Polyurethane composition for polyurethane buffer block, polyurethane buffer block as well as preparation method and application of polyurethane buffer block

Abstract

The invention relates to a polyurethane composition for a polyurethane buffer block as well as a preparation method and application of the polyurethane composition. The polyurethane composition comprises an isocyanate component and an isocyanate reactive component, wherein the isocyanate reactive component comprises polyether polyol 1, polyether polyol 2, polymer polyol, a flame retardant, a chain extender, a cross-linking agent, a catalyst, a foaming agent and a surfactant; wherein the polyether polyol 1, the polyether polyol 2 and the polymer polyol are accurately matched, so that the balance between the strength and the elastic property of a polyurethane buffer block workpiece can be accurately regulated and controlled. The polyurethane buffer block disclosed by the invention can meet the complex performance requirements of compression resistance, flame retardance and the like of the side surface of a battery of a new energy automobile, can reduce the influence of collision of the automobile on a battery pack, greatly reduces the invasion amount of impact on the battery pack, reduces the thermal runaway risk when the battery pack is collided, and improves the safety of the automobile. The method is used for stably manufacturing the new energy automobile battery pack side buffer block.

Description

Technical Field

[0001] The invention relates to the field of polyurethane materials, in particular to a polyurethane composition for a new energy battery buffer block, a polyurethane buffer block and a preparation method and application thereof. Background Art

[0002] New energy is one of the strategic emerging industries planned by my country, which is of great significance to my country's green and sustainable development. The development prospects of new energy are very promising.

[0003] As new energy vehicles pursue longer driving range and higher energy density, fire accidents caused by thermal runaway caused by impact damage to power batteries frequently occur. On April 22, 2023, a new energy vehicle under repair at a car service center caught fire. The accident vehicle had suffered a serious impact on the chassis before, causing large-scale deformation of the left rear shell and cooling plate of the power battery pack. After a period of time, the internal structure of the battery pack was squeezed and short-circuited, eventually causing a fire.

[0004] It can be seen that the impact load buffering performance and flame retardant performance of the new generation of high energy density power batteries are key technical issues that need to be solved urgently, which restrict the development of new energy vehicles. In particular, the research and development of battery pack side buffer materials should meet performance indicators such as high strength, high toughness, high flame retardancy, high interval strength, and high elasticity, and also achieve rapid automation risks to reduce the impact of vehicle collisions on battery packs, greatly reduce the impact of battery packs on the amount of penetration, reduce the risk of thermal runaway when the battery pack collides, and improve the side collision protection performance, thereby further improving the safety of new energy vehicles.

[0005] At present, the domestic polyurethane buffer material technology for new energy batteries is still in a blank stage. The existing technical patents CN202121961499.4 and CN201921870473.1 are all improvements to the macro buffer structure, but lack the improvement of the performance of the material itself.

[0006] Comprehensively analyzing the material performance requirements and lightweight demands of new energy batteries, the polyurethane buffer block material of new energy batteries should have the characteristics of both rigid foam structure and elastomer, that is, it should have certain strength and compressive resistance to resist impact loads, and certain deformability to absorb impact energy. This is in obvious contradiction with the performance characteristics of the polyurethane foam material itself. On this basis, it must also have high flame retardant properties. Summary of the invention

[0007] In order to solve the problems existing in the prior art, the present invention provides a polyurethane composition for a polyurethane battery buffer block, and a polyurethane buffer block made of the same. The polyurethane battery buffer block has the characteristics of both rigid foam and elastomer, and has lightweight, excellent mechanical and flame retardant properties.

[0008] Another object of the present invention is to provide a preparation method and application of the polyurethane buffer block.

[0009] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solution:

[0010] A polyurethane composition for a polyurethane buffer block is obtained by comprising an isocyanate component and an isocyanate reactive component, wherein the isocyanate reactive component comprises a polyether polyol 1, a polyether polyol 2, a polymer polyol, a flame retardant, a chain extender, a crosslinking agent, a catalyst, a foaming agent, and a surfactant; wherein

[0011] The polyether polyol 1 has an average functionality of 2 to 5, preferably 3 to 4, and a hydroxyl value of 400 to 1100 mgKOH / g, for example 400 mgKOH / g, 500 mgKOH / g, 100 mgKOH / g, 700

[0012] : The present invention relates to a polyol having an ethylene oxide content of 70 to 100%, for example, 70%, 75%, 80%, 82%, 85%, 90%, 95%, 100%, etc., preferably 80 to 100% by weight, based on the total mass of propylene oxide and ethylene oxide as 100%. The polyether polyol 1 is a class of compounds formed by starting with polyols and polymerizing alkylene oxides. Examples of initiators include but are not limited to ethylene glycol, propylene glycol, 1,4-butanediol, dipropylene glycol, diethylene glycol, triethylene glycol, bisphenol A, glycerol, trimethylolpropane, diethanolamine, triethanolamine, ethylenediamine, toluenediamine, pentaerythritol, sorbitol, xylitol, sucrose or mixtures thereof. Alkylene oxide monomers may be block addition or random addition, preferably random addition.

[0013] The polyether polyol 2 has an average functionality of 1.5 to 3.5, preferably 2, and a hydroxyl value of 30 to 200 mgKOH / g, such as 40 mgKOH / g, 50 mgKOH / g, 60 mgKOH / g, 70 mgKOH / g, 80 mgKOH / g, 90 mgKOH / g, 100 mgKOH / g, 130 mgKOH / g, 150 mgKOH / g, 180 mgKOH / g, 200 mgKOH / g, etc., preferably 50 to 100 mgKOH / g; and is prepared by ring-opening copolymerization of tetrahydrofuran and propylene oxide.

[0014] The polymer polyol, i.e. the graft copolymer polyether polyol, has an average functionality of 2 to 4.5, such as 2, 2.5, 3, 3.5, 4, 4.5, etc., preferably 3, a hydroxyl value of 10 to 80 mgKOH / g, such as 10 mgKOH / g, 15 mgKOH / g, 20 mgKOH / g, 25 mgKOH / g, 30 mgKOH / g, 35 mgKOH / g, 40 mgKOH / g, 45 mgKOH / g, 50 mgKOH / g, 60 mgKOH / g, 70 mgKOH / g, 80 mgKOH / g, etc., preferably 15 to 50 mgKOH / g, and a solid content of 20 to 50 wt%, such as 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, etc., preferably 25 to 45 wt%. The polymer polyol refers to a type of graft copolymer polyol obtained by reacting a polyether polyol and a vinyl monomer, wherein the polyether polyol may be polyoxyethylene polyol, polyoxypropylene polyol, polyoxyethylene-oxypropylene copolymer polyol, etc. commonly used in the art, and the vinyl monomer may be acrylonitrile, styrene, vinylidene chloride, hydroxyalkyl acrylate, alkyl acrylate, etc., preferably acrylonitrile and / or styrene.

[0015] Based on the total mass of the isocyanate-reactive components, the amount of the polyether polyol 1 (A) is 15% to 25%, for example, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, etc., the amount of the polyether polyol 2 (B) is 20% to 41%, for example, 20%, 21%, 22%, 23%, 24%, 25%, 28%, 30%, 31%, 33%, 35%, 38%, 40%, 41%, etc., and the amount of the polymer polyol (C) is 8.7% to 16%, for example, 8.7%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, etc.

[0016] In a preferred embodiment, the amount of the polyether polyol 1 (A), the amount of the polyether polyol 2 (B) and the amount of the polymer polyol (C) all satisfy the following relationship:

[0017]

[0018] In some specific embodiments, the isocyanate component refers to a class of compounds having an isocyanate group, examples of which include but are not limited to toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), dicyclohexylmethane diisocyanate (HMDI), naphthalene diisocyanate (DI), p-phenylene diisocyanate (PPDI), 1,4-cyclohexane diisocyanate (CHDI), xylylene diisocyanate (XDI), cyclohexane dimethylene diisocyanate (XDI), trimethyl-1,6-hexamethylene diisocyanate (TMHDI), tetramethyl meta-xylylene diisocyanate (TMXDI), norbornane diisocyanate (NBDI), dimethyl biphenyl diisocyanate (TODI), methylcyclohexyl diisocyanate (HTDI), etc., as well as prepolymers, modified products, polymers, etc. of such monomers. Such isocyanate compounds can be used alone or in combination. Preferably, the NCO content of the isocyanate component is 20-34wt%, for example, 20wt%, 22wt%, 25wt%, 28wt%, 30wt%, 32wt%, 34wt%, etc., preferably 31wt%.

[0019] In some specific embodiments, the catalyst is a class of compounds that have catalytic activity towards isocyanates and active hydrogen atoms, examples of which include but are not limited to triethylamine, tributylamine, triethylenediamine, N-ethylmorpholine, N,N,N',N'-tetramethyl-ethylenediamine, pentamethyldiethylene-triamine, N,N-methylaniline, N,N-dimethylaniline, tin (II) acetate, tin (II) octoate, tin ethylhexanoate, tin laurate, dibutyltin oxide, dibutyltin dichloride, dibutyltin diacetate, dibutyltin maleate, dioctyltin diacetate, etc., which can be used alone or in combination.

[0020] In some specific embodiments, the foaming agent can be selected from physical foaming agents, chemical foaming agents, etc. commonly used in the art, including but not limited to water, monochlorodifluoromethane, monochloromonofluoromethane, dichlorodifluoromethane, trichlorofluoromethane, butane, pentane, cyclopentane, hexane, cyclohexane, heptane, air, CO2 and N2, preferably water.

[0021] In some specific embodiments, the surfactant includes, but is not limited to, for example, a main structure of a polysiloxane-oxyalkylene block copolymer, etc., which can be used alone or in combination. For example, the surfactant is an AB-type linear block, an ABA-type linear block structure, etc.

[0022] In some specific embodiments, the chain extender can be a chain extender commonly used in the art, such as diols, diamines, diphenols, etc. Examples include but are not limited to ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, butanediol, cyclohexanediol, methylamine, ethylamine, hydrogenated bisphenol A, hydroquinone, etc. Such chain extenders can be used alone or in combination.

[0023] In some specific embodiments, the cross-linking agent can be a cross-linking agent commonly used in the art, such as polyols, polyamines, etc. Examples include but are not limited to trimethylolpropane, propylene glycol, pentaerythritol, diethanolamine, triethanolamine, ethylenediamine, phenylenediamine, sorbitol, etc. Such cross-linking agents can be used alone or in combination.

[0024] In some specific embodiments, examples of the flame retardant include, but are not limited to, halogenated phosphate flame retardants, phosphate flame retardants, halogenated hydrocarbons and other halogen-containing flame retardants, melamine and its salts, reactive flame retardants, inorganic flame retardants, etc. Such flame retardants can be used alone or in combination.

[0025] In some specific embodiments, the molar ratio of isocyanate groups in the isocyanate component to active hydrogen atoms in the isocyanate reactive component is 90-120:100, for example, 90:100, 95:100, 100:100, 105:100, 110:100, 115:100, 120:100, etc., preferably 95-110:100.

[0026] In a preferred embodiment, based on the total mass of the isocyanate reactive component, the mass percentage of each component is:

[0027] The amount of polyether polyol 1 is 15-25%, for example, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, etc.;

[0028] The amount of polyether polyol 2 is 20-41%, for example, 20%, 21%, 22%, 23%, 24%, 25%, 28%, 30%, 33%, 35%, 37%, 40%, 41%, etc.;

[0029] The amount of polymer polyol is 8.7-16%, for example, 8.7%, 9%, 9.5%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, etc.;

[0030] The amount of foaming agent is 0.1-1%, for example, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, etc.;

[0031] The amount of flame retardant is 10% to 36%, for example, 10%, 12%, 15%, 18%, 20%, 23%, 25%, 28%, 30%, 32%, 35%, 36%, etc.;

[0032] The amount of catalyst is 0.1-0.8%, for example, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, etc.;

[0033] The amount of chain extender is 5-10%, for example, 5%, 6%, 7%, 8%, 9%, 10%, etc.;

[0034] The amount of cross-linking agent is 1% to 8%, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, etc.;

[0035] The amount of surfactant used is 0.1% to 0.8%, for example 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8% and the like.

[0036] In the present invention, the polyurethane composition comprising the isocyanate component, polyether polyol 1, polyether polyol 2, polymer polyol, flame retardant, chain extender, crosslinking agent, catalyst, foaming agent, surfactant and other components, when used to prepare polyurethane foam, has excellent flame retardant properties and meets the special compression resistance requirements of new energy vehicle battery packs, can reduce the impact of vehicle collisions on battery packs, greatly reduce the amount of impact intrusion into the battery pack, and reduce the risk of thermal runaway when the battery pack collides.

[0037] In another aspect of the present invention, the polyurethane composition is used to prepare a polyurethane buffer block, comprising the following steps:

[0038] 1) mixing and stirring the isocyanate component and stirring the isocyanate reactive component;

[0039] 2) The isocyanate component and the isocyanate reactive component are mixed evenly by a device and then injected into a buffer block mold for reaction. After the reaction is completed, the mold is opened to obtain a polyurethane buffer block.

[0040] In another aspect of the present invention, the density of the polyurethane buffer block prepared by the above method is 600-900 kg / m 3 , preferably 700~800kg / m 3 The pressure of the pouring machine is 100-180 bar, preferably 130-170 bar, the mold temperature is 30-90° C., preferably 40-60° C., and the holding time is 3-20 minutes, preferably 5-15 minutes.

[0041] In another aspect of the present invention, the polyurethane buffer block prepared by the aforementioned method or the application of the aforementioned polyurethane buffer block in new energy vehicles, especially in power battery packaging materials.

[0042] The specific components involved in the polyurethane battery buffer block of the present invention, such as polyols, additives, etc., can be used alone or in combination unless otherwise specified. In addition, the raw materials, processes, methods, parameters, etc. required for the preparation of each component, the parts not described or recorded can refer to the commonly used technology in the field, and will not affect the implementation of the present invention, such as the preparation of polyether polyols, the preparation of polyester polyols, the preparation of polymer polyols, the preparation of polyurethane battery buffer blocks, etc.

[0043] The "hydroxyl value" in the present invention, unless otherwise specified, refers to the average hydroxyl value of the component.

[0044] In the present invention, the polyether polyol 1 introduces a hard segment into the molecular structure, which provides the polyurethane foam with strength under early low deformation; the polyether polyol 2 is a ring-opening polymerization product of tetrahydrofuran and propylene oxide, which provides high elasticity for the polyurethane foam; the polymer polyol is initiated by glycerol, polymerized by propylene oxide, terminated by ethylene oxide, and grafted with styrene and acrylonitrile, which provides additional space for molecular chain movement and intermolecular interaction force, thereby improving the elasticity and strength of the polyurethane foam.

[0045] According to the special mechanical performance requirements of new energy vehicles for battery buffer blocks: the compressive strength under 10% deformation is 6-9MPa, the compressive strength under 30% deformation is 14-18MPa, and the compressive strength under 50% deformation is 30-36MPa. Although the single strength value is in the rigid foam range, it is obviously different from the performance trend of conventional polyurethane rigid foam materials after unified consideration.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] The polyurethane composition of the present invention can be used to prepare a polyurethane buffer block, and by adjusting the amount of each component, the strength and elasticity of the polyurethane foam buffer block can be balanced, and the above-mentioned mechanical performance requirements and complex performance requirements such as high flame retardancy can be fully met at the same time. It can reduce the impact of a vehicle collision on the battery pack, greatly reduce the impact of the battery pack, and reduce the risk of thermal runaway when the battery pack collides. DETAILED DESCRIPTION

[0048] The specific implementation scheme of the method is further described below in conjunction with examples. However, the present invention is not limited to the listed embodiments, and should also include any other known changes within the scope of the rights claimed by the present invention.

[0049] The raw materials used in the embodiments and comparative examples are as follows:

[0050] Isocyanate component, WANNATE 82681, NCO content 31 wt%, viscosity 200 mPa·s at 25°C, Wanhua Chemical;

[0051] Polyether polyol 1-1, glycerol-initiated, ethylene oxide homopolymerized, hydroxyl value 500 mgKOH / g;

[0052] Polyether polyol 1-2, starting with pentaerythritol, random copolymerization of propylene oxide and ethylene oxide, ethylene oxide content 85wt%, hydroxyl value 700mgKOH / g;

[0053] Polyether polyol 1-3, average functionality 3.5, pentaerythritol and glycerol co-initiator, propylene oxide and ethylene oxide random copolymerization, ethylene oxide content 80wt%, hydroxyl value 900mgKOH / g;

[0054] Polyether polyol 2-1, average functionality 2, prepared by ring-opening copolymerization of tetrahydrofuran and propylene oxide, hydroxyl value 50 mgKOH / g;

[0055] Polyether polyol 2-2, average functionality 2, prepared by ring-opening copolymerization of tetrahydrofuran and propylene oxide, hydroxyl value 70 mgKOH / g;

[0056] Polyether polyol 2-3, average functionality 2, prepared by ring-opening copolymerization of tetrahydrofuran and propylene oxide, hydroxyl value 100 mgKOH / g;

[0057] Polymer polyol 1-1, glycerol-based, hydroxyl value 15 mgKOH / g, solid content 25 wt%;

[0058] Polymer polyol 1-2, trimethylolpropane starting material, hydroxyl value 35 mgKOH / g, solid content 30 wt%;

[0059] Polymer polyol 1-3, glycerol-based, hydroxyl value 50 mgKOH / g, solid content 45 wt%;

[0060] Flame retardant 1, TCPP, Jiahua Chemical;

[0061] Flame retardant 2, expanded graphite, rock sea carbon material;

[0062] Surfactant, BM023, Wanhua Chemical;

[0063] Catalyst, KC152, Wanhua Chemical;

[0064] Chain extender, ethylene glycol, CNOOC Shell;

[0065] Cross-linking agent, glycerol, Asahikawa Chemical;

[0066] Foaming agent, water.

[0067] Preparation method of polyurethane buffer block sample of embodiment and comparative example:

[0068] Step 1, respectively controlling the temperature of the isocyanate component and the isocyanate reactive component to 25° C.;

[0069] Step 2: inject the isocyanate component and the isocyanate reactive component into the buffer block mold through a high-pressure casting machine for reaction, and after the reaction is completed, open the mold to obtain a polyurethane buffer block. The density of the buffer block is 750±5kg / m 3 The pressure of the high-pressure casting machine is 150 bar, the mold temperature is 55°C, and the holding time is 6 minutes.

[0070] The raw materials used in the examples and comparative examples are listed in Table 1 and Table 2.

[0071] Table 1 (parts by mass)

[0072] Example 1 Example 2 Example 3 Example 4 Example 5 Polyether polyol 1-1 15 24 Polyether polyol 1-2 25 20 Polyether polyol 1-3 18.3 Polyether polyol 2-1 20 37 Polyether polyol 2-2 41 30 Polyether polyol 2-3 22 Polymer polyol 1-1 8.7 14.9 Polymer polyol 1-2 16 12.2 Polymer polyol 1-3 10 Foaming agent 1 0.5 0.1 0.8 0.6 Flame retardant 1 30.7 7.3 30 1 18.6 Flame retardant 2 5 4 6 9 5 catalyst 0.8 0.1 0.6 0.7 0.4 Chain Extender 10 5 6.3 7.25 8 Crosslinking agent 8 1 6 4.75 5 Surfactants 0.8 0.1 0.7 0.6 0.2 Molar ratio of NCO to active hydrogen atoms 95：100 110：100 100：100 102.3：100 108.5：100

[0073] Table 2 (parts by mass)

[0074]

[0075]

[0076] The standards for testing the buffer blocks obtained in the embodiments and comparative examples are as follows:

[0077] Density test standard: ISO 845;

[0078] Compression performance test standard: GB / T 2569;

[0079] Flame retardant performance test standard: UL94, thickness 4mm;

[0080] The buffer blocks obtained in the embodiments and comparative examples were tested, and the test results are listed in the following table.

[0081] Table 3 Performance of Examples and Comparative Examples

[0082]

[0083] It can be seen from the examples and the comparative examples that the examples have more excellent flame retardant properties and can meet the requirements of various levels of compression performance of new energy vehicle battery packs, thereby reducing the impact of vehicle collisions on battery packs, greatly reducing the amount of impact intrusion into battery packs, and reducing the risk of thermal runaway when battery packs collide. The comparative examples cannot meet the above requirements.

[0084] The present invention illustrates the detailed method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed method, that is, it does not mean that the present invention must rely on the above-mentioned detailed method to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A polyurethane composition for a polyurethane buffer block, comprising an isocyanate component and an isocyanate reactive component, characterized in that: The isocyanate reactive components include polyether polyol 1, polyether polyol 2, polymer polyol, flame retardant, chain extender, crosslinking agent, catalyst, foaming agent, surfactant; wherein The polyether polyol 1 has an average functionality of 2 to 5, preferably 3 to 4, and a hydroxyl value of 400 to 1100 mgKOH / g, preferably 500 to 900 mgKOH / g; it is obtained by reacting ethylene oxide and optional propylene oxide, and the ethylene oxide content is 70 to 100%, preferably 80 to 100% by weight, based on the total mass of propylene oxide and ethylene oxide as 100%; The polyether polyol 2 has an average functionality of 1.5 to 3.5, preferably 2, and a hydroxyl value of 30 to 200 mgKOH / g, preferably 50 to 100 mgKOH / g; it is prepared by ring-opening copolymerization of tetrahydrofuran and propylene oxide; Polymer polyol, i.e. graft copolymer polyether polyol, has an average functionality of 2 to 4.5, preferably 3; a hydroxyl value of 10 to 80 mgKOH / g, preferably 15 to 50 mgKOH / g; and a solid content of 20 to 50 wt%, preferably 25 to 45 wt%; The amount of the polyether polyol 1 (A) is 15% to 25%, the amount of the polyether polyol 2 (B) is 20% to 41% and the amount of the polymer polyol (C) is 8.7% to 16%.

2. The polyurethane composition for polyurethane buffer blocks according to claim 1, characterized in that: The amount of the polyether polyol 1 (A), the amount of the polyether polyol 2 (B) and the amount of the polymer polyol (C) satisfy the following relationship:

3. The polyurethane composition for polyurethane buffer blocks according to claim 1 or 2, characterized in that: The catalyst is a class of compounds having catalytic activity to isocyanate and active hydrogen atoms, and is preferably selected from at least one of triethylamine, tributylamine, triethylenediamine, N-ethylmorpholine, N,N,N',N'-tetramethyl-ethylenediamine, pentamethyldiethylene-triamine, N,N-methylaniline, N,N-dimethylaniline, tin (II) acetate, tin (II) octoate, tin ethylhexanoate, tin laurate, dibutyltin oxide, dibutyltin dichloride, dibutyltin diacetate, dibutyltin maleate, and dioctyltin diacetate.

4. The polyurethane composition for polyurethane buffer blocks according to claim 1 or 2, characterized in that: The surfactant is at least one selected from polysiloxane-oxyalkylene block copolymers.

5. The polyurethane composition for polyurethane buffer blocks according to claim 1 or 2, characterized in that: The foaming agent is any one of a physical foaming agent and a chemical foaming agent, preferably selected from one or more of water, monochloromonofluoromethane, monochlorodifluoromethane, dichlorodifluoromethane, trichlorofluoromethane, butane, hexane, cyclohexane, pentane, cyclopentane, heptane, N2, CO2 and air, more preferably water.

6. The polyurethane composition for polyurethane buffer blocks according to claim 1 or 2, characterized in that: The cross-linking agent is any one of a polyol and a polyamine, preferably at least one selected from trimethylolpropane, glycerol, pentaerythritol, diethanolamine, triethanolamine, ethylenediamine, phenylenediamine, and sorbitol; and / or The chain extender is at least one of diols, diamines and diphenols, preferably at least one of ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, butanediol, cyclohexanediol, methylamine, ethylamine, hydrogenated bisphenol A and hydroquinone; and / or The flame retardant is selected from at least one of halogenated phosphate flame retardants, phosphate flame retardants, halogenated hydrocarbons and other halogen-containing flame retardants, melamine and its salts, reactive flame retardants, and inorganic flame retardants.

7. The polyurethane composition for a polyurethane buffer block according to any one of claims 1 to 6, characterized in that: Based on the total mass of the isocyanate-reactive component, the isocyanate-reactive component comprises: Preferably, the molar ratio of isocyanate groups in the isocyanate component to active hydrogen atoms in the isocyanate-reactive component in the polyurethane composition is 90 to 120:100, preferably 95 to 110:

100.

8. A method for preparing a polyurethane buffer block, characterized in that: The following steps are involved: 1) mixing and stirring the isocyanate component and the isocyanate reactive component in the polyurethane composition for the polyurethane buffer block according to any one of claims 1 to 7 respectively and setting them aside; 2) The isocyanate component and the isocyanate reactive component are mixed evenly by a device and then injected into a buffer block mold for reaction. After the reaction is completed, the mold is opened to obtain a polyurethane buffer block.

9. A polyurethane buffer block prepared by the preparation method according to claim 8, characterized in that: The density of the polyurethane buffer block is 600-900 kg / m 3 , preferably 700~800kg / m 3 The pressure of the pouring machine is 100-180 bar, preferably 130-170 bar, the mold temperature is 30-90° C., preferably 40-60° C., and the holding time is 3-20 minutes, preferably 5-15 minutes.

10. Use of the polyurethane buffer block prepared by the preparation method of claim 8 or the polyurethane buffer block of claim 9 in new energy vehicles, especially in power battery packaging materials.

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