Flame-retardant, self-cleaning and detachable fluorine-containing reversible packaging material for power battery and preparation method of flame-retardant, self-cleaning and detachable fluorine-containing reversible packaging material

Abstract

The invention belongs to the technical field of preparation of a power battery packaging material, and particularly relates to a flame-retardant, self-cleaning and detachable fluorine-containing reversible packaging material for a power battery and a preparation method of the flame-retardant, self-cleaning and detachable fluorine-containing reversible packaging material. The preparation method comprises the following steps: reacting bifunctional fluorine-containing polyol with L-lysine diisocyanate to obtain an isocyanato-terminated prepolymer PU-1, reducing an ester group in the L-lysine diisocyanate into a hydroxyl group through a reduction reaction, reacting with amino-terminated disulfide to form a urea bond skeleton, reacting with metaboric acid to introduce a boric acid ester group, and carrying out a reaction to obtain the polyurethane prepolymer PU-1. Finally, phytic acid is introduced to regulate and control the crosslinking degree, and the fluorine-containing reversible packaging material is prepared. The material combines the characteristics of boric acid ester bonds, disulfide bonds, fluorine elements and phytic acid, and the flame retardance and the reversibility are remarkably enhanced. The prepared material is mainly suitable for packaging materials and other industries, the preparation process is simple and environmentally friendly, and the flame-retardant, self-cleaning and detachable effects are obvious and efficient.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of power battery packaging materials, and specifically relates to a fluorine-containing reversible packaging material for power batteries that is flame retardant, self-cleaning and detachable, and a preparation method thereof. Background Art

[0002] Polyurethane, a synthetic polymer with repeating urethane units in its backbone, is widely used in fields such as power battery packaging due to its highly designable molecular structure and excellent overall performance. Its corrosion resistance, low-temperature resistance, and processing flexibility have earned it a prominent position in both traditional and emerging applications such as sealants, coatings, and energy storage materials, earning it the nickname "universal polymer material."

[0003] While polyurethane materials have numerous advantages and can be applied in numerous fields, they still have significant drawbacks in complex environments. For example, conventional polyurethanes only achieve a flame retardancy rating of UL-94 V-1, making it difficult to effectively suppress flame spread in battery thermal runaway scenarios. Exposure to sunlight and acid rain can easily cause polymer chain degradation, leading to surface powdering and embrittlement, and loss of self-cleaning capabilities. Traditional thermosetting polyurethane encapsulation materials are cured through irreversible crosslinking, requiring mechanical destruction for disassembly, which can easily cause secondary damage to battery modules and prevent reuse. For example, patent CN 103788331A discloses a polyurethane flame retardant material prepared through a multi-step reaction under nitrogen protection. It burns smokelessly and achieves a flame retardancy rating of UL-94 V-1, but falls short of the more demanding V-0 rating and is irreversible. Patent CN119101477A primarily focuses on the heat resistance, thermal conductivity, and UV aging resistance of heat-resistant encapsulation materials, without addressing both flame retardancy and reversibility. Therefore, it is necessary to perform certain physical and chemical modifications on the polyurethane material to produce a new type of polyurethane packaging material with multiple functions and strong environmental adaptability. Summary of the Invention

[0004] This invention addresses the deficiencies of the existing technology and proposes a fluorinated reversible packaging material for power batteries that is flame-retardant, self-cleaning, and removable. First, a difunctional fluorinated polyol reacts with L-lysine diisocyanate to produce an isocyanate-terminated prepolymer, PU-1. The ester groups in the L-lysine diisocyanate are then reduced to hydroxyl groups through a reduction reaction, which reacts with an amino-terminated disulfide to form a urea bond skeleton. This is then reacted with metaboric acid to introduce borate groups. Finally, phytic acid is introduced to regulate the degree of crosslinking, resulting in a fluorinated reversible packaging material. This material combines the properties of borate bonds, disulfide bonds, fluorine, and phytic acid, significantly enhancing its flame retardancy and reversibility.

[0005] The chemical reaction equation for preparing the flame-retardant, self-cleaning and detachable fluorine-containing reversible packaging material is as follows:

[0006]

[0007]

[0008] The specific preparation method of the flame-retardant, self-cleaning and detachable fluorine-containing reversible packaging material of the present invention comprises the following steps:

[0009] (1) Add dehydrated bifunctional fluorinated polyol, L-lysine diisocyanate, organotin catalyst, and organic solvent in a stoichiometric ratio into a three-necked flask equipped with a stirring device and nitrogen, and react at 75-85° C. for 2-3 hours to polymerize to obtain an isocyanate-terminated polyurethane prepolymer PU-1;

[0010] The bifunctional fluorinated polyol is selected from the group consisting of 1H,1H,10H,10H-perfluoro-1,10-decanediol, 1H,1H,12H,12H-eicosine-1,12-dodecanediol, and 1H,1H,11H,11H-perfluoro-3,6,9-trioxaundecane-1,11-diol.

[0011] The molar ratio of L-lysine diisocyanate to difunctional fluorinated polyol is (2.2-2.4):1.

[0012] The organic tin catalyst is: dibutyltin dilaurate or stannous octoate, and the amount of the organic tin catalyst used is: 0.3-0.5wt% of the total mass of the reaction monomers.

[0013] (2) dissolving lithium aluminum hydride in an organic solvent and adding it to the PU-1 prepared in step (1) for reduction, reacting at 0-5° C. for 1-2 hours to obtain an isocyanate-terminated prepolymer PU-2;

[0014] The molar ratio of lithium aluminum hydride to the bifunctional fluorinated polyol is (1.1-1.3):1.

[0015] (3) dissolving the disulfide terminated with amino groups at both ends in an organic solvent and adding the solution to the PU-2 prepared in step (2), reacting at 40-50° C. for 1-2 h to form a urea bond skeleton, thereby obtaining a prepolymer PU-3 containing a disulfide bond;

[0016] The disulfide terminated with amino groups at both ends is one of 4,4'-diaminodiphenyl disulfide and 2,2'-diaminodiphenyl disulfide, and the molar ratio of the disulfide terminated with amino groups at both ends to the difunctional fluorinated polyol is:

[0017] (1.1-1.3):1.

[0018] (4) Dissolving metaboric acid and phytic acid in an organic solvent, adding the solution to the PU-3 prepared in step (3), and reacting at 60-70° C. for 2-3 hours to obtain a fluorine-containing reversible packaging material that is flame retardant, self-cleaning, and detachable.

[0019] The molar ratio of metaboric acid to the difunctional fluorine-containing polyol is (2.2-2.4):1, and the molar ratio of phytic acid to the difunctional fluorine-containing polyol is (0.2-0.4):1.

[0020] The organic solvent in steps (1)-(4) is N,N-dimethylformamide or N,N-dimethylacetamide.

[0021] Beneficial effects:

[0022] The fluorine-containing reversible packaging material prepared by the present invention imparts reversible properties to the material by introducing structures such as borate and disulfide bonds, so that the cross-linked network can be broken and reorganized under specific conditions, thereby improving the speed of cross-linking and solving the problem that traditional thermosetting polyurethane packaging materials are difficult to disassemble and have slow debonding due to irreversible cross-linked networks. At the same time, a large amount of fluorine is introduced into the material, so that the prepared material has a lower surface energy and a stronger self-cleaning function. The introduced phytic acid group greatly improves the flame retardant performance, which can effectively inhibit the spread of fire during thermal runaway of the battery. It has broad application prospects in the fields of packaging materials and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the infrared spectrum of the packaging material prepared in Example 1. DETAILED DESCRIPTION

[0024] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0025] Example 1

[0026] Under nitrogen atmosphere, 50 g of dehydrated 1H,1H,10H,10H-perfluoro-1,10-decanediol, 56 g of L-lysine diisocyanate, 0.4 g of dibutyltin dilaurate and 110 g of N,N-dimethylformamide were added to a three-necked flask equipped with a mechanical stirring device and a condenser. After mixing evenly, the mixture was stirred and reacted at 80 ° C for 2.5 h to obtain an isocyanate-terminated polyurethane prepolymer PU-1; 5 g of LiAlH4 was dissolved in 40 g of N,N-dimethylformamide and added to PU-1, and the reduction reaction was carried out at 0 ° C for 1.5 h to convert the ester group into a hydroxyl group to obtain an isocyanate-terminated polyurethane prepolymer PU-2; 32 g of 4,4'-diaminodiphenyl disulfide was dissolved in 40 g N,N-dimethylformamide was then added to PU-2, and the system was reacted at 45°C for 1.5 hours to undergo amino-isocyanate polymerization to form a urea bond skeleton, thereby obtaining polyurethane PU-3 containing a disulfide bond; 11g of metaboric acid and 10g of phytic acid were dissolved in 90g of N,N-dimethylformamide and then added to PU-3, and the reaction was carried out at 65°C for 2.5 hours to finally obtain a fluorine-containing reversible packaging material that is flame retardant, self-cleaning, and detachable.

[0027] Example 2

[0028] Under nitrogen atmosphere, 50 g of dehydrated 1H,1H,12H,12H-twenty-fluoro-1,12-dodecanediol, 45 g of L-lysine diisocyanate, 0.3 g of stannous octoate and 65 g of N,N-dimethylformamide were added to a three-necked flask equipped with a mechanical stirring device and a condenser. After mixing evenly, the mixture was stirred and reacted at 75 ° C for 2 h to obtain an isocyanate-terminated polyurethane prepolymer PU-1; 3.7 g of LiAlH4 was dissolved in 25 g of N,N-dimethylformamide and then added to PU-1. The reaction was carried out at 0 ° C for 1 h to convert the ester group into a hydroxyl group to obtain an isocyanate-terminated polyurethane prepolymer PU-2; 25 g of 4,4'-diaminodiphenyl disulfide was dissolved in 25 g N,N-dimethylformamide was then added to PU-2, and the system was reacted at 40°C for 1 hour to undergo amino-isocyanate polymerization to form a urea bond skeleton, thereby obtaining polyurethane PU-3 containing a disulfide bond; 8.2g of metaboric acid and 5.5g of phytic acid were dissolved in 50g of N,N-dimethylformamide and then added to PU-3, and the reaction was carried out at 60°C for 2 hours, finally obtaining a fluorine-containing reversible packaging material that is both flame retardant, self-cleaning and detachable.

[0029] Example 3

[0030] Under nitrogen atmosphere, 50 g of dehydrated 1H,1H,11H,11H-perfluoro-3,6,9-trioxaundecane-1,11-diol, 66 g of L-lysine diisocyanate, 0.6 g of dibutyltin dilaurate and 150 g of N,N-dimethylformamide were added to a three-necked flask equipped with a mechanical stirring device and a condenser. After mixing evenly, the mixture was stirred and reacted at 85 ° C for 3 h to obtain an isocyanate-terminated polyurethane prepolymer PU-1; 6 g of LiAlH4 was dissolved in 60 g of N,N-dimethylformamide and added to PU-1, and the reaction was carried out at 5 ° C for 2 h to convert the ester group into a hydroxyl group to obtain an isocyanate-terminated polyurethane prepolymer PU-2; 40 g of 2,2'-diaminodiphenyl disulfide was dissolved in 60 g N,N-dimethylformamide was then added to PU-2, and the system was reacted at 50°C for 2 hours to carry out amino-isocyanate polymerization to form a urea bond skeleton to obtain polyurethane PU-3 containing disulfide bonds; 13g of metaboric acid and 14.5g of phytic acid were dissolved in 130g of N,N-dimethylformamide and then added to PU-3, and the reaction was carried out at 70°C for 3 hours to finally obtain a fluorine-containing reversible packaging material that is flame retardant, self-cleaning and detachable.

[0031] Example 4

[0032] The preparation of isocyanate-terminated polyurethane prepolymer PU-2 is the same as in Example 1.

[0033] Dissolve 20g of 4,4'-diaminodiphenyl disulfide in 40g of N,N-dimethylformamide and add it to PU-2. The system reacts at 45°C for 1.5 hours for amino-isocyanate polymerization to form a urea bond skeleton, producing polyurethane PU-3 containing disulfide bonds. The preparation steps for the flame-retardant, self-cleaning, and removable fluorine-containing reversible encapsulation material are the same as those in Example 1.

[0034] Example 5

[0035] The preparation of isocyanate-terminated polyurethane prepolymer PU-2 is the same as in Example 1.

[0036] Dissolve 45g of 4,4'-diaminodiphenyl disulfide in 40g of N,N-dimethylformamide and add to PU-2. The system reacts at 45°C for 1.5 hours for amino-isocyanate polymerization to form a urea bond skeleton, producing polyurethane PU-3 containing disulfide bonds. The preparation steps for the flame-retardant, self-cleaning, and removable fluorine-containing reversible encapsulation material are the same as in Example 1.

[0037] Example 6

[0038] The preparation of polyurethane PU-3 containing disulfide bonds is the same as in Example 1.

[0039] 7.5g of metaboric acid and 10g of phytic acid were dissolved in 90g of N,N-dimethylformamide and added to PU-3. The mixture was reacted at 65°C for 2.5 hours. This resulted in a fluorine-containing reversible encapsulation material that was flame-retardant, self-cleaning, and removable.

[0040] Example 7

[0041] The preparation of polyurethane PU-3 containing disulfide bonds is the same as in Example 1.

[0042] 15g of metaboric acid and 10g of phytic acid were dissolved in 90g of N,N-dimethylformamide and added to PU-3. The mixture was reacted at 65°C for 2.5 hours. This resulted in a fluorine-containing reversible encapsulation material that was flame-retardant, self-cleaning, and removable.

[0043] Example 8

[0044] Under nitrogen atmosphere, 50 g of dehydrated 1H,1H,11H,11H-perfluoro-3,6,9-trioxaundecane-1,11-diol, 63 g of L-lysine diisocyanate, 0.5 g of dibutyltin dilaurate and 120 g of N,N-dimethylformamide were added to a three-necked flask equipped with a mechanical stirring device and a condenser. After mixing evenly, the mixture was stirred and reacted at 80 ° C for 2.5 h to obtain an isocyanate-terminated polyurethane prepolymer PU-1; 5.5 g of LiAlH4 was dissolved in 45 g of N,N-dimethylformamide and then added to PU-1. The reaction was carried out at 0 ° C for 1.5 h to convert the ester group into a hydroxyl group to obtain an isocyanate-terminated polyurethane prepolymer PU-2; 36 g of 2,2'-diaminodiphenyl disulfide was dissolved in 45 g N,N-dimethylformamide was then added to PU-2, and the system was reacted at 45°C for 1.5 hours to carry out amino-isocyanate polymerization to form a urea bond skeleton to obtain polyurethane PU-3 containing disulfide bonds; 12g of metaboric acid and 11g of phytic acid were dissolved in 90g of N,N-dimethylformamide and then added to PU-3, and the reaction was carried out at 65°C for 2.5 hours to finally obtain a fluorine-containing reversible packaging material that is flame retardant, self-cleaning and detachable.

[0045] Example 9

[0046] Under a nitrogen atmosphere, 50 g of dehydrated 1H,1H,10H,10H-perfluoro-1,10-decanediol, 30 g of L-lysine diisocyanate, 0.4 g of dibutyltin dilaurate, and 110 g of N,N-dimethylformamide were added to a three-necked flask equipped with a mechanical stirrer and a condenser. The mixture was uniformly mixed and stirred at 80°C for 2.5 h to obtain an isocyanate-terminated polyurethane prepolymer PU-1.

[0047] The steps for preparing the flame-retardant, self-cleaning and detachable fluorine-containing reversible packaging material are the same as those in Example 1.

[0048] Comparative Example 1

[0049] The L-lysine diisocyanate in the preparation steps of Example 1 was replaced by hexamethylene diisocyanate, and the other preparation steps were the same as in Example 1.

[0050] Comparative Example 2

[0051] The 4,4'-diaminodiphenyl disulfide in the preparation steps of Example 1 was replaced with 1,10-diaminodecane, and the other preparation steps were the same as those of Example 1.

[0052] Comparative Example 3

[0053] The metaboric acid in the preparation steps of Example 1 was replaced by terephthalic acid, and the other preparation steps were the same as in Example 1.

[0054] test

[0055] (1) Debonding efficiency of encapsulating materials: To verify the ability of encapsulating materials to achieve reversibility by breaking disulfide bonds and borate bonds, the material sample was first cut and weighed (m0), and then immersed in 0.1M acetate buffer with a pH of 5 containing 50mM tris(2-carboxyethyl)phosphine hydrochloride. After keeping it for 10 minutes, it was taken out, washed, dried, and weighed (m1). The debonding efficiency was calculated based on the mass difference. The calculation formula of the debonding efficiency (η) is: η = (m0-m1)÷m0×100%.

[0056] (2) Limiting oxygen index of packaging materials: In order to evaluate the flame retardant properties of packaging materials, the limiting oxygen index test of packaging materials is carried out in accordance with ISO 4589 standard.

[0057] (3) Water contact angle of packaging materials: In order to measure the self-cleaning ability of packaging materials, the contact angle formed by water droplets on the surface of packaging materials is measured for evaluation.

[0058] Table 1 Test data of each embodiment

[0059] Debonding efficiency Limiting oxygen index Water contact angle Example 1 65％ 38％ 155° Example 2 63％ 36％ 152° Example 3 62％ 37％ 150° Example 4 38％ 33％ 140° Example 5 46％ 32％ 145° Example 6 42％ 30％ 138° Example 7 33％ 34％ 135° Example 8 64％ 37％ 153° Example 9 41％ 33％ 139° Comparative Example 1 12％ 29％ 95° Comparative Example 2 8％ 27％ 88° Comparative Example 3 10％ 26％ 91°

[0060] With the above-described preferred embodiments of the present invention as a guide, and with reference to the above description, relevant personnel are fully capable of making various changes and modifications without departing from the technical scope of this invention. The technical scope of this invention is not limited to the contents of the specification and must be determined according to the scope of the claims.

Claims

1. A method for preparing a flame-retardant, self-cleaning and detachable fluorine-containing reversible packaging material, characterized in that: The preparation method comprises the following steps: (1) A difunctional fluorinated polyol, L-lysine diisocyanate, an organotin catalyst, and an organic solvent are reacted at 75-85°C for 2-3 hours to prepare an isocyanate-terminated polyurethane prepolymer PU-1; (2) dissolving lithium aluminum hydride in an organic solvent and adding it to PU-1, reacting at 0-5°C for 1-2 hours to obtain an isocyanate-terminated prepolymer PU-2; (3) dissolving the disulfide terminated with amino groups at both ends in an organic solvent and adding it to PU-2, reacting at 40-50°C for 1-2 hours to obtain a prepolymer containing disulfide bonds, PU-3; (4) Boric acid and phytic acid are dissolved in an organic solvent and added to PU-3, and reacted at 60-70°C for 2-3 hours to obtain a fluorine-containing reversible packaging material that is flame retardant, self-cleaning, and detachable.

2. The method for preparing the flame-retardant, self-cleaning and detachable fluorine-containing reversible packaging material according to claim 1, characterized in that: In step (1), the difunctional fluorinated polyol is selected from the group consisting of 1H,1H,10H,10H-perfluoro-1,10-decanediol, 1H,1H,12H,12H-eicosine-1,12-dodecanediol, and 1H,1H,11H,11H-perfluoro-3,6,9-trioxaundecane-1,11-diol.

3. The method for preparing the flame-retardant, self-cleaning and detachable fluorine-containing reversible packaging material according to claim 1, characterized in that: In step (1), the molar ratio of L-lysine diisocyanate to difunctional fluorinated polyol is 2.2-2.4:

1.

4. The method for preparing the flame-retardant, self-cleaning and detachable fluorine-containing reversible packaging material according to claim 1, characterized in that: In step (1), the organic tin catalyst is: dibutyltin dilaurate or stannous octoate, and the amount of the organic tin catalyst used is: 0.3-0.5wt% of the total mass of the monomers in the reaction system.

5. The method for preparing the flame-retardant, self-cleaning and detachable fluorine-containing reversible packaging material according to claim 1, characterized in that: In step (2), the molar ratio of lithium aluminum hydride to the difunctional fluorinated polyol is 1.1-1.3:

1.

6. The method for preparing the flame-retardant, self-cleaning and detachable fluorine-containing reversible packaging material according to claim 1, characterized in that: In step (3), the disulfide terminated with amino groups at both ends is 4,4'-diaminodiphenyl disulfide or 2,2'-diaminodiphenyl disulfide, and the molar ratio of the disulfide terminated with amino groups at both ends to the difunctional fluorinated polyol is 1.1-1.3:

1.

7. The method for preparing the flame-retardant, self-cleaning and detachable fluorine-containing reversible packaging material according to claim 1, characterized in that: In step (4), the molar ratio of metaboric acid to the difunctional fluorinated polyol is 2.2-2.4:1, and the molar ratio of phytic acid to the difunctional fluorinated polyol is 0.2-0.4:

1.

8. The method for preparing the flame-retardant, self-cleaning and detachable fluorine-containing reversible packaging material according to claim 1, characterized in that: In steps (1)-(4), the organic solvent is: N,N-dimethylformamide or N,N-dimethylacetamide.

9. A flame-retardant, self-cleaning and detachable fluorine-containing reversible packaging material prepared by the method according to any one of claims 1 to 8, characterized in that: The general structural formula of the fluorine-containing reversible packaging material is as follows:

10. An application of the flame-retardant, self-cleaning and detachable fluorine-containing reversible packaging material according to claim 9, characterized in that: The fluorine-containing reversible packaging material is used as a packaging material for power batteries.

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