Highly waterproof two-component polyurethane adhesive for sealing battery pack and preparation method of highly waterproof two-component polyurethane adhesive

Abstract

The invention discloses a highly waterproof two-component polyurethane adhesive for sealing a battery pack and a preparation method of the highly waterproof two-component polyurethane adhesive. A component A comprises polyester polyol, polyether polyol, hydroxyl-terminated polybutadiene polyol, fluorine-containing hydrophobic polyol, a water absorbent, a plasticizer, a catalyst and filler; and the component B comprises the following raw materials: polyol, isocyanate, a coupling agent, a dewatering agent, an antioxidant, a filler, white carbon black, a plasticizer and a flame retardant. The fluorine-containing hydrophobic polyol is prepared by performing fluorine modification on the hydrophobic polyol through a chemical modification method, and the sealant prepared from the fluorine-containing hydrophobic polyol has better stability, chemical corrosion resistance and waterproof performance.

Description

Technical Field

[0001] This invention mainly uses hydrophobic polyols and fluorinated hydrophobic polyols as the main raw materials to prepare a two-component polyurethane sealant for battery packs with high waterproof effect, which can effectively improve the water vapor barrier properties of the battery pack, ensure the safety of the battery cells, and extend the service life of the battery pack. Background Technology

[0002] With the accelerated global energy transition towards cleaner energy, electric vehicles are experiencing explosive growth. As a crucial component of new energy vehicles, the reliability and stability of the battery pack are paramount. To ensure the normal operation of the battery pack, a series of sealants with different properties are used. For example, CN116875268A prepares a thermally conductive silicone sealant for new energy vehicle battery packs, which can improve the mechanical strength, thermal conductivity, and curing speed of the silicone sealant while ensuring that its flowability, adhesion, and chemical resistance are not reduced. CN 115612433A prepares a fatigue-resistant two-component polyurethane thermally conductive structural adhesive, using a novel flame retardant to ensure flame retardant performance while improving the fatigue resistance of the colloid.

[0003] However, there is currently little attention paid to the waterproof performance of battery packs. When an electric vehicle is exposed to moisture and submerged for extended periods, significant amounts of water can seep into the battery cells, leading to serious consequences. These consequences can range from battery malfunction to short circuits and fires, ultimately causing property damage and personal injury. Therefore, the sealant used in the battery pack has excellent waterproof properties, which is crucial for battery safety. The outer packaging structure of the battery pack is the first physical barrier against the external environment and a core line of defense ensuring the stable operation of the battery cell system. Improving its waterproof performance provides a dry environment for the internal battery cell system, protecting its safety.

[0004] Currently, there are different solutions for improving the sealing of battery pack outer packaging. One solution is to install sealing gaskets in the recesses of the casing, but battery pack manufacturers need to customize different molds with the gasket manufacturers in advance, which is costly. Using sealants, such as polyurethane and silicone, is cheaper and more convenient, but none of them address waterproofing. When exposed to moisture or immersion for extended periods, insufficient waterproofing of the sealant can lead to seal failure, reducing the safety of the battery pack. Summary of the Invention

[0005] Existing battery pack sealants lack adequate waterproofing performance. In harsh environments such as high humidity or immersion, large amounts of moisture can penetrate the battery pack, compromising its safety. The outer packaging structure of the battery pack is the first physical barrier against external environmental factors and a crucial line of defense for ensuring the stable operation of the battery cell system. Improving its waterproofing provides a dry environment for the internal battery cells, protecting their safety. To address the problems of poor waterproofing and stability in existing battery packs, this invention develops a two-component polyurethane sealant with high waterproofing performance. This sealant is used to seal the outer packaging structure of the battery pack, creating a dry environment inside the cells, extending the battery pack's lifespan, and ensuring the safety of electric vehicles.

[0006] This invention modifies hydrophobic polyols to obtain fluorinated hydrophobic polyols, and prepares a two-component polyurethane sealant with low surface energy and high water-blocking effect. It can effectively reduce water vapor adhesion and block water vapor ingress. The synergistic effect of fluorine and hydrophobic polyol has an ultra-high waterproof effect, thereby effectively extending the battery pack life and improving the safety of electric vehicle use.

[0007] To improve the waterproof performance of the battery pack sealing system, extend the battery pack's service life, and ensure the safety of electric vehicles, this invention provides a highly waterproof two-component polyurethane sealant with low surface energy and ultra-low water vapor permeability. This sealant not only has excellent bonding and sealing performance and easy disassembly performance, but also has an ultra-low water vapor permeability. Compared with existing sealing systems, it can effectively reduce water vapor penetration under extreme conditions (long-term exposure to high humidity or immersion in water), thereby improving battery pack safety and battery life.

[0008] This invention provides a highly waterproof two-component polyurethane sealant for sealing battery packs, consisting of component A and component B in a volume ratio of (0.9~1.1):1.

[0009] By weight, component A includes the following raw materials: 5-15 parts polyester polyol, 5-15 parts polyether polyol, 10-40 parts hydroxyl-terminated polybutadiene polyol, 10-40 parts fluorinated hydrophobic polyol, 1-10 parts water absorbent, 5-20 parts plasticizer, 0.01-0.1 parts catalyst, and 25-60 parts filler.

[0010] By weight, component B includes the following raw materials: 15-40 parts of polyol, 5-15 parts of isocyanate, 1-5 parts of coupling agent, 1-2 parts of dehydrating agent, 0.1-3 parts of antioxidant, 15-50 parts of filler, 2-10 parts of silica, 2-10 parts of plasticizer, and 10-30 parts of flame retardant.

[0011] Polyester polyols can be selected with a molecular weight of 2000~6000 and a functionality of 2~4, such as one or more of Huide Technology's 7720, 7250, and Kuraray P-2010.

[0012] The polyether polyols can be selected with a molecular weight of 2000-4000 and a functionality of 2-4, such as Wanhua C2040D or C2020, and Lanxing Dongda's DL-2000 with a functionality of 2. This invention uses a compound of polyester polyols and polyether polyols to give the polyurethane sealant excellent impact resistance.

[0013] This invention does not impose any particular restrictions on the source of the liquid hydroxyl-terminated polybutadiene polyol; commercially available products well-known to those skilled in the art can be used. For example, the hydroxyl-terminated polybutadiene polyol can be purchased from any one or a combination of at least two of Evonik Polyvest HT, Cray Valley Poly bd R45V, and Tianyuan Aerospace Materials' hydroxyl-terminated polybutadiene HTPB-Ⅰ, HTPB-Ⅱ, HTPB Ⅳ, and HFHTPB-I types. More preferably, it is Evonik Polyvest HT or Cray Valley Poly bd R45V.

[0014] The preparation method of the fluorinated hydrophobic polyol is as follows: Hydroxyl-terminated polybutadiene (preferably Evonik Polyvest HT) with a molecular weight of 2500–3000 g / mol and a functional group degree of 2.2–2.4 is reacted with pentafluorostyrene isocyanate at a molar ratio of 1:1. The reaction temperature is 68–72 °C, and the reaction time is 3.0–4.0 h (preferably 70 °C, 3.5 h). The successful synthesis of the fluorinated hydrophobic polyol is confirmed by the disappearance of the -NCO characteristic peak monitored by infrared spectroscopy and by titration of di-n-butylamine to determine that the -NCO content is <0.1%. The fluorinated hydrophobic polyol is terminally capped with hydroxyl groups, and the hydroxyl groups in the structure can further react with the isocyanate in component B to cure and form polyurethane.

[0015] In polyurethane adhesive systems, a higher proportion of fluorinated hydrophobic polyols or a significantly reduced amount of hydroxyl-terminated polybutadiene results in excellent weather resistance and high strength retention after xenon lamp aging. However, fluorination increases the system's rigidity, making the sealant brittle and reducing elongation at break. Hydroxyl-terminated polybutadiene can impart good elasticity to the system. Therefore, it is necessary to rationally control the amounts of hydroxyl-terminated polybutadiene polyol and fluorinated hydrophobic polyol. In this invention, 10-40 parts of hydroxyl-terminated polybutadiene polyol and 10-40 parts of fluorinated hydrophobic polyol are used.

[0016] In this invention, hydrophobic polyols are fluorinated using chemical modification methods, and the resulting fluorinated hydrophobic polyols have the following advantages:

[0017] 1. The phase structure is more stable. Fluorinated hydrophobic polyols connected by chemical bonds are less likely to undergo phase separation or other physical changes when environmental conditions change.

[0018] 2. Improved chemical corrosion resistance: Fluorine atoms are tightly bonded to hydrophobic polyols via chemical bonds, forming a stable chemical structure. This tight bonding allows fluorine atoms to form a more stable and continuous protective layer on the material surface, better enhancing its corrosion resistance and preventing the hydrophobic polyol from being corroded by chemical substances.

[0019] 3. Superior low surface energy characteristics: In the fluorine-modified hydrophobic polyol system, fluorine atoms are uniformly distributed in the molecular chain, fully demonstrating the low surface energy of fluorine atoms, which makes the sealant layer more hydrophobic and can effectively improve the waterproof performance of the sealant.

[0020] Therefore, the sealant prepared using fluorinated hydrophobic polyols in this invention exhibits better stability, chemical resistance, and waterproofing. In battery pack casing sealing, its surface can better form a continuous and stable hydrophobic film, reducing moisture adhesion and acting as the first line of defense against moisture. Furthermore, the fluorinated polyol in the system can further enhance the system's weather resistance.

[0021] The desiccant in component A is one or more of the following: 3A or 4A molecular sieves, 325-mesh or 1250-mesh calcium oxide. Adding the desiccant to component A reduces air bubbles generated after mixing the raw materials. The dehydrating agent in component B is p-toluenesulfonyl isocyanate, which improves the storage stability of component B.

[0022] The plasticizer is one or more of phthalates and phosphates. The preferred plasticizer is a phosphate ester, specifically triisopropylphenyl phosphate. In component B, there are no particular restrictions on the type of flame retardant, but triisopropylphenyl phosphate is preferred. Using triisopropylphenyl phosphate not only weakens the stress between molecular chains and increases the slippage of molecular chains, but also provides a flame-retardant effect.

[0023] The catalyst is one or more of dibutyltin dilaurate, bismuth neodecanoate, bismuth isooctanoate, and bismuth naphthenate. The catalyst is adjusted according to the application. The coupling agent is one or more of 3-isocyanopropyltriethoxysilane, 3-isocyanopropyltrimethoxysilane, and γ-glycidoxypropyltrimethoxysilane, used in combination to improve adhesion to the substrate. The antioxidant uses hindered phenolic primary antioxidants and organophosphite auxiliary antioxidants for synergistic effects, such as BASF Irganox 1010, BASF Irgafos 168, and BASF Irganox B215 to extend the material's service life.

[0024] Hydrophobic fumed silica is used, such as Evonik AEROSIL R202, AEROSIL R974, and CAB-O-SIL TS-720, with Evonik AEROSIL R202 and CAB-O-SIL TS-720 being preferred. Hydrophobic fumed silica increases the thixotropic and mechanical properties of the product, and its low hygroscopicity prevents the introduction of bound water, which could lead to undesirable bubbles or compromise the system's storage stability after mixing.

[0025] The filler used in component A is any one or a combination of two of heavy calcium carbonate and nano calcium carbonate. For heavy calcium carbonate, the Yixin heavy calcium carbonate series can be selected, and for nano calcium carbonate, the Warner CCS series nano calcium carbonate can be selected. The filler in component B is preferably heavy calcium carbonate. There are no special requirements for the fillers in components A and B.

[0026] The isocyanate used in component B is one or more selected from diphenylmethane diisocyanate, toluene diisocyanate, and dicyclohexylmethane diisocyanate. The preferred isocyanate is diphenylmethane diisocyanate. The polyol used in component B is Evonik PolyvestHT, a hydroxyl-terminated polybutadiene with a molecular weight of 2500–3000 g / mol and a functionality of 2.2–2.4.

[0027] The aforementioned two-component battery pack sealant with high waterproof performance is prepared by the following steps:

[0028] Preparation of Component A: Polyester polyol, polyether polyol, hydroxyl-terminated polybutadiene polyol, fluorinated hydrophobic polyol, plasticizer, and filler are dispersed evenly and then dehydrated at a temperature of 110~120℃ and a vacuum degree of -0.085~0.1MPa for 2~3 hours. After dehydration, the temperature is lowered to below 50℃ and water absorbent and catalyst are added. The mixture is then dispersed at a vacuum degree of -0.085~0.1MPa for at least 30 minutes before being discharged to obtain Component A.

[0029] Preparation of Component B: The polyol is heated to 110~120℃ and dehydrated under a vacuum of -0.085~0.1MPa for 2~3 hours. After dehydration, the temperature is lowered to below 80℃, and isocyanate is added and reacted for 1.5~3 hours to obtain isocyanate-terminated prepolymer. The isocyanate-terminated prepolymer, coupling agent, dehydrating agent, antioxidant, filler, silica, plasticizer, and flame retardant are dispersed under a vacuum of -0.085~0.1MPa for at least 30 minutes and then discharged to obtain Component B.

[0030] Mix the above components A and B at a volume ratio of (0.9~1.1):1 until homogeneous to obtain the battery pack sealant.

[0031] The following beneficial effects were obtained from using this two-component sealant in battery pack sealing:

[0032] 1. In this invention, through chemical modification, fluorine atoms are evenly distributed on the surface of the battery pack sealing layer to form a stable hydrophobic layer with excellent low surface energy characteristics, effectively reducing the adhesion of water vapor on the surface of the battery pack sealing layer, and playing the first line of defense against water vapor.

[0033] 2: Fluorine atoms are tightly bonded to hydrophobic polyols through chemical bonds. Thanks to the steric hindrance and shielding effect of fluorine atoms, they can effectively block the contact of active groups with the polyurethane backbone, thereby reducing hydrolysis, oxidation and other reactions, and thus improving the weather resistance of polyurethane sealants.

[0034] 3. The hydroxyl-terminated polybutadiene polyol used in this invention has good water-blocking properties. Under prolonged high temperature and humidity or immersion conditions, it can prevent water vapor penetration, avoiding water vapor accumulation inside the battery pack and thus affecting battery life. Therefore, this sealing system utilizes the synergistic effect of hydrophobic polyols, namely hydroxyl-terminated polybutadiene polyol and fluorinated modified hydrophobic polyol. On the one hand, the introduction of fluorine atoms improves the hydrophobic performance of the system, forming a hydrophobic layer, and can also shield the active groups from attacking the polyurethane backbone, thereby improving weather resistance. On the other hand, under prolonged high humidity and immersion conditions, the hydroxyl-terminated polybutadiene polyol has a high water vapor barrier rate, effectively preventing water vapor from entering. Therefore, the two-component sealant prepared from hydroxyl-terminated polybutadiene polyol and fluorinated hydrophobic polyol has an extremely high waterproof effect, reducing water vapor penetration, reducing damage to the battery cell, and effectively extending the battery pack's lifespan. Attached Figure Description

[0035] Figure 1 This is a schematic diagram illustrating hydrophobicity. The two-component sealant acts as an adhesive between the upper and lower shells, and its surface has a large number of fluorine atoms, giving the battery pack shell strong hydrophobicity. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0037] Preparation of fluorinated hydrophobic polyols used in each example and comparative example:

[0038] Hydroxyl-terminated polybutadiene Evonik Polyvest HT was reacted with pentafluorostyrene isocyanate at a molar ratio of 1:1 at a reaction temperature of 70℃ for 3.5 h. The successful synthesis of the fluorinated hydrophobic polyol was confirmed by the disappearance of the characteristic peak of -NCO by infrared monitoring and the determination of -NCO content <0.1% by di-n-butylamine titration.

[0039] Example 1

[0040] Preparation of Component A: 5 parts polyester polyol, 5 parts polyether polyol, 10 parts hydroxyl-terminated polybutadiene, 40 parts fluorinated hydrophobic polyol, 15 parts plasticizer, 30 parts heavy calcium carbonate, and 20 parts nano calcium carbonate were heated to 120℃ and dehydrated for 3 hours under a vacuum of -0.09 MPa. After dehydration, the temperature was lowered to 40℃ and 5 parts water absorbent and 0.05 parts catalyst were added sequentially. The mixture was then mixed for 30 minutes under a vacuum of -0.09 MPa to obtain Component A.

[0041] Preparation of Component B: 30 parts of hydroxyl-terminated polybutadiene were heated to 120℃ and dehydrated for 2 hours under a vacuum of -0.09 MPa. The temperature was then lowered to 80℃, and 9 parts of diphenylmethane diisocyanate MDI-100 were added and reacted for 2 hours to obtain an isocyanate-terminated prepolymer. Then, 1.5 parts of dehydrating agent p-toluenesulfonyl isocyanate, 4 parts of coupling agent 3-isocyanopropyltriethoxysilane, 1 part of antioxidant BASF Irganox 1010, 1 part of auxiliary antioxidant BASF Irgafos 168, 15 parts of triisopropylphenyl phosphate as flame retardant and plasticizer, 40 parts of heavy calcium carbonate, and 5 parts of silica Evonik AEROSIL R202 were dispersed under a vacuum of -0.09 MPa for 30 minutes before being discharged to obtain Component B.

[0042] Mix the above components A and B at a volume ratio of 1:1 until homogeneous to obtain a highly waterproof two-component polyurethane adhesive for sealing battery packs.

[0043] The information of each raw material in the examples is as follows. Except for the fluorinated hydrophobic polyol, which is self-made, there are no special restrictions on the source of the other raw materials. Well-known commercially available ones can be used.

[0044] The polyester polyol used is Kuraray P-2010 with 2 functionalities and a molecular weight of 2000; the polyether polyol used is Lanxing Dongda DL-2000 with 2 functionalities; and the hydroxyl-terminated polybutadiene used is Evonik Polyvest HT with a molecular weight of 2500–3000 g / mol and a functional group degree of 2.2–2.4. The heavy calcium carbonate used is Yixin heavy calcium carbonate, and the nano calcium carbonate used is Warner CCS-25. The water-absorbing agent in component A is 3A molecular sieve, and the catalyst is dibutyltin dilaurate. The isocyanate used is BASF's diphenylmethane diisocyanate MDI-100. In component B, the dehydrating agent is p-toluenexanoyl isocyanate, the coupling agent is 3-isocyanopropyltriethoxysilane coupling agent (Y25E), the antioxidant is a combination of 1010 and 168, the flame retardant and plasticizer are triisopropylphenyl phosphate, and the silica is Evonik AEROSIL R202. Other embodiments or comparative examples where the material type is not specified are the same as in Example 1.

[0045] Example 2

[0046] Preparation of Component A: 10 parts of polyester polyol P-2010, 10 parts of polyether polyol DL-2000, 20 parts of hydroxyl-terminated polybutadiene Evonik Polyvest HT, 20 parts of fluorinated hydrophobic polyol, 15 parts of plasticizer, 15 parts of heavy calcium carbonate, and 35 parts of nano calcium carbonate CCS-25 were heated to 120℃ and dehydrated for 3 hours under a vacuum of -0.09MPa. After dehydration, the temperature was lowered to 40℃ and 5 parts of water-absorbing agent 3A molecular sieve and 0.06 parts of catalyst dibutyltin dilaurate were added sequentially. The mixture was then mixed for 30 minutes under a vacuum of -0.09MPa to obtain Component A.

[0047] Preparation of Component B: 30 parts of hydroxyl-terminated polybutadiene (Evonik Polyvest HT) were heated to 120℃ and dehydrated for 2 hours under a vacuum of -0.09 MPa. The temperature was then lowered to 80℃, and 10 parts of diphenylmethane diisocyanate (MDI-100) were added and reacted for 2 hours to obtain an isocyanate-terminated prepolymer. Then, 1.5 parts of dehydrating agent p-toluenesulfonyl isocyanate, 4 parts of coupling agent 3-isocyanopropyltriethoxysilane Y25E, 0.5 parts of antioxidant 1010, 0.5 parts of auxiliary antioxidant 168, 15 parts of triisopropylphenyl phosphate as flame retardant and plasticizer, 40 parts of heavy calcium carbonate, and 5 parts of silica (Evonik AEROSIL R202) were dispersed under a vacuum of -0.09 MPa for 30 minutes before being discharged to obtain Component B.

[0048] Mix the above components A and B at a volume ratio of 1:1 until homogeneous to obtain a highly waterproof two-component polyurethane adhesive for sealing battery packs.

[0049] Example 3

[0050] Preparation of Component A: 5 parts of polyester polyol P-2010, 15 parts of polyether polyol DL-2000, 20 parts of hydroxyl-terminated polybutadiene Evonik Polyvest HT, 20 parts of fluorinated hydrophobic polyol, 15 parts of plasticizer, 25 parts of heavy calcium carbonate, and 25 parts of nano calcium carbonate CCS-25 were heated to 120℃ and dehydrated for 3 hours under a vacuum of -0.09MPa. After dehydration, the temperature was lowered to 40℃ and 5 parts of water absorbent and 0.06 parts of dibutyltin dilaurate were added sequentially. The mixture was then mixed for 30 minutes under a vacuum of -0.09MPa to obtain Component A.

[0051] Preparation of Component B: 30 parts of hydroxyl-terminated polybutadiene (Evonik Polyvest HT) were heated to 120℃ and dehydrated for 2 hours under a vacuum of -0.09 MPa. The temperature was then lowered to 80℃, and 10 parts of diphenylmethane diisocyanate (MDI-100) were added and reacted for 2 hours to obtain an isocyanate-terminated prepolymer. Then, 1.5 parts of p-toluenesulfonyl isocyanate, 3 parts of coupling agent 3-isocyanopropyltriethoxysilane Y25E, 1 part of antioxidant 1010, 1 part of auxiliary antioxidant 168, 15 parts of triisopropylphenyl phosphate as flame retardant and plasticizer, 43 parts of heavy calcium carbonate, and 2 parts of silica (Evonik AEROSIL R202) were dispersed under a vacuum of -0.09 MPa for 30 minutes before being discharged to obtain Component B.

[0052] Mix the above components A and B at a volume ratio of 1:1 until homogeneous to obtain a highly waterproof two-component polyurethane adhesive for sealing battery packs.

[0053] Example 4

[0054] Preparation of Component A: 15 parts of polyester polyol P-2010, 15 parts of polyether polyol DL-2000, 15 parts of hydroxyl-terminated polybutadiene Evonik Polyvest HT, 15 parts of fluorinated hydrophobic polyol, 10 parts of plasticizer, 20 parts of heavy calcium carbonate, and 30 parts of nano calcium carbonate CCS-25 were heated to 120℃ and dehydrated for 3 hours under a vacuum of -0.09 MPa. After dehydration, the temperature was lowered to 40℃ and 5 parts of water absorbent and 0.09 parts of catalyst dibutyltin dilaurate were added sequentially. The mixture was then mixed for 30 minutes under a vacuum of -0.09 MPa to obtain Component A.

[0055] Preparation of Component B: 30 parts of hydroxyl-terminated polybutadiene (Evonik Polyvest HT) were heated to 120℃ and dehydrated for 2 hours under a vacuum of -0.09 MPa. The temperature was then lowered to 80℃, and 11 parts of diphenylmethane diisocyanate (MDI-100) were added and reacted for 2 hours to obtain an isocyanate-terminated prepolymer. Then, 1.5 parts of p-toluenesulfonyl isocyanate, 3 parts of coupling agent 3-isocyanopropyltriethoxysilane Y25E, 1 part of antioxidant 1010, 1 part of auxiliary antioxidant 168, 15 parts of triisopropylphenyl phosphate as flame retardant and plasticizer, 40 parts of heavy calcium carbonate, and 6 parts of silica (Evonik AEROSIL R202) were dispersed under a vacuum of -0.09 MPa for 30 minutes before being discharged to obtain Component B.

[0056] Mix the above components A and B at a volume ratio of 1:1 until homogeneous to obtain a highly waterproof two-component polyurethane adhesive for sealing battery packs.

[0057] Comparative Example 1

[0058] Preparation of Component A: 10 parts of hydroxyl-terminated polybutadiene, 50 parts of fluorinated hydrophobic polyol, 15 parts of plasticizer, 30 parts of heavy calcium carbonate, and 20 parts of nano calcium carbonate were heated to 120℃ and dehydrated for 3 hours under a vacuum of -0.09 MPa. After dehydration, the temperature was lowered to 40℃ and 5 parts of water absorbent and 0.05 parts of catalyst were added sequentially. The mixture was then mixed for 30 minutes under a vacuum of -0.09 MPa to obtain Component A.

[0059] Preparation of Component B: 30 parts of hydroxyl-terminated polybutadiene were heated to 120℃ and dehydrated for 2 hours under a vacuum of -0.09 MPa. The temperature was then lowered to 80℃, and 9 parts of diphenylmethane diisocyanate MDI-100 were added and reacted for 2 hours to obtain an isocyanate-terminated prepolymer. Then, 1.5 parts of dehydrating agent p-toluenesulfonyl isocyanate, 4 parts of coupling agent 3-isocyanopropyltriethoxysilane, 1 part of antioxidant BASF Irganox 1010, 1 part of auxiliary antioxidant BASF Irgafos 168, 15 parts of triisopropylphenyl phosphate as flame retardant and plasticizer, 40 parts of heavy calcium carbonate, and 5 parts of silica Evonik AEROSIL R202 were dispersed under a vacuum of -0.09 MPa for 30 minutes before being discharged to obtain Component B.

[0060] Mix the above components A and B at a volume ratio of 1:1 until homogeneous to obtain the two-component polyurethane adhesive for sealing battery packs.

[0061] Comparative Example 2

[0062] Preparation of Component A: 5 parts polyester polyol, 5 parts polyether polyol, 50 parts fluorinated hydrophobic polyol, 15 parts plasticizer, 30 parts heavy calcium carbonate, and 20 parts nano calcium carbonate were heated to 120℃ and dehydrated for 3 hours under a vacuum of -0.09 MPa. After dehydration, the temperature was lowered to 40℃ and 5 parts water absorbent and 0.05 parts catalyst were added sequentially. The mixture was then mixed for 30 minutes under a vacuum of -0.09 MPa to obtain Component A.

[0063] Preparation of Component B: 30 parts of hydroxyl-terminated polybutadiene were heated to 120℃ and dehydrated for 2 hours under a vacuum of -0.09 MPa. The temperature was then lowered to 80℃, and 9 parts of diphenylmethane diisocyanate MDI-100 were added and reacted for 2 hours to obtain an isocyanate-terminated prepolymer. Then, 1.5 parts of dehydrating agent p-toluenesulfonyl isocyanate, 4 parts of coupling agent 3-isocyanopropyltriethoxysilane, 1 part of antioxidant BASF Irganox 1010, 1 part of auxiliary antioxidant BASF Irgafos 168, 15 parts of triisopropylphenyl phosphate as flame retardant and plasticizer, 40 parts of heavy calcium carbonate, and 5 parts of silica Evonik AEROSIL R202 were dispersed under a vacuum of -0.09 MPa for 30 minutes before being discharged to obtain Component B.

[0064] Mix the above components A and B at a volume ratio of 1:1 until homogeneous to obtain the two-component polyurethane adhesive for sealing battery packs.

[0065] Comparative Example 3

[0066] Preparation of Component A: 10 parts of polyester polyol P-2010, 10 parts of polyether polyol DL-2000, 40 parts of hydroxyl-terminated polybutadiene Evonik Polyvest HT, 15 parts of plasticizer, 15 parts of heavy calcium carbonate, and 35 parts of nano calcium carbonate CCS-25 were heated to 120℃ and dehydrated for 3 hours under a vacuum of -0.09MPa. After dehydration, the temperature was lowered to 40℃ and 5 parts of water-absorbing agent 3A molecular sieve and 0.06 parts of catalyst dibutyltin dilaurate were added sequentially. The mixture was then mixed for 30 minutes under a vacuum of -0.09MPa to obtain Component A.

[0067] Preparation of Component B: 30 parts of hydroxyl-terminated polybutadiene (Evonik Polyvest HT) were heated to 120℃ and dehydrated for 2 hours under a vacuum of -0.09 MPa. The temperature was then lowered to 80℃, and 11 parts of diphenylmethane diisocyanate (MDI-100) were added and reacted for 2 hours to obtain an isocyanate-terminated prepolymer. Then, 1.5 parts of dehydrating agent p-toluenesulfonyl isocyanate, 4 parts of coupling agent 3-isocyanopropyltriethoxysilane Y25E, 0.5 parts of antioxidant 1010, 0.5 parts of auxiliary antioxidant 168, 15 parts of triisopropylphenyl phosphate as flame retardant and plasticizer, 40 parts of heavy calcium carbonate, and 5 parts of silica (Evonik AEROSIL R202) were dispersed under a vacuum of -0.09 MPa for 30 minutes before being discharged to obtain Component B.

[0068] Mix the above components A and B at a volume ratio of 1:1 until homogeneous to obtain the two-component polyurethane adhesive for sealing battery packs.

[0069] Comparative Example 4

[0070] Preparation of Component A: 5 parts of polyester polyol P-2010, 15 parts of polyether polyol DL-2000, 20 parts of hydroxyl-terminated polybutadiene Evonik Polyvest HT, 20 parts of fluorinated hydrophobic polyol, 25 parts of heavy calcium carbonate, and 25 parts of nano calcium carbonate CCS-25 were heated to 120℃ and dehydrated for 3 hours under a vacuum of -0.09MPa. After dehydration, the temperature was lowered to 40℃ and 5 parts of water-absorbing agent and 0.06 parts of dibutyltin dilaurate were added sequentially. The mixture was then mixed for 30 minutes under a vacuum of -0.09MPa to obtain Component A.

[0071] Preparation of Component B: 30 parts of hydroxyl-terminated polybutadiene (Evonik Polyvest HT) were heated to 120℃ and dehydrated for 2 hours under a vacuum of -0.09 MPa. The temperature was then lowered to 80℃, and 10 parts of diphenylmethane diisocyanate (MDI-100) were added and reacted for 2 hours to obtain an isocyanate-terminated prepolymer. Then, 1.5 parts of p-toluenesulfonyl isocyanate, 3 parts of coupling agent 3-isocyanopropyltriethoxysilane Y25E, 1 part of antioxidant 1010, 1 part of auxiliary antioxidant 168, 5 parts of triisopropylphenyl phosphate as plasticizer, 43 parts of heavy calcium carbonate, and 2 parts of silica (Evonik AEROSIL R202) were dispersed under a vacuum of -0.09 MPa for 30 minutes before being discharged to obtain Component B.

[0072] Comparative Example 5

[0073] Preparation of Component A: 15 parts of polyester polyol P-2010, 15 parts of polyether polyol DL-2000, 15 parts of hydroxyl-terminated polybutadiene Evonik Polyvest HT, 15 parts of fluorinated hydrophobic polyol, 10 parts of plasticizer, 20 parts of heavy calcium carbonate, and 30 parts of nano calcium carbonate CCS-25 were heated to 120℃ and dehydrated for 3 hours under a vacuum of -0.09 MPa. After dehydration, the temperature was lowered to 40℃ and 5 parts of water absorbent and 0.09 parts of catalyst dibutyltin dilaurate were added sequentially. The mixture was then mixed for 30 minutes under a vacuum of -0.09 MPa to obtain Component A.

[0074] Preparation of Component B: 30 parts of polyester polyol 7720 were heated to 120℃ and dehydrated for 2 hours under a vacuum of -0.09MPa. The temperature was then lowered to 100℃, and 11 parts of diphenylmethane diisocyanate MDI-100 were added and reacted for 2 hours to obtain an isocyanate-terminated prepolymer. Then, 1.5 parts of p-toluenesulfonyl isocyanate, 3 parts of coupling agent 3-isocyanopropyltriethoxysilane Y25E, 1 part of antioxidant 1010, 1 part of auxiliary antioxidant 168, 15 parts of triisopropylphenyl phosphate as flame retardant and plasticizer, 40 parts of heavy calcium carbonate, and 6 parts of silica Evonik AEROSIL R202 were dispersed under a vacuum of -0.09MPa for 30 minutes before being discharged to obtain Component B.

[0075] Mix the above components A and B at a volume ratio of 1:1 until homogeneous to obtain the two-component polyurethane adhesive for sealing battery packs.

[0076] The products obtained in the examples and comparative examples were subjected to performance tests. The hardness test method was based on GB / T531.1-2008, the tensile strength and elongation at break test method was based on GB / T 528-2009, the shear strength test method was based on GB / T7124-2008, the water vapor transmission rate test method was based on GB / T 26253-2010, and the flame retardant performance test method was based on GB / T 2408-2008.

[0077] The performance test results of the examples and comparative examples are shown in Tables 1 and 2 below.

[0078] Table 1 Performance Tests of Examples

[0079] project Example 1 Example 2 Example 3 Example 4 Hardness (Shore A) 80 78 68 69 Tensile strength (MPa) 3.83 3.75 3.42 3.63 Elongation at break (%) 210 289 310 350 Aluminum-aluminum shear strength (MPa / 23℃, 7d) 3.64 3.38 3.16 3.48 Aluminum-aluminum shear strength (MPa / double 85, 14d) 3.26 2.94 2.82 2.89 Aluminum-aluminum shear strength (MPa / immersion in water at 32℃, 14 days) 3.18 3.08 2.88 3.05 <![CDATA[Aluminum-aluminum shear strength (MPa / Xenon lamp aging exposure 2500 KJ / m 2 )]]> 3.43 3.23 2.96 3.09 Water contact angle (°) 118 115 113 110 <![CDATA[Water vapor transmission rate (g / m 2 .24h)]]> 0.85 1.12 2.15 8.18 Waterproof rating IP68 IP68 IP68 IP67 Flame retardant properties V-2 V-2 V-2 V-2

[0080] Table 2 Comparative Performance Tests

[0081] project Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Hardness (Shore A) 90 88 73 76 74 Tensile strength (MPa) 4.35 4.15 3.32 3.65 3.66 Elongation at break (%) 80 120 410 240 380 Aluminum-aluminum shear strength (MPa / 23℃, 7d) 4.21 4.10 3.22 3.43 3.55 Aluminum-aluminum shear strength (MPa / double 85, 14d) 4.15 3.98 2.68 2.99 2.69 Aluminum-aluminum shear strength (MPa / immersion in water at 32℃, 14 days) 3.88 3.75 2.76 3.08 1.95 <![CDATA[Aluminum-aluminum shear strength (MPa / xenon lamp aging exposure 2500 KJ / m 2 )]]> 4.11 3.91 1.69 3.18 2.91 Water contact angle (°) 120 119 82 110 93 <![CDATA[Water vapor transmission rate (g / m 2 .24 h)]]> 0.66 0.78 155.63 2.25 540.67 Waterproof rating IP68 IP68 IPX7 IP68 IPX5 Flame retardant properties V-2 V-2 V-2 / V-2

[0082] As shown in Tables 1 and 2, Examples 1-4 exhibit low water vapor permeability and good surface hydrophobicity. A water contact angle ≥110° indicates low surface energy of the polyurethane adhesive. After aging under double 85°C conditions and immersion in water, the adhesive demonstrates high shear strength and excellent waterproof performance. Furthermore, it exhibits high elongation at break, good impact resistance, and high shear strength retention after xenon lamp aging, indicating excellent weather resistance. The sealant itself has relatively low tensile strength (3-4 MPa), making it easy to disassemble.

[0083] Compared to Example 1, Comparative Example 1's component A did not contain polyether polyol or polyester polyol, and Comparative Example 2's component A did not contain hydroxyl-terminated polybutadiene. Both Comparative Examples 1 and 2 increased the amount of fluorinated polyol, resulting in high colloid hardness and low elongation at break, thus leading to poor elasticity and impact resistance in the polyurethane adhesive. Compared to Example 2, Comparative Example 3's system did not contain fluorinated hydrophobic polyol, resulting in a hydrophilic surface that easily attracts moisture. Furthermore, the shear strength retention rate after xenon lamp aging was only 52%, indicating poor weather resistance. Compared to Example 4, Comparative Example 3 reduced the amount of triisopropylphenyl phosphate plasticizer in components A and B, resulting in poor flame retardant performance and no flame retardant rating. In Comparative Example 5, component B prepolymer used Huide Technology polyester polyol 7720 with a molecular weight of 2000 and a functionality of 2 instead of hydroxyl-terminated polybutadiene. Compared to Example 4, the system contained less hydrophobic polyol, resulting in higher water vapor permeability, reduced waterproof performance, and lower shear strength after double 85 and immersion aging. Therefore, the interaction of the raw materials in this invention through appropriate proportions can achieve excellent waterproofing while also giving the system good flame retardancy, impact resistance, and weather resistance.

[0084] Although the invention has been described herein with reference to illustrative embodiments, it should be understood that many other modifications and implementations can be devised by those skilled in the art, which will fall within the scope and spirit of the principles disclosed herein. More specifically, various variations and modifications can be made to the components and / or layout of the subject matter combination within the scope of this disclosure. Besides variations and modifications to the components and / or layout, other uses will be apparent to those skilled in the art.

Claims

1. A highly waterproof two-component polyurethane adhesive for sealing battery packs, characterized in that, It consists of component A and component B; By weight, component A includes the following raw materials: 5-15 parts polyester polyol, 5-15 parts polyether polyol, 10-40 parts hydroxyl-terminated polybutadiene polyol, 10-40 parts fluorinated hydrophobic polyol, 1-10 parts water absorbent, 5-20 parts plasticizer, 0.01-0.1 parts catalyst, and 25-60 parts filler. Component B, measured in parts by weight, comprises the following raw materials: Polyol 15-40 parts, isocyanate 5-15 parts, coupling agent 1-5 parts, dehydrating agent 1-2 parts, antioxidant 0.1-3 parts, filler 15-50 parts, silica 2-10 parts, plasticizer 2-10 parts, flame retardant 10-30 parts.

2. The high waterproof two-component polyurethane adhesive for sealing battery packs according to claim 1, characterized in that, The preparation method of the fluorinated hydrophobic polyol is as follows: hydroxyl-terminated polybutadiene with a molecular weight of 2500-3000 g / mol and a functional group degree of 2.2-2.4 reacts with pentafluorostyrene isocyanate at a molar ratio of 1:1, and the reaction is completed when the -NCO content is <0.1%.

3. The high waterproof two-component polyurethane adhesive for sealing battery packs according to claim 2, characterized in that, The fluorinated hydrophobic polyol is capped with a hydroxyl group.

4. The highly waterproof two-component polyurethane adhesive for sealing battery packs according to claim 2, characterized in that, The reaction temperature was 68–72℃, the reaction time was 3.0–4.0 h, and the reaction was completed when the -NCO characteristic peak disappeared by infrared monitoring and the -NCO content was <0.1% by di-n-butylamine titration.

5. The high waterproof two-component polyurethane adhesive for sealing battery packs according to claim 1, characterized in that, Polyester polyols can be selected with a molecular weight of 2000~6000 and a functionality of 2~4; polyether polyols can be selected with a molecular weight of 2000~4000 and a functionality of 2~4.

6. The high waterproof two-component polyurethane adhesive for sealing battery packs according to claim 1, characterized in that, Hydroxyl-terminated polybutadiene polyols can be purchased from any one or at least a combination of two of the following: Evonik Polyvest HT, Cray Valley Poly bd R45V, Tianyuan Aerospace Materials HTPB-Ⅰ, HTPB-Ⅱ, HTPB Ⅳ, and HFHTPB-I types.

7. The high waterproof two-component polyurethane adhesive for sealing battery packs according to claim 1, characterized in that, In component A, the water absorbent is one or more of the following: 3A or 4A molecular sieves, 325 mesh or 1250 mesh calcium oxide; in component B, the water remover is p-toluenesulfonyl isocyanate.

8. The highly waterproof two-component polyurethane adhesive for sealing battery packs according to claim 1, characterized in that, The plasticizer is one or more of phthalates and phosphates; The flame retardant is triisopropylphenyl phosphate; The catalyst is one or more of the following: dibutyltin dilaurate, bismuth neodecanoate, bismuth isooctanoate, and bismuth naphthenate; The coupling agent is one or more of 3-isocyanopropyltriethoxysilane, 3-isocyanopropyltrimethoxysilane, and γ-glycidoxypropyltrimethoxysilane; The antioxidants selected are hindered phenolic primary antioxidants and organophosphite auxiliary antioxidants for synergistic effect; The filler is any one or a combination of two of heavy calcium carbonate and nano calcium carbonate.

9. The high waterproof two-component polyurethane adhesive for sealing battery packs according to claim 1, characterized in that, The isocyanate used in component B is one or more of diphenylmethane diisocyanate, toluene diisocyanate, and dicyclohexylmethane diisocyanate.

10. A method for preparing the highly waterproof two-component polyurethane adhesive for sealing battery packs according to any one of claims 1 to 9, characterized in that, Includes the following steps: Preparation of Component A: Polyester polyol, polyether polyol, hydroxyl-terminated polybutadiene polyol, fluorinated hydrophobic polyol, plasticizer, and filler are dispersed evenly and then dehydrated at 110~120℃ and under a vacuum of -0.085~0.1MPa for 2~3 hours. After dehydration, the temperature is lowered to below 50℃, and water absorbent and catalyst are added. The mixture is then dispersed under a vacuum of -0.085~0.1MPa for at least 30 minutes before being discharged to obtain Component A. Preparation of Component B: The polyol is heated to 110~120℃ and dehydrated under a vacuum of -0.085~0.1MPa for 2~3 hours. After dehydration, the temperature is lowered to below 80℃, and isocyanate is added and reacted for 1.5~3 hours to obtain an isocyanate-terminated prepolymer. The isocyanate-terminated prepolymer, coupling agent, dehydrating agent, antioxidant, filler, silica, plasticizer, and flame retardant are dispersed under a vacuum of -0.085~0.1MPa for at least 30 minutes and then discharged to obtain Component B. Mix the above components A and B at a volume ratio of (0.9~1.1):1 until homogeneous to obtain the battery pack sealant.

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