A copolyamide material, its preparation method and use

Abstract

The application provides a copolyamide material and a preparation method and application thereof. Raw materials of the copolyamide material include polyamide 66 salt and long carbon chain amide salt. In the application, the copolyamide material takes the polyamide 66 salt and the long carbon chain amide salt as raw materials, introduces the long carbon chain structure into the polyamide 66, reduces the proportion of amide groups in the copolymer, and the hygroscopicity of the copolyamide is reduced compared with that of the polyamide 66, so that the copolyamide has good dimensional stability in a humid environment. Meanwhile, the long carbon chain structure introduced into the copolyamide brings the methylene long chain with free stretching and rotation, improves the toughness and softness of the product, so that the polyamide has high impact toughness and softness at a lower temperature. Meanwhile, the copolyamide material has excellent tensile strength or is not deteriorated substantially.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a copolyamide material, its preparation method, and its application. Background Technology

[0002] Polyamide 66 (PA66) is a thermoplastic resin with high mechanical strength, hardness, and rigidity, making it suitable for use as an engineering plastic. It is widely used in mechanical components such as gears and lubricated bearings. Furthermore, polyamide 66 exhibits excellent hygroscopicity, allowing it to be used in humid environments. However, this very hygroscopicity also leads to a decrease in strength and toughness, and a decline in dimensional stability, due to moisture absorption. Therefore, improving the strength and toughness of polyamide 66 in humid environments while maintaining its dimensional stability is a significant concern.

[0003] Existing technologies often modify polyamide 66 to reduce its water absorption and improve its strength and toughness. For example, CN102226036A discloses a calcium sulfate-corn starch-polyamide 66 composite material and its preparation process; the composite material is made from the following raw materials by weight percentage: calcium sulfate 15-50wt%, corn starch 10-40wt%, polyamide 66 20-60wt%, heat stabilizer T-68 1-10wt%, antioxidant 1010 1-10wt%, and stearic acid 1-20wt%. By modifying PA66 with corn starch and calcium sulfate, its water absorption is reduced. However, the toughness of the composite material needs further improvement.

[0004] For example, CN103044913A discloses an in-situ compatibilization method for preparing ultra-tough polyamide 66 nanocomposites and its preparation method; the polyamide 66 nanocomposites include polyamide 66, ethylene propylene diene monomer (EPDM) rubber, initiator, maleic anhydride, and organomontmorillonite. The ultra-tough polyamide 66 nanocomposites exhibit excellent low-temperature impact resistance and low water absorption; however, its strength needs further improvement.

[0005] Therefore, providing a copolyamide material with excellent tensile strength, good flexural strength, good compressive strength, good toughness, and good dimensional stability, or with excellent impact toughness, good elongation at break, good dimensional stability, and no significant reduction in tensile strength, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a copolyamide material, its preparation method, and its applications. The copolyamide material uses polyamide 66 salt and long-chain amide salt as raw materials. Introducing a long-chain structure into polyamide 66 results in a product with good strength and toughness, and good dimensional stability.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a copolyamide material, wherein the raw materials of the copolyamide material include polyamide 66 salt and long-chain amide salt.

[0009] In this invention, specific raw materials are selected to introduce a long carbon chain structure into the molecular structure of polyamide 66, thereby reducing the proportion of amide groups in the copolymer, which in turn weakens the hygroscopicity of polyamide 66 and improves its dimensional stability. At the same time, the introduction of the long carbon chain structure brings a long methylene chain with free extension and rotation to the copolyamide, which improves the toughness and softness of the product, so that the polyamide has high impact toughness, softness and strength at lower temperatures and good dimensional stability.

[0010] Preferably, the mass ratio of the polyamide 66 salt to the long-chain amide salt is (0.1–9):1, for example, it can be 0.1:1, 0.15:1, 0.2:1, 0.25:1, 0.3:1, 0.35:1, 0.4:1, 0.45:1, 0.5:1, 0.55:1, 0.6:1, 0.65:1, 0.7:1, 0.75:1, 0.8:1, 0.85:1, 0.9:1, 0.95:1, 1:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1, 2:1, 2.2:1, etc. 1, 2.4:1, 2.6:1, 2.8:1, 3:1, 3.2:1, 3.4:1, 3.6:1, 3.8:1, 4:1, 4.2:1, 4.4:1, 4.6:1, 4.8:1, 5:1, 5.2:1, 5.4:1, 5.6:1, 5.8:1, 6:1, 6.2:1, 6.4:1, 6.6:1, 6.8:1, 7:1, 7.2:1, 7.4:1, 7.6:1, 7.8:1, 8:1, 8.2:1, 8.4:1, 8.6:1, 8.8:1, 9:1, etc.

[0011] In this invention, the ratio of polyamide 66 salt to long-chain amide salt is in the range of greater than 1:1 and less than or equal to 9:1, preferably (2-8):1. This ensures that the copolyamide material possesses excellent tensile strength while also exhibiting good strength and toughness, good dimensional stability, and can be used as a modified base material in fields such as electronics, automobiles, and home appliances. The mass ratio of polyamide 66 salt to long-chain amide salt is in the range of (0.1-1):1, preferably (0.2-0.8):1. This ensures that the copolyamide material possesses excellent impact toughness (including simply supported beam impact strength) and dimensional stability while also maintaining good elongation at break, and without significant deterioration in tensile strength. This can be used as a modified base material in fields such as precision mechanical parts, powder coatings, transmission gears, and sheathing layers for wires and cables.

[0012] Preferably, the raw materials for the polyamide 66 salt include adipic acid and hexamethylenediamine. In this invention, the preparation method of the polyamide 66 salt is not limited; conventional methods can be used. For example, hexamethylenediamine and adipic acid are dissolved separately in a solvent, and then the two solutions are mixed, cooled, separated, washed, and dried to obtain the polyamide 66 salt.

[0013] Alternatively, hexamethylenediamine and adipic acid can be directly mixed in water to prepare a saturated aqueous solution. After adjusting the pH of the solution, it can be cooled, separated, and dried to obtain polyamide 66 salt.

[0014] Alternatively, adipic acid can be heated to a temperature above the melting point of hexamethylenediamine but below the melting point of adipic acid, while the diamine is heated to a temperature above its melting point. Liquid hexamethylenediamine can then be added to adipic acid via spraying to directly obtain polyamide 66 salt.

[0015] Preferably, the raw materials for the long-chain amide salt include long-chain dicarboxylic acids and diamines.

[0016] Preferably, the long-chain dicarboxylic acid has ≥10 carbon atoms, for example, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, etc.

[0017] Preferably, the long-chain polyacid includes at least one of sebacic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, or pentadecanoic acid.

[0018] Preferably, the diamine includes C4 to C14 alkyl diamines, such as C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14 alkyl diamines, etc., wherein C4 to C14 alkyl diamines do not include hexamethylenediamine.

[0019] Preferably, the diamine includes at least one selected from butanediamine, pentanediamine, heptadecanediamine, octanediamine, decanedanediamine, undecanediamine, dodecanediamine, and tridecanediamine.

[0020] In this invention, pentanediamine is selected, and the resulting copolyamide material not only has good performance (including strength) but also low cost.

[0021] In this invention, the long-chain amide salt refers to the raw material being a long-chain dicarboxylic acid, that is, a dicarboxylic acid with 10 to 20 carbon atoms.

[0022] In this invention, the preparation method of the long-chain amide salt is not limited, and conventional methods can be used for preparation. For example, the method includes: sequentially adding water, diamine and long-chain dicarboxylic acid to a salt-forming tank to carry out a salt-forming reaction to obtain the long-chain amide salt.

[0023] In a second aspect, the present invention provides a method for preparing the copolyamide material according to the first aspect, the method comprising the following steps:

[0024] The copolyamide material is obtained by reacting polyamide 66 salt with a long-chain amide salt.

[0025] Preferably, the polyamide 66 salt exists in the form of a polyamide 66 salt solution.

[0026] Preferably, the pH value of the polyamide 66 salt solution is 7.10 to 7.70, for example, it can be 7.10, 7.20, 7.30, 7.40, 7.50, 7.60, 7.70, etc.; the concentration of the polyamide 66 salt solution is 50% to 65%, for example, it can be 52%, 54%, 56%, 58%, 60%, 62%, 64%, etc.

[0027] Preferably, the long-chain amide salt exists in the form of a long-chain amide salt solution.

[0028] Preferably, the pH value of the long-chain amide salt solution is 8.00 to 8.80, for example, it can be 8.10, 8.20, 8.30, 8.40, 8.50, 8.60, 8.70, 8.80, etc.; the concentration of the long-chain amide salt solution is 60% to 70%, for example, it can be 60%, 62%, 64%, 66%, 68%, 70%, etc.

[0029] Preferably, the reaction includes a pressurization stage, a holding stage, a depressurization stage, and a post-polymerization stage performed sequentially.

[0030] Preferably, the duration of the boost phase is 20 to 40 minutes, for example, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, etc.

[0031] Preferably, the pressure during the pressure holding stage is 1.4 to 1.8 MPa, for example, it can be 1.4 MPa, 1.45 MPa, 1.5 MPa, 1.55 MPa, 1.6 MPa, 1.65 MPa, 1.7 MPa, 1.75 MPa, 1.8 MPa, etc.

[0032] Preferably, the initial temperature of the pressure holding stage is 200-250℃, for example, 200℃, 205℃, 210℃, 215℃, 220℃, 225℃, 230℃, 235℃, 240℃, 245℃, 250℃, etc.; the pressure holding stage lasts for 1-3 hours, for example, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, etc.

[0033] Preferably, the pressure reduction phase lasts for 40 to 80 minutes, for example, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, 65 minutes, 70 minutes, 75 minutes, 80 minutes, etc.; the pressure is reduced to -0.002 to -0.03 MPa, for example, -0.02 MPa, -0.01 MPa, -0.005 MPa, -0.002 MPa, etc.

[0034] Preferably, the pressure in the post-polymerization stage is -0.005 to -0.02 MPa, for example, it can be -0.005 MPa, -0.01 MPa, -0.015 MPa, -0.02 MPa, etc.

[0035] Preferably, the temperature of the post-polymerization stage is 230-270°C, for example, 230°C, 235°C, 240°C, 245°C, 250°C, 255°C, 260°C, 265°C, 270°C, etc.

[0036] Preferably, the time for the post-polymerization stage is 20 to 40 minutes, for example, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, etc.

[0037] In this invention, the reaction is carried out in the presence of a protective atmosphere, which includes, but is not limited to, nitrogen.

[0038] As a preferred technical solution of the present invention, the preparation method includes:

[0039] Polyamide 66 salt solution and long-chain amide salt solution are introduced into a sealed reactor. Within 20–40 minutes, the pressure inside the reactor is increased to 1.4–1.8 MPa and the temperature is increased to 200–250 °C. The pressure is maintained for 1–3 hours. Then, the pressure is reduced to -0.002–-0.02 MPa within 40–80 minutes. Subsequently, the post-polymerization stage is entered, and the reaction is carried out for 20–40 minutes under the conditions of -0.005–-0.02 MPa and 230–270 °C to obtain the copolyamide material.

[0040] In this invention, the copolyamide resin raw material uses polyamide 66 salt solution and long-chain amide salt solution, which are formed by parallel salting and then introduced into the reactor for polymerization to obtain copolyamide. The parallel salting method is conducive to precise control of multiple salt solution raw materials and to obtaining a copolymer product with small viscosity fluctuation.

[0041] Thirdly, the present invention provides a modified base material, said modified base material comprising the copolyamide material as described in the first aspect.

[0042] Preferably, the modified base material is used in the fields of electronics, automobiles, and home appliances.

[0043] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0044] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0045] The copolyamide material provided by this invention introduces a long carbon chain structure into polyamide 66 by using polyamide 66 salt and long carbon chain amide salt as raw materials, so that polyamide 66 still has good strength and toughness and good dimensional stability in humid environments. Detailed Implementation

[0046] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention.

[0047] Example 1

[0048] This embodiment provides a copolyamide material, the raw materials of which include polyamide 66 salt and long-chain amide salt; the mass ratio of polyamide 66 salt (PA66 salt) to long-chain amide salt (PA510 salt) is 7.5:2.5; the raw materials of polyamide 66 salt include adipic acid and hexamethylenediamine; the raw materials of long-chain amide salt solution include sebacic acid and pentanediamine.

[0049] This embodiment provides a method for preparing a copolyamide material, the method comprising the following steps:

[0050] Under nitrogen protection, a PA66 salt solution was prepared by mixing hexamethylenediamine, adipic acid, and water. The pH of the PA66 salt solution was adjusted to 7.30 and the concentration to 60% by controlling the ratio of adipic acid to hexamethylenediamine. A PA510 salt solution was prepared by mixing sebacic acid, pentanediamine, and water. The pH of the PA510 salt solution was adjusted to 8.40 and the concentration to 65% by controlling the ratio of sebacic acid to pentanediamine. The PA66 and PA510 salt solutions were mixed and introduced into a reactor. The pressure inside the reactor was increased to 1.65 MPa and the material temperature was increased to 210°C within 30 minutes. After maintaining the pressure under these conditions for 1.5 hours, the material temperature was increased to 240°C. Then, the pressure was reduced to -0.013 MPa and the temperature was increased to 255°C within 60 minutes. Subsequently, the reaction continued for 30 minutes in the post-polymerization stage to obtain the copolyamide material.

[0051] Example 2

[0052] This embodiment provides a copolyamide material, the raw materials of which include polyamide 66 salt and long-chain amide salt; the mass ratio of polyamide 66 salt to long-chain amide salt (PA512 salt) is 8:2; the raw materials of polyamide 66 salt include adipic acid and hexamethylenediamine; the raw materials of long-chain amide salt include dodecanoic acid and pentanediamine.

[0053] This embodiment provides a method for preparing a copolyamide material, and the specific steps of the preparation method are the same as those in Embodiment 1.

[0054] Example 3

[0055] This embodiment provides a copolyamide material, the raw materials of which include polyamide 66 salt and long-chain amide salt; the mass ratio of polyamide 66 salt to long-chain amide salt (PA510 salt) is 8.65:1.35; the raw materials of polyamide 66 salt include adipic acid and hexamethylenediamine; the raw materials of long-chain amide salt solution include sebacic acid and pentanediamine.

[0056] This embodiment provides a method for preparing a copolyamide material, and the specific steps of the preparation method are the same as those in Embodiment 1.

[0057] Example 4

[0058] This embodiment provides a copolyamide material, the raw materials of which include polyamide 66 salt and long-chain amide salt; the mass ratio of polyamide 66 salt to long-chain amide salt is 9:1; the raw materials of polyamide 66 salt include adipic acid and hexamethylenediamine; the raw materials of long-chain amide salt include sebacic acid and pentanediamine.

[0059] This embodiment provides a method for preparing a copolyamide material, the method comprising the following steps:

[0060] Under nitrogen protection, hexamethylenediamine, adipic acid, and water were mixed to prepare a PA66 salt solution. The pH of the PA66 salt solution was adjusted to 7.20 and the concentration to 55% by controlling the ratio of adipic acid to hexamethylenediamine. Sebacic acid, pentanediamine, and water were mixed to prepare a PA510 salt solution. The pH of the PA510 salt solution was adjusted to 8.70 and the concentration to 70% by controlling the ratio of sebacic acid to pentanediamine. The PA66 and PA510 salt solutions were mixed and introduced into a reactor. Within 25 minutes, the pressure inside the reactor was increased to 1.75 MPa and the material temperature was increased to 215°C. After maintaining the pressure under these conditions for 1 hour, the material temperature was increased to 250°C. Then, the pressure was reduced to -0.03 MPa and the temperature was increased to 265°C within 45 minutes. The polymerization stage continued for 20 minutes to obtain the copolyamide material.

[0061] Example 5

[0062] This embodiment provides a copolyamide material, the raw materials of which include polyamide 66 salt and long-chain amide; the mass ratio of polyamide 66 salt to long-chain amide salt is 6:5; the raw materials of polyamide 66 salt include adipic acid and hexamethylenediamine; the raw materials of long-chain amide salt include sebacic acid and pentanediamine.

[0063] This embodiment provides a method for preparing a copolyamide material, the method comprising the following steps:

[0064] Under nitrogen protection, hexamethylenediamine, adipic acid, and water were used to prepare a PA66 salt solution. The pH of the PA66 salt solution was adjusted to 7.70 and the concentration to 65% by controlling the ratio of adipic acid to hexamethylenediamine. Sebacic acid, pentanediamine, and water were used to prepare a PA510 salt solution. The pH of the PA510 salt solution was adjusted to 8.10 and the concentration to 60% by controlling the ratio of sebacic acid to pentanediamine. The PA66 and PA510 salt solutions were mixed and introduced into a reactor. Within 35 minutes, the pressure inside the reactor was increased to 1.55 MPa and the material temperature was increased to 205°C. After maintaining the pressure for 2 hours, the material temperature was increased to 230°C. Then, the pressure was reduced to -0.005 MPa and the temperature was increased to 245°C within 75 minutes. The polymerization stage continued for 40 minutes to obtain the copolyamide material.

[0065] Example 6

[0066] This embodiment provides a copolyamide material, which differs from Example 5 only in that the total amount of PA66 salt and PA510 salt remains unchanged, the mass ratio is 5:5, and the other raw material types, amounts and preparation methods are the same as in Example 5.

[0067] Example 7

[0068] This embodiment provides a copolyamide material, which differs from Example 1 only in that the total amount of PA66 salt and PA510 salt remains unchanged, the mass ratio is 10:1, and the other raw material types, amounts and preparation methods are the same as in Example 1.

[0069] Example 8

[0070] This embodiment provides a copolyamide material, which differs from Example 1 only in that the total amount of PA66 salt and PA510 salt remains unchanged, with a mass ratio of 0.08:1. The other raw material types, amounts, and preparation methods are the same as in Example 1.

[0071] Example 9

[0072] This embodiment provides a copolyamide material, which differs from Example 1 only in that the total amount of PA66 salt and PA510 salt remains unchanged, with a mass ratio of 0.65:1. The other raw material types, amounts, and preparation methods are the same as in Example 1.

[0073] Example 10

[0074] This embodiment provides a copolyamide material, which differs from Example 1 only in that the total amount of PA66 salt and PA510 salt remains unchanged, with a mass ratio of 0.55:1. The other raw material types, amounts, and preparation methods are the same as in Example 1.

[0075] Example 11

[0076] This embodiment provides a copolyamide material, which differs from Example 1 only in that the total amount of PA66 salt and PA510 salt remains unchanged, with a mass ratio of 0.4:1. The other raw material types, amounts, and preparation methods are the same as in Example 1.

[0077] Example 12

[0078] This embodiment provides a copolyamide material, which differs from Example 1 only in that the sebacic acid is replaced with an equimolar amount of octanoic acid, while the other raw material types, amounts, and preparation methods are the same as in Example 1.

[0079] Example 13

[0080] This embodiment provides a copolyamide material, which differs from Example 1 only in that the sebacic acid is replaced with an equimolar amount of hexadecanoic acid, while the other raw material types, amounts, and preparation methods are the same as in Example 1.

[0081] Example 14

[0082] This embodiment provides a copolyamide material, which differs from Example 1 only in that the pentanediamine is replaced with an equimolar amount of hexamethylenediamine, while the other raw material types, amounts, and preparation methods are the same as in Example 1.

[0083] Comparative Example 1

[0084] This comparative example provides a copolyamide material, which differs from Example 1 only in that the types and amounts of raw materials remain unchanged, including hexamethylenediamine, adipic acid, pentanediamine, and sebacic acid; the preparation method includes: mixing hexamethylenediamine, adipic acid, pentanediamine, sebacic acid, and water, and reacting them by pressurization, pressure holding, pressure reduction, and post-polymerization to obtain the copolyamide material. Other steps and parameters are the same as in Example 1.

[0085] Comparative Example 2

[0086] This comparative example provides a copolyamide material, which differs from Example 1 only in that the types and amounts of raw materials remain unchanged, including PA66 salt, pentanediamine, and sebacic acid; the preparation method includes: mixing PA66 salt, pentanediamine, sebacic acid, and water, and reacting by pressurization, pressure holding, pressure reduction, and post-polymerization to obtain the copolyamide material, with other steps and parameters being the same as in Example 1.

[0087] Comparative Example 3

[0088] This comparative example provides a polyamide composite material, which differs from Example 1 only in that the preparation method of the polyamide composite material includes: PA66 salt and PA510 salt undergoing pressure holding, pressure reduction, and post-polymerization reaction to obtain PA66 and PA510 respectively, and then PA66 and PA510 are melt-mixed at 285°C to obtain the polyamide composite material. Other steps and parameters are the same as in Example 1.

[0089] Performance testing

[0090] (1) Relative viscosity: According to GB / T 12006.1 Plastics Polyamide Part 1: Determination of viscosity;

[0091] (2) Tensile strength: Determination of tensile properties of plastics according to GB / T 1040.1

[0092] (3) Elongation at break: According to GB / T 1040.1 Determination of tensile properties of plastics

[0093] (4) Melting point: According to GB / T 19466.3 Differential scanning calorimetry (DSC) for plastics, Part 3: Determination of melting and crystallization temperature and enthalpy;

[0094] (5) Impact strength of simply supported beams: GB / T 1043.1 Determination of impact performance of simply supported beams;

[0095] (6) Dimensional change rate: The sample was injection molded to a size of 100mm (length) × 100mm (width) × 1mm.

[0096] For a (thick) sample, at room temperature of 23℃, the injection-molded sample was placed in a brown desiccator for 24 hours and then quickly removed to measure its vertical dimension as initial data. The sample was placed in an environment of 23℃ and 100% relative humidity (immersed in deionized water) for 180 days, and the vertical dimension of the sample was quickly removed to measure as experimental data. The dimensional change rate (L) was calculated according to formula (1):

[0097] L=[(S1-S0) / S0]×100% (1)

[0098] S1 is the length of the sample in the vertical direction after it has absorbed moisture from the environment, and S0 is the initial length of the sample in the vertical direction.

[0099] The specific test results are shown in Table 1:

[0100] Table 1

[0101]

[0102] *: Indicates that two melting points exist, and the melting point of the blend cannot be determined.

[0103] As shown in the table above, the copolyamide material provided by this invention, by using polyamide 66 salt and long-chain amide salt as raw materials, introduces a long-chain structure into the molecular structure of polyamide 66 and controls the ratio of polyamide 66 salt to long-chain amide salt, thus enabling the copolyamide to possess both good strength and toughness. As shown in Examples 1-14, the tensile strength of the copolyamide material is 51.3-74.9 MPa, the elongation at break is 63.0-119.1%, and the impact strength is 5.6-9.0 kJ / m. 2 It has a melting point of 208–252℃ and a dimensional change rate of 1.08–1.56%.

[0104] In summary, the copolyamide provided in this application adopts a parallel salting method, using polyamide 66 salt and long-chain amide salt as raw materials to modify polyamide 66, and by controlling the ratio of the two, the copolyamide has good toughness and dimensional stability.

[0105] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A copolyamide material, characterized in that, The raw material for the copolyamide material is obtained by reacting polyamide 66 salt and long-chain amide salt; The mass ratio of the polyamide 66 salt to the long-chain amide salt is (0.4~9):1; The raw materials for the long-chain amide salt include long-chain dicarboxylic acids and diamines; The long-chain dicarboxylic acid has ≥10 carbon atoms; The diamine includes C4-C14 alkyl diamines, wherein the C4-C14 alkyl diamines do not include hexamethylenediamine.

2. The copolyamide material according to claim 1, characterized in that, The raw materials for the polyamide 66 salt include adipic acid and hexamethylenediamine.

3. The copolyamide material according to claim 1, characterized in that, The long-chain dicarboxylic acid includes at least one of sebacic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, or pentadecanoic acid.

4. The copolyamide material according to claim 1, characterized in that, The diamine includes at least one of butanediamine, pentanedanediamine, heptanedanediamine, octanediamine, decanedanediamine, undecanediamine, dodecanediamine, or tridecanediamine.

5. A method for preparing a copolyamide material according to any one of claims 1 to 4, characterized in that, The preparation method includes the following steps: The copolyamide material is obtained by reacting polyamide 66 salt with a long-chain amide salt.

6. The preparation method according to claim 5, characterized in that, The polyamide 66 salt exists in the form of a polyamide 66 salt solution.

7. The preparation method according to claim 6, characterized in that, The pH value of the polyamide 66 salt solution is 7.10~7.70, and the concentration of the polyamide 66 salt solution is 50~65%.

8. The preparation method according to claim 5, characterized in that, The long-chain amide salt exists in the form of a long-chain amide salt solution.

9. The preparation method according to claim 8, characterized in that, The pH value of the long-chain amide salt solution is 8.00~8.80, and the concentration of the long-chain amide salt solution is 60~70%.

10. The preparation method according to claim 5, characterized in that, The reaction includes a pressurization stage, a holding stage, a depressurization stage, and a post-polymerization stage, which proceed sequentially.

11. The preparation method according to claim 10, characterized in that, The duration of the pressure boosting phase is 20-40 minutes.

12. The preparation method according to claim 10, characterized in that, The pressure during the pressure holding stage is 1.4~1.8 MPa.

13. The preparation method according to claim 10, characterized in that, The initial temperature of the pressure holding stage is 200~250℃, and the pressure holding stage lasts for 1~3 hours.

14. The preparation method according to claim 10, characterized in that, The pressure reduction phase lasts for 40 to 80 minutes, reducing the pressure to -0.002 to -0.03 MPa.

15. The preparation method according to claim 10, characterized in that, The pressure during the post-polymerization stage is -0.005 to -0.02 MPa.

16. The preparation method according to claim 10, characterized in that, The temperature of the post-polymerization stage is 230~270℃.

17. The preparation method according to claim 10, characterized in that, The post-polymerization stage lasts for 20-40 minutes.

18. The preparation method according to claim 5, characterized in that, The preparation method includes: Polyamide 66 salt solution and long-chain amide salt solution are introduced into a closed reactor. Within 20-40 min, the pressure inside the reactor is increased to 1.4-1.8 MPa and the temperature is increased to 200-250℃. The pressure is maintained for 1-3 h. Then, the pressure is reduced to -0.002--0.03 MPa within 40-80 min, and then the post-polymerization stage is entered. The reaction is carried out at a pressure of -0.005--0.02 MPa and a temperature of 230-270℃ for 20-40 min to obtain the copolyamide material.

19. A modified base material, characterized in that, The modified base material includes the copolyamide material as described in any one of claims 1 to 4.

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