Lightweight energy-absorbing polyurethane power battery potting adhesive, preparation method and application thereof

Abstract

The application discloses a light-weight energy-absorbing polyurethane power battery pouring sealant and a preparation method and application thereof, the preparation method uses liquid MDI and polytetrahydrofuran diol as raw materials to prepare a polyurethane prepolymer with an isocyanate group, then uses the polyurethane prepolymer and 1,4-butanediol to react to generate microporous foaming polyurethane by adjusting a chain extension coefficient, so as to prepare the polyurethane power battery pouring sealant, and the microporous structure is formed through the reaction, so as to meet the light-weight, energy-absorbing and other related performance requirements of the power battery pouring sealant; the polyurethane pouring sealant prepared by the application has the advantages of light weight, excellent energy-absorbing shock-absorbing performance, mechanical property, thermal stability and adhesive property; the preparation process is simple, controllable, environmentally-friendly, reliable and low in cost, the stability and safety of the power battery can be improved, the development of new energy vehicles is promoted, and the environmental protection requirements are met.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of functional materials, and relates to a polyurethane pouring sealant, in particular to a light-weight energy-absorbing polyurethane power battery pouring sealant as well as a preparation method and application thereof. BACKGROUND

[0002] With the implementation of the automobile environmental protection plan of each country, the production and sales of new energy vehicles will continue to increase rapidly, and the market scale will continue to expand. The development of new energy vehicles is conducive to solving energy and environmental problems, and makes the automobile free from dependence on oil, and has the hope of becoming the main direction of future development of the automobile industry. The overall performance of new energy vehicles depends largely on the performance of its motor, power battery and electric control. As one of the core components of new energy vehicles, the power battery has very high requirements for its various performances. The power battery pouring sealant, as one of the key materials of the power battery, is used to protect the internal structure of the power battery and prevent internal leakage. With the continuous development and progress of the battery technology of new energy vehicles, the requirements for the light weight, shock absorption and energy absorption performance of the power battery pouring sealant are also becoming higher and higher.

[0003] Lithium batteries have unique advantages such as high voltage, high energy density, long cycle life, energy saving and environmental protection, and are widely used in new energy vehicles, i.e. high-voltage power batteries. In addition to high requirements for flame retardancy and thermal conductivity, reducing the weight of the power battery is also crucial for new energy vehicles, so as to maximize the driving range in a given battery. Light weight of electric vehicles has become an inevitable trend for the future development of new energy vehicle technology, so the power battery pouring sealant also needs to be lightened. In the automobile battery board, a single battery pack composed of many lithium batteries is used to form a battery pack, and then the battery pack is used to form a battery board. In the high-speed running state, the automobile is bound to produce bumps, and the battery inside is severely shaken and vibrated. Therefore, the pouring sealant needs to have good shock absorption and adhesion, and realize organic interaction between the polar groups on the surface of the battery shell plastic and aluminum parts, so as to fully play the advantages of adhesion and stability.

[0004] Pouring sealant is usually used for adhesion, sealing and coating protection of power batteries, and is an indispensable part of protecting power batteries. The power battery pouring sealants widely used in the market at present are epoxy resin, organic silicon and polyurethane. The epoxy resin pouring sealant has the advantages of high temperature resistance, good adhesion, excellent electrical insulation ability, etc., but has the disadvantages of poor toughness, easy cracking under cold and hot impact, poor moisture resistance, etc., and is mainly used for sealing of electronic components such as transformers, capacitors and driving power supplies. The organic silicon pouring sealant has the advantages of good weather resistance, wide working temperature, no cracking, excellent waterproof performance and shock resistance, but has the disadvantages of low adhesion strength, low strength and poor tear resistance, and is not easy to keep the battery fixed after being extruded, causing power battery failure.

[0005] The polyurethane pouring sealant has the characteristics of adjustable hardness, wide strength range, adjustable modulus, high elasticity, high impact resistance, high wear resistance, high adhesion and excellent low temperature resistance, etc. Combined with the design of the power battery pack, the polyurethane pouring sealant can better match the adhesion and fixation of the battery cell and the heat conduction, and is more and more widely used in new energy batteries. Polyurethane is widely concerned and applied due to its unique structural characteristics, which can overcome the disadvantages of epoxy resin brittleness and low mechanical strength and poor adhesion of silicone resin. The polyurethane pouring sealant is mainly composed of isocyanate and polyol, filler, chain extender, catalyst and foam stabilizer, etc. After curing, a plurality of urethane bonds (-NHCOO-) are formed, the soft and hard segments are alternately arranged, and a repeated structural unit is formed. Isocyanate as a hard segment provides mechanical strength, and polyol as a soft segment provides elasticity, so that the sealant has both strength and elasticity. Commonly used isocyanate products include toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI, such as MDI-100 and MDI-50), polymethylene polyphenyl isocyanate (PAPI, such as PM-200), isophorone diisocyanate (IPDI) and modified MDI (liquefied MDI), etc. Among them, MDI, TDI and PAPI are widely used in the production of polyurethane pouring sealant. Low molecular weight polyol is basically divided into hydroxyl-terminated polybutadiene (HTPB), polyether polyol (such as polytetrahydrofuran diol), polyester polyol (such as polyethylene glycol adipate diol) and castor oil low molecular weight polyol, especially castor oil, which is now widely used in the production of pouring sealant. The existing preparation process of polyurethane pouring sealant is complex, the mass-volume ratio is large, and the performance such as thermal stability and shock absorption still needs to be improved. SUMMARY

[0006] In view of the deficiencies of the prior art, the purpose of the present application is to provide a light-weight energy-absorbing polyurethane power battery pouring sealant, its preparation method and application. The polyurethane pouring sealant is light in weight, has excellent comprehensive performance, and has a simple and controllable preparation process, is environmentally friendly and reliable, and has low cost. It can improve the stability and safety of the power battery and promote the development of new energy vehicles and meet environmental protection requirements.

[0007] In order to achieve the above purpose, the following technical solutions are adopted:

[0008] A preparation method of a light-weight energy-absorbing polyurethane power battery pouring sealant, comprising the following steps:

[0009] Step one, taking 100 parts of polytetrahydrofuran diol and 56.31 parts of diphenylmethane diisocyanate by mass fraction, and loading into a 80℃ reaction kettle, stirring for 4-5h, to obtain a polyurethane prepolymer;

[0010] Step two, in mass fraction, take step one configuration good polyurethane prepolymer 100 parts, bismuth zinc catalyst 0.1~0.3 parts, silicone foam stabilizer 0.1~0.3 parts, water 0~0.25 parts, 1,4-butanediol 7.57~10.09 parts into the reaction kettle, stirring at room temperature for 5~10 min, polyurethane potting glue slurry is obtained.

[0011] The application also has the following technical features:

[0012] Preferably, the average molecular weight of the polytetrahydrofuran diol is 2000.

[0013] Preferably, the molar ratio of elemental bismuth to zinc in the bismuth-zinc catalyst is 1:3.

[0014] Preferably, the stirring speed during the stirring process in step one and step two is 180 r / min.

[0015] The application also protects a lightweight energy-absorbing polyurethane power battery potting adhesive prepared by the above method and its application in power batteries. The polyurethane potting adhesive slurry is poured into the gap of the power battery pack, and then cured at a temperature of 20~40℃ for 7~8d to obtain a sealed power battery pack.

[0016] Compared with the prior art, the application has the following technical effects:

[0017] The application uses liquid MDI and polytetrahydrofuran diol (PTMG-2000) as raw materials to prepare polyurethane prepolymer with terminal isocyanate groups, and then uses it to react with 1,4-butanediol (BDO) by adjusting the chain extension coefficient to prepare microcellular foaming polyurethane for preparing polyurethane power battery potting adhesive. The microcellular structure is formed by reaction, and the polyurethane power battery potting adhesive is produced by reaction molding process. According to the required foaming volume, the chain extension coefficient is adjusted for pouring, so as to achieve the purpose of lightweight, meet the performance requirements such as lightweight and energy absorption of power battery potting adhesive, and adjust the performance of polyurethane power battery potting adhesive by synthesizing prepolymer and using different chain extension coefficients to adjust the cell rate, cell size and crosslinking degree. The process has high controllability, and compared with the wet solidification process, the same foaming effect is achieved, the wet process, workshop and equipment are less than ordinary wet process, and the process is stable. By controlling the chain extension coefficient to adjust the foaming volume, the amount of slurry used can be reduced, the cost is reduced, and it is suitable for large-scale production.

[0018] The present application is a process without using any solvent, and no solvent pollution is generated, and belongs to an environment-friendly process; the product has no solvent residue, and belongs to a green product; the solvent-free system is used, and no pollution is generated, and the solvent-free polyurethane can meet various safety and environmental protection indexes; no solvent vapor and water vapor are discharged, and even little heat is discharged, and zero emission is truly achieved; in order to improve the stability and safety of the power battery, promote the development of new energy vehicles, and meet the environmental protection requirements,

[0019] The polyurethane pouring sealant prepared in the present application has light weight, excellent energy absorption and shock absorption performance, mechanical properties, thermal stability and adhesion. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 A light-weight energy-absorbing polyurethane power battery pouring sealant preparation and a power battery pouring process flow chart are provided.

[0021] Figure 2 The SEM images of the polyurethane power battery pouring sealant of Examples 1-6 are shown in (a) 75%, 80%, 85%, 90%, 95% and 100%. DETAILED DESCRIPTION

[0022] The specific content of the present application is further explained and described in detail in combination with the following examples.

[0023] In the following examples, polytetrahydrofuran diol PTMG-2000 is used, the number average molecular weight is 2000, and the manufacturer is Chongqing Chisheng Chemical Co., Ltd. (Chongqing, China);

[0024] Diphenyl methane diisocyanate MDI-50 is selected, and the manufacturer is Wanhua Chemical Group Co., Ltd. (Yantai, China);

[0025] Bismuth-zinc catalyst PC-02 is selected, and the manufacturer is Yantai Sunshine Plastic Co., Ltd. (Yantai, China), the molar ratio of bismuth to zinc in the bismuth-zinc catalyst is 1:3;

[0026] Silicone foam stabilizer Sicare-2003 is selected, and the manufacturer is Guangzhou Slocore New Material Co., Ltd. (Guangzhou, China).

[0027] In the following examples, the stirring speed of the stirrer in the reaction kettle during the stirring reaction process is 180 r / min.

[0028] Example 1

[0029] The present application is a process without using any solvent, and no solvent pollution is generated, and belongs to an environment-friendly process; the product has no solvent residue, and belongs to a green product; the solvent-free system is used, and no pollution is generated, and the solvent-free polyurethane can meet various safety and environmental protection indexes; no solvent vapor and water vapor are discharged, and even little heat is discharged, and zero emission is truly achieved; in order to improve the stability and safety of the power battery, promote the development of new energy vehicles, and meet the environmental protection requirements,

[0030] Step one, in mass fraction, take PTMG-2000 100 parts, MDI-50 56.31 parts, into 80℃ reaction kettle, stirring reaction 4h, get polyurethane prepolymer;

[0031] Step two, in mass fraction, take step one configuration good polyurethane prepolymer 100 parts, bismuth zinc catalyst 0.2 parts, silicone foam stabilizer 0.2 parts, 1, 4-butanediol 10.09 parts into reaction kettle, stirring 10 min at room temperature, get polyurethane pouring sealant slurry.

[0032] Pour the prepared slurry into the gap of power battery pack, then mature at 25℃ for 8d, get sealed power battery pack.

[0033] Example 2

[0034] The preparation method of a kind of lightweight energy-absorbing polyurethane power battery pouring sealant in this embodiment includes the following steps:

[0035] Step one, in mass fraction, take PTMG-2000 100 parts, MDI-50 56.31 parts, into 80℃ reaction kettle, stirring reaction 4h, get polyurethane prepolymer;

[0036] Step two, in mass fraction, take step one configuration good polyurethane prepolymer 100 parts, bismuth zinc catalyst 0.2 parts, silicone foam stabilizer 0.2 parts, water 0.05 parts, 1, 4-butanediol 9.59 parts into reaction kettle, stirring 10 min at room temperature, get polyurethane pouring sealant slurry.

[0037] Pour the prepared slurry into the gap of power battery pack, then mature at 25℃ for 8d, get sealed power battery pack.

[0038] Example 3

[0039] The preparation method of a kind of lightweight energy-absorbing polyurethane power battery pouring sealant in this embodiment includes the following steps:

[0040] Step one, in mass fraction, take PTMG-2000 100 parts, MDI-50 56.31 parts, into 80℃ reaction kettle, stirring reaction 4h, get polyurethane prepolymer;

[0041] Step two, in mass fraction, take step one configuration good polyurethane prepolymer 100 parts, bismuth zinc catalyst 0.2 parts, silicone foam stabilizer 0.2 parts, water 0.10 parts, 1, 4-butanediol 9.08 parts into reaction kettle, stirring 10 min at room temperature, get polyurethane pouring sealant slurry.

[0042] The prepared slurry is poured into the gap of the power battery pack; then, the power battery pack is sealed by aging at 25℃ for 8d.

[0043] Example 4

[0044] The preparation method of the light-weight energy-absorbing polyurethane power battery potting adhesive comprises the following steps:

[0045] In step one, 100 parts of PTMG-2000 and 56.31 parts of MDI-50 are taken by mass fraction, and are loaded into a 80℃ reaction kettle for stirring reaction for 4h, so as to obtain a polyurethane prepolymer.

[0046] In step two, 100 parts of the polyurethane prepolymer prepared in step one, 0.2 parts of bismuth-zinc catalyst, 0.2 parts of silicone foam stabilizer, 0.15 parts of water and 8.58 parts of 1,4-butanediol are taken by mass fraction, and are loaded into a reaction kettle for stirring at room temperature for 10min, so as to obtain a polyurethane potting adhesive slurry.

[0047] The prepared slurry is poured into the gap of the power battery pack; then, the power battery pack is sealed by aging at 25℃ for 8d.

[0048] Example 5

[0049] The preparation method of the light-weight energy-absorbing polyurethane power battery potting adhesive comprises the following steps:

[0050] In step one, 100 parts of PTMG-2000 and 56.31 parts of MDI-50 are taken by mass fraction, and are loaded into a 80℃ reaction kettle for stirring reaction for 4h, so as to obtain a polyurethane prepolymer.

[0051] In step two, 100 parts of the polyurethane prepolymer prepared in step one, 0.2 parts of bismuth-zinc catalyst, 0.2 parts of silicone foam stabilizer, 0.15 parts of water and 8.58 parts of 1,4-butanediol are taken by mass fraction, and are loaded into a reaction kettle for stirring at room temperature for 10min, so as to obtain a polyurethane potting adhesive slurry.

[0052] The prepared slurry is poured into the gap of the power battery pack; then, the power battery pack is sealed by aging at 25℃ for 8d.

[0053] Example 6

[0054] The preparation method of the light-weight energy-absorbing polyurethane power battery potting adhesive comprises the following steps:

[0055] In step one, 100 parts of PTMG-2000 and 56.31 parts of MDI-50 are taken by mass fraction, and are loaded into a 80℃ reaction kettle for stirring reaction for 4h, so as to obtain a polyurethane prepolymer.

[0056] Step two, in mass fraction, take the polyurethane prepolymer 100 parts, bismuth zinc catalyst 0.2 parts, silicone foam stabilizer 0.2 parts, water 0.25 parts, 1, 4-butanediol 7.57 parts of step one is configured into the reaction kettle, stirring at room temperature for 10 min, polyurethane potting adhesive slurry is obtained.

[0057] The prepared slurry is poured into the gap of the power battery pack, and then cured at 25 DEG C for 7 days to obtain a sealed power battery pack.

[0058] Example 7

[0059] The preparation method of the light-weight energy-absorbing polyurethane power battery potting adhesive comprises the following steps:

[0060] Step one, in mass fraction, take PTMG-2000 100 parts, MDI-50 56.31 parts, and load into an 80 DEG C reaction kettle, and stir for 4 h to obtain a polyurethane prepolymer;

[0061] Step two, in mass fraction, take the polyurethane prepolymer 100 parts, bismuth zinc catalyst 0.3 parts, silicone foam stabilizer 0.3 parts, water 0.25 parts, 1, 4-butanediol 7.57 parts of step one is configured into the reaction kettle, stirring at room temperature for 8 min, polyurethane potting adhesive slurry is obtained.

[0062] The prepared slurry is poured into the gap of the power battery pack, and then cured at 20 DEG C for 8 days to obtain a sealed power battery pack.

[0063] Example 8

[0064] The preparation method of the light-weight energy-absorbing polyurethane power battery potting adhesive comprises the following steps:

[0065] Step one, in mass fraction, take PTMG-2000 100 parts, MDI-50 56.31 parts, and load into an 80 DEG C reaction kettle, and stir for 4.5 h to obtain a polyurethane prepolymer;

[0066] Step two, in mass fraction, take the polyurethane prepolymer 100 parts, bismuth zinc catalyst 0.1 parts, silicone foam stabilizer 0.1 parts, water 0.25 parts, 1, 4-butanediol 7.57 parts of step one is configured into the reaction kettle, stirring at room temperature for 5 min, polyurethane potting adhesive slurry is obtained.

[0067] The prepared slurry is poured into the gap of the power battery pack, and then cured at 40 DEG C for 7.5 days to obtain a sealed power battery pack.

[0068] Figure 1 The preparation method of the light-weight energy-absorbing polyurethane power battery potting adhesive and the power battery potting process flow chart of the application;

[0069] Figure 2 SEM images of the cross-section of the polyurethane power battery potting adhesive of Examples 1-6: (a) 75%; (b) 80%; (c) 85%; (d) 90%; (e) 95%; (f) 100%. The images were taken by SEM. Figure 2 It can be seen that, with the increase of the chain extension coefficient, the number of cells in the cross-section of the polyurethane power battery potting adhesive gradually decreases, and the cell density decreases. This phenomenon is mainly because the NCO groups in the prepolymer decrease, the CO2 produced by the reaction of H2O and H2O in the air decreases, and the cells produced by the molding decrease. When the curing coefficient of the PPBSs is 90%, 95%, and 100%, the cells in the cross-section of the PPBSs are relatively sparse, and the cross-section surface is relatively smooth. When the curing coefficient of the potting adhesive is 75%, 80%, and 85%, the cells are in a closed or semi-open state, spherical, and the cell distribution is relatively uniform and dense.

[0070] Table 3 is the performance test results of the polyurethane power battery potting adhesives with different chain extension coefficients prepared in Examples 1-6.

[0071] Table 3 is the performance test results of the polyurethane power battery potting adhesives with different chain extension coefficients prepared in Examples 1-6.

[0072]

[0073] As can be seen from Table 3, the tensile strength increases with the increase of the chain extension coefficient, and the elongation at break decreases. The tensile strength of the PPBS with a chain extension coefficient of 85% is 3.45 MPa, and the elongation at break is 480.18%. The hardness of the PPBSs ranges from 47HA to 57HA, which has a moderate hardness and can provide a certain high elasticity. Taking the potting adhesive with a chain extension coefficient of 85% as an example, the compressive stress of the PPBSs is 1.89 MPa when compressed by 50%. The change of the chain extension coefficient will change the foaming volume of the potting adhesive, which can play a role in lightweight by adjusting. The hysteresis energy density of the potting adhesive with a strain of 50% is 2.470 J / m 3 , which has a relatively high ability to resist external force damage, thereby protecting the power battery. The potting adhesive has a relatively high adhesive strength to 304 steel. The maximum lap shear force of the potting adhesive with a chain extension coefficient of 85% to the 304 steel substrate is 744.59 N, and the lap shear strength is 2.38 MPa. The maximum lap shear force of the potting adhesive with a chain extension coefficient of 85% to the PET film substrate is 278.10 N, and the lap shear strength is 0.89 MPa.

[0074] TGA tests were performed on the samples of Examples 1-6. It can be seen from the TGA test that all the samples have basically no mass loss below 260°C, indicating that the polyurethane power battery potting adhesives with different chain extension coefficients all exhibit high thermal stability, which can ensure the protection of the power battery during use.

[0075] By adjusting the chain extension coefficient, the potting adhesive shows excellent comprehensive performance, and becomes an effective solution for solving the energy absorption and lightweight of the power battery sealing adhesive. The potting adhesive can provide better mechanical properties, thermal stability and adhesion, and has great prospects in the application of power batteries.

[0076] The above embodiments are only used to illustrate the technical solutions of the present application, but not limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the present application.

Claims

1. A method for preparing a lightweight energy-absorbing polyurethane power battery potting compound, characterized in that, Includes the following steps: Step 1: Take 100 parts by mass of polytetrahydrofuran diol and 56.31 parts by mass of diphenylmethane diisocyanate, put them into an 80 ℃ reactor, stir and react for 4-5 h to obtain polyurethane prepolymer. Step 2: By mass, take 100 parts of the polyurethane prepolymer prepared in Step 1, 0.1-0.3 parts of bismuth-zinc catalyst, 0.1-0.3 parts of silicone foam stabilizer, 0-0.25 parts of water, and 7.57-10.09 parts of 1,4-butanediol and put them into a reaction vessel. Stir at room temperature for 5-10 minutes to obtain polyurethane potting slurry, wherein the water content is not 0. The average molecular weight of the polytetrahydrofuran diol is 2000; The molar ratio of bismuth to zinc in the bismuth-zinc catalyst is 1:

3.

2. The preparation method of the lightweight energy-absorbing polyurethane power battery potting compound as described in claim 1, characterized in that, During the stirring process described in steps one and two, the stirrer speed is 180 r / min.

3. A lightweight energy-absorbing polyurethane power battery potting compound prepared by the method of any one of claims 1 or 2.

4. The application of the lightweight energy-absorbing polyurethane power battery potting compound as described in claim 3 in a power battery, characterized in that, Polyurethane potting compound is poured into the gaps of the power battery pack, and then cured at a temperature of 20-40 ℃ for 7-8 days to obtain a sealed power battery pack.

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