material samples were demolded and post-cured at 60°C for 1 hour. Mechanical and thermal properties were then tested to ensure that the curing condition was similar to that used in EV battery packs. Some potting material samples were found to fracture and / or break during demolding or during the stamping of the samples into a dog-bone shape, and were classified as "Cannot test" due to their brittle nature. Table 2: Comparison of Sample Formulations Components C1 C2 C3 C4 C5 C6 Polyol 1 52.7 54.4 35.1 52.7 54.4 26.2 Polyol 2 38.4 25.6 38.4 19.1 Polyol 3 3.0 5.9 2.0 3.0 5.9 1.5 Polyol 4 - 33.1 - - 33.1 - Additive-1 4.9 5.9 3.3 4.9 5.9 2.5 Catalyst-1 0.7 0.35 0.5 0.7 0.35 0.6 Catalyst-2 0.249 0.18 0.15 0.249 0.18 0.30 Catalyst-3 - - 0.15 - - Additive-2 0.10 0.12 0.10 0.10 0.12 0.10 FR Additive-2 - - 33.1 - - 49.7 Total (isocyanate reactive components) 100 100 100 100 100 100 Hollow Particle-1 18.9 19.8 Hollow Particle-2 - - - - - - Isocyanate-1 132.8 - 88.6 144.3 - 66.1 Isocyanate-2 - 154.8 - - 154.8 - Isocyanate-3 - - - - - - Table 3: Sample Formulation of the Invention Components I1 I2 I3 I4 I5 I6 Polyol 1 23.1 23.1 23.1 23.1 23.1 23.1 Polyol 3 5.0 5.0 5.0 5.0 5.0 5.0 Polyol 4 14.1 14.1 14.1 14.1 14.1 14.1 Additive-1 5.0 5.0 5.0 5.0 5.0 5.0 Catalyst-1 0.30 0.30 0.30 0.30 0.30 0.30 Catalyst-2 0.15 0.15 0.15 0.15 0.15 0.15 Additive-2 0.10 0.10 0.10 0.10 0.10 0.10 FR Additive-2 52.2 52.2 52.2 52.2 52.2 52.2 Total (isocyanate reactive components) 100 100 100 100 100 100 Hollow Particle-1 - - - 14.0 20.0 - Hollow Particle-2 14.5 13.5 20.0 - - 14.0 Isocyanate-1 87.6 - - - - - Isocyanate-2 - 79.7 79.7 79.7 79.7 - Isocyanate-3 - - - - - 81.5

[0065] The various physical characteristics (1) to (13) of the sample formulations were then tested, as listed below. The test results for each formulation are shown in Tables 4 and 5.

[0066] UL 94 Vertical Burning Test (1): Using the procedure described above, the potting material prepared in a metal mold to a thickness of 12.7 mm is then cut into 5 mm thicknesses, as well as 0.5-inch and ≥10 cm dimensions. The pre-made potting material samples (individual potting materials) are tested using the standard UL 94 vertical burning protocol, and the performance is classified into the appropriate categories: V0 (best and desired performance), V1, V2, and non-compliance (non-compliance means that the potting material sample burns all the way to the fixture during and / or after flame exposure).

[0067] Thermal conductivity (2): Using a Hot Disk AB TPS 2500S instrument with a Kapton thermal insulation 5465 F1 sensor, thermal conductivity was measured on a 2 mm thick pre-cured potting material sample according to ISO 22007-2, using an isotropic (standard) module with a heating power of 50 mW and a measurement time of 5 seconds, and standard analysis. The potting material sheet for testing was prepared with a thickness of 2 mm using the procedure described above.

[0068] Density (3): Calculated as the density (i.e., weight / volume) of the cured potting material sheet sample, performed according to ASTM D3574-17 Test A. The weight of the sheet is measured in grams, and the height of the sheet is measured in cm. The width and thickness of the sheet are 12.5 cm and 0.2 cm, respectively. Density of the potting material sample (in g / cm³ or g / mL): weight of potting material sample * 1000 / (height * 12.5 * 0.2).

[0069] Viscosity (4 to 6): The flowability of the potting material in actual complex battery pack assemblies was quantified using the reactive viscosity of polyol + isocyanate measured on the AREG G2 from TA Instruments. A 50 mm conical plate geometry made of stainless steel was used. The pre-blended polyol side (with or without pre-mixed bubbles according to the formulation) was placed in a rapid mixer cup (maximum 20 cups) and an appropriate amount and type of isocyanate was added (according to the formulation from Table 4). The mixture was mixed at 2100 rpm for 8 to 10 seconds, and an appropriate amount of liquid was poured (within 3 to 4 seconds after mixing) onto the AREG G2 rheometer pan, with the gap set to 2 mm (excess was wiped off with a cotton swab) and measurement started as soon as possible (within 3 to 5 seconds after adding to the pan). The measurement temperature was set to 25°C ± 2°C, the oscillating strain coefficient was 5%, and the angular frequency was 10 rad / sec. Measurement continued for at least 5 minutes. The reactive viscosity at the first data point (t = 6 sec), 2 minutes, and 5 minutes is reported in Tables 4 and 5.

[0070] Modulus of elasticity (7), ultimate tensile strength (8), and elongation at break (9): For the cured potting material sheet samples prepared using the procedure described above, the modulus of elasticity (E), elongation at break (%), and ultimate tensile strength (MPa) were obtained on an MTS machine using ASTM D1708. Micro-stretched samples were stamped into dog-bone shapes from sheets molded with a 2 mm thick metal die. Due to inherent brittleness, the samples fractured during the cutting of the 2 mm thick sheet into dog-bone shapes; "N / A" samples (C1 to C2) could not be tested.

[0071] Shear modulus at -30℃ (10), 25℃ (11), 50℃ (12), and 60℃ (13): The shear modulus in torsion mode (physical characteristics (10) to (13)) was obtained by dynamic mechanical analysis (DMA) according to ASTM D5279-21 on an Advanced Rheometric Expansion System (ARES-G2) from TA Instruments equipped with liquid nitrogen environmental control and a torsion rectangular fixture. Rectangular samples with a thickness of 2 mm were cut from the potting material sheet prepared from metal molds (A and B) according to the above procedure, and the dimensions were cut to a length of 45 mm and a width of 12.8 mm. The sample length was aligned with the torsion axis, and the DMA experiment was performed in torsion mode. The temperature was increased from -70℃ to 150℃ at a heating rate of 3℃ / min. At 0.05% torsional strain, the test frequency was 1 Hz, with an axial tensile force of 0.098 N applied to keep the sample taut, and data collection was performed at 30-second intervals per point. The output from the characterization is the stored modulus (G') in shear mode over the temperature range. Table 4: Performance Criteria and Properties of Comparative Samples (C1 to C6) nature Test nature Target C1 C2 C3 C4 C5 C6 1 UL 94 vertical burning at 5 mm V0 Not passed Not passed V2 Not passed Not passed V0 2 Thermal conductivity (W / mK) ≤ 0.2 0.24 0.23 0.22 0.17 0.16 0.27 3 Density (g / mL) ≤ 1 1.23 1.18 1.19 0.87 0.91 1.15 4 Viscosity of the mixed components at 6 seconds < 1500 cP 491 266 300 1712 6524 346 5 Viscosity of the mixed components at 2 min < 2500 cP 1042 338 790 3323 5051 835 6 Viscosity of the mixed components at 5 min < 3500 cP 3542 791 1271 10461 8802 1277 7 Elastic modulus (MPa) at 25℃ > 150 N / A N / A 813 1038 880 505 8 Tensile strength (MPa) at 25°C > 10 N / A N / A 55.6 50.5 33.9 30 9 Elongation at break (%) at 25°C > 4 N / A N / A 9.4 7 5.4 44 10 Storage modulus (MPa) at -30°C > 100 1171 1194 1264 1038 1044 960 11 Storage modulus (MPa) at 25°C > 100 985 961 909 894 879 272 12 Storage modulus (MPa) at 50°C > 100 848 828 413 802 713 10 13 Storage modulus (MPa) at 60°C > 100 746 754 53 750 630 3 Table 5: Performance Criteria and Properties of Samples of the Invention (I1 to I6) nature Test nature Target I1 I2 I3 I4 I5 I6 1 UL 94 vertical burning at 5 mm V0 V0 V0 V0 V0 V0 V0 2 Thermal conductivity (W / m·K) ≤ 0.2 0.17 0.16 0.15 0.16 0.15 0.17 3 Density (g / mL) < 1 0.96 0.91 0.85 0.96 0.85 0.92 4 Viscosity of the mixed components at 6 seconds < 1500 cP 718 362 416 253 1169 <1200 (*calculate) 5 Viscosity of the mixed components at 2 min < 2500 cP 853 517 560 377 1387 1363 6 Viscosity of the mixed components at 5 min < 3500 cP 1224 635 659 466 2066 1519 7 Elastic modulus (MPa) at 25℃ > 150 921 742 1136 1016 1049 830 8 Tensile strength (MPa) at 25°C > 10 46.9 34 48.5 49.2 45.8 43.7 9 Elongation at break (%) at 25°C > 4 7.4 6.3 5.8 6.7 5.7 7.1 10 Storage modulus (MPa) at -30°C > 100 996 1071 967 927 830 1068 11 Storage modulus (MPa) at 25°C > 100 757 815 755 657 675 788 12 Storage modulus (MPa) at 50°C > 100 452 415 384 330 384 537 13 Storage modulus (MPa) at 60°C > 100 238 103 155 115 163 407 *The “calculation” for sample I6 means that, due to the lack of mixing for isocyanate-3, the values ​​are extrapolated from the viscosity versus time curve measured using a rheometer (as described in the previous procedure) (simultaneously with all other examples), and the backward intercept is thus calculated.

[0072] The potting material formulations provided in Tables 4 and 5 were produced without chemical or physical foaming agents and therefore do not exhibit foaming. For C1 and C2, the non-foaming liquid was cured into a PU elastomer, but neither passed the UL 94 fire resistance (FR) test. For C3 and C6, FR additives were provided in a 5 mm thick potting material, resulting in a V2 rating for C3 and a V0 rating for C6 in the UL 94 vertical burning test, but increasing the thermal conductivity values ​​to 0.22 and 0.27, respectively. Samples C1 to C3 and C6 have a density >1 g / mL and a thermal conductivity higher than 0.2 W / mK. Samples C4 and C5 incorporate hollow particles and exhibit lower thermal conductivity (< 0.2 W / mK) and density. However, the potting materials failed the UL-94 vertical combustion test and showed high viscosity after mixing (>10,000 and >8,000 cP after 5 minutes, respectively). Therefore, C1 to C6 are considered unsuitable for EV battery pack potting / encapsulation material applications.

[0073] In contrast, examples of the present invention combining polyols, liquid FR additives, and hollow particles achieve the desired performance parameters. For I1 to I6, all samples exhibit UL-94 V0 performance, while also demonstrating acceptable flowability with low viscosity, high mechanical strength, and a softening point above 60°C in potting applications. I1 to I6 also demonstrate that isocyanates types 1, 2, and 3 can be used individually (or in combination) to achieve the potting properties (1) to (14) and the desired performance in I1 to I6.

[0074] While the foregoing is for exemplary embodiments, other and additional embodiments may be designed without departing from its basic scope, and the scope thereof is determined by the following claims.

[0075] none

Claims

1. A polyurethane composition for use as a potting material in battery packs or stationary electrical storage for electric vehicles, comprising the following reaction products: 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 an added third component, wherein the polyurethane composition has a tensile strength of >10 MPa according to ASTM D1708 at 25°C.

2. The composition of claim 1 further comprises a flame retardant in the range of 5 wt% to 60 wt% by weight of the composition.

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

4. A composition of any one of claims 1 to 3, wherein the polyurethane composition has a density in accordance with ASTM D3574-17 in the range of 0.3 g / mL to less than 1 g / mL.

5. A composition of any one of claims 1 to 3, wherein the hollow particles comprise a range of 0.5 wt% to 35 wt% of the polyurethane composition by weight percentage (wt%).

6. A composition of any one of claims 1 to 3, wherein the polyurethane composition has a vertical flammability of at least V2 according to UL 94.

7. A composition of any one of claims 1 to 3, wherein the polyurethane composition has a viscosity of less than 3500 cP after mixing at 25°C + / -2°C for 5 minutes.

8. A composition of any one of claims 1 to 3, wherein the polyurethane composition has a viscosity of less than 1500 cP after mixing at 25°C + / -2°C for 6 seconds.

9. A polyurethane article prepared from any of the polyurethane compositions of claims 1 to 8.

10. A method for preparing a polyurethane composition as claimed in claim 1, comprising: combining the isocyanate component and the isocyanate reactive component to form a mixture; and reacting the mixture to form the polyurethane composition.

11. A method of manufacturing a composite article comprising depositing a composition as described in any one of claims 1 to 8 onto a substrate and curing the composition to produce the composite article comprising a polyurethane article on the substrate.