Polyurethane composite material as well as preparation process and application thereof

Abstract

The invention provides a polyurethane composite material. The polyurethane composite material comprises 30-60% by volume of reinforcing fibers and 40-70% by volume of polyurethane cured resin, the polyurethane cured resin is obtained from a polyurethane composition comprising the following components: a component A) comprising one or more organic polyisocyanates; the component B) comprises B1) one or more organic polyols, and the content of the organic polyols is 1-60 wt.%; b2) one or more compounds with the structure of formula (I); the content of the component B2 is 1 to 50 weight percent; component C) a free radical initiator; a component D), a flame retardant; component E), an internal release agent, which is a condensation product having an ester group, formed from one or more fatty acids having 10 to 40 carbon atoms or derivatives thereof with one or more monoalcohols and / or polyols. The polyurethane composite material provided by the invention has enough operation time and shorter demolding time, and can be used in the application field with high requirements on damp-heat aging resistance.

Description

Technical Field

[0001] The invention relates to a polyurethane composite material and a preparation process and application thereof. Background Art

[0002] Traditional polyurethane formulas react quickly and have short working time, while polyurethane formulas with long working time have long curing time. When producing products with high temperature resistance requirements, higher mold temperatures are required, which further shortens the working time, making this problem more prominent.

[0003] In order to solve the above problems, most polyurethane formulations will sacrifice curing time to extend the operating window, or reduce mold temperature to extend the operating time. These methods are difficult to apply to thin-sized products with temperature resistance requirements, such as new energy electric vehicle battery shells, resulting in thin-sized products made of polyurethane composite materials having different performance properties compared with other materials (such as epoxy resin), such as resistance to moisture and heat aging.

[0004] CN106232671A discloses a composite formula composition of polyurethane, which includes two or more thermosensitive catalysts, but does not involve improvement of moisture and heat aging resistance, and is not suitable for thin-size products with temperature resistance requirements.

[0005] CN110922554A discloses a polyurethane composite material, which is prepared by VARTM and HP-RTM processes. The polyurethane composition includes reactive and non-reactive flame retardants (ratio 1 to 3:1) and metal thermosensitive catalysts. In this patent application, when the mold temperature reaches 80°C, the operable time becomes significantly shorter, which cannot meet the operational requirements of high temperature resistant products, and the long-term resistance to wet heat aging also needs to be improved.

[0006] CN112011027A uses at least one metal thermosensitive catalyst, reactive and non-reactive flame retardants (ratio 1 to 4:1) to form a formula to produce polyurethane composite materials. However, if it is used in HP-RTM process production, the operating window is narrow and the long-term moisture and heat aging resistance of the product needs to be improved.

[0007] CN114672149A discloses a foamed polyurethane composite material, which can be used as the upper cover of a battery pack. The polyurethane material in the polyurethane composite material is foam, which will increase the thickness of the battery shell product, and the air tightness is at risk, which is not conducive to the design of the battery pack, and does not involve the improvement of the long-term resistance to moisture and heat aging of the product.

[0008] Therefore, it is particularly important to develop a polyurethane formula that can balance sufficient operating time and shorter demolding time to obtain a polyurethane composite material with excellent resistance to moisture and heat aging and high temperature requirements to achieve continuous production. Summary of the invention

[0009] In one aspect, the present invention provides a polyurethane composite material comprising 30-60% by volume of reinforcing fibers and 40-70% by volume of a polyurethane curing resin, based on the total volume of the polyurethane composite material;

[0010] The polyurethane curing resin is obtained from a polyurethane composition comprising the following components:

[0011] Component A) comprising one or more organic polyisocyanates;

[0012] Component B) comprising:

[0013] B1) one or more organic polyols, the content of the organic polyol is 1-60wt.%, preferably 5-40wt.%, more preferably 10-35wt.%, based on the mass percentage of the total mass of components B) to F) in the polyurethane composition;

[0014] B2) one or more compounds having the structure of formula (I); the content of component B2) is 1-50wt.%, preferably 5-40wt.%, more preferably 10-35wt.%, based on the mass percentage of the total mass of components B) to F) in the polyurethane composition;

[0015]

[0016] Among them, R 1 is selected from hydrogen, methyl and ethyl; R 2 is selected from an alkylene group having 2 to 6 carbon atoms, 2,2-di(4-phenylene)-propane, 1,4-di(methylene)benzene, 1,3-di(methylene)benzene and 1,2-di(methylene)benzene; n is an integer selected from 1 to 6;

[0017] Component C), one or more free radical initiators;

[0018] Component D), one or more flame retardants;

[0019] Component E), one or more internal mold release agents, which are condensation products having ester groups, of one or more fatty acids having 10 to 40 carbon atoms or derivatives thereof and one or more monohydric and / or polyhydric alcohols; and

[0020] Optional component F), other additives.

[0021] On the other hand, the present invention provides a method for preparing a polyurethane composite material, which includes using processes such as pultrusion, vacuum infusion, hand lay-up, wet compression molding (WCM), high pressure resin transfer (HP-RTM), prepreg compression molding (PCM), sheet molding compound (SMC), bulk molding compound (BMC), winding, vacuum autoclave or injection molding to make the polyurethane composition impregnate reinforcing fibers and then cure them into a polyurethane curing resin.

[0022] On the other hand, the present invention further provides a battery pack cover, which includes the polyurethane composite material described in the present invention.

[0023] On the other hand, the present invention further provides a battery pack casing, which includes the polyurethane composite material described in the present invention.

[0024] On the other hand, the present invention further provides an automobile underbody guard plate, which comprises the polyurethane composite material of the present invention. DETAILED DESCRIPTION

[0025] General Definitions and Terminology

[0026] Unless otherwise indicated, all publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In the event of a conflict, the definitions provided herein shall prevail.

[0028] Unless otherwise stated, all percentages, parts, ratios, etc. are by weight. It will be appreciated by those skilled in the art that the sum of all components in the composition can be suitably 100%. When providing quantity, concentration or other values ​​or parameters as scope, preferred range or preferred upper limit and lower limit or specific value, it should be understood as specifically disclosing all ranges formed by paired values ​​from any upper limit range or preferred value and any lower limit range or preferred value, and no matter whether scope is disclosed individually. Unless otherwise stated, when numerical range is quoted herein, described scope refers to and includes its endpoints and integers and fractions in all such scopes.

[0029] The terms "about" and "approximately" when used with a numerical variable generally refer to the value of that variable and all values ​​of that variable are within experimental error (e.g., within a 95% confidence interval for the mean) or within ±10% of the specified value, or a wider range.

[0030] The term "optional" or "optionally" as used herein means that the event or situation described subsequently may or may not occur, and the description includes the occurrence of the event or situation and the non-occurrence of the event or situation, and also includes the situation where the content described subsequently is arbitrarily selected. For example, when the content of a certain ingredient in this article is 0%-5%, it means that the component can be optionally present, that is, it covers the situation of absence (0%) and presence (>0-5%).

[0031] The terms "include", "comprising", "having", "containing" or "involving" and other variations thereof herein are inclusive or open-ended and do not exclude other unlisted elements or method steps. It will be understood by those skilled in the art that the above terms such as "comprising" encompass the meaning of "consisting of". The expression "consisting of" excludes any element, step or ingredient not specified. The expression "consisting essentially of" means that the scope is limited to the specified elements, steps or ingredients, plus the optional presence of elements, steps or ingredients that do not substantially affect the basic and new features of the claimed subject matter. It should be understood that the expression "comprising" encompasses the expressions "consisting essentially of" and "consisting of". The term "selected from..." refers to one or more elements in the groups listed later, independently selected, and may include combinations of two or more elements therein.

[0032] As used herein, the terms "one or more" or "at least one" refer to one, two, three, four, five, six, seven, eight, nine or more.

[0033] The term "and / or" as used herein encompasses "and" and "or". A plurality of elements, components or steps defined with "and / or" represent any one of the elements, components or steps and any combination thereof. For example, A and / or B encompasses A, B and A+B; A, B and / or C encompasses A, B, C, A+B, A+C, B+C and A+B+C.

[0034] Unless otherwise specified, the terms "combination thereof", "any combination thereof" and "mixture thereof" mean a multi-component mixture of the elements, such as a mixture of two, three, four and up to the maximum possible multi-component mixture.

[0035] In addition, if the number of parts or components of the present invention is not indicated before, it means that there is no limit to the number of occurrences (or existence) of the parts or components. Therefore, it should be interpreted as including one or at least one, and the singular form of the parts or components also includes the plural form, unless the numerical value obviously represents the singular.

[0036] In this article, "multiple" or "several" means two or more, and there is no special requirement for which specific ones, unless otherwise clearly specified. Unless the context clearly indicates, "one" can include singular references as well as plural references.

[0037] Herein, the polyurethane cured resin refers to a resin obtained after the polyurethane composition is cured.

[0038] In the present invention, unless otherwise specified, the functionality and hydroxyl value of organic polyols refer to the average functionality and average hydroxyl value. The measurement method of hydroxyl value is ISO 14900-2010. The functionality of organic polyols refers to the value obtained by measuring according to the industry formula: functionality = hydroxyl value × molecular weight / 56100; wherein the molecular weight is measured by GPC high performance liquid chromatography.

[0039] The present invention provides a polyurethane composite material, which comprises 30-60 volume % of reinforcing fibers and 40-70 volume % of polyurethane curing resin, based on the total volume of the polyurethane composite material;

[0040] The polyurethane curing resin is obtained from a polyurethane composition comprising the following components:

[0041] Component A) comprising one or more organic polyisocyanates;

[0042] Component B) comprising:

[0043] B1) one or more organic polyols, the content of the organic polyol is 1-60wt.%, preferably 5-40wt.%, more preferably 10-35wt.%, based on the mass percentage of the total mass of components B) to F) in the polyurethane composition;

[0044] B2) one or more compounds having the structure of formula (I); the content of component B2) is 1-50wt.%, preferably 5-40wt.%, more preferably 10-35wt.%, based on the mass percentage of the total mass of components B) to F) in the polyurethane composition;

[0045]

[0046] Among them, R 1 is selected from hydrogen, methyl and ethyl; R 2 is selected from an alkylene group having 2 to 6 carbon atoms, 2,2-di(4-phenylene)-propane, 1,4-di(methylene)benzene, 1,3-di(methylene)benzene and 1,2-di(methylene)benzene; n is an integer selected from 1 to 6;

[0047] Component C), a free radical initiator;

[0048] Component D), flame retardant;

[0049] Component E), an internal mold release agent, which is a condensation product having an ester group, of one or more fatty acids having 10 to 40 carbon atoms or derivatives thereof and one or more monohydric and / or polyhydric alcohols; and

[0050] Optional component F), other additives.

[0051] In a preferred embodiment of the present invention, the polyurethane curing resin is obtained from a polyurethane composition comprising the following components:

[0052] Component A), one or more organic polyisocyanates;

[0053] Component B1) one or more organic polyols, the content of the organic polyol is 1-60wt.%, preferably 5-40wt.%, more preferably 10-35wt.%, based on the mass percentage of the total mass of components B) to F) in the polyurethane composition;

[0054] Component B2) one or more compounds having the structure of formula (I); the content of component B2) is 1-50wt.%, preferably 5-40wt.%, more preferably 10-35wt.%, most preferably 15-35wt.%, based on the total mass percentage of components B) to F) in the polyurethane composition;

[0055]

[0056] Among them, R 1 is selected from hydrogen, methyl and ethyl; R 2 is selected from an alkylene group having 2 to 6 carbon atoms, 2,2-di(4-phenylene)-propane, 1,4-di(methylene)benzene, 1,3-di(methylene)benzene and 1,2-di(methylene)benzene; n is an integer selected from 1 to 6; components B1) and B2) constitute component B);

[0057] Component C), a free radical initiator;

[0058] Component D), flame retardant;

[0059] Component E), an internal mold release agent, which is a condensation product having an ester group, of one or more fatty acids having 10 to 40 carbon atoms or derivatives thereof and one or more monohydric and / or polyhydric alcohols; and

[0060] Optional component F), other additives.

[0061] Component A) described in the present invention comprises at least one organic polyisocyanate. The organic polyisocyanate can be one or more of any pure aliphatic, alicyclic and aromatic polyisocyanates known for preparing polyurethane, preferably aromatic polyisocyanates. The organic polyisocyanate of the present invention is an isocyanate containing two or more isocyanate groups, and therefore includes diisocyanates and triisocyanates.

[0062] Aromatic polyisocyanates include, but are not limited to, phenylene diisocyanate (PDI), toluene diisocyanate (TDI), p-phenylene diisocyanate (PPDI), diphenylmethane diisocyanate (MDI), polyphenylmethane polyisocyanate (pMDI), 1,5-naphthalene diisocyanate (NDI), xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), polymers thereof and / or combinations thereof. The aromatic isocyanates include isomers thereof, for example, diphenylmethane diisocyanate (MDI) includes 4,4'-diphenylmethane diisocyanate, 2,4-diphenylmethane diisocyanate and mixtures thereof.

[0063] Pure aliphatic polyisocyanates include, but are not limited to, hexamethylene diisocyanate (HDI), pentamethylene diisocyanate (PDI), polymers thereof, or combinations thereof.

[0064] Alicyclic polyisocyanates include, but are not limited to, methylcyclohexyl diisocyanate (HTDI), 4,4'-dicyclohexylmethane diisocyanate (H 12 MDI), isophorone diisocyanate (IPDI), 1,4-cyclohexane diisocyanate (CHDI), polymers thereof or combinations thereof.

[0065] The functionality of the organic polyisocyanate that can be used in the present invention is preferably 2.0-3.5, particularly preferably 2.1-2.9, as determined by GPC. The viscosity of the organic polyisocyanate is preferably 5-700 mPa·s, particularly preferably 10-300 mPa·s, more preferably 100-300 mPa·s, as determined at 25°C according to DIN 53019-1-3.

[0066] The organic polyisocyanate can include polyisocyanate dimers, trimers, tetramers, pentamers, other polymers or combinations thereof. In a preferred embodiment of the present invention, the organic polyisocyanate of component A) can be selected from diphenylmethane diisocyanate (MDI), polyphenylmethane polyisocyanate (pMDI), polymers thereof, prepolymers thereof and combinations thereof.

[0067] Polyisocyanates of the present invention can also include liquefied MDI variants, which are modified MDIs known in the art, and which have a higher functionality than MDI. Common liquefied MDI can be a liquid product obtained by introducing urethane, allophanate, urea, biuret, carbodiimide, uretonimine and / or isocyanurate residues (residues) etc. into MDI, and combinations thereof.

[0068] The isocyanate NCO% content in the organic polyisocyanate of component A) of the present invention is preferably 5-33.6% by weight, more preferably 10-32% by weight, measured according to GB / T 12009.4-2016.

[0069] In a preferred embodiment of the present invention, component A) is composed of one or more organic polyisocyanates. That is, in this preferred embodiment, component A) contains only organic polyisocyanate components and does not include additives.

[0070] Isocyanate-terminated prepolymers can also be used as component A) organic polyisocyanates, which can be prepared by reacting an excess of polyisocyanates or a combination thereof with a polyol compound, wherein the molar ratio of isocyanate groups NCO in the polyisocyanate to hydroxyl groups OH in the polyol is preferably 2 to 4: 1. Those skilled in the art are familiar with these compounds and their preparation methods.

[0071] In the present invention, the organic polyisocyanate component A) may be composed of one or more polyisocyanates and / or isocyanate-terminated prepolymers.

[0072] In the present invention, the molar ratio of isocyanate NCO in component A) to hydroxyl OH in component B) is preferably 0.9:1-1.15:1.

[0073] In the present invention, the component B) includes component B1) one or more organic polyols and component B2) one or more compounds of formula (I).

[0074] In a preferred embodiment of the present invention, the component B) consists of component B1) and component B2).

[0075] The content of the one or more organic polyols in B1) is 1-60 wt.%, preferably 5-40 wt.%, more preferably 10-35 wt.%, based on the total mass of components B) to F) in the polyurethane composition.

[0076] The organic polyol may be an organic polyol commonly used in the art for preparing polyurethane, including but not limited to: polyether polyol, polyether carbonate polyol, polyester polyol, polymer polyol, plant oil-based polyol and / or a combination thereof.

[0077] The functionality of the organic polyol is preferably 1.7-6, more preferably 1.9-4.5, measured according to ISO 14900-2010. The hydroxyl value of the organic polyol is preferably 100-2000 mgKOH / g, more preferably 200-2000 mgKOH / g, measured according to ISO 14900-2010.

[0078] The polyether polyol can be prepared by a known process, for example, by reacting an olefin oxide with an initiator in the presence of a catalyst. The catalyst is preferably, but not limited to, one or more of an alkaline hydroxide, an alkaline alkoxide, antimony pentachloride, boron fluoride etherate and a mixture thereof. The olefin oxide is preferably, but not limited to, tetrahydrofuran, ethylene oxide, propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide, styrene oxide, or a mixture thereof.

[0079] In one embodiment of the present invention, the oxidized olefin is an alkylene oxide, preferably an alkylene oxide having 2 to 6 carbon atoms, more preferably one or more of ethylene oxide, propylene oxide and tetrahydrofuran.

[0080] The initiator can be adjusted according to the properties of the polyether polyol such as functionality and viscosity, and is preferably, but not limited to, polyols and / or polyamines, and more preferably polyols. The polyols may include, but are not limited to, sorbitol, sucrose, 1,3-propylene glycol, glycerol, ethylene glycol, 1,2-propylene glycol, diethylene glycol, trimethylolpropane, bisphenol A, bisphenol S, or a combination thereof, preferably sucrose, propylene glycol, sorbitol, glycerol, or a combination thereof.

[0081] The polyamine may include, but is not limited to, ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, diethylenetriamine, toluenediamine, meta-phenylenediamine or a combination thereof, preferably meta-phenylenediamine and / or ethylenediamine.

[0082] Polyether polyols also include embodiments of two or more different polyether polyols. This is also the case within the polyol class. Thus, if, for example, "polyether polyol" (or "polyester polyol", etc.) is mentioned below, the term also includes embodiments in which two or more different polyether polyols (or two or more different polyester polyols, etc.) are used in the production of the polyurethane.

[0083] The viscosity of the polyether polyol of the present invention may be 5-20000 mPa·s, measured according to DIN53019-1-3 at 25° C. The number average molecular weight of the polyether polyol may be 50-18000 g / mol, preferably 50-6000 g / mol, measured by gel permeation chromatography.

[0084] The polyether carbonate polyols can also be used in the present invention, which can be prepared by addition of carbon dioxide and an alkylene oxide to a starter containing active hydrogen using a double metal cyanide catalyst.

[0085] In one embodiment, component B1) can also optionally include polyester polyols. The polyester polyol can be an aliphatic and / or aromatic polyester polyol, preferably an aromatic polyester polyol. Polyester polyols can be prepared by reacting dicarboxylic acids or dicarboxylic anhydrides with polyols. The dicarboxylic acids include but are not limited to aliphatic carboxylic acids containing 2-12 carbon atoms, and the aliphatic carboxylic acids containing 2-12 carbon atoms include but are not limited to succinic acid, malonic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, dodecyl carboxylic acid, maleic acid, fumaric acid and / or combinations thereof. The dicarboxylic acids can also include but are not limited to aromatic carboxylic acids containing 6-12 carbon atoms, including but not limited to phthalic acid, isophthalic acid, terephthalic acid and / or combinations thereof. The dicarboxylic anhydrides include but are not limited to phthalic anhydride, tetrachlorophthalic anhydride, maleic anhydride and / or combinations thereof. The polyols reacted with dicarboxylic acids or dicarboxylic anhydrides include, but are not limited to, ethylene glycol, diethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, dipropylene glycol, 1,3-methylpropanediol, 1,4-butylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 1,10-decanediol, glycerol, trimethylolpropane and / or combinations thereof. Polyester polyols may also include polyester polyols prepared from lactones. The polyester polyols prepared from lactones are preferably, but not limited to, ε-caprolactone.

[0086] The polyester polyol may also include polycarbonate polyol, preferably but not limited to polycarbonate diol. The polycarbonate diol may be prepared by reacting a diol with a dialkyl or diaryl carbonate or phosgene. The diol may preferably but not limited to 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, trioxymethylene glycol and / or a combination thereof. The dialkyl or diaryl carbonate may preferably but not limited to diphenyl carbonate.

[0087] Preferably, the viscosity of the polyester polyol may be 200-3000 mPa·s, preferably 500-3000 mPa·s, measured at 25° C. according to DIN 53019-1-3.

[0088] Preferably, the functionality of the polyester polyol is 2-6, preferably 2-4, more preferably 2-3.

[0089] Preferably, the polyester polyol has a hydroxyl value of 100-400 mgKOH / g, preferably 200-350 mgKOH / g, determined according to ISO 14900-2010.

[0090] The polymer polyol can be a polymer-modified polyether polyol, preferably a grafted polyether polyol and / or a polyether polyol dispersion. The grafted polyether polyol is preferably a grafted polyether polyol based on styrene and / or acrylonitrile; the styrene and / or acrylonitrile can be prepared by in-situ polymerization of styrene, acrylonitrile, or a mixture of styrene and acrylonitrile; in the mixture of styrene and acrylonitrile, the ratio of styrene to acrylonitrile is 90:10-10:90, preferably 70:30-30:70. The polymer polyol of the present invention can also be a bio-based polyol such as castor oil and wood tar. The polymer polyether polyol dispersion includes a dispersed phase, for example, a base-free filler, polyurea, polyhydrazide, a polyurethane containing a bonded tertiary amino group and / or melamine. The amount of the dispersed phase is 1-50wt.%, preferably 1-45wt.%, based on 100wt.% of the weight of the polymer polyether polyol. Preferably, the polymer solid content in the polymer polyether polyol is 20 wt.%-45 wt.%, based on 100% weight of the polymer polyether, and the hydroxyl value is 20-50 mgKOH / g, as determined according to ISO 14900-2010.

[0091] When used in the present invention, the polyol based on vegetable oil includes vegetable oil, vegetable oil polyol or its modified product. Vegetable oil is a compound prepared from unsaturated fatty acids and glycerol or extracts oil from the fruit, seed, germ of the plant, preferably but not limited to peanut oil, soybean oil, linseed oil, castor oil, rapeseed oil, palm oil. The vegetable oil polyol is a polyol initiated by one or more vegetable oils. The initiator of the synthetic vegetable oil polyol includes but is not limited to soybean oil, palm oil, peanut oil, canola oil and castor oil. The initiator of the vegetable oil polyol can introduce hydroxyl groups through processes such as cracking, oxidation or transesterification, and then prepare the corresponding vegetable oil polyol through the process for preparing organic polyols well known to those skilled in the art.

[0092] In an embodiment of the present invention, the component B) further comprises component B2) one or more compounds having the structure of formula (I).

[0093]

[0094] Among them, R 1 is selected from hydrogen, methyl and ethyl; R 2 Selected from alkylene groups having 2 to 6 carbon atoms, 2,2-di(4-phenylene)-propane, 1,4-di(methylene)benzene, 1,3-di(methylene)benzene and 1,2-di(methylene)benzene; n is an integer selected from 1-6.

[0095] In a preferred embodiment of the present invention, R 2 Selected from ethylene, propylene, butylene, pentylene, 1-methyl-1,2-ethylene, 2-methyl-1,2-ethylene, 1-ethyl-1,2-ethylene, 2-ethyl-1,2-ethylene, 1-methyl-1,3-propylene, 2-methyl-1,3-propylene, 3-methyl-1,3-propylene, 1-ethyl-1,3-propylene, 2-ethyl-1,3-propylene, 3-ethyl-1,3-propylene, 1-methyl-1,4-butylene, 2-methyl-1,4-butylene, 3-methyl-1,4-butylene and 4-methyl-1,4-butylene, 2,2-bis(4-phenylene)-propane, 1,4-dimethylenebenzene, 1,3-dimethylenebenzene and 1,2-dimethylenebenzene.

[0096] In the present invention, the compound of formula (I) is preferably selected from one or more of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, hydroxybutyl acrylate, and trimethylolpropane triacrylate; preferably hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate and / or a combination thereof.

[0097] The compound of formula (I) can be prepared by a commonly used method in the art, for example, by reacting (meth)acrylic anhydride or (meth)acrylic acid, (meth)acrylic acid halide with HO-(R 2 O) n -H is prepared by esterification reaction, and the preparation method is well known to those skilled in the art, such as the description in Chapter 3 of Handbook of Polyurethane Raw Materials and Additives (published by Liu Yijun on April 1, 2005) and Chapter 2 of Polyurethane Elastomers (published by Liu Houjun in August 2012), the entire contents of which are incorporated herein by reference.

[0098] In the present invention, the content of the one or more compounds of formula (I) described in B2) is 1-50 wt.%, preferably 5-40 wt.%, more preferably 10-35 wt.%, based on the total weight of the polyurethane composition.

[0099] In the present invention, the polyurethane composition further comprises component C) a free radical initiator. The free radical initiator includes, but is not limited to, peroxides, persulfides, peroxycarbonates, peroxyboric acid, azo compounds or other suitable free radical initiators that can initiate the curing of double bond-containing compounds, preferably tert-butyl oxyisopropyl carbonate, tert-butyl peroxy-3,5,5-trimethylhexanoate, methyl ethyl ketone peroxide and / or cumene hydroperoxide.

[0100] The content of the free radical initiator is usually 0.1-8wt.%, preferably 1-4wt.%, based on the mass percentage of the total mass of components B) to F). The free radical initiator used in the present invention can be optionally added together with component A) and / or component B), preferably added together with component B), and can also be added as an independent component to the mixture formed by component A) and component B).

[0101] In the present invention, the polyurethane composition further comprises component D) one or more flame retardants to achieve a flame retardancy rating of UL94 V-0.

[0102] The flame retardant may be any conventional flame retardant in the art, including but not limited to reactive flame retardant D1) and / or additive flame retardant D2).

[0103] The reactive flame retardant D1) is a flame retardant that allows the flame retardant component to be chemically bonded to the polyurethane material. The reactive flame retardant can be various liquid or solid flame retardant polyols containing phosphorus, nitrogen and / or halogen, including but not limited to tris(dipropylene glycol) phosphite (P430), tris(polyoxyalkylene) phosphate, tris(polyoxyalkylene) phosphite, N,N-bis(2-hydroxyethyl)aminomethylphosphonic acid dimethyl ester, tris(cyanide polyol) phosphate dibromopentanediol polyether polyol solution, brominated pentaerythritol and tetrabromophthalic anhydride diol, preferably one or more of tetrabromophthalic anhydride diol.

[0104] The additive flame retardant D2) refers to a flame retardant having a flame retardant effect but not participating in the polyurethane reaction, including but not limited to one or more of halogenated phosphate flame retardants, phosphonate flame retardants and inorganic solid flame retardants. The halogenated phosphate flame retardant can be selected from one or more of tris(2-chloropropyl) phosphate (TCPP), tris(2-chloroethyl) phosphate (TCEP), tris(dichloropropyl) phosphate (TDCPP), tris(dibromopropyl) phosphate, tetra(2-chloroethyl) ethylene diphosphate, bis[di(2-chloroethyl)] diethylene glycol phosphate, 2,2-dimethyl-3-chloropropyl bis(1,3-dichloro-2-propyl) phosphate, 2,2-dimethyl-3-bromo-propyl-β-bromoethyl phosphate and dimerization and polyphosphates. The phosphonate flame retardant can be selected from one or more of dimethyl methylphosphonate (DMMP), diethyl ethylphosphonate, dimethyl propylphosphonate, triisopropylphenyl phosphate and triethyl phosphate. The inorganic solid flame retardant can be selected from one or more of melamine and its derivatives, red phosphorus and its complexes, aluminum hydroxide powder and the like. The non-reactive flame retardant is preferably triethyl phosphate and / or tris(2-chloropropyl) phosphate.

[0105] In a preferred embodiment of the present invention, the component D) includes a reactive flame retardant D1) and an additive flame retardant D2), wherein the mass ratio of D1) to D2) is preferably (0.1-2):1, more preferably 0.8-2:1.

[0106] In a preferred embodiment of the present invention, the component D) is a mixture of a reactive flame retardant D1) and an additive flame retardant D2), wherein the mass ratio of D1) to D2) is preferably (0.1-2):1.

[0107] In a preferred embodiment of the present invention, the component D) comprises a reactive flame retardant D1) and an additive flame retardant D2), wherein the reactive flame retardant D1) is selected from tetrabromophthalic anhydride diol, and the additive flame retardant D2) is selected from tris(2-chloropropyl) phosphate; preferably, the mass ratio of D1) to D2) is (0.1-2):1.

[0108] The flame retardant is preferably used in an amount of 10-50 wt.%, calculated as a mass percentage based on the total mass of components B) to F).

[0109] The polyurethane composition of the present invention further comprises component E), one or more internal mold release agents, which are condensation products with ester groups, formed by one or more fatty acids or derivatives thereof with 10 to 40 carbon atoms and one or more monohydric alcohols and / or polyols. The condensation products with ester groups preferably have a number average molecular weight of 250-50000 g / mol, an acid value of less than 5 mg KOH / g, a hydroxyl value of 28-112 mg KOH / g, and a functionality of 1-4, wherein the hydroxyl value is determined according to ISO14900-2010 and the acid value is determined according to GB / T 12008.5-2010. The fatty acid may be a saturated fatty acid and / or an unsaturated fatty acid containing a carbon-carbon double bond, and the fatty acid may be a monoacid and / or a polyacid, and may include oleic acid, lauric acid, stearic acid, myristic acid, palmitoleic acid and / or ortho-eicosanoic acid, etc. The polyol preferably has a functionality of 1.5-6. The polyol preferably has a number average molecular weight less than or equal to 500 g / mol. The monohydric alcohol and / or polyhydric alcohol preferably is pentaerythritol, ethylene glycol, propylene glycol, butylene glycol, glycerol, diethylene glycol and / or sorbitol.

[0110] The internal mold release agent is prepared from the fatty acid and the monohydric alcohol and / or polyhydric alcohol by esterification, for example by heating the starting materials to a temperature of up to 220° C., preferably up to 180° C., in the presence of a catalytic amount of a Lewis acid or Bronsted acid, for example sulfuric acid, p-toluenesulfonic acid, tin dichloride or titanium tetrabutoxide, at a pressure of about 1000 to 0.1 mbar, while removing the water formed in the condensation reaction.

[0111] In an embodiment of the present invention, the polyurethane composition may also optionally include component F) other additives, and the other additives refer to other additives other than flame retardants, free radical initiators, and internal mold release agents. Optional examples include catalysts, catalysts for catalyzing the reaction of isocyanate groups (NCO) with hydroxyl groups (OH). Suitable catalysts for polyurethane reactions are preferably, but not limited to, amine catalysts, organometallic catalysts, and / or mixtures thereof. The amine catalysts are preferably, but not limited to, triethyldiamine (DABCO), tributylamine, triethylenediamine, N-ethylmorpholine, N,N,N',N'-tetramethyl-ethylenediamine, pentamethyldiethylene-triamine, N,N-methylaniline, N,N-dimethylaniline, and / or mixtures thereof. The organometallic catalysts are preferably, but not limited to, organotin compounds, such as tin acetate (II), tin octoate (II), tin ethylhexanoate, tin laurate, dibutyltin oxide, dibutyltin dichloride, dibutyltin diacetate, dibutyltin maleate, dioctyltin diacetate, and / or mixtures thereof. The amount of the catalyst used is preferably 0.0001-10 wt.%, more preferably 0.001-3 wt.%, based on the total mass of component B) to component F).

[0112] In an embodiment of the present invention, component F) may also include, but is not limited to, fillers, smoke suppressants, dyes, pigments, antistatic agents, antioxidants, UV stabilizers, diluents, defoamers, coupling agents, surface wetting agents, leveling agents, dewatering agents, molecular sieves, thixotropic agents, plasticizers, foaming agents, foam stabilizers, foam leveling agents, free radical reaction inhibitors and / or combinations thereof, which components may be optionally added together with component A) and / or component B), or may be added as independent ingredients to a mixture of component A) and component B), preferably added together with component B).

[0113] The antioxidant can effectively inhibit or reduce the thermal oxidation and photooxidation reaction speed of polyurethane, significantly improve the heat resistance and light resistance of polyurethane composite materials, delay their degradation and aging process, and thus extend the life of polyurethane composite materials. Conventional antioxidants in the art can be used, including but not limited to hindered phenol antioxidants, amine antioxidants, thio antioxidants and phosphate antioxidants.

[0114] In some embodiments of the present invention, the filler is selected from aluminum hydroxide, bentonite, fly ash, wollastonite, perlite powder, floating beads, calcium carbonate, talc, mica powder, porcelain clay, fumed silica, expandable microspheres, diatomaceous earth, volcanic ash, barium sulfate, calcium sulfate, glass microspheres, stone powder, wood powder, sawdust, bamboo powder, bamboo dust, rice grains, straw debris, sorghum stalk debris, graphite powder, metal powder, thermosetting composite material recycled powder, plastic particles or powder or a combination thereof. The glass microspheres can be solid or hollow.

[0115] Other additives that can be used in the present invention may also include dewatering agents, such as molecular sieves; defoaming agents, such as polydimethylsiloxane; coupling agents, such as monoethylene oxide or organic amine functionalized trialkoxysilane or a combination thereof, the coupling agent being particularly preferred for improving the adhesion between the resin matrix and the fiber-reinforced fibers; fine particle fillers, such as clay and fumed silica, which are often used as thixotropic agents.

[0116] In the present invention, the content of the component F) can be selected according to the conventional addition amount in the art, preferably 0.2-60 wt.%, more preferably 2-45 wt.%, calculated as a mass percentage of the total mass of components B) to F).

[0117] In the present invention, the reinforcing fiber in the polyurethane composite material can be selected from glass fiber, carbon nanotube, carbon fiber, polyester fiber, natural fiber, aromatic polyamide fiber, nylon fiber, basalt fiber, boron fiber, silicon carbide fiber, asbestos fiber, whisker, hard particles, metal fiber and / or a combination thereof, preferably glass fiber and / or carbon fiber. The cross-sectional diameter of the glass fiber and / or carbon fiber is preferably 2-30 μm, more preferably 13-23 μm.

[0118] The reinforcing fibers described in the present invention can be present in the polyurethane composite material in the form of one or more of long fiber monofilaments, multiple strands of long fibers, fiber mats, fiber fabrics, fiber mats, short fibers and / or ground fibers. The form of the reinforcing fibers can be selected according to the specific composite material molding process, preferably one or more of fiber fabrics, fiber mats, long fiber monofilaments and short fibers, more preferably fiber fabrics, such as fiber cloth.

[0119] In a preferred embodiment of the present invention, the number of layers of the fiber fabric, fiber mat or fiber felt in the polyurethane composite material can be single-layer or multi-layer, which can be selected according to the application field of the polyurethane composite material, preferably 1-5 layers.

[0120] In the present invention, the reinforcing fibers may have a length of 0.4-5000 mm, preferably 0.4-3000 mm, or may be chopped fibers having a length of 0.4-50 mm, preferably 0.4-20 mm.

[0121] In the polyurethane composite material of the present invention, the content of the reinforcing fibers is preferably 30-60% by volume, more preferably 40-60% by volume, based on the volume percentage of the polyurethane composite material.

[0122] In the present invention, the thickness of the polyurethane composite material can be adjusted according to actual application requirements, preferably 0.5-10 mm, more preferably 0.5-4 mm.

[0123] The polyurethane composite material of the present invention may also include a core material for use with the polyurethane curing resin and the reinforcing fibers. The polyurethane composite material of the present invention may use a core material commonly used in the art, examples of which include but are not limited to polystyrene foam, such as Polyester PET foam; polyimide PMI foam; polyvinyl chloride foam; metal foam, such as metal foam available from Mitsubishi Corporation; balsa wood, etc.

[0124] On the other hand, the present invention provides a method for preparing the polyurethane composite material, which comprises the following steps: using pultrusion, vacuum infusion, hand lay-up, wet compression molding (WCM), high pressure resin transfer molding (HP-RTM), prepreg compression molding (PCM), sheet molding compound molding (SMC), bulk molding compound molding (BMC), winding molding, vacuum autoclave molding or injection molding, wherein the polyurethane composition is impregnated with reinforcing fibers and then cured to form a polyurethane curing resin.

[0125] In the present invention, the preparation method of the polyurethane composite material is preferably wet compression molding, high pressure resin transfer molding, prepreg compression molding, sheet molding compound molding or bulk molding compound molding, more preferably wet compression molding or high pressure resin transfer molding.

[0126] In a preferred embodiment of the present invention, the method for preparing the polyurethane composite material comprises preparing the polyurethane composite material by wet compression molding, specifically comprising:

[0127] (1) mixing components B)-F) and then mixing with component A), or mixing components A)-F) to obtain a polyurethane composition;

[0128] (2) pouring the obtained polyurethane composition onto dried reinforcing fibers to obtain a combination of the polyurethane composition and the reinforcing fibers, wherein the reinforcing fibers are one or more of fiber fabrics, fiber felts and fiber mats;

[0129] (3) placing the obtained polyurethane composition and reinforcing fiber into a mold, closing the mold and hot pressing, and then demolding;

[0130] Wherein, the temperature of the mold is preferably set to 80-160°C.

[0131] In a preferred embodiment of the present invention, the method for preparing the polyurethane composite material comprises preparing the polyurethane composite material by high pressure resin transfer molding, specifically comprising:

[0132] (1) laying reinforcing fibers and optional pre-placed inserts in a mold, and vacuum-sealing the mold; the reinforcing fibers are one or more of fiber fabrics, fiber felts, and fiber mats;

[0133] (2) mixing components B) to F) to obtain a mixture, mixing the mixture with component A) under pressure and injecting the mixture into the mold;

[0134] (3) impregnating the reinforcing fiber with the polyurethane composition, and demoulding after curing;

[0135] Wherein, the temperature of the mold is preferably set to 80-160°C.

[0136] In a preferred embodiment of the present invention, the method for preparing the polyurethane composite material comprises preparing the polyurethane composite material by compression molding of prepreg, specifically comprising:

[0137] (1) mixing components B)-F) and then mixing with component A), or mixing components A)-F) to obtain a polyurethane composition;

[0138] (2) impregnating the reinforcing fiber with the polyurethane composition to obtain a prepreg, wherein the reinforcing fiber is one or more of a fiber felt, a fiber mat, a fiber fabric, a long fiber monofilament, and a plurality of long fibers;

[0139] (3) Place the prepreg into a mold, apply pressure to fill the mold with the prepreg, and demould after curing.

[0140] In a preferred embodiment of the present invention, the method for preparing the polyurethane composite material comprises preparing the polyurethane composite material by molding a sheet molding compound, specifically comprising:

[0141] (1) mixing components B)-F) and then mixing with component A), or mixing components A)-F) to obtain a polyurethane composition;

[0142] (2) impregnating the reinforcing fibers with the polyurethane composition to obtain a pretreated molded sheet, wherein the reinforcing fibers are one or more of fiber felt, fiber mat and fiber fabric;

[0143] (3) placing the pretreated molded sheet into a mold, heating and pressurizing the pretreated molded sheet to solidify it and then demolding it.

[0144] In a preferred embodiment of the present invention, the method for preparing the polyurethane composite material comprises preparing the polyurethane composite material by using a bulk molding compound, specifically comprising:

[0145] (1) mixing components B)-F) and then mixing with component A), or mixing components A)-F) to obtain a polyurethane composition;

[0146] (2) mixing the polyurethane composition with the reinforcing fibers to form a pelletized prepreg, wherein the reinforcing fibers are chopped fibers;

[0147] (3) placing the lump prepreg into a mold, heating and pressurizing the lump prepreg to solidify and shape it, and then demoulding it.

[0148] The polyurethane composite material of the present invention can be applied to various fields requiring thin-layer composite materials, such as battery pack housings of electric vehicles, vehicle underbody panels, etc. The battery pack is preferably a battery pack of an electric vehicle, which includes at least one battery module.

[0149] Therefore, the present invention also provides a battery pack cover, which includes the polyurethane composite material of the present invention. The battery pack is preferably a battery pack of an electric vehicle, which includes at least one battery module.

[0150] The present invention also provides a battery pack housing, which comprises the polyurethane composite material of the present invention. The battery pack is preferably a battery pack of an electric vehicle, which comprises at least one battery module.

[0151] The present invention also provides an automobile bottom guard plate, which comprises the polyurethane composite material of the present invention.

[0152] In a preferred embodiment of the present invention, the battery pack upper cover, battery pack outer shell or automobile underbody guard plate is prepared by the preparation method of the polyurethane composite material described in the present invention.

[0153] Beneficial Effects

[0154] The polyurethane composite material of the present invention can better balance sufficient operation time and shorter curing time / demolding time by optimizing the polyurethane composition formula, and can be better applied to the preparation process of thin-layer composite materials and realize continuous production. The present invention also provides a battery pack shell, an upper cover and an automobile underbody guard plate. The shell, upper cover and underbody guard plate made of the polyurethane composite material of the present invention can adopt a thin-layer processing technology that can be continuously produced, and solves the problem that the existing polyurethane formula is difficult to apply to this processing technology, and obtains a product with excellent resistance to moisture and heat aging. BRIEF DESCRIPTION OF THE DRAWINGS

[0155] Figure 1 The schematic diagram of the structure of the polyurethane composite material of the present invention, in which the polyurethane cured resin is not fully shown. 1-mold surface, 2-reinforcement fiber (glass fiber fabric), 3-resin-rich area.

[0156] Example

[0157] The present invention will be further described below in conjunction with specific examples. However, it should be understood that these examples are only used to illustrate the present invention and do not constitute a limitation to the scope of the present invention.

[0158] The test methods in the following examples without specifying specific conditions are usually carried out under conventional conditions or under conditions recommended by the manufacturer. Unless otherwise specified or conflicting, percentages and parts used herein are by weight.

[0159] Materials, instruments and test methods

[0160] Table 1

[0161]

[0162] The molecular weight was determined by GPC high performance liquid chromatography.

[0163] The functionality of a polyol refers to the value obtained by measuring the functional group according to the industry formula: functionality = hydroxyl value × molecular weight / 56100; wherein the molecular weight is measured by GPC high performance liquid chromatography.

[0164] The glass transition temperature is determined by means of DSC analysis (DSC Q20 differential scanning calorimeter from Twxasinstruments) in accordance with standard ISO 11357-2.

[0165] The flame retardancy was tested according to UL94 standard, and the thickness of the test sample was 1.5 mm.

[0166] Moisture-heat aging resistance test: The obtained polyurethane composite material was stored outdoors for one month, and then baked at 85°C for 40 hours to observe the changes in its appearance.

[0167] ++It means that there are no visible defects on the surface of the composite material in the resin-rich area and the surface is smooth and flat.

[0168] --Refers to defects visible to the naked eye on the surface of the composite material in the resin-rich area, including lack of glue, pinholes and texture.

[0169] Cure degree test: The degree of cure of the product was determined by DSC analysis (DSC Q20 differential scanning calorimeter from Twxas instruments) according to standard ISO11357-3. The specific operation is to first test the total amount of heat released by mixing the isocyanate component and the isocyanate reactive component until complete cure is achieved. T , take the cured resin sample without any treatment after demoulding and perform DSC test, and record the residual heat release E R , calculate the degree of curing according to the following formula.

[0170] Curing degree=(1-E T / E R )*100%

[0171] Table 2

[0172]

[0173] “ / ” The composite material in comparative example 3 failed the flame retardancy test, and therefore the moisture and heat aging resistance test was not performed; the demoulding property in comparative example 5 was poor, and the obtained composite material was deformed, which could not meet the needs of large-scale production.

[0174] Examples 1-3, Comparative Examples 1-6

[0175] All components were mixed to obtain a polyurethane composition according to the amounts of components listed in Table 2. The pre-cleaned mold was sprayed with Ewomold 5716 (from KVS) and external mold release agent Acmos 36-4570 (from Acmos Chemie), and three layers of glass fiber fabric were stacked in the automotive battery pack cover mold.

[0176] Through the wet compression molding process, the mold temperature is raised to 120°C, and then the polyurethane composition is vacuumed and degassed and introduced onto the fiber fabric to allow the polyurethane composition to fully flow and spread in the mold. The mold is closed and pressurized for 3 minutes (1000KN / m 2 ) after which the polyurethane composite material was demoulded to obtain the upper cover of the vehicle battery pack and tested. The results are listed in Table 2.

[0177] From the results in Table 2, it can be seen that the polyurethane formulas of Examples 1-3 can be used to prepare a battery pack cover with a thickness of 1.2 mm through a wet compression molding process, and have good resistance to moisture and heat aging, flame retardancy, demoulding, heat resistance, and the effect of curing in a short time. Comparative Example 1 failed to pass the moisture and heat aging resistance test, and a large number of defects were generated on the surface, which had a great impact on subsequent use; a degree of cure of less than 95% means that the curing time needs to be extended, resulting in a decrease in production efficiency. The composite material obtained in Comparative Example 4 has a glass transition temperature of less than 100°C and poor temperature resistance. The upper cover becomes soft and deformed during demolding. In Comparative Example 6, other types of internal release agents are selected, and the surface tension is significantly lower than the internal release agent selected in the present invention, which is not conducive to the subsequent bonding process.

[0178] Example 4

[0179] The pre-cleaned mold was sprayed with Ewomold 5716 (from KVS) and external mold release agent Acmos 36-4570 (from Acmos Chemie) respectively, and three layers of glass fiber fabric were stacked in the automobile underbody guard plate mold. According to the component amounts of Examples 1-3 listed in Table 2, all components were mixed to obtain a polyurethane composition.

[0180] The polyurethane composition is vacuum degassed and then injected into the mold under high pressure through a high-pressure resin transfer molding process to impregnate the glass fiber fabric with the polyurethane composition. The mold is closed and pressurized for 3 minutes (1000KN / m 2, the mold temperature is 120°C, and the polyurethane composite material is demoulded to obtain an automobile underbody guard plate (thickness 1.2 mm).

[0181] Although the specific embodiments of the present invention are described above, it should be understood by those skilled in the art that this is only for illustration and the protection scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A polyurethane composite material comprising 30-60% by volume of reinforcing fibers and 40-70% by volume of a polyurethane curing resin, based on the total volume of the polyurethane composite material; The polyurethane curing resin is obtained from a polyurethane composition comprising the following components: Component A) comprising one or more organic polyisocyanates; Component B) comprising: B1) one or more organic polyols, the content of the organic polyol is 1-60wt.%, preferably 5-40wt.%, more preferably 10-35wt.%, based on the mass percentage of the total mass of components B) to F) in the polyurethane composition; B2) one or more compounds having the structure of formula (I); the content of component B2) is 1-50wt.%, preferably 5-40wt.%, more preferably 10-35wt.%, based on the mass percentage of the total mass of components B) to F) in the polyurethane composition; Among them, R 1 is selected from hydrogen, methyl and ethyl; R 2 is selected from an alkylene group having 2 to 6 carbon atoms, 2,2-di(4-phenylene)-propane, 1,4-di(methylene)benzene, 1,3-di(methylene)benzene and 1,2-di(methylene)benzene; n is an integer selected from 1 to 6; Component C), a free radical initiator; Component D), flame retardant; Component E), an internal mold release agent, which is a condensation product having an ester group, of one or more fatty acids having 10 to 40 carbon atoms or derivatives thereof and one or more monohydric and / or polyhydric alcohols; and Optional component F), other additives.

2. The polyurethane composite material according to claim 1, characterized in that: The thickness of the polyurethane composite material is 0.5-10 mm, preferably 0.5-4 mm.

3. The polyurethane composite material according to claim 1 or 2, characterized in that: The functionality of the organic polyol is 1.7-6, and the hydroxyl value of the organic polyol is 150-2000 mgKOH / g, as determined according to ISO 14900-2010.

4. The polyurethane composite material according to any one of claims 1 to 3, characterized in that: The compound of formula (I) is selected from one or more of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, hydroxybutyl acrylate and trimethylolpropane triacrylate; preferably one or more of hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, hydroxyethyl acrylate and hydroxypropyl acrylate.

5. The polyurethane composite material according to any one of claims 1 to 4, characterized in that: The condensation product having an ester group has a number average molecular weight of 250-50000 g / mol, an acid value of less than 5 mgKOH / g, a hydroxyl value of 28-112 mgKOH / g and a functionality of 1-4; the fatty acid is preferably selected from oleic acid, lauric acid, stearic acid, myristic acid, palmitoleic acid and / or eicosanoic acid; the polyol preferably has a functionality of 1.5-6 and a number average molecular weight less than or equal to 500 g / mol; wherein the hydroxyl value is determined according to ISO14900-2010, and the acid value is determined according to GB / T 12008.5-2010.

6. The polyurethane composite material according to any one of claims 1 to 5, characterized in that: The flame retardant includes a reactive flame retardant D1) and / or an additive flame retardant D2); the reactive flame retardant D1) is selected from one or more of tris(dipropylene glycol)phosphite, tris(polyoxyalkylene)phosphate, tris(polyoxyalkylene)phosphite, N,N-di(2-hydroxyethyl)aminomethylphosphonic acid dimethyl ester, polyether polyol solution of tris(cyanide polyol)phosphate dibromopentanediol, brominated pentaerythritol and tetrabromophthalic anhydride diol, preferably tetrabromophthalic anhydride diol; the additive flame retardant D2) is selected from one or more of halogenated phosphate flame retardants, phosphonate flame retardants and inorganic solid flame retardants, preferably selected from tris(2-chloropropyl)phosphate , tris(2-chloroethyl) phosphate, tris(dichloropropyl) phosphate, tris(dibromopropyl) phosphate, tetrakis(2-chloroethyl)ethylene diphosphate, bis[di(2-chloroethyl)]diethylene glycol phosphate, 2,2-dimethyl-3-chloropropylbis(1,3-dichloro-2-propyl) phosphate, 2,2-dimethyl-3-bromo-propyl-β-bromoethyl phosphoric acid and dimerization, polyphosphate, dimethyl methylphosphonate, diethyl ethylphosphonate, dimethyl propylphosphonate, triisopropylphenyl phosphate, triethyl phosphate, melamine and its derivatives, red phosphorus and aluminum hydroxide, more preferably selected from triethyl phosphate and / or tris(2-chloropropyl) phosphate.

7. The polyurethane composite material according to claim 6, characterized in that: The component D) comprises a reactive flame retardant D1) and an additive flame retardant D2), wherein the mass ratio of D1) to D2) is preferably (0.1-2):

1.

8. The polyurethane composite material according to any one of claims 1 to 7, characterized in that: The molar ratio of isocyanate NCO in one or more organic polyisocyanates in component A) to hydroxyl OH in component B) is 0.9:1-1.15:1; and / or, the amount of the flame retardant is 10-50wt.%, based on the mass percentage of the total mass of components B) to F); and / or, the content of the free radical initiator is 0.1-8wt.%, preferably 1-4wt.%, based on the mass percentage of the total mass of components B) to F).

9. The polyurethane composite material according to any one of claims 1 to 8, characterized in that: The reinforcing fibers are long fiber monofilaments, multiple strands of long fibers, fiber mats, fiber fabrics, fiber felts, chopped fibers and / or ground fibers; and / or the number of layers of the fiber fabrics, fiber mats or fiber felts in the polyurethane composite material is 1-5.

10. A battery pack upper cover, a battery pack outer shell or an automobile underbody guard plate, comprising the polyurethane composite material according to any one of claims 1 to 9.

11. A method for preparing a polyurethane composite material according to any one of claims 1 to 9, comprising the following steps: pultrusion, vacuum infusion, hand lay-up, wet compression molding, high pressure resin transfer molding, prepreg compression molding, sheet molding compound molding, bulk molding compound molding, winding molding, vacuum autoclave molding or injection molding, preferably wet compression molding, high pressure resin transfer molding, prepreg compression molding, sheet molding compound molding or bulk molding compound molding, wherein the polyurethane composition is impregnated with reinforcing fibers and then cured to form a polyurethane curing resin.

12. A method for preparing the polyurethane composite material according to claim 11, characterized in that: The polyurethane composite material is prepared by wet compression molding, specifically comprising: (1) mixing components B)-F) and then mixing with component A), or mixing components A)-F) to obtain a polyurethane composition; (2) pouring the obtained polyurethane composition onto dried reinforcing fibers to obtain a combination of the polyurethane composition and the reinforcing fibers, wherein the reinforcing fibers are one or more of fiber fabrics, fiber felts and fiber mats; (3) placing the obtained polyurethane composition and reinforcing fiber into a mold, closing the mold and hot pressing, and then demolding; Wherein, the temperature of the mold is 80-160°C.

13. A method for preparing the polyurethane composite material according to claim 11, characterized in that: The polyurethane composite material is prepared by high pressure resin transfer molding, specifically comprising: (1) laying reinforcing fibers and optional pre-placed inserts in a mold, and vacuum-sealing the mold; the reinforcing fibers are one or more of fiber fabrics, fiber felts, and fiber mats; (2) mixing components B) to F) to obtain a mixture, mixing the mixture with component A) under pressure and injecting the mixture into the mold; (3) impregnating the reinforcing fiber with the polyurethane composition, and demoulding after curing; Wherein, the temperature of the mold is 80-160°C.

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