Normal-temperature curing protective environment-friendly flame-retardant water-based coating for battery pack of new energy vehicle

Abstract

The invention belongs to the technical field of surface protective coatings of battery packs for automobiles, and particularly relates to a normal-temperature curing protective environment-friendly flame-retardant water-based coating for a battery pack for a new energy vehicle. The environment-friendly coating is prepared from the following components in parts by weight: 40 to 45 parts of self-prepared acrylic emulsion PK-1220, 30 to 34 parts of 400-mesh aluminum hydroxide, 9 to 11 parts of wollastonite, 4 to 6 parts of expanded graphite, 1 to 2 parts of wood fiber, 0.1 to 0.2 part of thickening agent, 0.3 to 0.5 part of dispersing agent, 0.2 to 0.3 part of sterilizing agent and 0.5 to 1 part of coalescing agent. The high-environment-friendly flame-retardant water-based coating disclosed by the invention has the functions of protection and stone impact resistance, improves the safety of a battery pack or an oil tank in a driving process, can reduce noise in a vehicle, and can protect the safety of passengers and external personnel and avoid property loss especially when a fire breaks out.

Description

Technical Field

[0001] The present invention belongs to the technical field of protective coatings on the surface of automotive battery packs, and specifically relates to a protective, environmentally friendly, flame-retardant water-based coating that is cured at room temperature for battery packs of new energy vehicles. Background Art

[0002] In recent years, with the rapid development of China's manufacturing industry, China's automobile industry has also ushered in new opportunities and has occupied a leading position in the global automotive field. Therefore, the safety of automobile-related components is also a top priority, especially the protection of battery packs and fuel tank shells of passenger cars, including new energy vehicles. The traditional solution is to use PVC coating to spray its surface, and then cure it at high temperature (130-150°C) to make its surface have certain adhesion and other protection requirements. Although it has corresponding advantages, its disadvantages are also obvious, especially the flame retardant performance cannot be well reflected. After high-temperature baking, there will be a strong odor, and there is still a lot of improvement in VOC. The present invention provides a protective, environmentally friendly, flame-retardant water-based coating for battery packs for new energy vehicles that can be cured at room temperature. It can not only achieve high-strength flame retardancy, but also can be cured at room temperature. There is no other smell during construction and use. VOC can meet EU standards and meet the relevant technical requirements of automobile companies in terms of stone impact resistance and adhesion. Summary of the Invention

[0003] To address the aforementioned technical issues, the present invention aims to develop a water-based coating that cures at room temperature, reduces VOCs, and exhibits high flame retardancy. Because it is applied to battery pack surfaces, fuel tank surfaces, and fuel tank exteriors, it exhibits a strong flame retardant effect while also meeting environmental requirements.

[0004] The present invention adopts ultrafine aluminum hydroxide as the main flame retardant material, and uses 400 mesh aluminum hydroxide. After curing at room temperature, it has extremely high flame retardant and smoke suppression properties, and can also be lightweight. At the same time, as an inorganic flame retardant, it does not contain harmful elements such as halogens and phosphorus, and is relatively cheap. In addition, aluminum hydroxide can improve the mechanical strength and impact resistance of the product. Because of its uniform particle size, it can not only improve processing fluidity but also make its construction surface smoother.

[0005] It is also filled with needle-shaped wollastonite to form a reinforced network, which can significantly improve the tensile strength, bending strength and impact strength of the coating, and can also reduce its shrinkage rate, thereby increasing its durability; and in order to improve its flame retardant properties, expanded graphite and wood fiber are added to the product. The flexible graphite material maintains excellent sealing performance in the range of -200℃-450℃, and can form a thermal insulation expansion layer when it works. The added wood fiber can achieve a porous structure and rapid curing.

[0006] The present invention combines an acrylic emulsion synthesized from methyl methacrylate, lauryl acrylate, a halogenated monofunctional acrylic monomer (SW-513), and glycidyl methacrylate (GMA), and adds a bio-based alcohol to enhance film-forming properties and environmental friendliness, resulting in a water-based polymer system. Methyl methacrylate, due to its methyl and benzene rings, has a high glass transition temperature of approximately 100°C, which improves resin strength. Lauryl acrylate has a TG value of -6 / -30, providing excellent flexibility, impact resistance, adhesion, and leveling properties, enhancing structural strength during use. Furthermore, the halogenated monofunctional acrylic monomer and glycidyl methacrylate (GMA) contribute to the product's flame retardancy, weather resistance, film-forming properties, and weather resistance.

[0007] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a protective, environmentally friendly, flame-retardant water-based coating for a battery pack for new energy vehicles that is cured at room temperature. The water-based coating is prepared by weight and includes 40-45 parts of acrylic emulsion, 30-34 parts of 400-mesh aluminum hydroxide, 9-11 parts of wollastonite, 4-6 parts of expanded graphite, 1-2 parts of wood fiber, 0.1-0.2 parts of thickener, 0.3-0.5 parts of dispersant, 0.2-0.3 parts of fungicide, and 0.5-1 parts of C-12 film-forming aid.

[0008] The acrylic emulsion is named PK-1220. The raw materials are methyl methacrylate, lauryl acrylate, halogen monofunctional acrylic monomer (SW-513) and glycidyl methacrylate (GMA), water, sodium dodecyl diphenyl ether disulfonate, and azobisisobutylimidazoline hydrochloride (VA-044 initiator). The glass transition temperature Tg of the acrylic emulsion is 45°C, of ​​which the glass transition temperature of methyl methacrylate is 104-105°C, the decomposition temperature does not exceed 270°C, the flow temperature is about 160°C, and the glass transition temperature of lauryl acrylate is 104-105°C. It is -30℃, which is a soft monomer and enhances flexibility. The glass transition temperature of glycidyl methacrylate (GMA) is 40℃. High Tg GMA can improve the impact resistance of the coating. Its preparation method is briefly summarized. First, the monomer, initiator, emulsifier, etc. need to be stirred and emulsified into an emulsion in the emulsification tank. Then, water, emulsifier and bio-based alcohol (1,3-propylene glycol) are added to the reactor and heated to a certain temperature. Then, the emulsifier and initiator are added dropwise to the reactor. The time is generally 3 hours. After three hours, keep warm for 1-2 hours to obtain PK-1220.

[0009] The dispersant is BASF EfkaPx4787 high-performance dispersant, which can improve its tolerance, has a solid content of 70% and an active ingredient amine value of 15%.

[0010] The 400 mesh aluminum hydroxide can be obtained from Jinan Zhengpin Chemical Co., Ltd., with a density of 2.42 g / m 2, it should be noted that it will decompose into aluminum oxide and water when heated to 300℃.

[0011] Wollastonite is a single-chain silicate mineral, available in 325 mesh flakes, white with a slight gray tint, hardness 4.5-5.0, and density 2.78-2.91 g / cm 3 , has good reinforcement properties, improves the toughness and durability of the product, obtains better mechanical strength, increases durability, enhances adhesion and corrosion resistance, and the manufacturer used is Jiangxi Kete.

[0012] Expanded graphite, abbreviated as EGP, is a carbon material obtained by treating natural graphite flakes with chemical or physical intercalation, water washing, drying, and high-temperature expansion. It has a loose and porous worm-like form. We use graphite to acidify with chemical reagents such as concentrated sulfuric acid and concentrated nitric acid, and then wash, dry, and expand it at high temperature to obtain expanded graphite powder. The manufacturer is Jiangsu Xianfeng Nanomaterial Technology.

[0013] Wood fiber TMS-800 can form a three-dimensional spatial structure in the material, absorb 6-8 times its own weight in water, and also play a role in heat preservation and crack resistance, and improve surface strength and bonding strength. The manufacturer is Yi Bo Chemical.

[0014] ASE-60 is a thickener that does not contain cellulose, has strong antimicrobial ability, good long-term stability, and can improve splashing and anti-sagging properties. The manufacturer is Dongguan Yingke High-tech Materials Co., Ltd.

[0015] C-12 film-forming aid can improve the film-forming properties of the emulsion and lower the film-forming temperature. It has a melting point of -50°C, is insoluble in water but soluble in organic solvents, and is manufactured by Jinan Fangyu Chemical.

[0016] Fungicide 2.5SF contains two active ingredients, is suitable for water-based systems, has a low addition dosage, and has a stable pH range of 4-9. The manufacturer is Langfang Zhengchi New Materials.

[0017] Compared with traditional technologies, the highly environmentally friendly flame-retardant water-based coating has the following beneficial effects: 1. The environmentally friendly flame-retardant water-based coating of the present invention has the protection and stone-impact resistance of traditional PVC coatings, improves the safety of battery packs or fuel tanks during driving, and can reduce noise inside the vehicle, especially in the event of a fire. Because the fuel tank and battery pack are flammable and explosive components, improving the flame retardant performance is inevitable, which can protect the safety of passengers and outsiders and avoid property losses. At the same time, due to the traditional structure of PVC materials, it is easy to bubble during baking, and the PVC coating is cracked or cracked, which can easily affect its construction effect. It also has the disadvantages of a strong odor during baking. Moreover, if the surface is bumped or scratched during transportation, it is not easy to repair, and the bumps are prone to corrosion risks.

[0018] 2. The self-mixed PK-1220 acrylic emulsion of the present invention has the following advantages. First, it has outstanding acoustic properties and can effectively absorb and isolate noise. The coating or material formed can improve the sound insulation effect by more than 30%. Although sound absorption and insulation are not the main aspects we are concerned about, it is also beneficial; in addition, it has good damping performance and optimizes the sound insulation effect; third, the self-mixed emulsion has excellent anti-aging and water resistance, remains stable in outdoor or humid environments, and has a service life of more than ten years; and has excellent environmental protection characteristics. Due to the addition of bio-based alcohol, the film-forming performance is improved, VOC and waste rubber recyclability are reduced, and combined with relevant fillers, the bonding strength and stability can be improved.

[0019] 3. The acidified expanded graphite, aluminum hydroxide and wollastonite used in this product as ultrafine fillers can achieve the designed high environmental protection and flame retardant performance. They are applied to the surface of battery packs and fuel tanks to reduce their high risks. Moreover, the surface is loose and porous, which increases the volatilization of internal moisture, reduces the curing time, and improves construction efficiency, while also taking into account excellent toughness. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a diagram showing the working principle of the environmentally friendly flame-retardant water-based coating prepared in Example 1.

[0021] Figure 2 It is the anti-stone impact test diagram; A is the sample diagram after the anti-stone impact test, and B is the sample diagram after the impact resistance test.

[0022] Figure 3 This is a battery protection diagram of the environmentally friendly flame-retardant water-based coating prepared in Example 1, wherein 1 is the shell, 2 is the second skeleton, 3 is the battery core, and 4 is the first skeleton.

[0023] Figure 4 This is a top view of the battery and chassis.

[0024] Figure 5 This is a comparison chart of damping and sound insulation performance. DETAILED DESCRIPTION

[0025] The present invention is described in detail below with reference to the embodiments.

[0026] Example 1 A protective, environmentally friendly, flame-retardant water-based coating for a battery pack for a new energy vehicle cured at room temperature

[0027] (1) The formula composition is as follows

[0028] 45g PK-1220 (self-prepared acrylic emulsion), 34g aluminum hydroxide, 11g wollastonite, 6g expanded graphite, 2g wood fiber, 0.2g thickener ASE-60, 0.5g dispersant BASF EfkaPx4787, 0.3g fungicide 2.5SF, 1g film-forming aid C-12.

[0029] (2) The preparation method is as follows: 1. Preparation method of self-formulated acrylic emulsion PK-1220: 33g of methyl methacrylate, 12g of lauryl acrylate, 2.5g of halogen monofunctional acrylic monomer SW-513 and 4g of glycidyl methacrylate GMA were stirred and emulsified into an emulsion, 45g of water, 3g of bio-based alcohol (1,3-propylene glycol) and 8.5g of emulsifier (sodium dodecyl diphenyl ether disulfonate) were added, the temperature was raised to 50-70°C, and then 2g of initiator azobisisobutylimidazoline hydrochloride (VA-044 initiator) was added dropwise to the reactor for 3 hours. After three hours, the temperature was kept for 1-2 hours to obtain acrylic emulsion PK-1220.

[0030] 2. The preparation method of bio-based alcohol is glucose fermentation. Glucose first generates pyruvate through the glycolytic pathway, and then reacts to generate glycerol. Then, it is converted into 1,3-propanediol under the action of glycerol dehydratase and 1,3-propanediol oxidoreductase. The reaction process is as follows.

[0031]

[0032] 3. Turn on the circulating water according to the environment, add 45g of the self-prepared acrylic emulsion PK-1220 (-0.08MPa suction) into the reactor, start stirring, stir at low speed (speed of 30r / min), stir at high speed (speed of 300r / min), stir for 2 minutes, and the temperature reaches the range of 20-23℃.

[0033] 4. Start stirring at a speed of 30 r / min, mix the raw materials 34g aluminum hydroxide, 11g wollastonite, and 6g expanded graphite, and add them in 5 times, with an interval of 30 seconds between each addition. After all are added, stir for 3 minutes.

[0034] 5. Start stirring, stir at a low speed of 30 r / min and then at a high speed of 300 r / min. At the same time, start the circulation at 30 r / min, add 2g of wood fiber as raw material, and then start stirring at a low speed (30 r / min) for 5 minutes.

[0035] 6. Start low-speed stirring at a speed of 30 r / min, slowly add 0.5 g of dispersant BASF Efka Px4787, then start low-speed stirring (speed of 30 r / min), high-speed stirring (speed of 600 r / min), and start the circulation at 30 r / min and stir for 10 minutes.

[0036] 7. Start low-speed stirring (speed is 30r / min), add 0.3g fungicide 2.5SF, 1g film-forming aid C-12, then start low-speed stirring (speed is 30r / min), high-speed stirring (speed is 600r / min), and start the circulation at 30r / min for 10 minutes.

[0037] 8. Take samples and test their BH viscosity.

[0038] 9. Check the viscosity to see if it's within the 45,000-65,000 Pa.S range. If not, add 0.2g of thickener ASE-60. Start low-speed stirring (30 r / min), then high-speed stirring (600 r / min), and simultaneously start circulation (30 r / min). Vacuum degassing at -0.05 MPa for 2 minutes to 0.08 MPa for 10 minutes. (Use a temperature gun to measure the temperature; it should not exceed 30°C. If it exceeds this limit, immediately start cooling the circulating water.)

[0039] 10. Take samples for testing and test the adhesion of the 100-grid test. The result is ≤ level 2 and it is qualified.

[0040] 11. 20 mesh + 30 mesh double filtration packaging.

[0041] Figure 1 This is the location where the product is used. The environmentally friendly flame-retardant water-based coating prepared above is sprayed on the surface of the battery core shell to achieve anti-stone impact and flame-retardant protection functions.

[0042] Figure 3 This is a battery protection diagram, 3 is the battery core, 4 is the first skeleton, 2 is the second skeleton, and 1 is the shell. The environmentally friendly flame-retardant water-based coating prepared above is sprayed on the surface of the shell 1 and cured at room temperature to form a 1-2mm flame-retardant protective layer on its surface to protect the battery shell from damage.

[0043] Figure 4 This is a top view of the chassis battery, which allows for a clearer and more intuitive view of the usage areas and the importance of this environmentally friendly flame-retardant water-based coating to vehicle protection.

[0044] Example 2

[0045] In terms of weight, 45 g of Wanhua Emulsion 0656B and other ingredients remain the same as in Example 1. The trade names and manufacturers are the same as in Example 1, and the self-prepared acrylic emulsion is also described.

[0046] Comparative Example

[0047] 1. Comparative Example 1

[0048] 400 mesh calcium carbonate was used to replace the aluminum hydroxide in Example 1, and the other components and proportions remained unchanged.

[0049] 2. Comparative Example 2

[0050] Aqueous polyurethane emulsion with a glass transition temperature of 50° C. was used to replace the PK-1220 emulsion in Example 1, while the other components and proportions remained unchanged.

[0051] 3. Comparative Example 3

[0052] Ordinary graphite (particle size 1 μm-500 μm, 75% oversieve) was used to replace the expanded graphite in Example 1, and the other components and proportions remained unchanged.

[0053] 4. Comparative Example 4

[0054] Commercially available PVC coatings used by automotive OEMs.

[0055] Example 3 Performance Testing

[0056] (I) Specific testing technical indicators are shown in Table 1: Table 1 Comparison of coating properties prepared in Examples and Comparative Examples

[0057] As can be seen from Table 1, after using calcium carbonate in Comparative Example 1, the flame retardancy is reduced, the adhesion is poor, the safety is reduced, and the flame retardancy is far from meeting the requirements and standards designed in this application.

[0058] In Example 2, other acrylic emulsions were used, and the surface drying time exceeded the expected time, and the effect was not ideal.

[0059] Comparative Example 2 uses an aqueous polyurethane emulsion with a glass transition temperature that is not much different. Although it has a flame retardant effect to a certain extent, it has a strong odor and a prolonged curing time, which deviates from the original design of room temperature curing. The odor is not pleasant, and the adhesion cannot meet the corresponding technical standards.

[0060] Although the main body of Comparative Example 3 is not much different, the water-based coating of ordinary graphite has poor flowability and is prone to flow during construction and spraying, affecting the quality of the entire vehicle.

[0061] Although the PVC primer of Comparative Example 4 has good flexibility when used, it has a strong smell after high-temperature baking, and the VOC does not meet the standard. In addition, its flame retardancy is poor compared with that of the examples.

[0062] (2) Damping coefficient test

[0063] The damping coefficient test method is as follows: prepare 3mm damping splines with wet films of specifications of 210±0.5mm×10±0.5mm on the vehicle body steel plates of specifications of (240±0.3mm×10±0.3mm×1±0.02mm), place them at room temperature for 48 hours, and then clamp the specimens to the cantilever beam damping measuring instrument. The test frequency is (50-5000)HZ, and the corresponding damping coefficients are recorded at temperatures of 0℃, 20℃, 40℃, and 60℃ (each temperature needs to be kept constant for 10 minutes before measurement) (read the second-order resonance peak data near 200HZ).

[0064] Table 2 Damping and sound insulation performance test data of the embodiment and the comparative example

[0065] From Table 2, we can see that under the same conditions, the invention has better sound insulation and damping performance, and Figure 5 It can also be analyzed that its value is the maximum.

[0066] (2) Stone impact resistance test and impact resistance test

[0067] Figure 2 This is a stone impact test done in the laboratory, using dry film 500u, SAEJ400 flying stone method, pressure 0.049Mpa, and 5 rounds of testing. The pictures after impact are as follows Figure 2 As shown in A, there is no cracking or peeling, and the expected functional design is met.

[0068] Figure 2 Sample B in the middle is the sample after the impact resistance test, with no cracks or peeling after an impact of 50kg.cm.

Claims

1. A protective, environmentally friendly, flame-retardant water-based coating for a battery pack for a new energy vehicle that is cured at room temperature, characterized in that: The self-prepared acrylic emulsion PK-1220 is prepared in the following proportions: 40-45 parts of self-prepared acrylic emulsion PK-1220, 30-34 parts of 400 mesh aluminum hydroxide, 9-11 parts of wollastonite, 4-6 parts of expanded graphite, 1-2 parts of wood fiber, 0.1-0.2 parts of thickener, 0.3-0.5 parts of dispersant, 0.2-0.3 parts of fungicide, and 0.5-1 parts of film-forming aid. The self-prepared acrylic emulsion PK-1220 is prepared as follows: methyl methacrylate, lauric acrylate, halogen monofunctional acrylic monomer SW-513 and methacrylic acid shrink The glyceride is stirred and emulsified into an emulsion, water, bio-based alcohol, and emulsifier sodium dodecyl diphenyl ether disulfonate are added, the temperature is raised to 50-70°C, and an initiator azobisisobutylimidazoline hydrochloride is added dropwise for 3 hours. After three hours, the temperature is kept for 1-2 hours to obtain acrylic emulsion PK-1220; the bio-based alcohol is 1,3-propylene glycol, and the preparation method is a glucose fermentation method, wherein glucose first generates pyruvate through the glycolytic pathway, and then reacts to generate glycerol, which is then converted into 1,3-propylene glycol under the action of glycerol dehydratase and 1,3-propylene glycol oxidoreductase.

2. The protective, environmentally friendly, flame-retardant water-based coating for a new energy vehicle battery pack that is cured at room temperature according to claim 1, characterized in that: The dispersant is BASF EfkaPx4787 high-performance dispersant.

3. The protective, environmentally friendly, flame-retardant water-based coating for a new energy vehicle battery pack that is cured at room temperature according to claim 1, characterized in that: The density of the 400 mesh aluminum hydroxide is 2.42 g / m 2 , the decomposition temperature is 300℃.

4. The protective, environmentally friendly, flame-retardant water-based coating for a new energy vehicle battery pack that is cured at room temperature according to claim 1, characterized in that: The wollastonite is a single chain silicate mineral with a 325 mesh flake shape, a hardness of 4.5-5.0, and a density of 2.78-2.91 g / cm 3 .

5. The protective, environmentally friendly, flame-retardant water-based coating for a new energy vehicle battery pack that is cured at room temperature according to claim 1, characterized in that: The wood fiber is TMS-800.

6. The protective, environmentally friendly, flame-retardant water-based coating for a new energy vehicle battery pack that is cured at room temperature according to claim 1, characterized in that: The thickener is ASE-60.

7. The protective, environmentally friendly, flame-retardant water-based coating for a new energy vehicle battery pack that is cured at room temperature according to claim 1, characterized in that: The bactericide is 2.5SF.

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