Polyurethane adhesive for flexible package of new energy battery and preparation method of polyurethane adhesive

Abstract

The invention discloses a polyurethane adhesive for flexible packaging of a new energy battery and a preparation method of the polyurethane adhesive, and belongs to the technical field of adhesives. The adhesive is prepared by adopting hydrogenated bisphenol A as a polyol raw material and dicyclohexylmethane diisocyanate (HMDI) as isocyanate and cooperating with dimethylolpropionic acid, triethylamine, 1, 4-butanediol and other raw materials through the steps of prepolymer synthesis, chain extension reaction, neutralization reaction, addition of auxiliaries, emulsion preparation and the like. The core innovation lies in that the electrolyte erosion resistance is improved through an ether bond structure of hydrogenated bisphenol A, the weather resistance and rigidity are enhanced by using a hydrogenated alicyclic structure of hydrogenated bisphenol A, and meanwhile, the crosslinking density and the interface bonding force are balanced by optimizing the use amount of 1, 4-butanediol and adding a silane coupling agent KH-550. The adhesive has excellent electrolyte resistance (the adhesive strength retention rate after soaking is greater than or equal to 90%), good low-temperature resistance flexibility (no crack when bent at-40 DEG C) and prominent weather resistance (the performance retention rate after xenon lamp aging for 1000h is greater than 90%).

Description

Technical Field

[0001] This invention belongs to the field of adhesive technology, specifically relating to a polyurethane adhesive for soft packaging of new energy batteries using hydrogenated bisphenol A and dicyclohexylmethane diisocyanate (HMDI) and its preparation method, which is suitable for bonding battery soft packaging materials in high-voltage, long-term outdoor use environments. Background Technology

[0002] As new energy batteries develop towards higher voltage (≥4.5V) and longer cycle life, existing polyester polyol-IPDI adhesives have the following shortcomings:

[0003] 1. The ester groups in the polyester chain are easily eroded by electrolytes (such as LiPF6 / EC+DEC), leading to a decrease in adhesive strength;

[0004] 2. Insufficient flexibility in low-temperature environments (below -40℃), the adhesive layer is prone to cracking;

[0005] 3. Limited weather resistance, unable to meet the requirements of long-term outdoor use. Therefore, there is an urgent need to develop new adhesive systems that are resistant to electrolytes, have excellent weather resistance, and also possess a certain degree of low-temperature toughness. Summary of the Invention

[0006] Purpose of the invention: This invention addresses the problems of insufficient weather resistance and rigidity degradation at high temperatures in existing adhesives by using hydrogenated bisphenol A and dicyclohexylmethane diisocyanate (HMDI), thereby improving the reliability of adhesives in high-voltage and outdoor environments.

[0007] Technical solution: A polyurethane adhesive for soft packaging of new energy batteries, the formula comprising, by weight: 30-50 parts hydrogenated bisphenol A, 25-30 parts dicyclohexylmethane diisocyanate, 6-12 parts dimethylolpropionic acid, 4-9 parts triethylamine, 4-7 parts 1,4-butanediol, 25-35 parts dimethylformamide, 9-13 parts phosphate ester flame retardant, 1.2-2.2 parts silane coupling agent KH-550, 3-6 parts nano silica, 0.6-1.6 parts antioxidant, and 0.6-1.6 parts light stabilizer.

[0008] Preferably, the hydrogenated bisphenol A has a number-average molecular weight of 400-600 and a degree of hydrogenation ≥99%.

[0009] Preferably, the phosphate flame retardant is tri-(2-chloroethyl) phosphate.

[0010] Preferably, the nano-silica has a particle size of 20-50 nm and has undergone surface modification treatment with silane coupling agent KH-550.

[0011] Preferably, the antioxidant is hindered phenolic antioxidant 1010, and the light stabilizer is hindered amine light stabilizer 770.

[0012] Preparation methods include:

[0013] (1) Prepolymer Synthesis: Hydrogenated bisphenol A was added to a reactor according to the formula amount, and vacuum dehydrated at 110-120℃ for 2.5-3.5 h. After removing the water, the temperature was lowered to 75-85℃, dicyclohexylmethane diisocyanate was added, and the mixture was stirred evenly. The temperature was then raised to 95-105℃, and the reaction was carried out for 3-4 h to obtain the prepolymer. The reaction formula is as follows:

[0014]

[0015]

[0016] (2) Chain extension reaction: Dimethylolpropionic acid and 1,4-butanediol are added to the prepolymer, and the reaction is carried out at 75-85°C for 1.5-2 hours to obtain a hydroxyl-terminated polyurethane prepolymer, the reaction formula of which is as follows:

[0017]

[0018] (3) Neutralization reaction: The hydroxyl-terminated polyurethane prepolymer was cooled to 50–60°C, diluted with dimethylformamide, and then triethylamine was added for neutralization reaction. The reaction time was 0.5–1 h to obtain a water-soluble ammonium salt. The reaction formula is as follows:

[0019]

[0020] (4) Additives: Additives: Phosphate flame retardant, silane coupling agent KH-550, surface-modified nano silica (nano silica was vacuum dried at 120℃ for 4h to remove moisture. KH-550 was dissolved in ethanol, pH was adjusted to 4.5, and hydrolyzed by stirring at room temperature for 60min. Silica was added to the hydrolysate, and the reaction was stirred at 80℃ for 3h. The mixture was filtered and washed 3 times with ethanol / water, and dried at 100℃ for 4h), antioxidants and light stabilizers were added to the neutralized system and stirred evenly to obtain a polyurethane adhesive solution;

[0021] (5) Emulsion preparation: The polyurethane adhesive solution is slowly added to deionized water at 20-30℃ (the mass ratio of solution to water is 1:2-3), and emulsified under high-speed stirring at 1500-2000 rpm to form a stable waterborne polyurethane adhesive emulsion.

[0022] Polyurethane adhesives for flexible packaging of new energy batteries can be used as adhesives for bonding flexible packaging materials of new energy batteries.

[0023] New energy batteries are high-voltage batteries, and the soft packaging materials include aluminum-plastic composite film and polypropylene film.

[0024] Beneficial effects:

[0025] Electrolyte resistance: The ether bond structure of hydrogenated bisphenol A inhibits electrolyte penetration. When placed in a 1 mol / L LiPF6 / EC+DEC solution at 55℃, the electrolyte exhibits conductivity (≥10 mS / cm, 25℃) and density (1.20~1.30 g / cm³). 3 pH value (6.5–7.5), electrochemical window (≥4.8V vs Li) + After soaking in electrolyte for 72 hours, the bond strength retention rate is ≥90%.

[0026] Low-temperature resistance and flexibility: The moderate flexibility of the molecular chain enables the battery to bend without cracking at -40℃, adapting to battery deformation in medium and low temperature environments;

[0027] Weather resistance: The hydrogenated alicyclic structure of hydrogenated bisphenol A works synergistically with HMDI to resist UV aging, and the performance retention rate exceeds 90% after 1000 hours of xenon lamp aging;

[0028] Safety: Phosphate ester flame retardants enable adhesives to meet the UL94 V-0 flame retardant standard. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1:

[0031] Forty parts of hydrogenated bisphenol A (number average molecular weight 500, degree of hydrogenation 99%) were added to the reactor, the vacuum system was turned on (vacuum degree -0.085MPa), and the temperature was raised to 115℃ for dehydration for 3 hours. During this period, the pressure change inside the reactor was recorded every 30 minutes to ensure that the moisture content was <0.05%. The temperature was lowered to 80℃, and 25 parts of HMDI (preheated to 60℃) were added. The mixture was stirred at 200 rpm for 10 minutes until it was uniformly mixed. The temperature was raised to 100℃ and the reaction was maintained for 3.5 hours. During this period, the -NCO content was sampled and tested every hour. The target value was controlled at 3.0% to 3.5% to obtain the prepolymer.

[0032] Nine parts of dimethylolpropionic acid and five parts of 1,4-butanediol were added to the prepolymer, and the mixture was reacted at 80°C for 1.7 h to obtain a hydroxyl-terminated polyurethane prepolymer. The hydroxyl-terminated polyurethane prepolymer was cooled to 55°C, diluted with 30 parts of dimethylformamide, and then neutralized with 6 parts of triethylamine for 0.75 h to obtain a water-soluble ammonium salt. Eleven parts of phosphate ester flame retardant, 1.8 parts of silane coupling agent KH-550, and four parts of modified nano-silica (35 nm) were added to the neutralized system (the nano-silica was vacuum dried at 120°C for 4 h to remove impurities). Remove moisture. KH-550 was dissolved in ethanol, pH adjusted to 4.5, and hydrolyzed by stirring at room temperature for 60 min. Silica was added to the hydrolysate, and the mixture was stirred at 80°C for 3 h. The mixture was filtered and washed three times with ethanol / water, dried at 100°C for 4 h, and 1.2 parts of antioxidant 1010 and 1.2 parts of light stabilizer 770 were added and stirred until homogeneous to obtain a polyurethane adhesive solution. The polyurethane adhesive solution was mixed with deionized water at 25°C at a mass ratio of 1:2.5 and emulsified at a high speed of 1800 rpm for 30 min to form a stable waterborne polyurethane adhesive emulsion.

[0033] Example 2:

[0034] Add 30 parts of hydrogenated bisphenol A (number average molecular weight 400, degree of hydrogenation 99%) to the reactor, turn on the vacuum system (vacuum degree -0.09MPa), heat to 110℃ and dehydrate for 3.5h. During this period, record the pressure change inside the reactor every 30min to ensure that the moisture content is <0.05%. Cool down to 75℃, add 25 parts of HMDI (preheated to 60℃ in advance), stir at 200rpm for 10min until uniformly mixed. Heat up to 95℃ and maintain the reaction for 4h. During this period, take samples every hour to detect the -NCO content. The target value is controlled at 3.0%~3.5% to obtain the prepolymer.

[0035] Add 6 parts of dimethylolpropionic acid and 4 parts of 1,4-butanediol to the prepolymer, and react at 75°C for 2 hours to obtain a hydroxyl-terminated polyurethane prepolymer. Cool the hydroxyl-terminated polyurethane prepolymer to 50°C, add 25 parts of dimethylformamide for dilution, and then add 4 parts of triethylamine for neutralization reaction for 0.5 hours to obtain a water-soluble ammonium salt. Add 9 parts of phosphate ester flame retardant, 1.2 parts of silane coupling agent KH-550, and 3 parts of modified nano-silica (20nm) to the neutralized system (the nano-silica was vacuum dried at 120°C for 4 hours to remove impurities). Moisture. KH-550 was dissolved in ethanol, pH adjusted to 4.5, and hydrolyzed by stirring at room temperature for 60 min. Silica was added to the hydrolysate, and the mixture was stirred at 80 °C for 3 h. The mixture was filtered and washed three times with ethanol / water, dried at 100 °C for 4 h, and 0.6 parts of antioxidant 1010 and 0.6 parts of light stabilizer 770 were added and stirred until homogeneous to obtain a polyurethane adhesive solution. The polyurethane adhesive solution was mixed with deionized water at 20 °C at a mass ratio of 1:2 and emulsified at a high speed of 1500 rpm for 30 min to form a stable waterborne polyurethane adhesive emulsion.

[0036] Example 3:

[0037] Add 50 parts of hydrogenated bisphenol A (number average molecular weight 600, degree of hydrogenation 99%) to the reactor, turn on the vacuum system (vacuum degree -0.08MPa), heat to 120℃ and dehydrate for 2.5h. During this period, record the pressure change inside the reactor every 30min to ensure that the moisture content is <0.05%. Cool down to 85℃, add 30 parts of HMDI (preheated to 60℃ in advance), stir at 200rpm for 10min until uniformly mixed. Heat up to 105℃ and maintain the reaction for 3h. During this period, take samples every hour to detect the -NCO content. The target value is controlled at 3.0%~3.5% to obtain the prepolymer.

[0038] Add 12 parts of dimethylolpropionic acid and 7 parts of 1,4-butanediol to the prepolymer, and react at 85°C for 1.5 h to obtain a hydroxyl-terminated polyurethane prepolymer. Cool the hydroxyl-terminated polyurethane prepolymer to 60°C, add 35 parts of dimethylformamide for dilution, and then add 9 parts of triethylamine for neutralization reaction for 1 h to obtain a water-soluble ammonium salt. Add 13 parts of phosphate ester flame retardant, 2.2 parts of silane coupling agent KH-550, and 6 parts of modified nano-silica (50 nm) to the neutralized system (the nano-silica was vacuum dried at 120°C for 4 h to remove impurities). Remove moisture. KH-550 was dissolved in ethanol, pH adjusted to 4.5, and hydrolyzed by stirring at room temperature for 60 min. Silica was added to the hydrolysate, and the mixture was stirred at 80°C for 3 h. The mixture was filtered and washed three times with ethanol / water, dried at 100°C for 4 h, and then mixed with 1.6 parts antioxidant 1010 and 1.6 parts light stabilizer 770 to obtain a polyurethane adhesive solution. The polyurethane adhesive solution was mixed with deionized water at 30°C at a mass ratio of 1:3 and emulsified at high speed of 2000 rpm for 30 min to form a stable waterborne polyurethane adhesive emulsion.

[0039] Comparative Example 1

[0040] Forty parts of bisphenol A (unhydrogenated, number average molecular weight 400) were added to a reactor. The vacuum system was turned on (vacuum degree -0.085 MPa), and the temperature was raised to 115°C for dehydration for 3 hours. During this period, the pressure change inside the reactor was recorded every 30 minutes to ensure that the moisture content was <0.05%. The temperature was lowered to 80°C, and 25 parts of HMDI (preheated to 60°C) were added. The mixture was stirred at 200 rpm for 10 minutes until homogeneous. The temperature was raised to 100°C and the reaction was maintained for 3.5 hours. During this period, the -NCO content was sampled and tested every hour. The target value was controlled at 3.0% to 3.5%, and the prepolymer was obtained. The remaining formulation and process were the same as in Example 1.

[0041] Comparative Example 2

[0042] Forty parts of hydrogenated bisphenol A (number average molecular weight 500, degree of hydrogenation 99%) were added to a reactor. The vacuum system was turned on (vacuum degree -0.085 MPa), and the temperature was raised to 115°C for dehydration for 3 hours. During this period, the pressure change inside the reactor was recorded every 30 minutes to ensure that the moisture content was <0.05%. The temperature was lowered to 80°C, and 25 parts of IPDI (preheated to 60°C) were added. The mixture was stirred at 200 rpm for 10 minutes until homogeneous. The temperature was raised to 100°C and the reaction was maintained for 3.5 hours. During this period, samples were taken every hour to detect the -NCO content, and the target value was controlled at 3.0% to 3.5%, thus obtaining the prepolymer. The remaining formulation and process were the same as in Example 1.

[0043] Comparative Example 3

[0044] Forty parts of hydrogenated bisphenol A (number average molecular weight 500, degree of hydrogenation 99%) were added to the reactor, the vacuum system was turned on (vacuum degree -0.085MPa), and the temperature was raised to 115℃ for dehydration for 3 hours. During this period, the pressure change inside the reactor was recorded every 30 minutes to ensure that the moisture content was <0.05%. The temperature was lowered to 80℃, and 25 parts of HMDI (preheated to 60℃) were added. The mixture was stirred at 200 rpm for 10 minutes until it was uniformly mixed. The temperature was raised to 100℃ and the reaction was maintained for 3.5 hours. During this period, the -NCO content was sampled and tested every hour. The target value was controlled at 3.0% to 3.5% to obtain the prepolymer.

[0045] Nine parts of dimethylolpropionic acid and five parts of 1,4-butanediol were added to the prepolymer, and the mixture was reacted at 80°C for 1.7 h to obtain a hydroxyl-terminated polyurethane prepolymer. The hydroxyl-terminated polyurethane prepolymer was cooled to 55°C, diluted with 30 parts of dimethylformamide, and then neutralized with 6 parts of triethylamine for 0.75 h to obtain a water-soluble ammonium salt. Eleven parts of phosphate ester flame retardant and four parts of modified nano-silica (35 nm) were added to the neutralized system (the nano-silica was vacuum dried at 120°C for 4 h to remove moisture). 50% dissolved in ethanol, pH adjusted to 4.5, and hydrolyzed by stirring at room temperature for 60 min. Silica was added to the hydrolysate, and the mixture was stirred at 80℃ for 3 h. The mixture was filtered and washed three times with ethanol / water, dried at 100℃ for 4 h, and then mixed with 1.2 parts antioxidant 1010 and 1.2 parts light stabilizer 770 to obtain a polyurethane adhesive solution. The polyurethane adhesive solution was mixed with deionized water at 25℃ at a mass ratio of 1:2.5 and emulsified at high speed of 1800 rpm for 30 min to form a stable waterborne polyurethane adhesive emulsion.

[0046] Electrolyte retention test:

[0047] Instruments: Constant temperature immersion chamber, universal testing machine

[0048] Test parameters: 1 mol / L LiPF6 / EC+DEC electrolyte, soaking at 55℃ for 72 h.

[0049] Results analysis: The 180° peel strength of the samples was tested using a universal testing machine (tensile speed 50 mm / min) according to ASTM D543-21 standard, and the retention rate was calculated.

[0050] -40℃ Low Temperature Flexibility Test:

[0051] Instruments: Low-temperature constant temperature chamber, bending test machine

[0052] Test parameters: Aging at -40℃ for 2 hours

[0053] Results analysis: In accordance with the modified ASTM D746-20 standard, the samples were immediately subjected to a 180° bending test using a bending tester after removal, and the presence of cracks was observed.

[0054] Xenon lamp weathering resistance test:

[0055] Instruments: Xenon lamp aging test chamber, universal testing machine

[0056] Test parameters: Irradiance 0.35W / m2 (340nm), temperature 63℃, humidity 50% RH, irradiation for 1000h.

[0057] Results Analysis: The tensile strength of the samples was tested using a universal testing machine in accordance with ASTM G155-20 standard, and the retention rate was calculated.

[0058] Bond strength test:

[0059] Instrument: Universal testing machine

[0060] Test parameters: Aluminum-plastic film / polypropylene film composite sheet (cured at 50℃ for 5 days), tensile speed 50mm / min, 180° peel.

[0061] Results analysis: Five samples were tested according to ASTM D903-18 standard, and the average value was taken.

[0062] The test results are summarized in Table 1.

[0063] Table 1 Performance Comparison Analysis

[0064]

[0065] Examples 1-3 demonstrate that the synergistic effect of the ether bond structure of hydrogenated bisphenol A, the alicyclic structure of hydrogenated bisphenol A, and the weather resistance of HMDI significantly outperforms the comparative examples in terms of electrolyte resistance, low-temperature toughness, and weather resistance, thus verifying the core innovative value of the formulation design. Among them, Example 3 exhibits the best overall performance.

[0066] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments.

[0067] Or equivalent substitutions can be made for some of the technical features; and these modifications or substitutions do not

[0068] This causes the essence of the corresponding technical solution to deviate from the spirit and scope of the technical solutions in the various embodiments of the present invention.

Claims

1. A polyurethane adhesive for flexible packaging of new energy batteries, characterized in that, The formula, by weight, includes: 30-50 parts hydrogenated bisphenol A, 25-30 parts dicyclohexylmethane diisocyanate, 6-12 parts dimethylolpropionic acid, 4-9 parts triethylamine, 4-7 parts 1,4-butanediol, 25-35 parts dimethylformamide, 9-13 parts phosphate ester flame retardant, 1.2-2.2 parts silane coupling agent KH-550, 3-6 parts nano silica, 0.6-1.6 parts antioxidant, and 0.6-1.6 parts light stabilizer.

2. The polyurethane adhesive for flexible packaging of new energy batteries according to claim 1, characterized in that, The hydrogenated bisphenol A has a number-average molecular weight of 400-600 and a degree of hydrogenation ≥99%.

3. The polyurethane adhesive for soft packaging of new energy batteries according to claim 1, characterized in that, The phosphate flame retardant is tri-(2-chloroethyl) phosphate.

4. The polyurethane adhesive for soft packaging of new energy batteries according to claim 1, characterized in that, The nano-silica has a particle size of 20-50 nm and has undergone surface modification treatment with silane coupling agent KH-550.

5. The polyurethane adhesive for soft packaging of new energy batteries according to claim 1, characterized in that, The antioxidant is hindered phenolic antioxidant 1010, and the light stabilizer is hindered amine light stabilizer 770.

6. A method for preparing a polyurethane adhesive for soft packaging of new energy batteries as described in any one of claims 1 to 5, characterized in that, Includes the following steps: (1) Prepolymer Synthesis: Hydrogenated bisphenol A was added to a reactor according to the formula amount, and vacuum dehydrated at 110-120℃ for 2.5-3.5 h. After removing the water, the temperature was lowered to 75-85℃, dicyclohexylmethane diisocyanate was added, and the mixture was stirred evenly. The temperature was then raised to 95-105℃, and the reaction was carried out for 3-4 h to obtain the prepolymer. The reaction formula is as follows: (2) Chain extension reaction: Dimethylolpropionic acid and 1,4-butanediol are added to the prepolymer, and the reaction is carried out at 75-85°C for 1.5-2 hours to obtain a hydroxyl-terminated polyurethane prepolymer, the reaction formula of which is as follows: (3) Neutralization reaction: The hydroxyl-terminated polyurethane prepolymer was cooled to 50–60°C, diluted with dimethylformamide, and then triethylamine was added for neutralization reaction. The reaction time was 0.5–1 h to obtain a water-soluble ammonium salt. The reaction formula is as follows: (4) Adding additives: Add phosphate flame retardant, silane coupling agent KH-550, modified nano silica, antioxidant and light stabilizer to the neutralized system, stir evenly to obtain polyurethane adhesive solution. (5) Emulsion preparation: The polyurethane adhesive solution is slowly added to deionized water and emulsified under high-speed stirring at 1500-2000 rpm to form a stable waterborne polyurethane adhesive emulsion.

7. The preparation method according to claim 6, characterized in that, The vacuum degree of vacuum dehydration in step 1 is -0.09 to -0.08 MPa.

8. The preparation method according to claim 6, characterized in that, The temperature of the deionized water in step 5 is 20-30°C, and the mass ratio of the polyurethane adhesive solution to the deionized water is 1:(2-3).

9. The application of the polyurethane adhesive for flexible packaging of new energy batteries according to any one of claims 1 to 5 in the bonding of flexible packaging materials for new energy batteries.

10. The application according to claim 9, characterized in that, The new energy battery is a high-voltage battery, and the soft packaging material includes aluminum-plastic composite film and polypropylene film.

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