Polyurethane fireproof coating composition

Abstract

The invention discloses a polyurethane fireproof coating composition which is obtained by reacting at least the following components: a first component comprising at least one polyether polyol, at least one filler F and at least one flame retardant; and a second component comprising at least one polyisocyanate; wherein the polyether polyol comprises at least 10 wt% ethylene oxide based on the total weight of alkylene oxides in the polyether polyol; based on the total weight of the polyurethane fireproof coating composition, the content of the flame retardant is more than 30wt%; based on the total weight of the polyurethane fireproof coating composition, the content of the filler F is 18-40 wt%; further, based on the total weight of the filler F, the filler F contains at least 20 wt% of filler F having a melting point of 950 DEG C or less.

Description

Technical Field

[0001] The present disclosure relates to the field of polyurethane fire retardant coating compositions. More specifically, the present disclosure relates to a polyurethane fire retardant coating composition, a composite material, and a battery product at least partially coated with the polyurethane fire retardant coating composition. Background Art

[0002] When a car battery experiences thermal runaway, temperatures in certain areas of the battery and the gases produced can reach 800°C or even over 1000°C. To mitigate the risk of thermal runaway in new energy vehicle batteries, a common solution is to install a fire-resistant insulation layer in specific areas within the battery or on its surface. Commonly used inorganic insulation materials include mica sheets and metal oxide insulation layers. However, mica sheets and other materials increase the number of components and occupy more space.

[0003] Resin fire-resistant and thermal-insulating coatings, a new type of coating with excellent operability, have also been applied in this field. However, resin coatings, such as epoxy or polyurethane coatings, are very fragile and easily fall off after being subjected to high temperatures or combustion. Such a loose structure can easily peel off from the substrate under actual thermal runaway conditions due to vibration, external impact, and the impact of high-temperature flames, thus failing to provide continuous fire-resistant and thermal-insulating properties. Summary of the Invention

[0004] To address the above-mentioned issues, the present disclosure aims to provide a polyurethane fire-retardant coating composition capable of withstanding (ultra-)high temperatures and flame impact. The polyurethane coating prepared using the polyurethane fire-retardant coating composition of the present disclosure is capable of withstanding high temperatures and flame impact, exhibiting excellent fire resistance and thermal insulation properties. Furthermore, the residual layer formed after fire exposure is structurally intact and mechanically stable, thereby providing continued fire resistance and thermal insulation properties.

[0005] In a first aspect of the present disclosure, there is provided a polyurethane fire retardant coating composition obtained by reacting at least the following components:

[0006] The first component comprises

[0007] at least one polyether polyol;

[0008] at least one filler F; and

[0009] at least one flame retardant; and

[0010] a second component comprising at least one polyisocyanate;

[0011] Characterized in that the polyether polyol contains at least 10 wt% of ethylene oxide based on the total weight of alkylene oxide in the polyether polyol;

[0012] Based on the total weight of the polyurethane fire retardant coating composition, the content of the flame retardant is 30 wt% or more; and

[0013] Based on the total weight of the polyurethane fire retardant coating composition, the content of the filler F is 18wt%-40wt%; further, based on the total weight of the filler F, the filler F contains at least 20wt% of filler F1 with a melting point below 950°C.

[0014] In a second aspect of the present disclosure, a composite material is provided, which includes a substrate and a polyurethane coating prepared by the polyurethane fire retardant coating composition described in the first aspect, wherein the polyurethane fire retardant coating composition is coated on at least a portion of the surface of the substrate, and the thickness of the polyurethane coating is 0.5-2 mm, preferably 0.8-1.5 mm.

[0015] In a third aspect of the present disclosure, a battery product is provided, wherein the battery product is at least partially coated with the polyurethane fire retardant coating composition described in the first aspect. In some embodiments, the battery product is a battery case, a battery cell, a battery module, or a battery pack.

[0016] Beneficial effects

[0017] The polyurethane coating prepared according to the polyurethane fire retardant coating composition of the present disclosure can withstand high temperature and flame impact and provide continuous fire resistant and thermal insulation, thereby giving the composite material according to the present disclosure excellent fire resistant and thermal insulation performance. DETAILED DESCRIPTION

[0018] The following is a clear and complete description of the technical solutions in the embodiments of this disclosure. Obviously, the described embodiments are only part of the embodiments of this disclosure, not all of them. Based on the embodiments of this disclosure, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this disclosure.

[0019] The molecular weight described in this disclosure refers to the number average molecular weight Mn.

[0020] The functionality described in this disclosure is also referred to as equivalent functionality or average functionality. Methods for determining the functionality of polyols are known to those skilled in the art, for example, see M. Ionescu "Chemistry and Technology of Polyols for Polyurethanes", 2005, Rapra Technology Limited, pages 34 to 39.

[0021] The density described in this disclosure is measured according to ISO 1183 and is expressed in g / cm 3 express.

[0022] I. Polyurethane fire retardant coating composition

[0023] Provided is a polyurethane fire retardant coating composition obtained by reacting at least the following components:

[0024] The first component comprises

[0025] at least one polyether polyol;

[0026] at least one filler F; and

[0027] at least one flame retardant; and

[0028] a second component comprising at least one polyisocyanate;

[0029] Characterized in that the polyether polyol contains at least 10 wt% of ethylene oxide based on the total weight of alkylene oxide in the polyether polyol;

[0030] Based on the total weight of the polyurethane fire retardant coating composition, the content of the flame retardant is 30 wt% or more; and

[0031] Based on the total weight of the polyurethane fire retardant coating composition, the content of the filler F is 18wt%-40wt%; further, based on the total weight of the filler F, the filler F contains at least 20wt% of filler F1 with a melting point below 950°C.

[0032] The polyurethane coating prepared according to the polyurethane fire-retardant coating composition disclosed herein can withstand high temperatures and flame impact. The residual layer formed after experiencing ultra-high temperatures (for example, a fire caused by thermal runaway of a battery may cause the local temperature to reach 1000°C or even above 1200°C) has a dense structure and can maintain structural integrity, thereby continuing to provide fire-resistant and heat-insulating properties.

[0033] First component

[0034] As described above, the first component includes at least one polyether polyol, at least one filler, and at least one flame retardant. The following paragraphs will describe each component in detail.

[0035] Polyether polyols

[0036] Polyether polyols are organic compounds containing at least ether and OH groups as functional groups. They are prepared using catalysts, for example, from epoxides (e.g., propylene oxide and / or ethylene oxide) or tetrahydrofuran, and hydrogen-reactive starting compounds such as aliphatic alcohols, phenols, amines, carboxylic acids, water, and compounds based on natural substances (e.g., sucrose, sorbitol, or mannitol). These may include alkaline catalysts or double metal cyanide catalysts, as described, for example, in PCT / EP2005 / 010124, EP 90444, or WO 05 / 090440. Compared to polyester polyols, polyurethane coatings produced using polyether polyols are less susceptible to aging in hot and humid environments.

[0037] According to the present disclosure, the polyether polyol comprises at least 10 wt% ethylene oxide, e.g., at least 10 wt%, at least 20 wt%, at least 30 wt%, at least 40 wt%, at least 50 wt%, at least 60 wt% ethylene oxide, based on the total weight of alkylene oxide in the polyether polyol.

[0038] In some embodiments, the polyether polyol has an average functionality (ie, groups reactive toward isocyanate) of 2 to 4, such as 2, 3, or 4, ie, the polyether polyol may be a dihydroxy polyol, a trihydroxy polyol, or a tetrahydroxy polyol.

[0039] In some embodiments, the polyether polyol has a number average molecular weight of 1000-10,000 g / mol, preferably 2000-6000 g / mol. For example, the polyether polyol has a number average molecular weight of 1000 g / mol, 2000 g / mol, 3000 g / mol, 4000 g / mol, 5000 g / mol, 6000 g / mol, 8000 g / mol or 10,000 g / mol.

[0040] Examples of suitable commercially available polyether polyols include 2095 (from BASF), 2048 (from BASF).

[0041] Filler F

[0042] Adding fillers to polyurethane fire-retardant coating compositions can improve the mechanical strength of the resulting polyurethane coating. Furthermore, due to their inherent non-combustibility or flame retardancy, fillers can reduce the concentration of combustibles and delay or prevent combustion when incorporated into polymers. Furthermore, some fillers decompose at high temperatures to form non-combustible oxides and water. Because this decomposition reaction is endothermic, the generated non-combustible oxides and released water can both lower the temperature and isolate the material from oxygen, thereby extinguishing the fire.

[0043] In particular, when the polyurethane fire-retardant coating composition according to the present disclosure is used to coat battery products, the formed polyurethane coating can form a residual layer after being burned, and the filler can effectively control the expansion of the coating during the formation of the residual layer, so that the formed residual layer is more uniform and has a certain mechanical strength and can maintain structural integrity, which can effectively improve the fire resistance and heat insulation performance of the battery products.

[0044] Based on the total weight of the polyurethane fire retardant coating composition, the total amount of filler F is 18-40wt%, for example, 18wt%, 19wt%, 20wt%, 25wt%, 28wt%, 30wt%, 40wt%. In some embodiments, based on the total weight of the polyurethane fire retardant coating composition, the total amount of filler F is 19wt%-28wt%, or 18-30wt%.

[0045] According to the present disclosure, examples of suitable fillers include, but are not limited to, nitrides, metal oxides, metal hydroxides, ceramics, and / or (mineral) salts. Among them, (mineral) salt inorganic fillers include metal silicates, borates, and aluminates. Suitable metal silicates can be, for example, sodium silicate, potassium silicate, lithium silicate, calcium silicate, and magnesium silicate.

[0046] In some specific embodiments, the filler is selected from mica, talc, clay, magnesium calcium carbonate, calcium carbonate, calcium sulfate, calcium silicate, barium sulfate, silicon dioxide, aluminum hydroxide, magnesium hydroxide, silicon oxide, aluminum oxide, calcium oxide, titanium dioxide, magnesium oxide, zinc oxide, aluminum nitride, boron nitride, silicon nitride, hollow glass (microspheres), ceramic microspheres, vermiculite, diatomaceous earth, wollastonite, glass fiber, ceramic fiber, basalt fiber and / or silicate. It should be understood that the filler according to the present disclosure is at least one of the above fillers or any combination thereof.

[0047] In addition, the filler may be spherical, elliptical, flake or fibrous. The average particle size (D50) of the inorganic filler may be 200-3000 mesh, preferably 300-2000 mesh.

[0048] In some embodiments, the filler has an aspect ratio of 10-1000, such as a fibrous (also known as "needle-shaped" or "slender") filler or a plate-shaped filler. Fillers within this aspect ratio range (including fibrous and plate-shaped fillers) can effectively control the expansion of the polyurethane coating during the formation of the residual layer, resulting in a more uniform residual layer with sufficient mechanical strength and structural integrity.

[0049] The fibrous filler having an aspect ratio of 10-1000 can be selected from glass fibers, ceramic fibers (e.g., oxide (alumina / silicon dioxide) ceramic fibers), basalt fibers, glass flakes, mica, and / or wollastonite, which can be used alone or in combination. Wollastonite can also be a chain calcium silicate mineral containing a small amount of iron, aluminum, magnesium, manganese, titanium, and / or potassium.

[0050] According to the present disclosure, based on the total weight of the filler F, the filler F contains at least 20 wt%, preferably at least 50 wt%, of a filler F1 having a melting point below 950°C, for example, at least 20 wt%, at least 30 wt%, at least 40 wt%, at least 50 wt%, or at least 60 wt% of a filler F1 having a melting point below 950°C.

[0051] Suitable examples include glass powder / glass fiber (e.g., MF7980), borates (zinc borate), metal oxides (zinc oxide, boron oxide), etc., or combinations thereof. These fillers have a melting point below 950°C, thus acting as fluxing agents. Therefore, these fillers are also referred to as "fluxes." Adding a flux allows the filler to melt at lower temperatures (e.g., in the early stages of thermal runaway), forming a denser, continuous (ceramic) structure with other fillers, thereby improving the strength of the residual layer after ablation.

[0052] In some embodiments, the filler F1 having a melting point of 950° C. or less and a length-to-diameter ratio of 10-1000 may be a filler such as milled glass fiber, borate (zinc borate), metal oxide (zinc oxide, boron oxide), or a combination thereof. These fillers may have the advantages of the fillers described above, namely, they may melt at a lower temperature and improve the mechanical strength of the residual layer.

[0053] flame retardants

[0054] According to the present disclosure, flame retardants include solid flame retardants and liquid flame retardants. Suitable flame retardants include those described in US2011 / 0006579 or US89058601A, such as halogen- and / or phosphorus-containing compounds, antimony oxides, boron-containing compounds, hydrated aluminum oxide, or ammonium polyphosphate. It should be understood that the flame retardants according to the present disclosure include more than one flame retardant.

[0055] Based on the total weight of the polyurethane fire retardant coating composition, the total content of the flame retardant is 28 wt% or more, 30 wt% or more. In some embodiments, based on the total weight of the polyurethane fire retardant coating composition, the total content of the flame retardant is 30 wt% to 50 wt%, for example, 30 wt% to 40 wt%, or 30 wt% to 50 wt%.

[0056] In some embodiments, the flame retardant does not include conductive flame retardants such as carbon black and graphite.

[0057] In some embodiments, the flame retardant is a combination of a liquid flame retardant and a solid flame retardant.

[0058] Suitable flame retardants are one or more selected from the group consisting of acid sources, carbon sources, and intumescent flame retardants.

[0059] Acid-source flame retardants can release non-combustible gases such as sulfur dioxide and ammonia when the fire-retardant coating is exposed to high temperatures to dilute the surrounding oxygen density and promote the formation of an intumescent thermal insulation layer. Suitable acid sources include, but are not limited to, phosphorus-containing compounds and sulfur-containing compounds. The phosphorus-containing compounds include phosphates and phosphate esters, such as sodium phosphate, potassium phosphate or ammonium phosphate, ammonium polyphosphate (APP), monoammonium phosphate, diammonium hydrogen phosphate, trichloroethyl phosphate (TCEP), trichloropropyl phosphate (TCPP), ammonium pyrophosphate, triphenyl phosphate, etc. Sulfur-containing compounds include sulfonates, such as sodium sulfonate, potassium sulfonate or sulfonic acid, p-toluenesulfonic acid, sulfates, such as sodium sulfate, potassium sulfate or ammonium sulfate.

[0060] Carbon-based flame retardants convert to char when exposed to fire or heat, forming a fire-resistant protective layer on the substrate. They can be selected from a variety of hydroxyl-containing hydrocarbons. Common examples include starch, dextrin, polyfunctional alcohols, particularly monopentaerythritol, dipentaerythritol, and tripentaerythritol or mixtures thereof, sorbitol, resorcinol, trimethylolmelamine, triethylene glycol, phenol-formaldehyde, and phenol. Other hydroxyl-containing components may include certain oils, cellulose, starch, protein, glucose, maltose, mannitol, liquid polyols with linear C2-C5 chains, and more complex compounds.

[0061] Intumescent flame retardants can generate non-combustible gases when the fire-retardant coating is exposed to high temperatures, such as nitrogen, ammonia, etc., which further dilute the surrounding oxygen density and promote the expansion of the fire-retardant coating. Suitable expansion agents include, but are not limited to, melamine compounds and boron-containing compounds. The melamine compounds include melamine salts, such as tripolycyanamide, melamine cyanurate, melamine formaldehyde, hydroxymethylated melamine, hexamethoxymethyl melamine, melamine monophosphate, di(melamine phosphate), melamine dihydrogen phosphate, etc.; boron-containing compounds include boric acid, borates and boric esters, such as ammonium pentaborate, zinc borate, sodium borate, lithium borate, aluminum borate, magnesium borate and borosilicate.

[0062] Suitable liquid flame retardants include (halogenated) phosphate flame retardants, such as trichloroethyl phosphate (TCEP), trichloropropyl phosphate (TCPP), triethyl phosphate (TEP), and the like.

[0063] In addition to the above components, the first component optionally further comprises at least one chain extender and / or cross-linking agent, at least one diluent, at least one catalyst, at least one polymerization inhibitor and / or at least one defoaming agent.

[0064] Chain extenders / crosslinkers

[0065] In some embodiments, the first component according to the present disclosure further comprises a chain extender and / or a cross-linker. Chain extenders / cross-linkers suitable for the present disclosure have a molecular weight of less than 500 g / mol, such as less than 400 g / mol, less than 300 g / mol, less than 200 g / mol, or less than 100 g / mol.

[0066] The chain extender has two functional groups reactive with isocyanate, such as OH-, -SH or NH2 groups. Based on the total weight of the first component, the content of the chain extender is 5-30 wt%, preferably 10-25 wt%, more preferably 10-20 wt%.

[0067] Examples of chain extenders include monoethylene glycol (MEG), diethylene glycol (DEG), 1,2-propylene glycol, 1,3-propylene glycol (DPG), 1,4-butanediol (BDO), 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, tetraethylene glycol, dipropylene glycol, cyclohexanediol, and aliphatic or aromatic amine-based chain extenders, such as aliphatic or aromatic diamines such as ethylenediamine, triethylenediamine, and / or diethyltoluenediamine (DETDA). Other possible low molecular weight chain extenders are mentioned, for example, in "Polyurethane Handbook", Carl Hanser Verlag, 2nd edition, 1994, Chapters 3.2 and 3.3.2. In some preferred embodiments, the chain extender is selected from monoethylene glycol (MEG), 1,3-propylene glycol (DPG), and 1,4-butanediol (BDO).

[0068] Crosslinkers have at least three functional groups reactive toward isocyanates. Examples of crosslinkers include 1,2,4- and 1,3,5-trihydroxycyclohexane, glycerol (GLY), trimethylolpropane (TMP), pentaerythritol, triethanolamine (TEOA), diethanolamine (DEOA), and low-molecular-weight, hydroxyl-containing polyoxyalkylenes based on ethylene oxide and / or 1,2-propylene oxide and the aforementioned diols and / or triols. Other possible low-molecular-weight crosslinkers are mentioned, for example, in "Polyurethane Handbook," Carl Hanser Verlag, 2nd edition, 1994, Chapters 3.2 and 3.3.2.

[0069] diluent

[0070] The diluent is selected from reactive diluents and / or non-reactive diluents. By adding the diluent, the viscosity of the first component and the polyurethane fire retardant coating composition can be effectively reduced.

[0071] The reactive diluent is selected from styrene, C1-C10 alkyl acrylate and / or C1-C10 alkyl methacrylate; for example: hydroxyethyl methacrylate, hydroxypropyl methacrylate (HPMA), hydroxybutyl methacrylate, hydroxypentyl methacrylate, hydroxyhexyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate or a combination thereof.

[0072] In some embodiments, a non-reactive diluent may be further added. The diluent may be selected from esters, ethers, or ketones; the diluent may have a molecular weight of 300 g / mol or less and a viscosity of 20-400 cps. Ester compounds, such as trimethyl phosphate and triethyl phosphate (TEP), are more preferred, with triethyl phosphate (TEP) being particularly preferred because it functions as both a diluent and a flame retardant.

[0073] Based on the total weight of the first component, the content of the diluent is 1 wt% or more, preferably 5 wt% or more.

[0074] catalyst

[0075] In some embodiments, the first component according to the present disclosure further comprises a catalyst. The catalyst can accelerate the reaction between the polyol and the isocyanate. Examples of conventional catalysts for preparing polyurethanes include, for example, amidines such as 2,3-dimethyl-3,4,5,6-tetrahydropyrimidine; tertiary amines such as triethylamine, tributylamine, dimethylbenzylamine, N-methylmorpholine, N-ethylmorpholine, N-cyclohexylmorpholine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethylbutanediamine, N,N,N',N'-tetramethylhexanediamine, pentamethyldiethylenetriamine, tetramethyldiaminoethyl ether, bis(dimethylaminopropyl)urea, dimethylpiperazine, 1,2-dimethylimidazole, 1-azabicyclo(3,3,0)octane, preferably 1,4-diazabicyclo(2,2,2)octane and alkanolamine compounds such as triethanolamine, triisopropanolamine, N-methyldiethanolamine and N-ethyldiethanolamine and dimethylethanolamine. Likewise useful are organometallic compounds, preferably organotin compounds, such as tin(II) salts of organic carboxylic acids, for example tin(II) acetate, tin(II) octoate, tin(II) ethylhexanoate, tin(II) laurate; and dialkyltin(IV) salts of organic carboxylic acids, for example dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate, and dioctyltin diacetate; and bismuth carboxylates, such as bismuth(III) neodecanoate, bismuth 2-ethylhexanoate, and bismuth octoate, or mixtures thereof. The organometallic compounds can be used alone or, preferably, in combination with a strongly basic amine.

[0076] In some embodiments, the catalyst is preferably a trimerization catalyst, examples of which include alkali metal carboxylates, alkaline earth metal carboxylates, quaternary ammonium carboxylates, or any combination thereof. Examples of suitable alkali metal carboxylates include, but are not limited to, potassium pivalate, potassium formate, potassium acetate, potassium propionate, butanoate (butanoate) potassium, potassium pentanoate, potassium hexanoate, potassium neohexanoate, potassium heptanoate, potassium octanoate, potassium neooctanoate, 2-ethylhexanoate, potassium decanoate, butyrate (butyrate) potassium, isobutyrate (isobutyrate) potassium, potassium nonanoate, potassium stearate, potassium neodecanoate, potassium neoheptanoate, sodium octanoate, lithium stearate, sodium hexanoate, lithium octanoate etc., or any combination thereof. In another aspect, at least one carboxylate is potassium pivalate, potassium acetate, potassium octanoate, 2-ethylhexanoate potassium, or any combination thereof.

[0077] defoaming agent

[0078] In some embodiments, the first component according to the present disclosure further comprises a defoaming agent. A defoaming agent is a compound that has surface activity and prevents or inhibits foam formation. A preferred defoaming agent of the present disclosure is polysiloxane.

[0079] By adding a defoaming agent, polyurethane foaming can be inhibited, thereby reducing the pore structure in the polyurethane coating and improving the density and mechanical strength of the polyurethane coating.

[0080] Surfactants can also be used as defoaming agents. Examples of suitable surfactants include anionic, cationic or nonionic surfactants. The surfactant can be a single surfactant or a mixture of surfactants. In a preferred embodiment, the surfactant is nonionic.

[0081] foaming agent

[0082] As is known in the art, during the reaction of isocyanate and polyol, blowing agents promote the release of gas, which will form a porous structure in the polyurethane coating. However, in order to improve the mechanical strength of the polyurethane coating and the composite material described below, these porous structures are not desirable. Therefore, in some embodiments, the polyurethane fire retardant coating composition according to the present disclosure does not contain a blowing agent. The blowing agent includes a "physical blowing agent", a "chemical blowing agent" or a combination thereof.

[0083] The term "physical blowing agent" refers to a blowing agent that does not chemically react with the first and second components to provide a foaming gas. Physical blowing agents can be gaseous or liquid. Liquid physical blowing agents typically evaporate into a gas upon heating and evaporate from the resulting polyurethane elastomer. Examples include liquid carbon dioxide (CO2), HCFCs, HFOs, pentane and all its isomers, acetone, entrained air, other inert gases, or combinations thereof.

[0084] The term "chemical blowing agent" refers to a blowing agent that chemically reacts with the polyisocyanate component or with other components to release a gas. Examples include formic acid, methyl formate, water, and combinations thereof.

[0085] polymerization inhibitors

[0086] In some embodiments, the first component according to the present disclosure further comprises a polymerization inhibitor to prevent free radical polymerization of the (meth)acrylate. Preferred polymerization inhibitors include (2,2,6,6-tetramethylpiperidin-1-yl)hydroxybenzoate (TEMPO), monomethyl ether of hydroquinone (MEHQ), dihydroxybenzene, benzoquinone, hindered phenols, and hindered phenols based on triazine derivatives.

[0087] The viscosity of the first component according to the present disclosure is 100-5000 cps, such as 100 cps, 500 cps, 1000 cps, 2000 cps, 3000 cps, 4000 cps or 5000 cps. In some preferred embodiments, the viscosity of the first component is 100-3000 cps, more preferably 100-1000 cps.

[0088] Second component

[0089] As stated above, the second component according to the present disclosure includes at least one polyisocyanate.

[0090] polyisocyanates

[0091] The present disclosure is not limited to the type of polyisocyanate, which refers to an organic compound containing two or more reactive isocyanate groups per molecule, i.e., having a functionality of 2 (in which case polyisocyanates are also referred to as diisocyanates) or greater than 2. Examples of polyisocyanates include any aliphatic, alicyclic, araliphatic, and aromatic difunctional or polyfunctional isocyanates known in the art, and any desired mixtures thereof. Polyisocyanates may be monomers, prepolymers, and / or polymeric isocyanates.

[0092] Examples of suitable polyisocyanates include, but are not limited to, aromatic isocyanates, aliphatic isocyanates, cycloaliphatic isocyanates, and araliphatic isocyanates. Examples of suitable polyisocyanates include tri-, tetra-, penta-, hexa-, hepta- and / or octamethylene diisocyanate, 2-methylpentamethylene-1,5-diisocyanate, 2-ethylbutylene-1,4-diisocyanate, pentamethylene-1,5-diisocyanate, butylene-1,4-diisocyanate, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate, IPDI), 1,4- and / or 1,3-bis(isocyanatomethyl)cyclohexane (HXDI), cyclohexane-1,4- diisocyanates, 1-methylcyclohexane-2,4- and / or 2,6-diisocyanate and / or dicyclohexylmethane-4,4′-, 2,4′- and 2,2′-diisocyanate, diphenylmethane-2,2′-, 2,4′- and / or 4,4′-diisocyanate (MDI), polymeric MDI, naphthalene-1,5-diisocyanate (NDI), toluene-2,4- and / or 2,6-diisocyanate (TDI), 3,3′-dimethyldiphenyl diisocyanate, 1,2-diphenylethane diisocyanate and / or phenylene diisocyanate and combinations thereof.

[0093] In some embodiments, the polyisocyanate is one having two isocyanate groups. In other embodiments, the polyisocyanate is an aromatic isocyanate. Diphenylmethane diisocyanate (MDI) and / or toluene diisocyanate (TDI) are particularly preferred for the present disclosure.

[0094] Other possible polyisocyanates are given, for example, in “Kunststoffhandbuch, Band 7, Polyurethane” [Plastics Handbook, Volume 7, Polyurethanes], Carl Hanser Verlag, 3rd edition, 1993, Chapters 3.2 and 3.3.2.

[0095] Isocyanate prepolymers can be obtained by reacting the above-mentioned polyisocyanates in excess with polyols, for example, at a temperature of 30-100°C, preferably about 80°C. The prepolymers used in the present invention are preferably produced from 4,4'-MDI together with oxadiazine-modified MDI and commercially available polyols based on polyesters, such as those derived from adipic acid, or polyethers, such as those derived from ethylene oxide and / or propylene oxide. The prepolymers used in the present invention are preferably produced from 4,4'-MDI and polyols derived from ethylene oxide and / or propylene oxide.

[0096] Polyols for preparing isocyanate prepolymers are known to those skilled in the art and are described, for example, in “Kunststoffhandbuch [Plastics Handbook], Volume 7, Polyurethane [Polyurethane]”, Carl Hanser Verlag, 3rd edition 1993, Chapter 3.1.

[0097] Modified polyisocyanates are also commonly used, i.e. products obtained by chemical reaction of organic polyisocyanates having two or more reactive isocyanate groups per molecule. Particular mention may be made of polyisocyanates containing ester groups, urea groups, biuret groups, allophanate groups, carbodiimide groups, isocyanurate groups, uretdione groups, carbamate groups and / or urethane groups.

[0098] Preferred polyisocyanates are liquid at room temperature. In some embodiments, the polyisocyanate has a viscosity of 1-1,000 cps, more preferably 100-500 cps, as measured at 25°C according to ASTM D2196-15. For example, the polyisocyanate has a viscosity of 100 cps, 200 cps, 300 cps, 400 cps, or 500 cps.

[0099] Examples of suitable commercially available polyisocyanate compounds include M20S (from BASF) or MIPS (from BASF).

[0100] In addition to the above-mentioned components, the first component and / or the second component may also include at least one water scavenger and / or at least one flame retardant.

[0101] dewatering agent

[0102] As mentioned above, water and moisture contained in entrained air can also cause the formed polyurethane coating to develop a porous structure. To reduce the porous structure in the polyurethane coating, in some embodiments, the polyurethane fire retardant coating composition according to the present disclosure also includes a dewatering agent. The dewatering agent can help absorb residual water, thereby reducing the formation of porous structures that impair the mechanical properties of the resulting polyurethane coating.

[0103] Suitable water removal agents include zeolites, molecular sieves, activated silanes (such as vinyltrialkoxysilane), minerals (such as calcium oxide), and mixtures thereof.

[0104] Other components

[0105] The polyurethane fire retardant coating composition may further contain auxiliary agents and / or additives. Any known auxiliary agents and additives for the preparation of polyurethanes may be used herein. Suitable examples include release agents, dyes, pigments, hydrolysis inhibitors, antifungal and antibacterial substances, and stabilizers (preferably resistant to hydrolysis, light, heat, or discoloration). Such substances are known and are described, for example, in "Kunststoffhandbuch, Band 7, Polyurethane," Carl Hanser Verlag, 3rd edition, 1993, Chapters 3.4.4 and 3.4.6 to 3.4.11.

[0106] According to the present disclosure, the mixing ratio of the first component to the second component is 0.5:1 to 4:1, for example, 0.5:1, 1:1, 2:1, 3:1 or 4:1.

[0107] The polyurethane fire retardant coating composition according to the present disclosure has an isocyanate index (ie, NCO index) of 200-500, for example, 200, 300, 400, or 500. In some preferred embodiments, the isocyanate index is 250-400.

[0108] That is, when preparing the polyurethane fire retardant coating composition according to the present disclosure, the polyisocyanate and the isocyanate-reactive compound are reacted at an isocyanate index of 200-500, preferably 250-400. The isocyanate-reactive compound refers to a compound containing at least two groups reactive toward isocyanate (including the polyol component described above). Preferably, the isocyanate-reactive groups contain active hydrogen, such as OH-, SH-, NH-, and CH-acid groups.

[0109] II. Composite Materials

[0110] According to a second aspect of the present disclosure, there is provided a composite material comprising

[0111] substrate; and

[0112] The polyurethane coating prepared according to the polyurethane fire retardant coating composition as described above (see the first part, i.e. I. polyurethane fire retardant coating composition) is coated on at least a portion of the surface of the substrate, and the thickness of the polyurethane coating is 0.5-2mm, preferably 0.8-1.5mm.

[0113] This polyurethane coating can withstand (ultra-)high temperatures and flame impact, possessing strong fire-resistant and thermal-insulating properties. It can slow the transfer of high temperatures to the surrounding environment, thereby preventing the spread of high temperatures / combustion for a certain period of time. By applying a layer of polyurethane coating to the substrate, the composite material can act as a protective barrier to promptly prevent the high temperatures generated by localized thermal runaway from spreading to the surrounding area.

[0114] In particular, the residual layer formed by the polyurethane coating after being subjected to fire has good mechanical stability and can continue to provide fire-resistant thermal insulation performance.

[0115] In some embodiments, the substrate can be a metal material or a resin material, that is, the substrate can be made of a metal material or a resin material. As a structural component of the battery product, the substrate must have a certain mechanical strength to protect the internal battery components from being damaged when subjected to external impact or extrusion, and / or to bear the weight of the internal battery components. In addition, the substrate also has a waterproof effect. Exemplary metal materials include aluminum alloys, iron, steel, and aluminum. Exemplary resin materials include polyurethane, polyurea, epoxy resin, and unsaturated resin.

[0116] In some embodiments, the thickness of the substrate is 0.3 mm to 3.5 mm. In particular, when the substrate layer is made of a metal material, its thickness is preferably 0.5 mm to 2 mm, such as 0.5 mm, 0.8 mm, 1 mm, 1.5 mm, or 2 mm; when the substrate layer is made of a resin material, its thickness is preferably 1 mm to 3.5 mm, such as 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, or 3.5 mm. As described above, the polyurethane coating has excellent fire-resistant and thermal insulation properties, thereby allowing the thickness of the substrate to be set relatively low, thereby achieving the desired lightweight composite material.

[0117] In some embodiments, the polyurethane coating according to the present disclosure has a density of 1.2-2.1 g / cm 3 .

[0118] In some embodiments, the tensile strength of the polyurethane coating according to the present disclosure (measured according to DIN 53504) is greater than 4 MPa; and its adhesive strength (measured according to ISO 2813) is Grade 0.

[0119] The composite material according to the present disclosure can be prepared by the following method:

[0120] 1) providing a first component;

[0121] 2) providing a second component;

[0122] 3) mixing the first component and the second component in a certain proportion to react to obtain a polyurethane liquid reaction mixture (i.e., the polyurethane fire retardant coating composition described in the first aspect above);

[0123] 4) applying the polyurethane liquid reaction mixture obtained in the third step to the surface of the substrate;

[0124] 5) Curing to form a polyurethane coating.

[0125] III.Battery products

[0126] According to a third aspect of the present disclosure, a battery product is provided, which is at least partially coated with the polyurethane fire retardant coating composition according to the second aspect above. Examples of the battery product include battery shells, battery cells, battery modules, battery packs, battery cell shells, battery module shells, battery pack shells, trays, thermal management systems, cooling modules, cooling plates, cables (such as busbars) and electrical connectors. Furthermore, in some embodiments, the composite material is used as a shell of a battery product, such as a top cover; in some embodiments, the composite material can be used as the top cover, bottom plate and side plate of the battery product at the same time.

[0127] In some embodiments, the battery product is a battery cell, which includes a shell and a bare battery cell located inside the shell, and the material of the shell of the battery cell is the composite material according to the second aspect above.

[0128] In some embodiments, the battery product is a battery module, which includes a shell and a plurality of battery cells located inside the shell. Examples of the shell include a top cover, a bottom plate and a side plate, and the material of at least one of the top cover, the bottom plate and the side plate is the composite material according to the second aspect described above.

[0129] In some embodiments, the battery product is a battery pack, which includes a shell and a plurality of battery modules located inside the shell. An example of the shell includes a top cover, a bottom plate and a side plate, and the material of at least one of the top cover, the bottom plate and the side plate is the composite material according to the second aspect described above.

[0130] It should be understood that the above examples are merely illustrative of some application scenarios of the polyurethane fire retardant coating composition according to the present disclosure. Those skilled in the art will appreciate that the polyurethane fire retardant coating composition according to the present disclosure can also be applied to other products requiring thermal insulation or fire resistance.

[0131] Example

[0132] The present disclosure will now be described with reference to Examples and Comparative Examples, which are not intended to limit the present disclosure.

[0133] I. Materials:

[0134]

[0135]

[0136] II. Preparation of Composite Materials Examples 1-9 and Comparative Examples 1-6

[0137] The materials of the first component, as shown in Table 1 in the amounts (by weight %), were mixed and added to a reaction vessel and mixed at 1800 rpm for 3-5 minutes until uniformly mixed to prepare the first component. The materials of the second component, as shown in Table 1 in the amounts (by weight %), were added to another reaction vessel and mixed at 1800 rpm for 3-5 minutes to prepare the second component. The first and second components were mixed in the proportions according to the NCO index shown in Table 1 to obtain a polyurethane reaction mixture (i.e., a polyurethane fire retardant coating composition).

[0138] Excess polyurethane reaction mixture was poured onto the surface of a steel plate (11 x 13 cm, 0.8 mm thick). A scraper (scraper gap = 1.5 mm ± 0.2 mm) was then passed across the steel plate from one end to the other to remove the excess polyurethane reaction mixture and ensure that the initial coating thickness of Examples 1-9 remained consistent. The steel plate was then cured at 80°C to form a polyurethane coating. After curing, the polyurethane coating thickness was measured.

[0139] The preparation methods of the composite material comparative examples 1-6 are the same as the preparation steps of the above-mentioned examples 1-9, and the only difference is the formula of the first component and the second component, as shown in Table 3.

[0140] III. Fire test

[0141] In order to test the fire resistance and thermal insulation properties of these composite materials, a fire test was carried out according to GB 38031-2020 (8.2.7.1). The specific steps include:

[0142] Adjust the flame temperature to stabilize it at 1250℃;

[0143] Draw a cross on the front and back of the composite materials of Examples 1-9 and Comparative Examples 1-6 to determine the combustion point, aligning the thermocouple with the combustion point;

[0144] Aim the burner of the Bunsen burner at the burning point on the polyurethane-coated side of the composite material and ignite it at a vertical distance of 50 mm from the burning point;

[0145] Close the fume hood and conduct a 10-minute fire test using MAPP gas (a mixture of propyne and propadiene) supplied from the combustion chamber. Record the temperature of the composite material's backsheet (i.e., the side facing away from the polyurethane coating) (see "Backsheet Temperature (10 min)" in Tables 2 and 4). Furthermore, to further test the fire-resistant and thermal-insulating properties of the polyurethane fire-retardant coating compositions of the present disclosure, a 30-minute fire test was conducted on the composite materials prepared according to Examples 1 and 7. The specific test steps were the same as described above, with the only difference being that the fire was conducted for 30 minutes.

[0146]

[0147]

[0148]

[0149] Table 3 Composite Materials Comparative Examples 1-6

[0150]

[0151]

[0152] Table 4 Test results of composite materials comparative examples 1-6

[0153]

[0154] After the polyurethane coating is fired at 1250°C for 10 minutes, a carbonized structure (the "residual layer") forms on the steel plate surface. This layer is mainly composed of fillers. The strength of the residual layer and the degree of damage to the electrophoretic layer on the back of the steel plate (the side opposite the polyurethane coating) are evaluated according to the following standards:

[0155] Level 1: The residual layer is powdery, without a continuous phase, and can be easily removed without external force. The back electrophoretic layer is damaged (failure).

[0156] Level 2: The residual layer is powdery and has a continuous phase. The carbon layer can be easily destroyed by a light touch, and the back electrophoretic layer is not damaged.

[0157] Level 3: The residual layer is not powdered, there is a continuous phase, the surface is uneven, the carbon layer can be broken by pressing with fingers, and the back electrophoretic layer is not damaged. ++

[0158] Level 4: The residual layer is not powdered, there is a continuous phase, the surface is smooth, the carbon layer is continuous, it is not damaged by pressing with fingers, and the back electrophoretic layer is not damaged. +++

[0159] As shown in Table 3, after 10 minutes of ultra-high-temperature fire at 1250°C, the residual layers formed in Examples 1-9 all achieved a Grade 3 rating or higher, indicating that the residual layers were intact and structurally intact. This ensures that the residual layers continue to provide fire-resistant and heat-insulating properties and prevent gas diffusion. This is particularly advantageous for battery products, especially when thermal runaway occurs within the battery product. Applying the polyurethane coating disclosed herein to the battery product casing can maintain fire-resistant and heat-insulating properties, effectively preventing or reducing the ingress of external oxygen into the battery product, reducing the risk of further combustion.

[0160] Secondly, since the residual layer itself is non-flammable and has a low thermal conductivity, the residual layer can also weaken heat conduction. As shown in Table 3, the backboard temperatures (10 min) of Examples 1-9 are all lower than 265°C, indicating that the composite materials disclosed herein have good fire-resistant and heat-insulating properties. In contrast, the backboard temperatures of Comparative Examples 1-6 are all above 388°C. Furthermore, after the composite materials of Examples 1 and 7 were burned at 1250°C for 30 minutes, the backboard temperatures were 323°C and 268°C, which were still much lower than the backboard temperatures (10 min) of Comparative Examples 1-6.

[0161] Furthermore, visual inspection revealed no damage to the back electrophoretic layer of composite Examples 1-9. This further demonstrates that the composite materials disclosed herein possess excellent fire resistance and heat insulation properties, protecting the back electrophoretic layer from damage, thereby ensuring the electrical insulation properties of the composite materials. This is particularly advantageous when the composite materials are used in automotive battery products.

[0162] In contrast, as shown in Table 4, the polyurethane coatings of Comparative Examples 1-6 formed a residual layer of Grade 1 after being calcined at 1250°C for 10 minutes. This means that the residual layer was powdery and had no continuous phase, easily falling off without external force. Furthermore, the electrophoretic layer on the back was also damaged by the high-temperature impact.

[0163] The above describes the basic principles and exemplary embodiments of the present disclosure. It should be understood by those skilled in the art that the above description is merely for the purpose of illustrating the present disclosure and that the present disclosure is not limited to the above-described embodiments. Without departing from the spirit and scope of the present disclosure, the present disclosure may also have various changes and modifications, and these changes and modifications all fall within the scope of the present disclosure.

Claims

1. A polyurethane fire retardant coating composition, which is obtained by reacting at least the following components: The first component comprises at least one polyether polyol; at least one filler F; and at least one flame retardant; and a second component comprising at least one polyisocyanate; Characterized in that the polyether polyol contains at least 10 wt% of ethylene oxide based on the total weight of alkylene oxide in the polyether polyol; Based on the total weight of the polyurethane fire retardant coating composition, the content of the flame retardant is 30 wt% or more; and Based on the total weight of the polyurethane fire retardant coating composition, the content of the filler F is 18wt%-40wt%; further, based on the total weight of the filler F, the filler F contains at least 20wt% of filler F1 with a melting point below 950°C.

2. The polyurethane fire retardant coating composition according to claim 1, characterized in that: Based on the total weight of the filler F, the filler F comprises at least 50 wt % of a filler F1 having a melting point of 950° C. or less.

3. The polyurethane fire retardant coating composition according to claim 1, characterized in that The isocyanate index of the polyurethane fire retardant coating composition is 200-500, preferably 250-400.

4. The polyurethane fire retardant coating composition according to claim 1, characterized in that: The average functionality of the polyether polyol is 2 to 4; the number average molecular weight of the polyol is 1000-10000 g / mol, preferably 2000-6000 g / mol.

5. The polyurethane fire retardant coating composition according to claim 1, characterized in that: The filler F is one or more selected from the following: nitrides, metal oxides, metal hydroxides, ceramics and / or mineral salts.

6. The polyurethane fire retardant coating composition according to claim 1, characterized in that: The filler F is one or more selected from the following: mica, talc, clay, magnesium calcium carbonate, calcium carbonate, calcium sulfate, calcium silicate, barium sulfate, silicon dioxide, aluminum hydroxide, magnesium hydroxide, aluminum oxide, silicon oxide, calcium oxide, titanium dioxide, magnesium oxide, zinc oxide, aluminum nitride, boron nitride, silicon nitride, hollow glass, ceramic microspheres, vermiculite, diatomaceous earth, wollastonite, glass fiber, ceramic fiber, basalt fiber and / or silicate.

7. The polyurethane fire retardant coating composition according to claim 1, characterized in that: The filler F1 with a melting point of 950° C. or less is one or more selected from glass powder, glass fiber, borate, and metal oxide.

8. The polyurethane fire retardant coating composition according to claim 1, characterized in that: The flame retardant is one or more selected from acid source flame retardants, carbon source flame retardants and intumescent flame retardants.

9. The polyurethane fire retardant coating composition according to claim 1 or 2, characterized in that: The first component further comprises a chain extender, a cross-linking agent, a catalyst, a polymerization inhibitor and / or a defoaming agent.

10. The polyurethane fire retardant coating composition according to claim 1 or 2, characterized in that: The polyurethane fire retardant coating composition further comprises a water scavenger.

11. The polyurethane fire retardant coating composition according to claim 1 or 2, characterized in that: The polyurethane fire retardant coating composition does not contain a foaming agent.

12. The polyurethane fire retardant coating composition according to claim 1 or 2, characterized in that: The mixing ratio of the first component to the second component is 0.5:1 to 4:

1.

13. A composite material comprising substrate; and The polyurethane coating prepared by the polyurethane fire retardant coating composition according to any one of claims 1 to 13 is coated on at least a portion of the surface of the substrate, and the thickness of the polyurethane coating is 0.5-2 mm, preferably 0.8-1.5 mm.

14. The composite material according to claim 14, characterized in that The density of the polyurethane coating is 1.2-2.1 g / cm 3 .

15. The composite material according to claim 15, characterized in that According to DIN 53504, the tensile strength of the polyurethane coating is greater than 4 MPa.

16. The composite material according to claim 15, characterized in that According to ISO 2813, the bonding strength of the polyurethane coating is grade 0.

17. A battery product, characterized in that: The battery article is at least partially coated with the polyurethane fire retardant coating composition according to any one of claims 1 to 13.

18. The battery product according to claim 18, characterized in that The battery product is a battery shell, a battery cell, a battery module or a battery pack.

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