A flame-retardant and heat-conductive two-component polyurethane structural adhesive for new energy lithium batteries

Abstract

The present invention belongs to the field of polymer materials technology, specifically to a flame-retardant, heat-resistant, and thermally conductive two-component polyurethane structural adhesive for new energy lithium batteries. This invention prepares a flame-retardant, heat-resistant, and thermally conductive two-component polyurethane structural adhesive for new energy lithium batteries by modifying diphenylmethane diisocyanate, the main component of the two-component polyurethane structural adhesive, and simultaneously introducing functional fillers such as modified alumina and magnesium hydroxide composite materials. This effectively improves the tensile strength and thermal conductivity of the structural adhesive, while also achieving excellent flame retardancy.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and in particular relates to a flame-retardant and heat-conductive two-component polyurethane structural adhesive for new energy lithium batteries. Background Art

[0002] In recent years, with the continuous improvement of my country's new energy vehicle industry chain, new energy vehicles have flourished and sales have increased rapidly. Currently, the majority of new energy vehicle power batteries are lithium-ion batteries. The lithium-ion batteries in automotive battery packs generate heat during the charging and discharging process. If this heat is not removed promptly, it will accumulate within the battery, causing it to overheat. This not only reduces battery performance and lifespan, but can also pose safety hazards and even lead to serious consequences such as fire. Two-component polyurethane structural adhesives, with their lightweight, high toughness, excellent insulation, and vibration resistance and damping properties, are being increasingly adopted during the assembly and installation of power batteries in new energy vehicles, achieving structural bonding and sealing.

[0003] Patent publication number CN115558457B discloses a two-component polyurethane structural adhesive, its preparation method, and its application. The invention utilizes castor oil polyol, which has a high ignition point and good stability, improving the structural adhesive's flame retardancy. The benzene rings in the aromatic polyether polyol are heat-resistant, improving the adhesive's aging resistance. Non-halogenated phosphorus polyols are phosphorus-containing polyol flame retardants with flame retardant properties, reducing the amount of flame-retardant fillers and small-molecule flame retardants added, achieving lightweighting. The non-halogenated phosphorus polyols contain no halogen elements, emit no significant smoke during combustion, and are environmentally friendly and non-toxic. Furthermore, the non-halogenated phosphorus polyols participate in the curing reaction, preventing the small-molecule flame retardants from leaching out during use. However, existing two-component polyurethane structural adhesives still suffer from low tensile strength, poor flame retardancy, and a need for improved thermal conductivity, severely impacting their practical use.

[0004] Therefore, how to modify the components of two-component polyurethane structural adhesive, improve the tensile strength of the structural adhesive, increase the thermal conductivity, obtain good flame retardancy, and apply the structural adhesive to new energy lithium batteries has become a direction that needs to be focused on. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a flame-retardant and heat-resistant two-component polyurethane structural adhesive for new energy lithium batteries, aiming to solve the problems of low tensile strength, poor flame retardancy, and the need to improve thermal conductivity of the existing two-component polyurethane structural adhesive.

[0006] The present invention prepares a flame-retardant and heat-conductive two-component polyurethane structural adhesive for new energy lithium batteries by modifying diphenylmethane diisocyanate, the main component of the two-component polyurethane structural adhesive, and introducing functional fillers such as modified alumina and magnesium hydroxide composite materials. The tensile strength of the structural adhesive is effectively improved, the thermal conductivity is increased, and good flame retardancy is obtained.

[0007] The technical solutions of the present invention are as follows:

[0008] The present invention provides a flame-retardant and heat-conductive two-component polyurethane structural adhesive for new energy lithium batteries, which consists of component A and component B;

[0009] In parts by weight, the component A comprises: 20 to 30 parts of a polyurethane prepolymer, 10 to 20 parts of modified diphenylmethane diisocyanate, 50 to 60 parts of aluminum oxide, and 2 to 4 parts of vinyltrimethoxysilane;

[0010] In parts by weight, the component B comprises: 10-20 parts of ricinoleyl alcohol, 10-16 parts of polyether polyol, 4-8 parts of aldehyde-ketone resin, 60-70 parts of magnesium hydroxide, 1-3 parts of 3A molecular sieve raw powder, 1.2-1.6 parts of triethylamine and 0.6-0.8 parts of adhesion promoter;

[0011] The preparation method of the modified diphenylmethane diisocyanate comprises: firstly coupling 6 to 12 parts of talc powder by weight, then mixing with 2 to 6 parts of ethyl acetate, then adding 88 to 94 parts of diphenylmethane diisocyanate, stirring and dispersing at high speed, and then performing ultrasonic dispersion to obtain the modified diphenylmethane diisocyanate.

[0012] As a preferred technical solution of the present invention, the coupling treatment conditions include: mixing 80 to 90 parts of anhydrous ethanol and 10 to 20 parts of deionized water, then adding 2 to 4 parts of 3-aminopropyltriethoxysilane and stirring for 20 to 30 minutes, then adding 6 to 12 parts of talc and stirring for 30 to 40 minutes, and drying.

[0013] As a preferred technical solution of the present invention, the time for high-speed stirring and dispersing is 10 to 16 minutes, and the time for ultrasonic dispersing is 10 to 20 minutes.

[0014] The talc powder introduced by modified diphenylmethane diisocyanate can be evenly dispersed in the resin matrix after coupling treatment. By forming physical cross-linking points, the movement of polymer chain segments is restricted. This filling effect improves the rigidity and deformation resistance of the material, thereby improving the tensile strength of the structural adhesive.

[0015] As a preferred technical solution of the present invention, the alumina is modified alumina;

[0016] The preparation method of the modified alumina includes: adding 90 to 100 parts by weight of pseudo-boehmite to 200 to 240 parts of a boric acid aqueous solution with a mass concentration of 6 to 8% for doping treatment to obtain boron-doped alumina; adding 2 to 4 parts of γ-glycidyloxypropyltrimethoxysilane to 180 to 200 parts of anhydrous ethanol and mixing them evenly, and then adding 90 to 100 parts of the boron-doped alumina for surface treatment to obtain the modified alumina.

[0017] As a preferred technical solution of the present invention, the doping treatment conditions include: first impregnation for 30-40 minutes, then drying at 110-120°C for 50-60 minutes, and finally calcining at 540-550°C for 100-120 minutes.

[0018] As a preferred technical solution of the present invention, the surface treatment conditions include: adjusting the pH to 4.2-4.4, the treatment temperature to 40-50° C., and the treatment time to 2-4 hours.

[0019] The modified alumina contains boron-doped alumina, which can promote the carbonization reaction of the polymer matrix to form a dense carbon layer, further enhancing the heat insulation and oxygen isolation effects. The presence of the carbon layer not only improves the thermal stability of the material, but also reduces the release of combustible volatiles, thereby improving the flame retardant properties.

[0020] As a preferred technical solution of the present invention, the magnesium hydroxide is a magnesium hydroxide composite material;

[0021] The preparation method of the magnesium hydroxide composite material comprises: adding 20 to 30 parts by weight of graphene oxide to 100 to 120 parts of deionized water to form a suspension, first adding 2 to 4 parts of hydrochloric acid, and then adding 20 to 24 parts of magnesium chloride and 18 to 22 parts of potassium hydroxide to carry out heating reaction to obtain an intermediate product; and mixing 10 to 20 parts of the intermediate product and 10 to 20 parts of 3-aminopropyltriethoxysilane and performing ball milling to obtain the magnesium hydroxide composite material.

[0022] As a preferred technical solution of the present invention, the conditions of the heating reaction include: first drying at 80-90°C for 1-2 hours, then heat treating at 170-180°C for 4-6 hours, washing with water, and drying.

[0023] As a preferred technical solution of the present invention, the ball milling treatment conditions include: ball milling at a rotation speed of 300-400 r / min for 4-6 hours, washing with acetone, centrifuging at a rotation speed of 4000-5000 r / min for 6-10 minutes, drying, and grinding.

[0024] The graphene oxide contained in the magnesium hydroxide composite material has excellent two-dimensional thermal conductivity, while magnesium hydroxide provides a good thermal conduction path and thermal stability. The synergistic effect of the two can further optimize the thermal conduction network, thereby significantly improving the thermal conductivity of the structural adhesive.

[0025] As a preferred technical solution of the present invention, the preparation method of the polyurethane prepolymer includes: weighing 90 to 100 parts by weight of polypropylene carbonate diol and heating it to 56 to 60° C., adding 40 to 50 parts of diphenylmethane diisocyanate, heating it to 78 to 80° C. under vacuum conditions, and reacting at a constant temperature for 3 to 4 hours to obtain the polyurethane prepolymer.

[0026] As a preferred technical solution of the present invention, the adhesion promoter is methyltriethoxysilane and 3-aminopropyltriethoxysilane; the mass ratio of methyltriethoxysilane to 3-aminopropyltriethoxysilane in the adhesion promoter is (1~2):1.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The modified diphenylmethane diisocyanate of the present invention contains highly reactive isocyanate groups, which can not only undergo a ring-opening reaction with the epoxy groups in the modified alumina, but also undergo a nucleophilic addition reaction with the amino groups introduced into the magnesium hydroxide composite material by 3-aminopropyltriethoxysilane, thereby forming a network interconnected structure, effectively preventing the initiation and expansion of cracks and thus improving the tensile strength; at the same time, high thermal conductivity fillers such as graphene and alumina are evenly distributed and interconnected in the network interconnected structure, forming a continuous thermal conduction path, thereby improving the thermal conductivity coefficient of the material. In addition, the moisture released when the talc in the modified diphenylmethane diisocyanate decomposes can dilute the concentration of combustible gases in the combustion area and reduce the flame propagation speed; the boron-doped alumina in the modified alumina can promote the carbonization reaction of the polymer matrix and form a dense carbon layer, enhancing the heat insulation and oxygen isolation effects; the magnesium hydroxide in the magnesium hydroxide composite material decomposes at high temperatures to absorb a large amount of heat, reducing the material temperature, and graphene forms a dense barrier layer on the surface of the material to prevent the penetration of heat and oxygen; through the synergistic effect of multiple components of talc-boron-doped alumina-magnesium hydroxide-graphene, the flame retardant properties of the structural adhesive are improved.

[0029] (2) The talc powder introduced into the modified diphenylmethane diisocyanate of the present invention can be evenly dispersed in the resin matrix after coupling treatment, and the movement of polymer chain segments is restricted by forming physical cross-linking points. This filling effect improves the rigidity and deformation resistance of the material, thereby improving the tensile strength of the structural adhesive.

[0030] (3) The modified alumina of the present invention contains boron-doped alumina, which can promote the carbonization reaction of the polymer matrix to form a dense carbon layer, further enhancing the heat insulation and oxygen isolation effects. The presence of the carbon layer not only improves the thermal stability of the material, but also reduces the release of combustible volatiles, thereby improving the flame retardant performance.

[0031] (4) The graphene oxide contained in the magnesium hydroxide composite material of the present invention has excellent two-dimensional thermal conductivity, while magnesium hydroxide provides a good thermal conduction path and thermal stability. The synergistic effect of the two can further optimize the thermal conduction network, thereby significantly improving the thermal conductivity of the structural adhesive. DETAILED DESCRIPTION

[0032] For the convenience of understanding the present invention, the present invention is given below with examples. It should be understood by those skilled in the art that the examples are only for the purpose of helping to understand the present invention and should not be regarded as specific limitations of the present invention.

[0033] The sources of some components in the Examples and Comparative Examples are as follows:

[0034] Polypropylene carbonate diol, molecular weight 2000 g / mol, purchased from Zhongke Jinlong Environmental Protection New Materials Co., Ltd.

[0035] Commercially available diphenylmethane diisocyanate, brand MDI-100F, was purchased from Wanhua Chemical;

[0036] Commercially available alumina, product number A406645, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0037] Vinyltrimethoxysilane, CAS No. 2768-02-7, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0038] Ricinoleic acid, product number R341632, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0039] Polyether polyol, brand C2004, purchased from Wanhua Chemical;

[0040] Aldehyde and ketone resin, product number PA98876, was purchased from Guangdong Wengjiang Chemical Reagent Co., Ltd.

[0041] Commercially available magnesium hydroxide, CAS No. 1309-42-8, was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0042] 3A molecular sieve powder, model 3A-D-38, was purchased from Luoyang Jianlong Micro-Nano New Materials Co., Ltd.

[0043] Triethylamine, CAS No. 121-44-8, was purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0044] N,N-dimethylbenzylamine, CAS No. 103-83-3, was purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0045] Methyltriethoxysilane, CAS number 2031-67-6, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0046] 3-Aminopropyltriethoxysilane, CAS No. 919-30-2, was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0047] γ-Glycidyloxypropyltrimethoxysilane, CAS No. 2530-83-8, was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0048] Talc, CAS No. 14807-96-6, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0049] Ethyl acetate, CAS No. 141-78-6, was purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0050] 3-Aminopropyltriethoxysilane, CAS No. 919-30-2, was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0051] Pseudoboehmite, product number P790504, was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0052] Boric acid, CAS No. 10043-35-3, was purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0053] γ-Glycidyloxypropyltrimethoxysilane, CAS No. 2530-83-8, was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0054] Graphene oxide, product number G476611, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0055] Hydrochloric acid, CAS No. 7647-01-0, was purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0056] Magnesium chloride, CAS No. 7786-30-3, was purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0057] Potassium hydroxide, CAS No. 1310-58-3, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0058] Example 1:

[0059] This embodiment provides a flame retardant and heat-conductive two-component polyurethane structural adhesive for new energy lithium batteries, which consists of component A and component B;

[0060] In parts by weight, the component A comprises: 30 parts of polyurethane prepolymer, 20 parts of modified diphenylmethane diisocyanate, 60 parts of modified alumina and 4 parts of vinyltrimethoxysilane;

[0061] In parts by weight, the component B includes: 20 parts of castor oil alcohol, 16 parts of polyether polyol, 8 parts of aldehyde-ketone resin, 70 parts of magnesium hydroxide composite material, 3 parts of 3A molecular sieve raw powder, 1.6 parts of triethylamine and 0.6 parts of adhesion promoter (0.4 parts of methyltriethoxysilane and 0.2 parts of 3-aminopropyltriethoxysilane).

[0062] The modified diphenylmethane diisocyanate is prepared by mixing 90 parts of anhydrous ethanol and 20 parts of deionized water, then adding 4 parts of 3-aminopropyltriethoxysilane and stirring for 30 minutes, then adding 12 parts of talc and stirring for 40 minutes, drying, then mixing with 6 parts of ethyl acetate, then adding 94 parts of diphenylmethane diisocyanate and stirring and dispersing at high speed for 16 minutes, and then ultrasonically dispersing for 20 minutes to obtain the modified diphenylmethane diisocyanate.

[0063] Preparation of the modified alumina: In parts by weight, 100 parts of pseudo-boehmite are added to 240 parts of an 8% by mass boric acid aqueous solution for doping treatment, first impregnated for 40 minutes, then dried at 120°C for 50 minutes, and finally calcined at 550°C for 100 minutes to obtain boron-doped alumina; 4 parts of γ-glycidyloxypropyltrimethoxysilane are added to 200 parts of anhydrous ethanol and mixed evenly, and then 100 parts of the boron-doped alumina are added for surface treatment (adjusting the pH to 4.4, the treatment temperature to 50°C, and the treatment time to 2 hours) to obtain modified alumina.

[0064] The magnesium hydroxide composite material is prepared by adding 30 parts of graphene oxide to 120 parts of deionized water to form a suspension, first adding 4 parts of hydrochloric acid, then adding 24 parts of magnesium chloride and 22 parts of potassium hydroxide to carry out a heating reaction, first drying at 90°C for 2 hours, then heat treating at 180°C for 4 hours, washing with water, and drying to obtain an intermediate product; and mixing 20 parts of the intermediate product with 20 parts of 3-aminopropyltriethoxysilane and ball milling for 4 hours at a rotation speed of 400 r / min, washing with acetone, centrifuging at a rotation speed of 5000 r / min for 6 minutes, drying, and grinding to obtain the magnesium hydroxide composite material.

[0065] Preparation of the polyurethane prepolymer: 100 parts by weight of polypropylene carbonate diol are weighed and heated to 60° C., 50 parts of diphenylmethane diisocyanate are added, and the temperature is raised to 80° C. under vacuum conditions, and the reaction is carried out at a constant temperature for 3 hours to obtain a polyurethane prepolymer.

[0066] Example 2:

[0067] This embodiment provides a flame retardant and heat-conductive two-component polyurethane structural adhesive for new energy lithium batteries, which consists of component A and component B;

[0068] In parts by weight, the component A comprises: 20 parts of polyurethane prepolymer, 10 parts of modified diphenylmethane diisocyanate, 50 parts of modified alumina and 2 parts of vinyltrimethoxysilane;

[0069] In parts by weight, the component B includes: 10 parts of castor oil alcohol, 10 parts of polyether polyol, 4 parts of aldehyde-ketone resin, 60 parts of magnesium hydroxide composite material, 1 part of 3A molecular sieve raw powder, 1.2 parts of triethylamine and 0.8 parts of adhesion promoter (0.4 parts of methyltriethoxysilane and 0.4 parts of 3-aminopropyltriethoxysilane).

[0070] The modified diphenylmethane diisocyanate is prepared by mixing 80 parts of anhydrous ethanol and 10 parts of deionized water, adding 2 parts of 3-aminopropyltriethoxysilane, and stirring for 20 minutes. Then, 6 parts of talc are added, stirred for 30 minutes, and dried. Then, the mixture is mixed with 2 parts of ethyl acetate, and 88 parts of diphenylmethane diisocyanate is added, stirred and dispersed at high speed for 10 minutes, and then ultrasonically dispersed for 10 minutes to obtain the modified diphenylmethane diisocyanate.

[0071] Preparation of the modified alumina: 90 parts by weight of pseudo-boehmite are added to 200 parts of a 6% by mass boric acid aqueous solution for doping treatment, first immersed for 30 minutes, then dried at 110°C for 60 minutes, and finally calcined at 540°C for 120 minutes to obtain boron-doped alumina; 2 parts of γ-glycidyloxypropyltrimethoxysilane are added to 180 parts of anhydrous ethanol and mixed evenly, and then 90 parts of the boron-doped alumina are added for surface treatment (adjusting the pH to 4.2, the treatment temperature to 40°C, and the treatment time to 4 hours) to obtain modified alumina.

[0072] The magnesium hydroxide composite material is prepared by adding 20 parts of graphene oxide to 100 parts of deionized water to form a suspension, first adding 2 parts of hydrochloric acid, then adding 20 parts of magnesium chloride and 18 parts of potassium hydroxide to carry out a heating reaction, first drying at 80°C for 2 hours, then heat treating at 170°C for 6 hours, washing with water, and drying to obtain an intermediate product; and mixing 10 parts of the intermediate product with 10 parts of 3-aminopropyltriethoxysilane and ball milling for 6 hours at a rotation speed of 300 r / min, washing with acetone, centrifuging at a rotation speed of 4000 r / min for 10 minutes, drying, and grinding to obtain the magnesium hydroxide composite material.

[0073] Preparation of the polyurethane prepolymer: 90 parts by weight of polypropylene carbonate diol are weighed and heated to 56° C., 40 parts of diphenylmethane diisocyanate are added, and the temperature is raised to 78° C. under vacuum conditions, and the reaction is carried out at a constant temperature for 4 hours to obtain a polyurethane prepolymer.

[0074] Example 3:

[0075] This embodiment provides a flame retardant and heat-conductive two-component polyurethane structural adhesive for new energy lithium batteries, which consists of component A and component B;

[0076] In parts by weight, the component A comprises: 25 parts of polyurethane prepolymer, 15 parts of modified diphenylmethane diisocyanate, 55 parts of modified alumina and 3 parts of vinyltrimethoxysilane;

[0077] In parts by weight, the component B includes: 15 parts of castor oil alcohol, 12 parts of polyether polyol, 6 parts of aldehyde-ketone resin, 65 parts of magnesium hydroxide composite material, 2 parts of 3A molecular sieve raw powder, 1.4 parts of triethylamine and 0.7 parts of adhesion promoter (0.4 parts of methyltriethoxysilane and 0.3 parts of 3-aminopropyltriethoxysilane).

[0078] The modified diphenylmethane diisocyanate is prepared by mixing 85 parts of anhydrous ethanol and 15 parts of deionized water, then adding 3 parts of 3-aminopropyltriethoxysilane and stirring for 25 minutes, then adding 8 parts of talc and stirring for 35 minutes, drying, and then mixing with 4 parts of ethyl acetate, then adding 90 parts of diphenylmethane diisocyanate and stirring and dispersing at high speed for 12 minutes, and then ultrasonically dispersing for 15 minutes to obtain the modified diphenylmethane diisocyanate.

[0079] Preparation of the modified alumina: In parts by weight, 95 parts of pseudo-boehmite are added to 220 parts of a 7% by mass boric acid aqueous solution for doping treatment, first impregnated for 35 minutes, then dried at 115°C for 55 minutes, and finally calcined at 545°C for 110 minutes to obtain boron-doped alumina; 3 parts of γ-glycidyloxypropyltrimethoxysilane are added to 190 parts of anhydrous ethanol and mixed evenly, and then 95 parts of the boron-doped alumina are added for surface treatment (adjusting the pH to 4.3, the treatment temperature to 45°C, and the treatment time to 3 hours) to obtain modified alumina.

[0080] The magnesium hydroxide composite material is prepared by adding 25 parts of graphene oxide to 110 parts of deionized water to form a suspension, first adding 3 parts of hydrochloric acid, then adding 22 parts of magnesium chloride and 20 parts of potassium hydroxide to carry out a heating reaction, first drying at 85° C. for 2 hours, then heat treating at 175° C. for 5 hours, washing with water, and drying to obtain an intermediate product; and mixing 15 parts of the intermediate product and 15 parts of 3-aminopropyltriethoxysilane to carry out ball milling treatment, ball milling at a speed of 350 r / min for 5 hours, washing with acetone, centrifuging at a speed of 4500 r / min for 8 minutes, drying, and grinding to obtain the magnesium hydroxide composite material.

[0081] Preparation of the polyurethane prepolymer: 95 parts of polypropylene carbonate diol are weighed and heated to 58° C., 45 parts of diphenylmethane diisocyanate are added, and the temperature is raised to 79° C. under vacuum conditions, and the reaction is carried out at a constant temperature for 4 hours to obtain a polyurethane prepolymer.

[0082] Comparative Example 1:

[0083] The difference between this comparative example and Example 1 is that commercially available diphenylmethane diisocyanate (brand MDI-100F) is used instead of modified diphenylmethane diisocyanate, commercially available alumina (product number A406645) is used instead of modified alumina, and commercially available magnesium hydroxide (CAS number 1309-42-8) is used instead of the magnesium hydroxide composite material.

[0084] Comparative Example 2:

[0085] The difference between this comparative example and comparative example 1 is that modified diphenylmethane diisocyanate is used instead of commercially available diphenylmethane diisocyanate (brand number MDI-100F).

[0086] Comparative Example 3:

[0087] The difference between this comparative example and comparative example 1 is that a magnesium hydroxide composite material is used instead of commercially available magnesium hydroxide (CAS No. 1309-42-8).

[0088] Comparative Example 4:

[0089] The difference between this comparative example and Example 1 is that commercially available diphenylmethane diisocyanate (brand name MDI-100F) is used instead of modified diphenylmethane diisocyanate.

[0090] Comparative Example 5:

[0091] The difference between this comparative example and Example 1 is that commercially available alumina (product number A406645) is used instead of modified alumina.

[0092] Comparative Example 6:

[0093] The difference between this comparative example and Example 1 is that commercially available magnesium hydroxide (CAS No. 1309-42-8) is used instead of the magnesium hydroxide composite material.

[0094] The performance of the two-component polyurethane structural adhesive provided in the above embodiments and comparative examples was tested using the following test methods:

[0095] (1) Tensile strength test: refer to the requirements of GB / T 528-2009 Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber for testing.

[0096] (2) Flame retardancy test: Refer to the requirements of "GB / T 2408-2021 Plastics - Determination of combustion performance - Horizontal and vertical methods" for testing.

[0097] (3) Thermal conductivity test: Refer to the requirements of ASTM D5470-17 Standard Test Method for Thermal Conductivity of Thermally Conductive Insulating Materials for testing.

[0098] The above performance test data is shown in Table 1.

[0099] Table 1 Performance test results data table

[0100] Tensile strength MPa flame retardancy Thermal conductivity W / (m·K) Example 1 14.4 V0 2.08 Example 2 13.9 V0 2.01 Example 3 14.1 V0 2.05 Comparative Example 1 9.5 V1 0.86 Comparative Example 2 11.2 V1 0.89 Comparative Example 3 9.8 V1 1.37 Comparative Example 4 12.4 V1 1.81 Comparative Example 5 12.1 V1 1.78 Comparative Example 6 12.6 V1 1.83

[0101] From the above content, it can be seen that the present invention prepares flame-retardant and heat-conductive two-component polyurethane structural adhesives for new energy lithium batteries (Examples 1 to 3) by modifying diphenylmethane diisocyanate, the main component of the two-component polyurethane structural adhesive, and introducing functional fillers such as modified alumina and magnesium hydroxide composites. The tensile strength is 13.9~14.4MPa, the flame retardant grade is V0, and the thermal conductivity is 2.01~2.08W / (m·K).

[0102] Compared with Example 1, commercially available diphenylmethane diisocyanate was used instead of modified diphenylmethane diisocyanate (brand name MDI-100F), commercially available alumina (item number A406645) was used instead of modified alumina, and commercially available magnesium hydroxide (CAS number 1309-42-8) was used instead of the magnesium hydroxide composite material. The tensile strength was reduced, the flame retardancy was deteriorated, and the thermal conductivity was reduced (Comparative Example 1). Compared with Comparative Example 1, modified diphenylmethane diisocyanate was used instead of commercially available diphenylmethane diisocyanate (brand name MDI-100F), and the tensile strength was increased (Comparative Example 2). Compared with Comparative Example 1, the magnesium hydroxide composite material was used instead of commercially available magnesium hydroxide (CAS number 1309-42-8), the thermal conductivity increases (Comparative Example 3); compared with Example 1, using commercially available diphenylmethane diisocyanate (brand MDI-100F) instead of modified diphenylmethane diisocyanate, the tensile strength decreases, the flame retardancy deteriorates, and the thermal conductivity decreases (Comparative Example 4); compared with Example 1, using commercially available alumina (item number A406645) instead of modified alumina, the tensile strength decreases, the flame retardancy deteriorates, and the thermal conductivity decreases (Comparative Example 5); compared with Example 1, using commercially available magnesium hydroxide (CAS number 1309-42-8) instead of the magnesium hydroxide composite material, the tensile strength decreases, the flame retardancy deteriorates, and the thermal conductivity decreases (Comparative Example 6).

[0103] In summary, the present invention prepares a flame-retardant and heat-conductive two-component polyurethane structural adhesive for new energy lithium batteries by modifying the main component of the two-component polyurethane structural adhesive, diphenylmethane diisocyanate, and introducing functional fillers such as modified alumina and magnesium hydroxide composite materials. The tensile strength of the structural adhesive is effectively improved, the thermal conductivity is increased, and good flame retardancy is obtained.

Claims

1. A flame retardant and heat-conductive two-component polyurethane structural adhesive for new energy lithium batteries, characterized in that: It is composed of component A and component B; In parts by weight, the component A comprises: 20 to 30 parts of a polyurethane prepolymer, 10 to 20 parts of modified diphenylmethane diisocyanate, 50 to 60 parts of modified alumina, and 2 to 4 parts of vinyltrimethoxysilane; In parts by weight, the component B comprises: 10-20 parts of ricinoleyl alcohol, 10-16 parts of polyether polyol, 4-8 parts of aldehyde-ketone resin, 60-70 parts of magnesium hydroxide composite material, 1-3 parts of 3A molecular sieve raw powder, 1.2-1.6 parts of triethylamine and 0.6-0.8 parts of adhesion promoter; The preparation method of the modified diphenylmethane diisocyanate comprises: first subjecting 6 to 12 parts of talc powder, by weight, to a coupling treatment, then mixing the mixture with 2 to 6 parts of ethyl acetate, then adding 88 to 94 parts of diphenylmethane diisocyanate, stirring and dispersing the mixture at high speed, and then ultrasonically dispersing the mixture to obtain the modified diphenylmethane diisocyanate; the coupling treatment conditions comprise: by weight, mixing 80 to 90 parts of anhydrous ethanol and 10 to 20 parts of deionized water, then adding 2 to 4 parts of 3-aminopropyltriethoxysilane, stirring the mixture for 20 to 30 minutes, then adding 6 to 12 parts of talc powder, stirring the mixture for 30 to 40 minutes, and drying the mixture; The preparation method of the magnesium hydroxide composite material comprises: adding 20 to 30 parts by weight of graphene oxide to 100 to 120 parts of deionized water to form a suspension, first adding 2 to 4 parts of hydrochloric acid, and then adding 20 to 24 parts of magnesium chloride and 18 to 22 parts of potassium hydroxide to carry out heating reaction to obtain an intermediate product; mixing 10 to 20 parts of the intermediate product and 10 to 20 parts of 3-aminopropyltriethoxysilane and performing ball milling to obtain the magnesium hydroxide composite material; The preparation method of the modified alumina comprises: adding 90 to 100 parts by weight of pseudo-boehmite to 200 to 240 parts by weight of a boric acid aqueous solution having a mass concentration of 6 to 8% for doping treatment to obtain boron-doped alumina; adding 2 to 4 parts of γ-glycidyloxypropyltrimethoxysilane to 180 to 200 parts of anhydrous ethanol and mixing them uniformly; and then adding 90 to 100 parts of the boron-doped alumina for surface treatment to obtain the modified alumina; The preparation method of the polyurethane prepolymer comprises: weighing 90-100 parts by weight of polypropylene carbonate diol, heating the mixture to 56-60° C., adding 40-50 parts of diphenylmethane diisocyanate, heating the mixture to 78-80° C. under vacuum conditions, and reacting the mixture at a constant temperature for 3-4 hours to obtain the polyurethane prepolymer.

2. The flame-retardant and heat-conductive two-component polyurethane structural adhesive for new energy lithium batteries according to claim 1, characterized in that: The doping treatment conditions include: first dipping for 30-40 minutes, then drying at 110-120° C. for 50-60 minutes, and finally calcining at 540-550° C. for 100-120 minutes.

3. The flame-retardant and heat-conductive two-component polyurethane structural adhesive for new energy lithium batteries according to claim 1, characterized in that: The surface treatment conditions include: adjusting the pH to 4.2-4.4, the treatment temperature to 40-50° C., and the treatment time to 2-4 hours.

4. The flame-retardant and heat-conductive two-component polyurethane structural adhesive for new energy lithium batteries according to claim 1, characterized in that: The heating reaction conditions include: first drying at 80-90° C. for 1-2 hours, then heat treating at 170-180° C. for 4-6 hours, washing with water, and drying.

5. The flame-retardant and heat-conductive two-component polyurethane structural adhesive for new energy lithium batteries according to claim 1, characterized in that: The ball milling treatment conditions include: ball milling at a rotation speed of 300-400 r / min for 4-6 hours, washing with acetone, centrifuging at a rotation speed of 4000-5000 r / min for 6-10 minutes, drying, and grinding.

6. The flame-retardant and heat-conductive two-component polyurethane structural adhesive for new energy lithium batteries according to claim 1, characterized in that: The adhesion promoter is methyltriethoxysilane and 3-aminopropyltriethoxysilane; the mass ratio of methyltriethoxysilane to 3-aminopropyltriethoxysilane in the adhesion promoter is (1~2):1.