Semi-bio-based polyamide containing cross-linked structure, preparation method therefor and use thereof

Abstract

A semi-bio-based polyamide containing a cross-linked structure, a preparation method therefor and a use thereof, belonging to the technical field of polyamide preparation. The semi-bio-based polyamide containing a cross-linked structure has the structure of formula (I), and is polycondensed using, as raw materials, 2,5-furandicarboxylic acid and a derivative monomer thereof, and an aromatic diamine, derived from bio-based materials, and an aromatic triamine as a cross-linking agent. The cross-linked structure semi-bio-based polyamide has excellent thermal stability and excellent mechanical properties, has excellent wettability for an electrolyte, shows outstanding chemical stability and electrochemical stability, and can be applied to a lithium ion battery separator; as a lithium ion battery separator coating material having excellent performance and durability, the polyamide can further improve the performance of a separator, thereby improving battery capacity, cycle and rate discharge performance and safety.

Description

A semi-biobased polyamide containing a cross-linked structure and its preparation method and application

[0001] This application is based on the Chinese application with CN application number 2023112726973 and application date September 28, 2023, and claims its priority. The disclosed content of the CN application is again introduced as a whole into this application. Technical Field

[0002] The present invention belongs to the technical field of polyamide preparation, and in particular relates to a semi-biobased polyamide containing a cross-linked structure, a preparation method and an application thereof. Background Art

[0003] Lithium-ion batteries are sustainable energy storage systems that can convert electrical energy into chemical energy. They offer superior properties such as high energy density and specific energy, high operating voltage, long storage and cycle life, no memory effect, low self-discharge, and safety and pollution-free performance. These advantages fully meet the urgent demand for lightweight and miniaturized power supplies for electrical appliances. Lithium-ion batteries are now widely used in various fields, including various electronic appliances and electric vehicles.

[0004] Lithium-ion batteries are primarily composed of a positive electrode, a negative electrode, an electrolyte, and a separator. The separator is a crucial component, its primary function being to separate the positive and negative electrodes of the battery, preventing direct contact between the two electrodes and a short circuit. It also allows ions to pass freely through the battery. The performance of the separator material determines the battery's interface structure and internal resistance, thereby affecting its capacity, cycle and rate discharge performance, and safety. Polyamide is a commonly used separator material. For example, the method for preparing a water-based coated separator with high electrolyte wettability disclosed in Publication No. CN116315425A incorporates modified bio-based polyamide particles, which reduces the contact angle with the electrolyte and greatly improves the electrolyte wettability. Another example is the method for preparing nano-scale bio-based semi-aromatic polyamide particles disclosed in Publication No. CN116162266A, which can be used in any coating process using a water-based solvent system to effectively improve the heat resistance and membrane rupture temperature of the coated product.

[0005] However, the polyamide prepared by the existing polyamide preparation method still has certain problems in its dimensional stability, thermal stability, mechanical properties, wettability to electrolyte, chemical stability and electrochemical stability, and there is a lot of room for improvement.

[0006] Summary of the Invention

[0007] The purpose of the present invention is to provide a semi-biobased polyamide containing a cross-linked structure and a preparation method and application thereof in order to solve the above problems.

[0008] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0009] The first object of the present invention is to provide a semi-bio-based polyamide containing a cross-linked structure, wherein the semi-bio-based polyamide containing a cross-linked structure has the structure of the following formula (I):

[0010] In formula (I), m>1, k>1 and m:k=(20-100):1, m+k=500-2000; Ar1 ​​is a residue of a divalent aromatic amine, Ar2 is a residue of a trivalent aromatic amine, and R is a linear polymer chain cross-linked by the trivalent aromatic amine.

[0011] The second object of the present invention is to provide a method for preparing the above-mentioned semi-bio-based polyamide containing a cross-linked structure, comprising the following steps: (1) mixing a diamine monomer with a first organic solvent under an inert gas atmosphere to obtain a diamine solution; (2) taking 2,5-furandicarboxylic acid or a derivative monomer thereof, adding part of the 2,5-furandicarboxylic acid or the derivative monomer thereof to the diamine solution, reacting at a first predetermined temperature, then adding a triamine monomer, heating to a second predetermined temperature, to obtain a polyamide prepolymer solution; (3) adding another part of the 2,5-furandicarboxylic acid or the derivative monomer thereof to the polyamide prepolymer solution, then heating to a third predetermined temperature, to obtain a semi-bio-based polyamide solution containing a cross-linked structure having an expected apparent viscosity; (4) mixing the semi-bio-based polyamide solution with a second organic solvent, then adding water to obtain a semi-bio-based polyamide, and then beating the semi-bio-based polyamide, washing with water, filtering, and drying to obtain semi-bio-based polyamide particles containing a cross-linked structure.

[0012] As a further optimization solution of the present invention, in step (1), the inert gas includes one or more of nitrogen, helium and argon.

[0013] In step (1), the diamine monomer includes one or more of m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenyl ether, and 4,4'-diaminodiphenylmethane.

[0014] In step (1), the mass ratio of the diamine monomer to the first organic solvent is 1:(5-10).

[0015] As a further optimization scheme of the present invention, in step (1), after the diamine monomer is mixed with the first organic solvent, the process further comprises: heating to 60-80° C. to dissolve the diamine monomer, and then cooling to 0-10° C. to obtain the diamine solution.

[0016] As a further optimized solution of the present invention, in step (2), the derivative monomer of 2,5-furandicarboxylic acid is 2,5-furandicarboxylic acid chloride.

[0017] In step (2), the triamine monomer includes one or more of 1,3,5-triaminobenzene, 1,1'-biphenyl-3,3',5,5'-tetramine and 3,3',5,5'-tetraaminodiphenylmethane.

[0018] As a further optimized solution of the present invention, in step (2), the mass ratio of the portion of 2,5-furandicarboxylic acid or a monomer derived therefrom to the 2,5-furandicarboxylic acid or a monomer derived therefrom is 95-99%.

[0019] In step (2), the first predetermined temperature is no greater than 15°C.

[0020] In step (2), the second predetermined temperature is 20-25°C.

[0021] The molar ratio of the 2,5-furandicarboxylic acid or its derivative monomer to the diamine monomer is 1:(0.8-1).

[0022] The molar ratio of the triamine monomer to the diamine monomer is (0.01-0.05):1.

[0023] As a further optimization solution of the present invention, in step (3), the third predetermined temperature is 60-70°C.

[0024] In step (3), the expected apparent viscosity is 10,000-70,000 mPa·s. Specifically, during the temperature-raising reaction, 2,5-furandicarboxylic acid or a derivative monomer thereof is added according to the actual apparent viscosity until a cross-linked semi-bio-based polyamide solution having the expected apparent viscosity is obtained. The added 2,5-furandicarboxylic acid or a derivative monomer thereof is 0.1%-1% of the mass of the 2,5-furandicarboxylic acid or a derivative monomer thereof taken in step (2).

[0025] In step (4), the mass of the semi-bio-based polyamide solution is 3-10 times the mass of the second organic solvent; and the mass of the water is 8-10 times the mass of the semi-bio-based polyamide solution.

[0026] The first organic solvent and the second organic solvent independently include at least one of N,N-dimethylacetamide, N-methylpyrrolidone and N,N-dimethylformamide.

[0027] The third object of the present invention is to provide a lithium-ion battery separator. The raw material components of the lithium-ion battery separator include 0.8-1.5 parts of a third organic solvent, 0.01-0.5 parts of ceramic particles, 0.01-0.5 parts of the semi-biobased polyamide prepared above, and 0.01-0.2 parts of polyvinylidene fluoride, by weight.

[0028] The fourth object of the present invention is to provide a method for preparing the above-mentioned lithium-ion battery separator, comprising the following steps: (1) mixing a third organic solvent, ceramic particles, semi-bio-based polyamide and polyvinylidene fluoride to obtain a semi-bio-based coating slurry; (2) coating the semi-bio-based coating slurry on at least one side of a lithium-ion battery base membrane, and then extracting it with a mixed solvent, extracting it with water, and drying it to obtain a semi-bio-based polyamide separator containing a cross-linked structure.

[0029] As a further optimization scheme of the present invention, the mixed solvent includes a fourth organic solvent and water, and the volume ratio of the fourth organic solvent to water is (0.1-2):1; the third organic solvent and the fourth organic solvent each independently include at least one of N,N-dimethylacetamide, N-methylpyrrolidone and N,N-dimethylformamide.

[0030] The beneficial effects of the present invention are:

[0031] (1) The coated diaphragm prepared using the above-mentioned semi-bio-based polyamide material containing a cross-linked structure has a high porosity and electrolyte absorption rate, and an average tensile strength of 13.08 MPa, which can meet the requirements of the battery assembly process for the mechanical properties of the diaphragm; at the same time, the shrinkage rate is less than 2% at 150°C, and it has excellent thermal stability, ensuring the high safety of the battery under conditions such as high temperature or thermal runaway.

[0032] (2) Semi-biobased polyamide materials with cross-linked structures have excellent electrochemical stability due to their good pore structure and low swelling characteristics. Their application in lithium-ion battery separator coatings will improve battery capacity, cycle and rate discharge performance, and safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG1 is a DSC curve of a semi-biobased polyamide diaphragm containing a cross-linked structure prepared in Example 4 under a nitrogen atmosphere;

[0034] Figure 2 is an electron micrograph of a semi-bio-based polyamide diaphragm containing a cross-linked structure prepared in Example 3, (b) is a partial magnified view of (a);

[0035] FIG3 is an electron microscope image of a semi-bio-based polyamide diaphragm containing a cross-linked structure prepared in Example 4, and (b) is a partial enlarged view of (a). DETAILED DESCRIPTION

[0036] The embodiments of the present invention are described in detail below, which are intended to explain the present invention but are not to be construed as limiting the present invention.

[0037] In the first aspect of the present invention, the present invention provides a semi-bio-based polyamide containing a cross-linked structure having the structure of the following formula (I):

[0038] In formula (I), m>1, k>1 and m:k=(20-100):1, m+k=500-2000; Ar1 ​​is a residue of a divalent aromatic amine, Ar2 is a residue of a trivalent aromatic amine, and R is a linear polymer chain cross-linked by the trivalent aromatic amine.

[0039] By integrating di- and tri-aromatic amine residues, as well as linear polymer chains cross-linked by tri-aromatic amines, into a semi-bio-based polyamide, the polyamide is given a three-dimensional network structure, thereby improving the thermal stability, solvent resistance, and mechanical properties of the polyamide molecule. Coating the semi-bio-based polyamide onto lithium battery separators can improve the performance of the separators.

[0040] In the second aspect of the present invention, the present invention provides a method for preparing a semi-biobased polyamide material containing a cross-linked structure, which is achieved by the following technical solutions:

[0041] (1) Under an inert gas atmosphere, a diamine monomer is mixed with a first organic solvent to obtain a diamine solution.

[0042] Furthermore, the mass ratio of the diamine monomer to the first organic solvent is 1:(5-10), thereby allowing the diamine monomer to dissolve more fully.

[0043] Furthermore, after the diamine monomer is mixed with the first organic solvent, the process further includes heating to 60-80° C. to dissolve the diamine monomer, and then cooling to 0-10° C. to obtain a diamine solution. This makes the obtained diamine solution more stable and uniform, which is beneficial for the subsequent polymerization reaction.

[0044] It should be noted that the inert gas includes one or more of nitrogen, helium and argon; the diamine monomer includes one or more of m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenyl ether and 4,4'-diaminodiphenylmethane.

[0045] (2) taking 2,5-furandicarboxylic acid or a derivative monomer thereof, adding part of the 2,5-furandicarboxylic acid or a derivative monomer thereof to a diamine solution, reacting at a first predetermined temperature, then adding a triamine monomer, and heating to a second predetermined temperature to obtain a polyamide prepolymer solution.

[0046] Furthermore, the mass ratio of the portion of 2,5-furandicarboxylic acid or its derivative monomer to 2,5-furandicarboxylic acid or its derivative monomer is 95-99%; the first predetermined temperature is no more than 15°C; and the second predetermined temperature is 20-25°C.

[0047] Furthermore, the molar ratio of 2,5-furandicarboxylic acid or its derivative monomer to the diamine monomer is 1:(0.8-1); the molar ratio of the triamine monomer to the diamine monomer is (0.01-0.05):1.

[0048] It should be noted that the derivative monomer of 2,5-furandicarboxylic acid is 2,5-furandicarboxylic acid chloride; the triamine monomer includes one or more of 1,3,5-triaminobenzene, 1,1'-biphenyl-3,3',5,5'-tetramine and 3,3',5,5'-tetraaminodiphenylmethane.

[0049] (3) adding another portion of 2,5-furandicarboxylic acid or a derivative monomer thereof into the polyamide prepolymer solution, and then heating the solution to a third predetermined temperature to obtain a semi-biobased polyamide solution containing a cross-linked structure and having a desired apparent viscosity.

[0050] Furthermore, the third predetermined temperature is 60-70°C.

[0051] Furthermore, the expected apparent viscosity is 10,000-70,000 mPa·s. During the temperature-raising reaction, 2,5-furandicarboxylic acid or a derivative monomer thereof is added according to the actual apparent viscosity until a cross-linked semi-bio-based polyamide solution having the expected apparent viscosity is obtained. The added 2,5-furandicarboxylic acid or a derivative monomer thereof is 0.1%-1% of the mass of the 2,5-furandicarboxylic acid or a derivative monomer thereof taken in step (2).

[0052] By adding 2,5-furandicarboxylic acid or its derivative monomers in batches multiple times, the polymerization reaction can be made more complete, which is more conducive to obtaining a semi-bio-based polyamide solution with the required viscosity and molecular weight.

[0053] (4) mixing the semi-bio-based polyamide solution with a second organic solvent, and then adding water to obtain the semi-bio-based polyamide; then beating the semi-bio-based polyamide, washing it with water, filtering it with suction, and drying it to obtain semi-bio-based polyamide particles containing a cross-linked structure;

[0054] Furthermore, the mass of the semi-bio-based polyamide solution is 3-10 times the mass of the second organic solvent; and the mass of water is 8-10 times the mass of the semi-bio-based polyamide solution.

[0055] It should be noted that the first organic solvent and the second organic solvent independently include at least one of N,N-dimethylacetamide, N-methylpyrrolidone and N,N-dimethylformamide.

[0056] By polymerizing diamines with 2,5-furandicarboxylic acid or its derivatives and adding triamines as crosslinkers during the polymerization process, the properties of the resulting semi-biobased polyamide particles can be improved. During the polymerization reaction, the choice of crosslinker, the dosage, and the timing of its addition are crucial. If not precisely controlled, low crosslink density can lead to the failure of crosslinking, while high crosslink density can cause a dramatic increase in the viscosity and molecular weight of the polymer, making it impossible to obtain a suitable product.

[0057] In the third aspect of the present invention, the present invention provides a lithium-ion battery separator. The raw material components of the lithium-ion battery separator include 0.8-1.5 parts of a third organic solvent, 0.01-0.5 parts of ceramic particles, 0.01-0.5 parts of the semi-biobased polyamide prepared above, and 0.01-0.2 parts of polyvinylidene fluoride, by weight.

[0058] In a fourth aspect of the present invention, a method for preparing a lithium-ion battery separator is provided, comprising the following steps: (1) mixing a third organic solvent, ceramic particles, semi-bio-based polyamide and polyvinylidene fluoride to obtain a semi-bio-based coating slurry; and (2) coating the semi-bio-based coating slurry on at least one side of a lithium-ion battery base membrane, and then subjecting the mixture to mixed solvent extraction, water extraction, and drying to obtain a semi-bio-based polyamide separator containing a cross-linked structure.

[0059] Furthermore, the mixed solvent includes a fourth organic solvent and water, wherein the volume ratio of the fourth organic solvent to water is (0.1-2):1; the third organic solvent and the fourth organic solvent each independently include at least one of N,N-dimethylacetamide, N-methylpyrrolidone, and N,N-dimethylformamide. The drying temperature is set to 60-150°C.

[0060] The present invention is further explained below by means of specific examples. The methods used in the present invention are conventional methods known to those skilled in the art unless otherwise specified, and the reagents and other materials used are commercially available products unless otherwise specified.

[0061] Example 1

[0062] A 100L reactor was heated to 80°C to completely dry out the moisture. Argon was then used to displace the air in the reactor for 2 hours. Following this, 46.825kg of N,N-dimethylacetamide and 6.284kg of 4,4'-diaminodiphenyl ether were added to the reactor under argon and stirred at elevated temperature until completely dissolved. After dissolution, the temperature was lowered to 0°C to obtain a clear diamine solution. 5kg of 2,5-furandicarboxylic acid was first added to the reactor, with 4.9g of 2,5-furandicarboxylic acid chloride added at a controlled rate to maintain the temperature below 15°C. Then, 0.05kg of 1,3,5-triaminobenzene was quickly added, and the temperature was raised to 20-25°C with stirring for 2 hours to obtain a polyamide prepolymer solution. The remaining 0.1g of 2,5-furandicarboxylic acid was added to the polyamide prepolymer solution, and the temperature was raised to 60-70°C for 6 hours. During this time, 0.025kg of 2,5-furandicarboxylic acid was added according to the apparent viscosity until a semi-bio-based polyamide solution with a cross-linked structure and a viscosity of 43,400 mPa·s was obtained. Then, 200kg of N,N-dimethylacetamide and 400kg of water were added to the semi-bio-based polyamide solution and stirred to precipitate the semi-bio-based polyamide. The semi-bio-based polyamide particles with cross-linked structures were then obtained after beating, washing, filtering, and drying.

[0063] 81.2 kg of N,N-dimethylacetamide, 10.3 kg of ceramic particles, 5.4 kg of the semi-bio-based polyamide prepared above, and 1.8 kg of polyvinylidene fluoride were added to a stirring tank in sequence, and stirred for 2 hours to obtain a coating slurry; the coating slurry was applied to both sides of the lithium-ion battery base membrane, and after solvent extraction, water extraction, and drying at 75°C, a semi-bio-based polyamide membrane diaphragm with a cross-linked structure was prepared.

[0064] Example 2

[0065] A 50L reactor was heated to 80°C to completely dry out the moisture. The air in the reactor was then replaced with nitrogen for 2 hours. After this, 23.41 kg of N,N-dimethylacetamide and 2.52 kg of 4,4'-diaminodiphenyl ether were added to the reactor under argon and stirred until completely dissolved. After dissolution, the temperature was lowered to 0°C to obtain a clear diamine solution. 2.5 kg of 2,5-furandicarbonyl chloride was first added to the reactor, with 2.425 g added at a controlled rate to maintain the temperature below 15°C. Then, 0.055 kg of 1,1'-biphenyl-3,3',5,5'-tetramine was quickly added. The temperature was raised to 20-25°C and stirred for 2 hours to obtain a polyamide prepolymer solution. Then, the remaining 2,5-furandicarboxylic acid chloride is added to the polyamide prepolymer solution, and the temperature is raised to 60-70°C for reaction for 6 hours. During this period, 0.025 kg of 2,5-furandicarboxylic acid chloride is added according to the apparent viscosity until a semi-bio-based polyamide solution with a viscosity of 62010 mPa·s and a cross-linked structure is obtained; then, 120 kg of N,N-dimethylacetamide and 200 kg of water are added to the semi-bio-based polyamide solution, and the semi-bio-based polyamide is precipitated by stirring. After beating, washing, filtering, and drying, semi-bio-based polyamide particles with a cross-linked structure are obtained.

[0066] 81.2 kg of N,N-dimethylacetamide, 10.3 kg of ceramic particles, 5.4 kg of the semi-bio-based polyamide prepared above, and 1.8 kg of polyvinylidene fluoride were added to a stirring tank in sequence, and stirred for 2 hours to obtain a coating slurry; the coating slurry was applied to both sides of the lithium-ion battery base membrane, and after solvent extraction, water extraction, and drying at 75°C, a semi-bio-based polyamide membrane diaphragm with a cross-linked structure was prepared.

[0067] Example 3

[0068] A 50L reactor was heated to 80°C to completely dry out the moisture. Argon was then used to displace the air in the reactor for 2 hours. After this, 28.44 kg of N,N-dimethylformamide and 3.73 kg of 4,4'-diaminodiphenyl ether were added to the reactor under argon, heated and stirred until completely dissolved. After dissolution, the temperature was lowered to 0°C to obtain a clear diamine solution. 3 kg of 2,5-furandicarboxylic acid was first added to the reactor, with 2.88 g of 2,5-furandicarboxylic acid chloride added at a controlled rate to maintain the temperature below 15°C. Then, 0.047 kg of 1,3,5-triaminobenzene was quickly added, and the temperature was raised to 20-25°C with stirring for 1 hour to obtain a polyamide prepolymer solution. The remaining 0.12g of 2,5-furandicarboxylic acid was added to the polyamide prepolymer solution, and the temperature was raised to 60-70°C for 5 hours. During this time, 0.031kg of 2,5-furandicarboxylic acid was added according to the apparent viscosity until a semi-bio-based polyamide solution with a cross-linked structure and a viscosity of 57790mPa·s was obtained. Then, 150kg of N,N-dimethylformamide and 300kg of water were added to the semi-bio-based polyamide solution and stirred to precipitate the semi-bio-based polyamide. The semi-bio-based polyamide particles with cross-linked structures were then obtained after beating, washing, filtering, and drying.

[0069] 81.2 kg of N,N-dimethylacetamide, 10.3 kg of ceramic particles, 5.4 kg of the semi-bio-based polyamide prepared above, and 1.8 kg of polyvinylidene fluoride were added to a stirring tank in sequence and stirred for 2 hours to obtain a coating slurry. This coating slurry was applied to both sides of the lithium-ion battery base membrane. After solvent extraction, water extraction, and drying at 75°C, a semi-bio-based polyamide membrane separator with a cross-linked structure was prepared. An electron micrograph of the prepared semi-bio-based polyamide membrane separator is shown in Figure 2.

[0070] Example 4

[0071] A 100L reactor was heated to 85°C to completely dry out the moisture. Argon was then used to displace the air in the reactor for 2 hours. Following this, 46.825kg of N,N-dimethylacetamide and 4.99kg of 4,4'-diaminodiphenylmethane were added to the reactor under argon and stirred until completely dissolved. After dissolution, the temperature was lowered to 0°C to obtain a clear diamine solution. 5kg of 2,5-furandicarboxylic acid chloride was first added to the reactor, with 4.75g added. The addition rate was controlled to maintain the temperature below 15°C. Then, 0.63kg of 1,3,5-triaminobenzene was quickly added. The temperature was raised to 20-25°C and stirred for 2 hours to obtain a polyamide prepolymer solution. The remaining 0.25g of 2,5-furandicarboxylic acid chloride was added to the polyamide prepolymer solution, and the temperature was raised to 60-70°C for 5.5 hours. During this time, 0.06kg of 2,5-furandicarboxylic acid chloride was added according to the apparent viscosity until a semi-bio-based polyamide solution with a cross-linked structure and a viscosity of 36,300 mPa·s was obtained. Then, 200kg of N,N-dimethylacetamide and 400kg of water were added to the semi-bio-based polyamide solution, and the semi-bio-based polyamide was precipitated with stirring. The semi-bio-based polyamide was then slurried, washed, filtered, and dried to obtain cross-linked semi-bio-based polyamide particles.

[0072] 81.2 kg of N,N-dimethylacetamide, 10.3 kg of ceramic particles, 5.4 kg of the semi-bio-based polyamide prepared above, and 1.8 kg of polyvinylidene fluoride were added to a stirring tank in sequence and stirred for 2 hours to obtain a coating slurry. This coating slurry was applied to both sides of the lithium-ion battery base membrane. After solvent extraction, water extraction, and drying at 75°C, a semi-bio-based polyamide membrane separator with a cross-linked structure was prepared. The DSC curve of the prepared semi-bio-based polyamide membrane separator under a nitrogen atmosphere is shown in Figure 1. An electron micrograph of the prepared semi-bio-based polyamide membrane separator is shown in Figure 3.

[0073] Example 5

[0074] A 100L reactor was heated to 80°C to completely dry out the moisture. Argon was then used to displace the air in the reactor for 2 hours. Following this, 48.7kg of N,N-dimethylacetamide and 2.857kg of p-phenylenediamine were added to the reactor under argon and stirred until completely dissolved. After dissolution, the temperature was lowered to 0°C to obtain a clear diamine solution. 5.2kg of 2,5-furandicarboxylic acid chloride was first added to the reactor, with 5.096g added at a controlled rate to maintain the temperature below 10°C. Then, 0.122kg of 3,3',5,5'-tetraaminodiphenylmethane was quickly added. The temperature was raised to 20-25°C and stirred for 2 hours to obtain a polyamide prepolymer solution. The remaining 0.104g of 2,5-furandicarboxylic acid chloride was added to the polyamide prepolymer solution, and the temperature was raised to 60-70°C for 6 hours. During this time, 0.04kg of 2,5-furandicarboxylic acid chloride was added according to the apparent viscosity until a semi-bio-based polyamide solution with a cross-linked structure and a viscosity of 24090mPa·s was obtained. Then, 230kg of N,N-dimethylacetamide and 400kg of water were added to the semi-bio-based polyamide solution and stirred to precipitate the semi-bio-based polyamide. The semi-bio-based polyamide particles with cross-linked structures were then obtained after beating, washing, filtering, and drying.

[0075] 81.2 kg of N,N-dimethylacetamide, 10.3 kg of ceramic particles, 5.4 kg of the semi-bio-based polyamide prepared above, and 1.8 kg of polyvinylidene fluoride were added to a stirring tank in sequence, and stirred for 2 hours to obtain a coating slurry; the coating slurry was applied to both sides of the lithium-ion battery base membrane, and after solvent extraction, water extraction, and drying at 75°C, a semi-bio-based polyamide membrane diaphragm with a cross-linked structure was prepared.

[0076] Example 6

[0077] Heat a 100L reactor to 80°C to completely dry out the moisture. Replace the air in the reactor with argon for 2 hours. Once complete, add 53.456kg of N-methylpyrrolidone and 2.857kg of m-phenylenediamine to the reactor under argon, heating and stirring until completely dissolved. After dissolution, cool to 0°C to obtain a clear diamine solution. Add 4.94g of 2,5-furandicarboxylic acid chloride to the reactor at a controlled rate to maintain the temperature below 15°C. Then, quickly add 0.05kg of 1,3,5-triaminobenzene. Heat to 20-25°C and stir for 2 hours to obtain a polyamide prepolymer solution. The remaining 0.26g of 2,5-furandicarboxylic acid chloride was added to the polyamide prepolymer solution, and the temperature was raised to 60-70°C for 6 hours. During this time, 0.025kg of 2,5-furandicarboxylic acid chloride was added according to the apparent viscosity until a semi-bio-based polyamide solution with a cross-linked structure and a viscosity of 36,900 mPa·s was obtained. Then, 200kg of N,N-dimethylacetamide and 400kg of water were added to the semi-bio-based polyamide solution, and the semi-bio-based polyamide was precipitated with stirring. The semi-bio-based polyamide was then slurried, washed, filtered, and dried to obtain cross-linked semi-bio-based polyamide particles.

[0078] 81.2 kg of N,N-dimethylacetamide, 10.3 kg of ceramic particles, 5.4 kg of the semi-bio-based polyamide prepared above, and 1.8 kg of polyvinylidene fluoride were added to a stirring tank in sequence, and stirred for 2 hours to obtain a coating slurry; the coating slurry was applied to both sides of the lithium-ion battery base membrane, and after solvent extraction, water extraction, and drying at 75°C, a semi-bio-based polyamide membrane diaphragm with a cross-linked structure was prepared.

[0079] Example 7

[0080] A 100L reactor was heated to 80°C to completely dry out the moisture. Argon was then used to displace the air in the reactor for 2 hours. Following this, 46.825kg of N,N-dimethylacetamide and 5.036kg of 4,4'-diaminodiphenylmethane were added to the reactor under argon and stirred until completely dissolved. After dissolution, the temperature was lowered to 0°C to obtain a clear diamine solution. 5kg of 2,5-furandicarboxylic acid chloride was first added to the reactor, with 4.9g added at a controlled rate to maintain the temperature below 15°C. Then, 0.117kg of 3,3',5,5'-tetraaminodiphenylmethane was quickly added. The temperature was raised to 20-25°C and stirred for 2 hours to obtain a polyamide prepolymer solution. The remaining 0.1 g of 2,5-furandicarboxylic acid chloride was added to the polyamide prepolymer solution, and the temperature was raised to 60-70° C. for reaction for 6 hours. During this period, 0.029 kg of 2,5-furandicarboxylic acid chloride was added according to the apparent viscosity until a semi-bio-based polyamide solution containing a cross-linked structure with a viscosity of 50894 mPa·s was obtained. Then, 200 kg of N,N-dimethylacetamide and 400 kg of water were added to the semi-bio-based polyamide solution, and the semi-bio-based polyamide was precipitated by stirring. The semi-bio-based polyamide particles containing a cross-linked structure were obtained after beating, washing, filtering, and drying.

[0081] 81.2 kg of N,N-dimethylacetamide, 10.3 kg of ceramic particles, 5.4 kg of the semi-bio-based polyamide prepared above, and 1.8 kg of polyvinylidene fluoride were added to a stirring tank in sequence, and stirred for 2 hours to obtain a coating slurry; the coating slurry was applied to both sides of the lithium-ion battery base membrane, and after solvent extraction, water extraction, and drying at 75°C, a semi-bio-based polyamide membrane diaphragm with a cross-linked structure was prepared.

[0082] Example 8

[0083] A 100L reactor was heated to 80°C to completely dry out the moisture. Argon was then used to displace the air in the reactor for 2 hours. Following this, 46.825kg of N,N-dimethylacetamide and 5.032kg of 4,4'-diaminodiphenyl ether were added to the reactor under argon and stirred until completely dissolved. After dissolution, the temperature was lowered to 0°C to obtain a clear diamine solution. 5kg of 2,5-furandicarbonyl chloride was first added to the reactor, with 4.9g added at a controlled rate to maintain the reaction temperature below 15°C. Then, 0.117kg of 3,3',5,5'-tetraaminodiphenylmethane was quickly added. The temperature was raised to 20-25°C and stirred for 2 hours to obtain a polyamide prepolymer solution. The remaining 0.1 g of 2,5-furandicarboxylic acid chloride was added to the polyamide prepolymer solution, and the temperature was raised to 60-70° C. for reaction for 6 hours. During this period, 0.028 kg of 2,5-furandicarboxylic acid chloride was added according to the apparent viscosity until a semi-bio-based polyamide solution containing a cross-linked structure with a viscosity of mPa·s was obtained. Then, 200 kg of N,N-dimethylacetamide and 420 kg of water were added to the semi-bio-based polyamide solution, and stirred to precipitate the semi-bio-based polyamide. The semi-bio-based polyamide particles containing a cross-linked structure were obtained after beating, washing, filtering, and drying.

[0084] 81.2 kg of N,N-dimethylacetamide, 10.3 kg of ceramic particles, 5.4 kg of the semi-bio-based polyamide prepared above, and 1.8 kg of polyvinylidene fluoride were added to a stirring tank in sequence, and stirred for 2 hours to obtain a coating slurry; the coating slurry was applied to both sides of the lithium-ion battery base membrane, and after solvent extraction, water extraction, and drying at 75°C, a semi-bio-based polyamide membrane diaphragm with a cross-linked structure was prepared.

[0085] Effect verification:

[0086] The performance of the semi-biobased polyamide diaphragms containing cross-linked structures prepared in Examples 1-8 was tested according to existing testing techniques in the art. The results are shown in Table 1 below.

[0087] Table 1 Performance test data of semi-biobased polyamide membrane containing cross-linked structure

[0088] As shown in Table 1, the performance test data of the semi-bio-based polyamide membrane diaphragm prepared according to Examples 1 to 8, including air permeability, electrolyte absorption rate, tensile strength, and thermal shrinkage, fully demonstrate the excellent performance of the diaphragm material.

[0089] The above-described embodiments merely illustrate several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, and all such variations and improvements fall within the scope of protection of the present invention.

Claims

1. A semi-biobased polyamide containing a cross-linked structure, characterized in that: The semi-biobased polyamide containing a cross-linked structure has a structure of the following formula (I): In formula (I), m>1, k>1 and m:k=(20-100):1, m+k=500-2000; Ar1 is a residue of a divalent aromatic amine, Ar2 is a residue of a trivalent aromatic amine, and R is a linear polymer chain cross-linked by the trivalent aromatic amine.

2. A method for preparing the semi-biobased polyamide containing a cross-linked structure according to claim 1, characterized in that: The following steps are involved: (1) mixing a diamine monomer with a first organic solvent under an inert gas atmosphere to obtain a diamine solution; (2) taking 2,5-furandicarboxylic acid or a derivative monomer thereof, adding part of the 2,5-furandicarboxylic acid or a derivative monomer thereof to the diamine solution, reacting at a first predetermined temperature, then adding a triamine monomer, and heating to a second predetermined temperature to obtain a polyamide prepolymer solution; (3) adding another portion of the 2,5-furandicarboxylic acid or its derivative monomer into the polyamide prepolymer solution, and then heating the solution to a third predetermined temperature to obtain a semi-biobased polyamide solution containing a cross-linked structure and having a desired apparent viscosity; (4) mixing the semi-bio-based polyamide solution with a second organic solvent, and then adding water to obtain semi-bio-based polyamide, and then pulping, washing, filtering, and drying the semi-bio-based polyamide to obtain the semi-bio-based polyamide containing a cross-linked structure.

3. The method for preparing a semi-biobased polyamide containing a cross-linked structure according to claim 2, characterized in that: In step (1), the inert gas includes one or more of nitrogen, helium and argon; In step (1), the diamine monomer includes one or more of m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenyl ether, and 4,4'-diaminodiphenylmethane; In step (1), the mass ratio of the diamine monomer to the first organic solvent is 1:(5-10).

4. The method for preparing a semi-biobased polyamide containing a cross-linked structure according to claim 2, characterized in that: In step (1), after the diamine monomer is mixed with the first organic solvent, the method further comprises: heating to 60-80° C. to dissolve the diamine monomer, and then cooling to 0-10° C. to obtain the diamine solution.

5. The method for preparing a semi-biobased polyamide containing a cross-linked structure according to claim 2, characterized in that: In step (2), the derivative monomer of 2,5-furandicarboxylic acid is 2,5-furandicarboxylic acid chloride; In step (2), the triamine monomer includes one or more of 1,3,5-triaminobenzene, 1,1'-biphenyl-3,3',5,5'-tetramine and 3,3',5,5'-tetraaminodiphenylmethane.

6. The method for preparing a semi-biobased polyamide containing a cross-linked structure according to claim 2, characterized in that: In step (2), the mass ratio of the portion of 2,5-furandicarboxylic acid or a derivative monomer thereof to the 2,5-furandicarboxylic acid or a derivative monomer thereof is 95-99%; In step (2), the first predetermined temperature is no greater than 15°C; In step (2), the second predetermined temperature is 20-25°C; The molar ratio of the 2,5-furandicarboxylic acid or its derivative monomer to the diamine monomer is 1:(0.8-1); The molar ratio of the triamine monomer to the diamine monomer is (0.01-0.05):

1.

7. The method for preparing a semi-biobased polyamide containing a cross-linked structure according to claim 2, characterized in that: In step (3), the third predetermined temperature is 60-70°C; In step (3), the expected apparent viscosity is 10000-70000 mPa·s; In step (4), the mass of the semi-bio-based polyamide solution is 3-10 times the mass of the second organic solvent; the mass of the water is 8-10 times the mass of the semi-bio-based polyamide solution; The first organic solvent and the second organic solvent independently include at least one of N,N-dimethylacetamide, N-methylpyrrolidone and N,N-dimethylformamide.

8. A lithium ion battery separator, characterized in that: The raw material components of the lithium-ion battery separator include, by weight: 0.8-1.5 parts of a third organic solvent, 0.01-0.5 parts of ceramic particles, 0.01-0.5 parts of semi-biobased polyamide, and 0.01-0.2 parts of polyvinylidene fluoride; Wherein, the semi-biobased polyamide is prepared by using the semi-biobased polyamide containing a cross-linked structure as claimed in claim 1 or by using the method as described in any one of claims 2-7.

9. A method for preparing the lithium ion battery separator according to claim 8, characterized in that: The following steps are involved: (1) mixing a third organic solvent, ceramic particles, semi-bio-based polyamide and polyvinylidene fluoride to obtain a semi-bio-based coating slurry; (2) The semi-biobased coating slurry is coated on at least one side of a lithium-ion battery base membrane, and then subjected to mixed solvent extraction, water extraction, and drying to obtain the lithium-ion battery separator.

10. The method for preparing a lithium ion battery separator according to claim 9, characterized in that: In step (2), the mixed solvent includes a fourth organic solvent and water, and the volume ratio of the fourth organic solvent to the water is (0.1-2):1; The third organic solvent and the fourth organic solvent each independently include at least one of N,N-dimethylacetamide, N-methylpyrrolidone and N,N-dimethylformamide.

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