Semi-aromatic polyamide resin and synthetic method thereof

Abstract

The invention discloses semi-aromatic polyamide resin and a synthesis method thereof, and the semi-aromatic polyamide resin is synthesized from the following raw materials: decamethylene diamine, terephthalic acid, phosphamide salt, caprolactam, 2, 2 '-(1, 3-phenylene)-dioxazoline, organic carbon nanotubes, benzoic acid and a high-temperature-resistant antioxidant. The semi-aromatic polyamide resin has excellent mechanical properties, flame retardance and electromagnetic shielding performance, and can be widely applied to the field of communication devices needing flame retardance and electromagnetic shielding.

Description

Technical Field

[0001] This invention belongs to the field of materials, and in particular relates to a semi-aromatic polyamide resin and its synthesis method. Background Technology

[0002] Polyamide (PA) resins can be produced through lactam self-polymerization or diamine / diacid condensation polymerization. Based on their main chain structure, they can be classified into aliphatic PA, semi-aromatic PA, and fully aromatic PA. While the most widely used aliphatic PA6 / PA66 possesses excellent mechanical properties, wear resistance, and self-lubricating properties, its flame retardancy is poor (UL94 vertical burning rating is only V-2), and it completely lacks electromagnetic shielding functionality. With the development of SMT technology (heat resistance requirement ≥270℃) and the increasing demands for comprehensive material performance in the aerospace field, the defects of traditional PA, such as easy thermal decomposition at high temperatures (thermal weight loss initiation temperature <300℃) and the formation of molten droplets during combustion, are becoming increasingly prominent. Although fully aromatic PA has excellent heat resistance, it suffers from fundamental drawbacks such as difficult melt processing, high cost of flame retardant modification (requiring the addition of 15%-30% flame retardant), and the inability to achieve electromagnetic shielding functionality. Although semi-aromatic PA improves heat resistance by introducing benzene ring structure, its flame retardant performance (oxygen index of about 27%) is still significantly lower than the flame retardant requirements of engineering plastics, and its electromagnetic shielding effectiveness is far from meeting the protection needs of electronic devices.

[0003] Common modification methods to improve the flame retardant properties of polyamides include additive flame retardancy (such as halogen-antimony synergistic systems, phosphorus-based flame retardants, inorganic hydroxides, etc.), reactive flame retardancy (introducing flame retardant elements into the molecular chain through copolymerization), and composite flame retardant systems (such as glass fiber reinforcement + flame retardant synergy, nanocomposites, etc.). Among these, halogen-based flame retardants (such as decabromodiphenyl ethane) combined with antimony oxide can significantly improve flame retardant efficiency, but pose environmental concerns; phosphorus-based flame retardants (such as ammonium polyphosphate) can form a char layer during combustion, inhibiting flame spread; while inorganic hydroxides (such as aluminum hydroxide, magnesium hydroxide), although environmentally friendly, require high addition levels (above 50%) to be effective, often affecting the material's mechanical properties. Furthermore, introducing phosphorus- or nitrogen-containing monomers (such as bis(hydroxyethyl)methylphosphine oxide) through copolymerization can improve flame retardant durability, but the process is complex. Nanocomposite flame retardant technologies (such as carbon nanotubes, layered silicates) have attracted attention due to their combination of flame retardant reinforcement and mechanical property optimization.

[0004] Currently, some research has been conducted on copolymer flame-retardant polyamide materials in the existing technology. For example, Chinese patent CN112048061A discloses a copolymer flame-retardant polyamide and its preparation method. The preparation method is as follows: the flame retardant salt is mixed with polyamide 66 oligomer and / or polyamide 6 oligomer and then subjected to polycondensation reaction to obtain copolymer flame-retardant polyamide; the flame retardant salt is obtained by reacting N,N-bis(6-aminohexyl)phenylphosphamide and diacid HOOCR1COOH under high temperature and high pressure. Chinese patent CN104231262A discloses a preparation method of organophosphorus copolymer flame-retardant polyamide material for textiles, engineering plastics and films. The preparation method of this organophosphorus copolymer flame-retardant polyamide material specifically includes the following steps: (1) reacting the flame retardant with diamine monomers in advance to prepare a prepolymer; (2) adding the polymer monomer, catalyst and the prepolymer to the reaction vessel to obtain organophosphorus copolymer flame-retardant polyamide material. Chinese patent CN 112144141A discloses a copolymer flame-retardant polyamide fiber and its preparation method. The preparation method is as follows: flame-retardant polyamide copolymer is used as all or part of the spinning raw material to obtain copolymer flame-retardant polyamide fiber; the flame-retardant polyamide copolymer is obtained by mixing flame retardant salt with polyamide 6 oligomer and / or polyamide 66 oligomer and then carrying out a polycondensation reaction; the flame retardant salt is obtained by reacting DOPO derivative and diamine NH2R2NH2 under high temperature and high pressure; the high temperature is 200-250℃ and the high pressure is 1.2-1.8MPa; the main material of the finally obtained copolymer flame-retardant polyamide fiber is flame-retardant polyamide copolymer. Chinese patent CN 112048779A discloses a copolymer flame-retardant polyamide fiber and its preparation method. The preparation method involves spinning a flame-retardant polyamide copolymer as all or part of the spinning raw material to obtain the copolymer flame-retardant polyamide fiber. The flame-retardant polyamide copolymer is obtained by mixing a flame retardant salt with polyamide 66 oligomer and / or polyamide 6 oligomer and then carrying out a polycondensation reaction. The flame retardant salt is obtained by reacting N,N-bis(6-aminohexyl)phenylphosphamide and a diacid HOOCR1COOH under high temperature and high pressure. The high temperature is 210-220℃, and the high pressure is 1.7-1.9 MPa. The main material of the finally obtained copolymer flame-retardant polyamide fiber is the flame-retardant polyamide copolymer. Chinese patent CN 115894903A discloses a copolymer flame-retardant polyamide 66 and its preparation method. First, an aqueous solution of polyamide 66 salt is added to a high-pressure reactor for pre-concentration. Then, the flame retardant salt is slowly added to the reaction system via a post-feeding method. After the polycondensation reaction is completed, the material is discharged, cooled, and granulated to obtain copolymerized flame retardant polyamide 66. The flame retardant salt is prepared by the salt formation reaction of DOPO, itaconic acid, and barium hydroxide Ba(OH)2.Chinese patent CN 105131280A discloses a halogen-free flame-retardant copolymer polyamide 66 resin and its preparation method. The key feature is the use of an organophosphorus ammonium salt, prepared from a phosphonic diacid and a commonly used diamine, as the flame-retardant component, which is then copolymerized with the polyamide salt to prepare the halogen-free copolymer flame-retardant polyamide 66 resin. Chinese patent CN 116789959A discloses a flame-retardant polyamide and its preparation method, relating to the field of polyamide technology. This method addresses the problem of a wide molecular weight distribution in the production of high-viscosity flame-retardant polyamides in existing technologies. The preparation method includes: forming polyamide prepolymer particles with a particle size of 20 μm to 800 μm from a polyamide prepolymer; and subjecting the polyamide prepolymer particles to solid-state thickening polymerization to obtain the flame-retardant polyamide. It can be seen that the existing technologies for copolymerizing flame-retardant polyamides mainly exhibit the following characteristics: (1) The preparation process generally adopts the route of condensation copolymerization of flame retardant salts and polyamide oligomers (such as PA6 / PA66), in which the flame retardant salts are mostly prepared by reacting diamines / diacids with phosphorus compounds (such as DOPO derivatives, N,N-bis(6-aminohexyl)phenylphosphamide, etc.) under high temperature and high pressure (200-250℃ / 1.2-1.9MPa); (2) The technical solutions can be divided into prepolymer method (such as CN104231262A, which first prepares flame retardant prepolymers) and direct copolymerization method ( For example, CN112048061A directly mixes flame retardant salt with oligomers for polycondensation; (3) The application fields cover engineering plastics (CN105131280A), fibers (CN112144141A) and films, among which the fiber preparation mostly uses flame retardant copolymers as spinning raw materials; (4) The innovation points are concentrated in flame retardant structure design (such as CN115894903A using DOPO-barium itaconic acid salt), process optimization (such as CN116789959A solving the molecular weight distribution problem through solid phase thickening) and halogen-free (CN105131280A) etc. Summary of the Invention

[0005] Based on this, one of the objectives of this invention is to obtain a phosphorus-containing amide salt by reacting 2-carboxyethylphenyl hypophosphoric acid with decanediamine, and then disperse organic carbon nanotubes in a semi-aromatic polyamide resin by in-situ polymerization. This semi-aromatic polyamide resin has excellent mechanical properties, flame retardant properties and electromagnetic shielding properties, and can be widely used in the field of communication devices that require flame retardancy and electromagnetic shielding.

[0006] The specific technical solution to achieve the above-mentioned objectives is as follows:

[0007] A semi-aromatic polyamide resin, which is prepared from the following raw materials in parts by weight:

[0008] 172 portions of decanediamine,

[0009] 166 parts of terephthalic acid

[0010] Contains 40-80 parts of phosphoramide salt,

[0011] 12-24 parts of caprolactam

[0012] 4-8 parts of 2,2'-(1,3-phenylene)-dioxazoline

[0013] 22–42 parts of organic carbon nanotubes,

[0014] 2-4 parts benzoic acid

[0015] 1.3–2.7 parts of high-temperature resistant antioxidant;

[0016] The phosphoramide salt is obtained by salt formation reaction of 2-carboxyethylphenyl hypophosphoric acid and decanediamine; the organic carbon nanotubes are obtained by organic modification of carbon nanotubes with γ-aminopropyltriethoxysilane; the high-temperature resistant antioxidant is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-phenylenediamide.

[0017] In some embodiments, the semi-aromatic polyamide resin is prepared from the following raw materials in parts by weight:

[0018] 172 portions of decanediamine,

[0019] 166 parts of terephthalic acid

[0020] Contains 45-75 parts of phosphoramide salt.

[0021] 14-22 parts of caprolactam

[0022] 4.5–7.5 parts of 2,2'-(1,3-phenylene)-dioxazoline

[0023] 25–39 parts of organic carbon nanotubes,

[0024] Benzoic acid 2.3–3.7 parts,

[0025] 1.5 to 2.5 parts of high-temperature resistant antioxidant.

[0026] In some embodiments, the semi-aromatic polyamide resin is prepared from the following raw materials in parts by weight:

[0027] 172 portions of decanediamine,

[0028] 166 parts of terephthalic acid

[0029] Contains 50-70 parts of phosphoramide salt,

[0030] 16-20 parts of caprolactam

[0031] 5.5–6.5 parts of 2,2'-(1,3-phenylene)-dioxazoline

[0032] 28–36 parts of organic carbon nanotubes,

[0033] Benzoic acid 2.6–3.4 parts,

[0034] 1.7 to 2.3 parts of high-temperature resistant antioxidant.

[0035] In some embodiments, the preparation method of the phosphoramide salt includes the following steps: 214.16 g of 2-carboxyethylphenyl hypophosphite and 172.31 g of decanediamine are added to a stirred polymerization reactor, followed by the addition of 150 mL to 200 mL of deionized water. The reactor is then evacuated for 2 to 6 minutes, and nitrogen is purged for 2 to 6 minutes. This cycle is repeated 3 to 5 times, controlling the system pressure inside the stirred polymerization reactor to 0.1 MPa to 0.3 MPa. The stirred polymerization reactor is then heated to 85°C to 95°C in a sealed environment for 0.5 to 1.5 hours, with the stirring speed controlled at 50 r / min to 100 r / min. After the salt-forming reaction is completed for 1 to 2 hours, the pressure inside the reactor is reduced to 0.1 MPa, the material is discharged, and vacuum dried for later use.

[0036] In some embodiments, the method for preparing the organic carbon nanotubes includes the following steps: adding 100 g of carbon nanotubes and 2 g to 3 g of γ-aminopropyltriethoxysilane to a high-speed stirrer and stirring at room temperature for 7 min to 11 min to obtain organic carbon nanotubes.

[0037] In some embodiments, the average diameter of the carbon nanotubes in the organic carbon nanotubes is 8 nm to 10 nm, and their structure is array-type.

[0038] Another object of the present invention is to provide a method for preparing the above-mentioned semi-aromatic polyamide resin.

[0039] The specific technical solution to achieve the above-mentioned objectives is as follows:

[0040] A method for preparing a semi-aromatic polyamide resin includes the following steps:

[0041] (1) Vacuum-dried decanediamine and terephthalic acid are added to a stirred polymerization reactor, along with phosphoramide salt, caprolactam, 2,2'-(1,3-phenylene)-dioxazoline, organic carbon nanotubes, benzoic acid, high-temperature antioxidant and appropriate amount of water. Then, the reactor is evacuated for 2 min to 6 min and purged with nitrogen for 2 min to 6 min. This cycle is repeated 3 to 5 times, and the system pressure in the stirred polymerization reactor is controlled to be 0.1 MPa to 0.3 MPa.

[0042] (2) Adjust the stirring speed of the stirred polymerization reactor to 20 r / min to 40 r / min, and heat the stirred polymerization reactor to 274℃ to 278℃ in a closed and uniform manner for 2 to 4 hours. When the temperature of the stirred polymerization reactor reaches 209℃, release the gas to 1.8 MPa and maintain the pressure at 1.8 MPa. After reacting for 1 to 2 hours (prepolymerization reaction), release the gas to atmospheric pressure and raise the temperature to 310℃ to 316℃. Continue to react for 1 to 2 hours (postpolymerization reaction). Maintain constant temperature and vacuum for 15 min to 45 min (viscosification reaction). When the reaction is completed, add nitrogen gas when discharging to obtain the product.

[0043] In some embodiments, the method for preparing the semi-aromatic polyamide resin includes the following steps:

[0044] (1) Vacuum-dried decanediamine and terephthalic acid are added to a stirred polymerization reactor, along with phosphoramide salt, caprolactam, 2,2'-(1,3-phenylene)-dioxazoline, organic carbon nanotubes, benzoic acid, high-temperature antioxidant and appropriate amount of water. Then, the reactor is evacuated for 3 min to 5 min and purged with nitrogen for 3 min to 5 min. This cycle is repeated 3 to 5 times, and the system pressure in the stirred polymerization reactor is controlled to be 0.15 MPa to 0.25 MPa.

[0045] (2) Adjust the stirring speed of the stirred polymerization reactor to 25 r / min to 35 r / min, and heat the stirred polymerization reactor to 275℃ to 277℃ in a closed and uniform manner for 2.5 hours to 3.5 hours. When the temperature of the stirred polymerization reactor reaches 209℃, release the gas to 1.8 MPa and maintain the pressure at 1.8 MPa. After reacting for 1.2 hours to 1.8 hours (prepolymerization reaction), release the gas to atmospheric pressure and simultaneously raise the temperature to 312℃ to 314℃. Continue to react for 1.2 hours to 1.8 hours (postpolymerization reaction). Maintain constant temperature and continuously evacuate for 20 min to 40 min (viscosification reaction). When the reaction is completed, add nitrogen gas when discharging to obtain the final product.

[0046] The functions of each raw material in the semi-aromatic polyamide resin of the present invention are as follows:

[0047] This invention lowers the melting point of semi-aromatic polyamide resin (PA10T) by adding caprolactam as a comonomer. The mechanism is mainly reflected in the following aspects: (1) The ε-caprolactam structure formed after caprolactam ring opening is inserted into the PA10T main chain as an aliphatic segment. Its flexible characteristics form steric hindrance with the rigid terephthalic acid unit of PA10T, which destroys the regular arrangement of the molecular chain and thus inhibits the crystallization ability. (2) The amide bond density introduced by caprolactam is lower than that of PA10T (the benzene ring shortens the effective chain length), and the aliphatic segment spacing increases, resulting in a reduction of hydrogen bond interaction points and a weakening of intermolecular forces. This effect further reduces the crystallinity of the material and widens the processing window.

[0048] This invention employs a compound of phosphoramide salts (polymerized and inserted into the PA10T main chain) and organic carbon nanotubes to significantly enhance the flame retardant properties of semi-aromatic polyamide resins through multiple synergistic mechanisms. The mechanisms are as follows: Upon heating, carbon nanotubes form a dense nano-network structure, delaying heat and oxygen diffusion. Simultaneously, their interwoven network and the char layer catalyzed by the phosphoramide structural units synergistically enhance the strength and density of the char layer. The adsorption of free radicals at the active sites on the carbon nanotube surface terminates the chain reaction, and the inert gas generated by the decomposition of the phosphoramide structural units dilutes the concentration of combustibles. Furthermore, the compound system optimizes the polymer's thermal degradation pathway, promoting stable char formation and reducing combustible release, thereby achieving highly efficient flame retardancy. Simultaneously, the organic carbon nanotubes significantly enhance the electromagnetic shielding performance of semi-aromatic polyamide resins through multi-dimensional synergistic mechanisms. Surface modifications (such as amylation) optimize dispersibility, constructing a continuous conductive network in the matrix. Electromagnetic wave reflection loss is achieved through free electron migration, and polarization relaxation induced by tube wall defects and functional groups enhances absorption loss. The stable matrix of semi-aromatic polyamide maintains network integrity, while interfacial hydrogen bonding reduces signal transmission, ultimately achieving efficient electromagnetic shielding through the synergistic effect of "conductivity-dissipation-interface".

[0049] This invention utilizes 2,2'-(1,3-phenylene)-dioxazoline to improve the compatibility between organic carbon nanotubes and semi-aromatic polyamide resins. Specifically, the oxazoline group of 2,2'-(1,3-phenylene)-dioxazoline can react with the terminal amino groups of both the organic carbon nanotubes and the semi-aromatic polyamide resins, thereby enhancing the compatibility and interfacial adhesion between them.

[0050] As a monofunctional compound, benzoic acid undergoes a condensation reaction between its terminal carboxyl group and the terminal amino group of semi-aromatic polyamides during melt polymerization. Since the benzoic acid molecule loses its ability to further participate in chain growth after the reaction, it can be used as a molecular weight regulator to effectively control the molecular weight (i.e., intrinsic viscosity) of the polymer.

[0051] The high-temperature resistant antioxidant N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-phenylenediamide exhibits excellent thermal stability under high-temperature conditions, which stems from the steric hindrance effect of the four methyl groups on the piperidine ring. This steric hindrance structure effectively captures free radicals, thereby delaying material aging. Furthermore, during the synthesis of semi-aromatic polyamide resins, the amide groups of N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-phenylenediamide can react with the end groups of the semi-aromatic polyamide resin, effectively improving its compatibility with the copolymer. Simultaneously, it acts as an end-capping agent to control the molecular weight of the semi-aromatic polyamide resin and can be permanently bonded to the polymer backbone through chemical bonding. This not only endows the material with excellent antioxidant properties but also significantly enhances the dyeing properties of the copolymer.

[0052] Compared with the prior art, the semi-aromatic polyamide resin and its synthesis method provided by the present invention have the following beneficial effects:

[0053] 1. To address the shortcomings of semi-aromatic polyamide resins, such as a narrow processing temperature range, poor flame retardancy, and lack of electromagnetic shielding, this invention designs a new resin molecular structure. By adding caprolactam to lower the melting point of the copolymer, and by compounding with phosphoramide salts and organic carbon nanotubes, the flame retardancy of the semi-aromatic polyamide resin is synergistically improved. Furthermore, the electromagnetic shielding performance of the semi-aromatic polyamide is enhanced by organic carbon nanotubes. This results in a semi-aromatic polyamide resin with excellent mechanical properties, flame retardancy, and electromagnetic shielding properties, which can be widely used in communication devices requiring flame retardancy and electromagnetic shielding.

[0054] 2. This invention achieves multiple synergistic performance enhancements in semi-aromatic polyamide resin by combining phosphoramide-containing salts and organic carbon nanotubes: In terms of flame retardancy, carbon nanotubes form a nano-network structure upon heating, delaying heat diffusion and synergistically enhancing the char layer strength with the char layer catalyzed by phosphoramide; carbon nanotubes adsorb free radicals to terminate chain reactions, while phosphoramide decomposes inert gases to dilute the concentration of combustibles, and simultaneously optimizes the degradation pathway to reduce combustible release, significantly improving flame retardant efficiency. In terms of electromagnetic shielding performance, the surface modification of organic carbon nanotubes optimizes dispersibility, constructing a continuous conductive network to achieve reflection loss through free electron migration; tube wall defects and functional groups induce polarization relaxation to enhance absorption loss, while the semi-aromatic polyamide matrix maintains network integrity, and interfacial hydrogen bonds reduce signal transmission, ultimately achieving highly efficient electromagnetic shielding through a synergistic "conductivity-dissipation-interface" mechanism.

[0055] 3. This invention provides a highly efficient preparation method for semi-aromatic polyamide resin, whose innovative process design significantly improves reaction efficiency and product quality. The specific implementation steps include: firstly, nitrogen gas is introduced to replace oxygen in the system before the reaction to effectively suppress side reactions; then, an appropriate amount of water is injected, and the steam pressure generated during heating is used to optimize the mass and heat transfer conditions in the reactor. Vacuum treatment is used during the reaction stage to remove low-molecular-weight byproducts generated during polymerization in a timely manner, thereby promoting the forward shift of the reaction equilibrium. The advantages of this process are: (1) low-molecular-weight substances can be separated without the need for additional extraction equipment, which shortens the process flow and reduces energy consumption; (2) the melt polycondensation process is used throughout, avoiding the use of organic solvents and fundamentally eliminating the solvent recovery link; (3) residual trace low-molecular-weight substances have no negative impact on material performance, ensuring the stability of product quality. This simple and environmentally friendly preparation method achieves a dual improvement in production efficiency and product performance. Attached Figure Description

[0056] Figure 1 This is a flow chart of the preparation process of the semi-aromatic polyamide resin of the present invention. Detailed Implementation

[0057] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0058] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used in this invention includes any and all combinations of one or more of the associated listed items.

[0059] The reaction mechanism of the semi-aromatic polyamide resin of this invention is as follows (see the preparation process flow chart). Figure 1 ):

[0060]

[0061] Where a = 30~80, b = 1~10, c = 1~10, d = 1~3.

[0062] Reaction mechanism

[0063] As can be seen from the above reaction formula, the terminal carboxyl group of 2-carboxyethylphenyl hypophosphite reacts with the terminal amino group of decanediamine to obtain a phosphorus-containing amide salt. Then, the phosphorus-containing amide salt, terephthalic acid, decanediamine, caprolactam, and 2,2'-(1,3-phenylene)-dioxazoline react to obtain a semi-aromatic polyamide resin.

[0064] The raw materials used in the embodiments of the present invention are as follows:

[0065] Sebacdiamine was selected from Wuxi Yinda Nylon Co., Ltd.

[0066] Terephthalic acid, selected from Beijing Yanshan Petrochemical Company.

[0067] Contains phosphoramide salts, self-made; the 2-carboxyethylphenyl hypophosphite in the raw materials is selected from Zhejiang Jiaxing Alpha Fine Chemical Co., Ltd.

[0068] Caprolactam, selected from Zhejiang Baling Hengyi Caprolactam Co., Ltd.

[0069] 2,2'-(1,3-phenylene)-dioxazoline was selected from Hubei Jiufenglong Chemical Co., Ltd.

[0070] Organic carbon nanotubes, self-made, with an average diameter of 9 nm and an array structure, were selected from LG Chem (China) Investment Co., Ltd.; γ-aminopropyltriethoxysilane was selected from Nanjing Youpu Chemical Co., Ltd.

[0071] Benzoic acid was selected from Sinopharm Chemical Reagent Co., Ltd.

[0072] N,N'-Bis(2,2,6,6-Tetramethyl-4-piperidinyl)-1,3-phenylenediamide, selected from Clariant Chemicals (China) Co., Ltd.

[0073] The phosphoramide salts used in the following examples were prepared using the following steps: 214.16 g of 2-carboxyethylphenylphosphonic acid and 172.31 g of decanediamine were added to a stirred polymerization reactor, followed by the addition of 175 mL of deionized water. The reactor was evacuated for 4 min, then purged with nitrogen for 4 min, and this cycle was repeated 4 times, maintaining the system pressure in the stirred polymerization reactor at 0.2 MPa. The stirred polymerization reactor was then heated to 90°C in a sealed environment for 1 hour, with the stirring speed controlled at 75 r / min. After the salt formation reaction was completed, the pressure inside the reactor was reduced to 0.1 MPa, the product was discharged, and vacuum dried for later use.

[0074] The organic carbon nanotubes used in the following examples are prepared by the following steps: 100 g of carbon nanotubes and 2.5 g of γ-aminopropyltriethoxysilane are added to a high-speed stirrer and stirred at room temperature for 9 min to obtain organic carbon nanotubes.

[0075] The present invention will be described in detail below with reference to specific embodiments.

[0076] Example 1 Semi-aromatic polyamide resin and its synthesis method

[0077] The semi-aromatic polyamide resin of this embodiment is prepared from the following raw materials in parts by weight:

[0078] 172 portions of decanediamine,

[0079] 166 parts of terephthalic acid

[0080] Contains 40 parts of phosphoramide salt,

[0081] 12 parts caprolactam

[0082] 4 parts of 2,2'-(1,3-phenylene)-dioxazoline

[0083] 22 portions of organic carbon nanotubes,

[0084] 2 parts benzoic acid

[0085] 1.3 parts of high-temperature resistant antioxidant.

[0086] The high-temperature resistant antioxidant is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-phenylenediamide.

[0087] The preparation method of the above-mentioned semi-aromatic polyamide resin includes the following steps:

[0088] (1) Vacuum-dried decanediamine and terephthalic acid were added to a stirred polymerization reactor, along with phosphoramide salt, caprolactam, 2,2'-(1,3-phenylene)-dioxazoline, organic carbon nanotubes, benzoic acid, high-temperature antioxidant and 200 mL of water. The reactor was then evacuated for 2 min and purged with nitrogen for 2 min. This process was repeated 5 times, and the system pressure in the stirred polymerization reactor was controlled to be 0.1 MPa.

[0089] (2) Adjust the stirring speed of the stirred polymerization reactor to 20 r / min, and heat the stirred polymerization reactor to 274°C in a closed and uniform manner within 2 hours. When the temperature of the stirred polymerization reactor reaches 209°C, release the gas to 1.8 MPa and maintain the pressure at 1.8 MPa. After reacting for 1 hour (prepolymerization reaction), release the gas to atmospheric pressure and raise the temperature to 310°C. Continue to react for 1 hour (postpolymerization reaction), and maintain the constant temperature and vacuum for 45 min (viscosification reaction). When the reaction is completed, add nitrogen gas when discharging to obtain the product.

[0090] Example 2 Semi-aromatic polyamide resin and its synthesis method

[0091] The semi-aromatic polyamide resin of this embodiment is prepared from the following raw materials in parts by weight:

[0092] 172 portions of decanediamine,

[0093] 166 parts of terephthalic acid

[0094] Contains 45 parts of phosphoramide salt,

[0095] 14 parts of caprolactam

[0096] 4.5 parts of 2,2'-(1,3-phenylene)-dioxazoline

[0097] 25 parts of organic carbon nanotubes,

[0098] Benzoic acid 2.3 parts,

[0099] 1.5 parts of high-temperature resistant antioxidant.

[0100] The high-temperature resistant antioxidant is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-phenylenediamide.

[0101] The preparation method of the above-mentioned semi-aromatic polyamide resin includes the following steps:

[0102] (1) Vacuum-dried decanediamine and terephthalic acid were added to a stirred polymerization reactor, along with phosphoramide salt, caprolactam, 2,2'-(1,3-phenylene)-dioxazoline, organic carbon nanotubes, benzoic acid, high-temperature antioxidant and 200 mL of water. The reactor was then evacuated for 6 min and purged with nitrogen for 6 min. This cycle was repeated 3 times, and the system pressure in the stirred polymerization reactor was controlled to be 0.3 MPa.

[0103] (2) Adjust the stirring speed of the stirred polymerization reactor to 40 r / min, and heat the stirred polymerization reactor to 278°C in a closed and uniform manner within 4 hours. When the temperature of the stirred polymerization reactor reaches 209°C, release the gas to 1.8 MPa and maintain the pressure at 1.8 MPa. After reacting for 2 hours (prepolymerization reaction), release the gas to atmospheric pressure and raise the temperature to 316°C. Continue to react for 2 hours (postpolymerization reaction), and maintain the temperature under vacuum for 15 minutes (viscosification reaction). When the reaction is completed, add nitrogen gas when discharging to obtain the final product.

[0104] Example 3 Semi-aromatic polyamide resin and its synthesis method

[0105] The semi-aromatic polyamide resin of this embodiment is prepared from the following raw materials in parts by weight:

[0106] 172 portions of decanediamine,

[0107] 166 parts of terephthalic acid

[0108] Contains 50 parts of phosphoramide salt,

[0109] 16 parts of caprolactam

[0110] 5.5 parts of 2,2'-(1,3-phenylene)-dioxazoline

[0111] 28 portions of organic carbon nanotubes,

[0112] Benzoic acid 2.6 parts,

[0113] 1.7 parts of high-temperature resistant antioxidant.

[0114] The high-temperature resistant antioxidant is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-phenylenediamide.

[0115] The preparation method of the above-mentioned semi-aromatic polyamide resin includes the following steps:

[0116] (1) Vacuum-dried decanediamine and terephthalic acid were added to a stirred polymerization reactor, along with phosphoramide salt, caprolactam, 2,2'-(1,3-phenylene)-dioxazoline, organic carbon nanotubes, benzoic acid, high-temperature antioxidant and 200 mL of water. The reactor was then evacuated for 3 min and purged with nitrogen for 3 min. This cycle was repeated 5 times, and the system pressure in the stirred polymerization reactor was controlled to be 0.15 MPa.

[0117] (2) Adjust the stirring speed of the stirred polymerization reactor to 25 r / min, and heat the stirred polymerization reactor to 275°C in a closed and uniform manner within 2.5 hours. When the temperature of the stirred polymerization reactor reaches 209°C, release the gas to 1.8 MPa and maintain the pressure at 1.8 MPa. After reacting for 1.2 hours (prepolymerization reaction), release the gas to atmospheric pressure and simultaneously raise the temperature to 312°C. Continue to react for 1.2 hours (postpolymerization reaction), and maintain the constant temperature and vacuum for 40 minutes (viscosification reaction). When the reaction is completed, add nitrogen gas when discharging to obtain the final product.

[0118] Example 4 Semi-aromatic polyamide resin and its synthesis method

[0119] The semi-aromatic polyamide resin of this embodiment is prepared from the following raw materials in parts by weight:

[0120] 172 portions of decanediamine,

[0121] 166 parts of terephthalic acid

[0122] Contains 60 parts of phosphoramide salt,

[0123] 18 parts of caprolactam

[0124] 6 parts of 2,2'-(1,3-phenylene)-dioxazoline

[0125] 32 portions of organic carbon nanotubes,

[0126] Benzoic acid 3 parts,

[0127] Two parts of high-temperature resistant antioxidant.

[0128] The high-temperature resistant antioxidant is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-phenylenediamide.

[0129] The preparation method of the above-mentioned semi-aromatic polyamide resin includes the following steps:

[0130] (1) Vacuum-dried decanediamine and terephthalic acid were added to a stirred polymerization reactor, along with phosphoramide salt, caprolactam, 2,2'-(1,3-phenylene)-dioxazoline, organic carbon nanotubes, benzoic acid, high-temperature antioxidant and 200 mL of water. The reactor was then evacuated for 5 min and purged with nitrogen for 5 min. This cycle was repeated 3 times, and the system pressure in the stirred polymerization reactor was controlled to be 0.25 MPa.

[0131] (2) Adjust the stirring speed of the stirred polymerization reactor to 35 r / min, and heat the stirred polymerization reactor to 277°C in a closed and uniform manner within 3.5 hours. When the temperature of the stirred polymerization reactor reaches 209°C, release the gas to 1.8 MPa and maintain the pressure at 1.8 MPa. After reacting for 1.8 hours (prepolymerization reaction), release the gas to atmospheric pressure and simultaneously raise the temperature to 314°C. Continue to react for 1.8 hours (postpolymerization reaction), and maintain the constant temperature and vacuum for 20 minutes (viscosification reaction). When the reaction is completed, add nitrogen gas when discharging to obtain the final product.

[0132] Example 5 Semi-aromatic polyamide resin and its synthesis method

[0133] The semi-aromatic polyamide resin of this embodiment is prepared from the following raw materials in parts by weight:

[0134] 172 portions of decanediamine,

[0135] 166 parts of terephthalic acid

[0136] Contains 70 parts of phosphoramide salt,

[0137] 20 parts caprolactam

[0138] 6.5 parts of 2,2'-(1,3-phenylene)-dioxazoline

[0139] 36 portions of organicated carbon nanotubes,

[0140] Benzoic acid 3.4 parts,

[0141] 2.3 parts of high-temperature resistant antioxidant.

[0142] The high-temperature resistant antioxidant is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-phenylenediamide.

[0143] The preparation method of the above-mentioned semi-aromatic polyamide resin includes the following steps:

[0144] (1) Vacuum-dried decanediamine and terephthalic acid were added to a stirred polymerization reactor, along with phosphoramide salt, caprolactam, 2,2'-(1,3-phenylene)-dioxazoline, organic carbon nanotubes, benzoic acid, high-temperature antioxidant and 200 mL of water. The reactor was then evacuated for 4 min and purged with nitrogen for 4 min. This cycle was repeated 4 times to control the system pressure in the stirred polymerization reactor to be 0.2 MPa.

[0145] (2) Adjust the stirring speed of the stirred polymerization reactor to 30 r / min, and heat the stirred polymerization reactor to 276°C in a sealed and uniform manner within 3 hours. When the temperature of the stirred polymerization reactor reaches 209°C, release the gas to 1.8 MPa and maintain the pressure at 1.8 MPa. After reacting for 1.5 hours (prepolymerization reaction), release the gas to atmospheric pressure and simultaneously raise the temperature to 313°C. Continue to react for 1.5 hours (postpolymerization reaction), and maintain the constant temperature and vacuum for 30 minutes (viscosification reaction). When the reaction is completed, add nitrogen gas when discharging to obtain the final product.

[0146] Example 6 Semi-aromatic polyamide resin and its synthesis method

[0147] The semi-aromatic polyamide resin of this embodiment is prepared from the following raw materials in parts by weight:

[0148] 172 portions of decanediamine,

[0149] 166 parts of terephthalic acid

[0150] Contains 75 parts of phosphoramide salt,

[0151] 22 parts of caprolactam

[0152] 7.5 parts of 2,2'-(1,3-phenylene)-dioxazoline

[0153] 39 portions of organic carbon nanotubes,

[0154] Benzoic acid 3.7 parts,

[0155] 2.5 parts of high-temperature resistant antioxidant.

[0156] The high-temperature resistant antioxidant is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-phenylenediamide.

[0157] The preparation method of the above-mentioned semi-aromatic polyamide resin includes the following steps:

[0158] (1) Vacuum-dried decanediamine and terephthalic acid were added to a stirred polymerization reactor, along with phosphoramide salt, caprolactam, 2,2'-(1,3-phenylene)-dioxazoline, organic carbon nanotubes, benzoic acid, high-temperature antioxidant and 200 mL of water. The reactor was then evacuated for 4 min and purged with nitrogen for 4 min. This cycle was repeated 4 times to control the system pressure in the stirred polymerization reactor to be 0.2 MPa.

[0159] (2) Adjust the stirring speed of the stirred polymerization reactor to 30 r / min, and heat the stirred polymerization reactor to 276°C in a sealed and uniform manner within 3 hours. When the temperature of the stirred polymerization reactor reaches 209°C, release the gas to 1.8 MPa and maintain the pressure at 1.8 MPa. After reacting for 1.5 hours (prepolymerization reaction), release the gas to atmospheric pressure and simultaneously raise the temperature to 313°C. Continue to react for 1.5 hours (postpolymerization reaction), and maintain the constant temperature and vacuum for 30 minutes (viscosification reaction). When the reaction is completed, add nitrogen gas when discharging to obtain the final product.

[0160] Example 7 Semi-aromatic polyamide resin and its synthesis method

[0161] The semi-aromatic polyamide resin of this embodiment is prepared from the following raw materials in parts by weight:

[0162] 172 portions of decanediamine,

[0163] 166 parts of terephthalic acid

[0164] Contains 80 parts of phosphoramide salt,

[0165] 24 parts of caprolactam

[0166] 8 parts of 2,2'-(1,3-phenylene)-dioxazoline

[0167] 42 portions of organic carbon nanotubes,

[0168] 4 parts benzoic acid

[0169] 2.7 parts of high-temperature resistant antioxidant.

[0170] The high-temperature resistant antioxidant is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-phenylenediamide.

[0171] The preparation method of the above-mentioned semi-aromatic polyamide resin includes the following steps:

[0172] (1) Vacuum-dried decanediamine and terephthalic acid were added to a stirred polymerization reactor, along with phosphoramide salt, caprolactam, 2,2'-(1,3-phenylene)-dioxazoline, organic carbon nanotubes, benzoic acid, high-temperature antioxidant and 200 mL of water. The reactor was then evacuated for 4 min and purged with nitrogen for 4 min. This cycle was repeated 4 times to control the system pressure in the stirred polymerization reactor to be 0.2 MPa.

[0173] (2) Adjust the stirring speed of the stirred polymerization reactor to 30 r / min, and heat the stirred polymerization reactor to 276°C in a sealed and uniform manner within 3 hours. When the temperature of the stirred polymerization reactor reaches 209°C, release the gas to 1.8 MPa and maintain the pressure at 1.8 MPa. After reacting for 1.5 hours (prepolymerization reaction), release the gas to atmospheric pressure and simultaneously raise the temperature to 313°C. Continue to react for 1.5 hours (postpolymerization reaction), and maintain the constant temperature and vacuum for 30 minutes (viscosification reaction). When the reaction is completed, add nitrogen gas when discharging to obtain the final product.

[0174] Comparative Example 1

[0175] The semi-aromatic polyamide resin of this comparative example is prepared from the following raw materials in parts by weight:

[0176] 172 portions of decanediamine,

[0177] 166 parts of terephthalic acid

[0178] 24 parts of caprolactam

[0179] 8 parts of 2,2'-(1,3-phenylene)-dioxazoline

[0180] 42 portions of organic carbon nanotubes,

[0181] 4 parts benzoic acid

[0182] 2.7 parts of high-temperature resistant antioxidant.

[0183] The high-temperature resistant antioxidant is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-phenylenediamide.

[0184] The preparation method of the above-mentioned semi-aromatic polyamide resin includes the following steps:

[0185] (1) Vacuum-dried decanediamine and terephthalic acid were added to a stirred polymerization reactor, along with caprolactam, 2,2'-(1,3-phenylene)-dioxazoline, organic carbon nanotubes, benzoic acid, high-temperature antioxidant and 200 mL of water. The reactor was then evacuated for 4 min and purged with nitrogen for 4 min. This cycle was repeated 4 times to control the system pressure in the stirred polymerization reactor to 0.2 MPa.

[0186] (2) Adjust the stirring speed of the stirred polymerization reactor to 30 r / min, and heat the stirred polymerization reactor to 276°C in a sealed and uniform manner within 3 hours. When the temperature of the stirred polymerization reactor reaches 209°C, release the gas to 1.8 MPa and maintain the pressure at 1.8 MPa. After reacting for 1.5 hours (prepolymerization reaction), release the gas to atmospheric pressure and simultaneously raise the temperature to 313°C. Continue to react for 1.5 hours (postpolymerization reaction), and maintain the constant temperature and vacuum for 30 minutes (viscosification reaction). When the reaction is completed, add nitrogen gas when discharging to obtain the final product.

[0187] Comparative Example 2

[0188] The semi-aromatic polyamide resin of this comparative example is prepared from the following raw materials in parts by weight:

[0189] 172 portions of decanediamine,

[0190] 166 parts of terephthalic acid

[0191] Contains 80 parts of phosphoramide salt,

[0192] 8 parts of 2,2'-(1,3-phenylene)-dioxazoline

[0193] 42 portions of organic carbon nanotubes,

[0194] 4 parts benzoic acid

[0195] 2.7 parts of high-temperature resistant antioxidant.

[0196] The high-temperature resistant antioxidant is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-phenylenediamide.

[0197] The preparation method of the above-mentioned semi-aromatic polyamide resin includes the following steps:

[0198] (1) Vacuum-dried decanediamine and terephthalic acid were added to a stirred polymerization reactor, along with phosphoramide salt, 2,2'-(1,3-phenylene)-dioxazoline, organic carbon nanotubes, benzoic acid, high-temperature antioxidant and 200 mL of water. The reactor was then evacuated for 4 min and purged with nitrogen for 4 min. This cycle was repeated 4 times, and the system pressure in the stirred polymerization reactor was controlled to be 0.2 MPa.

[0199] (2) Adjust the stirring speed of the stirred polymerization reactor to 30 r / min, and heat the stirred polymerization reactor to 276°C in a sealed and uniform manner within 3 hours. When the temperature of the stirred polymerization reactor reaches 209°C, release the gas to 1.8 MPa and maintain the pressure at 1.8 MPa. After reacting for 1.5 hours (prepolymerization reaction), release the gas to atmospheric pressure and simultaneously raise the temperature to 313°C. Continue to react for 1.5 hours (postpolymerization reaction), and maintain the constant temperature and vacuum for 30 minutes (viscosification reaction). When the reaction is completed, add nitrogen gas when discharging to obtain the final product.

[0200] Comparative Example 3

[0201] The semi-aromatic polyamide resin of this comparative example is prepared from the following raw materials in parts by weight:

[0202] 172 portions of decanediamine,

[0203] 166 parts of terephthalic acid

[0204] Contains 80 parts of phosphoramide salt,

[0205] 24 parts of caprolactam

[0206] 42 portions of organic carbon nanotubes,

[0207] 4 parts benzoic acid

[0208] 2.7 parts of high-temperature resistant antioxidant.

[0209] The high-temperature resistant antioxidant is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-phenylenediamide.

[0210] The preparation method of the above-mentioned semi-aromatic polyamide resin includes the following steps:

[0211] (1) Vacuum-dried decanediamine and terephthalic acid were added to a stirred polymerization reactor, along with phosphoramide salt, caprolactam, organic carbon nanotubes, benzoic acid, high-temperature antioxidant and 200 mL of water. The reactor was then evacuated for 4 min and purged with nitrogen for 4 min. This process was repeated 4 times to control the system pressure in the stirred polymerization reactor to 0.2 MPa.

[0212] (2) Adjust the stirring speed of the stirred polymerization reactor to 30 r / min, and heat the stirred polymerization reactor to 276°C in a sealed and uniform manner within 3 hours. When the temperature of the stirred polymerization reactor reaches 209°C, release the gas to 1.8 MPa and maintain the pressure at 1.8 MPa. After reacting for 1.5 hours (prepolymerization reaction), release the gas to atmospheric pressure and simultaneously raise the temperature to 313°C. Continue to react for 1.5 hours (postpolymerization reaction), and maintain the constant temperature and vacuum for 30 minutes (viscosification reaction). When the reaction is completed, add nitrogen gas when discharging to obtain the final product.

[0213] Comparative Example 4

[0214] The semi-aromatic polyamide resin of this comparative example is prepared from the following raw materials in parts by weight:

[0215] 172 portions of decanediamine,

[0216] 166 parts of terephthalic acid

[0217] Contains 80 parts of phosphoramide salt,

[0218] 24 parts of caprolactam

[0219] 8 parts of 2,2'-(1,3-phenylene)-dioxazoline

[0220] 4 parts benzoic acid

[0221] 2.7 parts of high-temperature resistant antioxidant.

[0222] The high-temperature resistant antioxidant is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-phenylenediamide.

[0223] The preparation method of the above-mentioned semi-aromatic polyamide resin includes the following steps:

[0224] (1) Vacuum-dried decanediamine and terephthalic acid were added to a stirred polymerization reactor, along with phosphoramide salt, caprolactam, 2,2'-(1,3-phenylene)-dioxazoline, benzoic acid, high-temperature antioxidant and 200 mL of water. The reactor was then evacuated for 4 min and purged with nitrogen for 4 min. This cycle was repeated 4 times to control the system pressure in the stirred polymerization reactor to 0.2 MPa.

[0225] (2) Adjust the stirring speed of the stirred polymerization reactor to 30 r / min, and heat the stirred polymerization reactor to 276°C in a sealed and uniform manner within 3 hours. When the temperature of the stirred polymerization reactor reaches 209°C, release the gas to 1.8 MPa and maintain the pressure at 1.8 MPa. After reacting for 1.5 hours (prepolymerization reaction), release the gas to atmospheric pressure and simultaneously raise the temperature to 313°C. Continue to react for 1.5 hours (postpolymerization reaction), and maintain the constant temperature and vacuum for 30 minutes (viscosification reaction). When the reaction is completed, add nitrogen gas when discharging to obtain the final product.

[0226] Comparative Example 5

[0227] The semi-aromatic polyamide resin of this comparative example is prepared from the following raw materials in parts by weight:

[0228] 172 portions of decanediamine,

[0229] 166 parts of terephthalic acid

[0230] Contains 80 parts of phosphoramide salt,

[0231] 24 parts of caprolactam

[0232] 8 parts of 2,2'-(1,3-phenylene)-dioxazoline

[0233] 42 portions of organic carbon nanotubes,

[0234] 2.7 parts of high-temperature resistant antioxidant.

[0235] The high-temperature resistant antioxidant is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-phenylenediamide.

[0236] The preparation method of the above-mentioned semi-aromatic polyamide resin includes the following steps:

[0237] (1) Vacuum-dried decanediamine and terephthalic acid were added to a stirred polymerization reactor, along with phosphoramide salt, caprolactam, 2,2'-(1,3-phenylene)-dioxazoline, organic carbon nanotubes, high-temperature antioxidant and 200 mL of water. The reactor was then evacuated for 4 min and purged with nitrogen for 4 min. This cycle was repeated 4 times, and the system pressure in the stirred polymerization reactor was controlled to be 0.2 MPa.

[0238] (2) Adjust the stirring speed of the stirred polymerization reactor to 30 r / min, and heat the stirred polymerization reactor to 276°C in a sealed and uniform manner within 3 hours. When the temperature of the stirred polymerization reactor reaches 209°C, release the gas to 1.8 MPa and maintain the pressure at 1.8 MPa. After reacting for 1.5 hours (prepolymerization reaction), release the gas to atmospheric pressure and simultaneously raise the temperature to 313°C. Continue to react for 1.5 hours (postpolymerization reaction), and maintain the constant temperature and vacuum for 30 minutes (viscosification reaction). When the reaction is completed, add nitrogen gas when discharging to obtain the final product.

[0239] Comparative Example 6

[0240] The semi-aromatic polyamide resin of this comparative example is prepared from the following raw materials in parts by weight:

[0241] 172 portions of decanediamine,

[0242] 166 parts of terephthalic acid

[0243] Contains 80 parts of phosphoramide salt,

[0244] 24 parts of caprolactam

[0245] 8 parts of 2,2'-(1,3-phenylene)-dioxazoline

[0246] 42 portions of organic carbon nanotubes,

[0247] 4 parts benzoic acid.

[0248] The preparation method of the above-mentioned semi-aromatic polyamide resin includes the following steps:

[0249] (1) Vacuum-dried decanediamine and terephthalic acid were added to a stirred polymerization reactor, along with phosphoramide salt, caprolactam, 2,2'-(1,3-phenylene)-dioxazoline, organic carbon nanotubes, benzoic acid and 200 mL of water. The reactor was then evacuated for 4 min and purged with nitrogen for 4 min. This process was repeated 4 times to control the system pressure in the stirred polymerization reactor to 0.2 MPa.

[0250] (2) Adjust the stirring speed of the stirred polymerization reactor to 30 r / min, and heat the stirred polymerization reactor to 276°C in a sealed and uniform manner within 3 hours. When the temperature of the stirred polymerization reactor reaches 209°C, release the gas to 1.8 MPa and maintain the pressure at 1.8 MPa. After reacting for 1.5 hours (prepolymerization reaction), release the gas to atmospheric pressure and simultaneously raise the temperature to 313°C. Continue to react for 1.5 hours (postpolymerization reaction), and maintain the constant temperature and vacuum for 30 minutes (viscosification reaction). When the reaction is completed, add nitrogen gas when discharging to obtain the final product.

[0251] The following is a list of the raw material composition of Examples 1-7 and Comparative Examples 1-6.

[0252] Table 1. Summary of raw material composition for Examples 1-7 and Comparative Examples 1-6

[0253]

[0254]

[0255] In the above examples and comparative examples, the amount of decanediamine added was 172 parts and the amount of terephthalic acid added was 166 parts; the high-temperature resistant antioxidant was N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-phenylenediamide.

[0256] Examples 1-7 were used to prepare semi-aromatic polyamide resins by adjusting the amounts of phosphoramide salt, caprolactam, 2,2'-(1,3-phenylene)-dioxazoline, organic carbon nanotubes, benzoic acid, and high-temperature antioxidant. Comparative Examples 1-6 were used to prepare semi-aromatic polyamide resins based on the raw materials of Example 7. Comparative Example 1 prepared a semi-aromatic polyamide resin without adding phosphoramide salt; Comparative Example 2 prepared a semi-aromatic polyamide resin without adding caprolactam; Comparative Example 3 prepared a semi-aromatic polyamide resin without adding 2,2'-(1,3-phenylene)-dioxazoline; Comparative Example 4 prepared a semi-aromatic polyamide resin without adding organic carbon nanotubes; Comparative Example 5 prepared a semi-aromatic polyamide resin without adding benzoic acid; and Comparative Example 6 prepared a semi-aromatic polyamide resin without adding a high-temperature antioxidant. The semi-aromatic polyamide resins prepared in the above examples and comparative examples were subjected to the following performance tests:

[0257] Tensile properties: Tested according to GB / T 1040-2006 standard, the tensile rate is 50 mm / min.

[0258] Notched impact performance: tested according to GB / T 1843-2008 standard.

[0259] Flame retardant performance: According to GB / T 2406.2-2009 standard, the limiting oxygen index of the sample was determined using an oxygen index meter. The sample size was 100 mm × 10 mm × 4 mm.

[0260] Microwave absorption performance: Tested according to GJB 5239-2004 standard using a vector network analyzer from Agilent Technologies, USA. The sample was a coaxial ring specimen with a thickness of 2mm, an outer diameter of 7mm, and an inner diameter of 3mm. A wider microwave frequency bandwidth indicates better coverage, and a higher microwave frequency indicates even better performance. Microwave absorption performance reflects a material's ability to absorb electromagnetic waves; a larger absolute value indicates greater attenuation of electromagnetic waves after passing through the material, resulting in better absorption performance and thus better electromagnetic shielding.

[0261] Intrinsic viscosity: Tested according to GB / T 1632-2008 standard, with concentrated sulfuric acid as the solvent.

[0262] Melting temperature: Tested according to GB / T 19466.3-2004 standard.

[0263] The performance test results are shown in Table 2.

[0264] Table 2. Performance of the semi-aromatic polyamide resins in Examples 1-7 and Comparative Examples 1-6

[0265]

[0266]

[0267]

[0268] As can be seen from Table 2:

[0269] As the amount of organic carbon nanotubes added increases, the tensile strength of semi-aromatic polyamide resin shows an increasing trend. This is mainly due to the influence of two factors: (1) Organic carbon nanotubes play a reinforcing role for semi-aromatic polyamide resin, which is the main effect; (2) The higher the intrinsic viscosity of semi-aromatic polyamide resin, the higher the van der Waals forces between its molecules, and the higher its tensile strength, which is the secondary effect.

[0270] With increasing caprolactam content, the notched impact properties of semi-aromatic polyamide resins show an increasing trend. This is because the ε-caprolactam structure formed after caprolactam ring opening inserts as an aliphatic segment into the PA10T main chain. Its flexible characteristics create steric hindrance with the rigid terephthalic acid units of PA10T, disrupting the regular arrangement of the molecular chains, thereby inhibiting crystallization ability and improving impact performance.

[0271] With increasing additions of phosphoramide salts and organic carbon nanotubes, the flame retardant and microwave absorption properties of semi-aromatic polyamide resins show an increasing trend. This is because carbon nanotubes form a dense nano-network structure upon heating, delaying the diffusion of heat and oxygen. Simultaneously, their interwoven network and the carbon layer catalyzed by phosphoramide structural units synergistically enhance the strength and density of the carbon layer. The adsorption of free radicals at the active sites on the carbon nanotube surface terminates the chain reaction, and the inert gas generated by the decomposition of phosphoramide structural units dilutes the concentration of combustibles. Furthermore, the compound system optimizes the polymer's thermal degradation pathway, promoting stable char formation and reducing the release of combustibles, thus achieving highly efficient flame retardancy. Simultaneously, organic carbon nanotubes significantly improve the electromagnetic shielding performance of semi-aromatic polyamide resins through a multi-dimensional synergistic mechanism. Surface modifications (such as amylation) optimize dispersibility, constructing a continuous conductive network in the matrix, achieving electromagnetic wave reflection loss through free electron migration, and enhancing absorption loss through polarization relaxation induced by tube wall defects and functional groups. The stable matrix of semi-aromatic polyamide maintains network integrity, while interfacial hydrogen bonding reduces signal transmission, ultimately achieving efficient electromagnetic shielding through the synergistic effect of "conductivity-dissipation-interface".

[0272] As the amount of benzoic acid added increases, the intrinsic viscosity of the semi-aromatic polyamide resin shows a decreasing trend. This is because, as a monofunctional compound, the terminal carboxyl group of benzoic acid undergoes a condensation reaction with the terminal amino group of the semi-aromatic polyamide during melt polymerization. Since the benzoic acid molecule loses its ability to further participate in chain growth after the reaction, it can be used as a molecular weight regulator to effectively control the molecular weight (i.e., intrinsic viscosity) of the polymer.

[0273] As the amount of caprolactam added increases, the melting temperature of semi-aromatic polyamide resins tends to decrease. This is because the density of amide bonds introduced by caprolactam is lower than that of PA10T (the effective chain length is shortened by the benzene ring), and the spacing between aliphatic chain segments increases, resulting in fewer hydrogen bond interaction sites, weaker intermolecular forces, and easier relative displacement between polymer molecular chains, thus lowering the melting temperature.

[0274] In summary, by adjusting the amounts of phosphoramide salt, caprolactam, 2,2'-(1,3-phenylene)-dioxazoline, organic carbon nanotubes, benzoic acid, and high-temperature antioxidant, the semi-aromatic polyamide resin of this invention, with its excellent mechanical properties, flame retardant properties, and electromagnetic shielding properties, can be obtained under the synergistic effect of these additives.

[0275] Compared to Comparative Example 1, Example 7 prepared a semi-aromatic polyamide resin without adding phosphoramide salt. The combination of phosphoramide salt (polymerized and inserted into the PA10T backbone) and organic carbon nanotubes significantly improved the flame retardant properties of the semi-aromatic polyamide resin through multiple synergistic mechanisms. The mechanisms are as follows: carbon nanotubes form a dense nano-network structure upon heating, delaying heat and oxygen diffusion; simultaneously, their interwoven network and the char layer catalyzed by the phosphoramide structural units synergistically enhance the strength and density of the char layer; adsorbed free radicals at the active sites on the carbon nanotube surface terminate the chain reaction; and the inert gas generated by the decomposition of the phosphoramide structural units dilutes the concentration of combustibles. Furthermore, the compound system optimizes the polymer thermal degradation pathway, promotes stable char formation, and reduces the release of combustibles, thereby achieving highly efficient flame retardancy. Therefore, the flame retardant performance of Comparative Example 1 is lower than that of Example 7.

[0276] Compared with Comparative Example 2, Example 7 prepared a semi-aromatic polyamide resin without adding caprolactam. Since caprolactam, as a comonomer, lowers the melting point of the semi-aromatic polyamide resin (PA10T), its mechanism is mainly reflected in the following aspects: (1) The ε-caprolactam structure formed after caprolactam ring opening is inserted into the PA10T main chain as an aliphatic segment. Its flexible characteristics form steric hindrance with the rigid terephthalic acid unit of PA10T, which destroys the regular arrangement of the molecular chain and thus inhibits crystallization ability. (2) The amide bond density introduced by caprolactam is lower than that of PA10T (the benzene ring shortens the effective chain length), and the aliphatic segment spacing increases, resulting in a reduction of hydrogen bond interaction points and a weakening of intermolecular forces. This effect further reduces the crystallinity of the material and widens the processing window. Therefore, the melting temperature of Comparative Example 2 is higher than that of Example 7.

[0277] Compared to Comparative Example 3, Example 7 was prepared without the addition of 2,2'-(1,3-phenylene)-dioxazoline. 2,2'-(1,3-phenylene)-dioxazoline improves the compatibility between organic carbon nanotubes and the semi-aromatic polyamide resin. Specifically, the oxazoline group of 2,2'-(1,3-phenylene)-dioxazoline can react with the terminal amino groups of both the organic carbon nanotubes and the semi-aromatic polyamide resin, thereby improving the compatibility and interfacial adhesion between them. Therefore, the tensile strength and notched impact properties of Comparative Example 3 are lower than those of Example 7.

[0278] Compared to Comparative Example 4, Example 7 involved preparing a semi-aromatic polyamide resin without the addition of organic carbon nanotubes. Organic carbon nanotubes significantly enhance the electromagnetic shielding performance of the semi-aromatic polyamide resin through a multi-dimensional synergistic mechanism. Their surface modifications (such as amylation) optimize dispersibility, constructing a continuous conductive network within the matrix. Electromagnetic wave reflection loss is achieved through free electron migration, and polarization relaxation induced by tube wall defects and functional groups enhances absorption loss. The stable matrix of the semi-aromatic polyamide maintains network integrity, while interfacial hydrogen bonding reduces signal transmission. Ultimately, efficient electromagnetic shielding is achieved through a synergistic effect of "conductivity-dissipation-interface." Therefore, Comparative Example 4 does not possess microwave absorption properties.

[0279] Compared to Comparative Example 5, Example 7 involved preparing a semi-aromatic polyamide resin without the addition of benzoic acid. Since benzoic acid is a monofunctional compound, its terminal carboxyl group undergoes a condensation reaction with the terminal amino group of the semi-aromatic polyamide during melt polymerization. Because the benzoic acid molecule loses its ability to further participate in chain growth after the reaction, it can be used as a molecular weight regulator to effectively control the polymer's molecular weight (i.e., intrinsic viscosity). Therefore, the intrinsic viscosity of Comparative Example 5 is higher than that of Example 7.

[0280] Compared to Comparative Example 6, Example 7 involved preparing a semi-aromatic polyamide resin without adding a high-temperature antioxidant. The high-temperature antioxidant N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-phenylenediamide exhibits excellent thermal stability at high temperatures due to the steric hindrance effect of the four methyl groups on the piperidine ring. This steric hindrance structure effectively captures free radicals, thereby delaying material aging. Furthermore, during the synthesis of the semi-aromatic polyamide resin, the amide groups of N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-phenylenediamide can react with the end groups of the semi-aromatic polyamide resin, effectively improving its compatibility with the copolymer. Simultaneously, it acts as an end-capping agent to control the molecular weight of the semi-aromatic polyamide resin and can be permanently bonded to the polymer backbone through chemical bonding. This not only endows the material with good antioxidant properties but also significantly improves the dyeing properties of the copolymer. Therefore, the tensile strength and notched impact strength of Comparative Example 6 are lower than those of Example 7.

[0281] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0282] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A semi-aromatic polyamide resin, characterized in that, It is prepared from the following raw materials in parts by weight: 172 portions of decanediamine 166 parts of terephthalic acid Contains 40-80 parts of phosphoramide salt, 12-24 parts of caprolactam 4-8 parts of 2,2'-(1,3-phenylene)-dioxazoline 22–42 parts of organic carbon nanotubes, 2-4 parts benzoic acid 1.3–2.7 parts of high-temperature resistant antioxidant; The phosphoramide salt is obtained by salt formation reaction of 2-carboxyethylphenyl hypophosphoric acid and decanediamine; the organic carbon nanotubes are obtained by organic modification of carbon nanotubes with γ-aminopropyltriethoxysilane; the high-temperature resistant antioxidant is N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,3-phenylenediamide.

2. The semi-aromatic polyamide resin according to claim 1, characterized in that, It is prepared from the following raw materials in parts by weight: 172 portions of decanediamine 166 parts of terephthalic acid Contains 45-75 parts of phosphoramide salt. 14-22 parts of caprolactam 4.5–7.5 parts of 2,2'-(1,3-phenylene)-dioxazoline 25–39 parts of organic carbon nanotubes, Benzoic acid 2.3–3.7 parts, 1.5 to 2.5 parts of high-temperature resistant antioxidant.

3. The semi-aromatic polyamide resin according to claim 2, characterized in that, It is prepared from the following raw materials in parts by weight: 172 portions of decanediamine 166 parts of terephthalic acid Contains 50-70 parts of phosphoramide salt, 16-20 parts of caprolactam 5.5–6.5 parts of 2,2'-(1,3-phenylene)-dioxazoline 28–36 parts of organic carbon nanotubes, Benzoic acid 2.6–3.4 parts, 1.7 to 2.3 parts of high-temperature resistant antioxidant.

4. The semi-aromatic polyamide resin according to any one of claims 1 to 3, characterized in that, The preparation method of the phosphoramide salt includes the following steps: 214.16 g of 2-carboxyethylphenyl hypophosphite and 172.31 g of decanediamine are added to a stirred polymerization reactor, followed by the addition of 150 mL to 200 mL of deionized water. The reactor is then evacuated for 2 to 6 minutes and purged with nitrogen for 2 to 6 minutes. This cycle is repeated 3 to 5 times, and the system pressure inside the stirred polymerization reactor is controlled at 0.1 MPa to 0.3 MPa. The stirred polymerization reactor is then sealed and heated to 85°C to 95°C for 0.5 to 1.5 hours, with the stirring speed controlled at 50 r / min to 100 r / min. After the salt formation reaction is carried out for 1 to 2 hours, the reaction is completed, the pressure inside the reactor is reduced to 0.1 MPa, the material is discharged, and vacuum dried.

5. The semi-aromatic polyamide resin according to any one of claims 1 to 3, characterized in that, The preparation method of the organic carbon nanotubes includes the following steps: 100 g of carbon nanotubes and 2 g to 3 g of γ-aminopropyltriethoxysilane are added to a high-speed stirrer and stirred at room temperature for 7 min to 11 min to obtain organic carbon nanotubes.

6. The semi-aromatic polyamide resin according to any one of claims 1 to 3, characterized in that, The average diameter of the carbon nanotubes in the organic carbon nanotubes is 8 nm to 10 nm, and their structure is array-type.

7. The method for preparing the semi-aromatic polyamide resin according to any one of claims 1 to 6, characterized in that, Includes the following steps: (1) Vacuum-dried decanediamine and terephthalic acid are added to a stirred polymerization reactor, along with phosphoramide salt, caprolactam, 2,2'-(1,3-phenylene)-dioxazoline, organic carbon nanotubes, benzoic acid, high-temperature antioxidant and appropriate amount of water. Then, the reactor is evacuated for 2 min to 6 min and purged with nitrogen for 2 min to 6 min. This cycle is repeated 3 to 5 times, and the system pressure in the stirred polymerization reactor is controlled to be 0.1 MPa to 0.3 MPa. (2) Adjust the stirring speed of the stirred polymerization reactor to 20 r / min to 40 r / min, and heat the stirred polymerization reactor to 274℃ to 278℃ in a closed and uniform manner for 2 to 4 hours. When the temperature of the stirred polymerization reactor reaches 209℃, release the gas to 1.8 MPa and maintain the pressure at 1.8 MPa. After reacting for 1 to 2 hours, release the gas to atmospheric pressure and raise the temperature to 310℃ to 316℃. Continue to react for 1 to 2 hours, and maintain the constant temperature and vacuum for 15 to 45 minutes. When the reaction is completed, add nitrogen gas when discharging to obtain the product.

8. The method for preparing the semi-aromatic polyamide resin according to claim 7, characterized in that, In step (1), the vacuum is drawn for 3 min to 5 min, and nitrogen is purged for 3 min to 5 min. This cycle is repeated 3 to 5 times to control the system pressure inside the stirred polymerization reactor to be 0.15 MPa to 0.25 MPa.

9. The method for preparing the semi-aromatic polyamide resin according to claim 7, characterized in that, In step (2), the stirring speed of the stirred polymerization reactor is adjusted to 25 r / min to 35 r / min. The stirred polymerization reactor is heated to 275℃ to 277℃ in a closed and uniform manner for 2.5 hours to 3.5 hours. When the temperature of the stirred polymerization reactor reaches 209℃, the pressure is released to 1.8 MPa and maintained at 1.8 MPa. After reacting for 1.2 hours to 1.8 hours, the pressure is released to atmospheric pressure, and the temperature is raised to 312℃ to 314℃. The reaction continues for 1.2 hours to 1.8 hours. The temperature is kept constant and the vacuum is continuously applied for 20 minutes to 40 minutes. When the reaction ends, nitrogen is added when discharging the product to obtain the final product.

Images