Weather-resistant polyamide composition and preparation method thereof

Abstract

The invention discloses a weather-resistant polyamide composition and a preparation method thereof, and belongs to the technical field of polyamide composition preparation. The preparation method of the weather-resistant polyamide composition comprises the following steps: step 1, adding modified diamine and modified diacid into a reaction kettle, then adding deionized water, and heating and stirring for reaction to obtain a prepolymer; 2, mixing and stirring a light stabilizer and an antioxidant to obtain a mixture; and 3, adding the prepolymer and the mixture into a high-pressure reaction kettle, heating, carrying out vacuum-pumping polycondensation reaction, and after the reaction is finished, carrying out rotary evaporation, extrusion and curing to obtain the weather-resistant polyamide composition. The polyamide composition prepared by the method has excellent weather resistance, mechanical strength and low water absorption.

Description

Technical Field

[0001] The invention belongs to the technical field of polyamide preparation, and particularly relates to a weather-resistant polyamide composition and a preparation method thereof. Background Art

[0002] As one of the five major general-purpose engineering plastics, polyamide holds an irreplaceable position in numerous fields, including rail transportation, the automotive industry, electronics, and outdoor facilities, thanks to its excellent mechanical properties, wear resistance, chemical resistance, and self-lubrication. In automotive manufacturing, it is widely used in the manufacture of engine peripheral components and fuel lines, capable of withstanding high temperatures and chemical corrosion. In rail transportation, it is used in the manufacture of train interiors and connectors, ensuring stability and safety in complex operating environments. In the electronics and electrical industry, its excellent insulation and dimensional stability make it an ideal material for key components such as connectors and sockets. However, polyamide's insufficient weather resistance has long hampered its reliability in complex environments. The amide groups in the polyamide molecular chain are highly chemically active, making it vulnerable to environmental factors such as ultraviolet light, oxygen, and humidity. When these factors work together, they can easily trigger photooxidative degradation.

[0003] Patent CN115124828B discloses a polyamide composition and its preparation method, comprising the following components: 70-90 wt% semi-crystalline polyamide, 4-20 wt% amine-functionalized polyolefin elastomer, 4-20 wt% elastomeric copolymer modified with anhydride groups, and 1-3 wt% optional additives. The polyamide composition prepared by a twin-screw extrusion granulation process has excellent high and low temperature toughness and hydrolysis resistance, and is suitable for hydrolysis-resistant pipes, cables, and structural parts. However, although the polyamide composition performs well in many aspects, there is still room for improvement in weather resistance. In actual applications, materials are often exposed to various natural environmental conditions, such as sunlight, ultraviolet radiation, temperature changes, humidity fluctuations, and wind and rain erosion. These environmental factors can have varying degrees of impact on the performance of the material, leading to problems such as aging, discoloration, and decreased mechanical properties. Therefore, there is a need to improve polyamide so that it can exhibit excellent performance in a wider range of outdoor applications. Summary of the Invention

[0004] The object of the present invention is to provide a weather-resistant polyamide composition and a preparation method thereof, so as to solve the technical problems of poor weather resistance and mechanical strength of polyamide compositions in the prior art.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a method for preparing a weather-resistant polyamide composition, comprising the following steps: Step 1: Add modified diamine and modified diacid into a reactor, then add deionized water, heat and stir to react, and obtain a prepolymer; Step 2: Mixing and stirring the light stabilizer and the antioxidant to obtain a mixture; Step 3: Add the prepolymer and the mixed material into a high-pressure reactor, increase the temperature, and vacuumize the reactor for polycondensation reaction. After the reaction is completed, perform rotary evaporation, extrusion, and solidification to obtain a weather-resistant polyamide composition.

[0006] Preferably, the preparation method of the modified diamine comprises the following steps: Q1: Under argon protection, 4,7-dibromo-2,1,3-benzothiadiazole, potassium fluoride, cuprous iodide, and dimethyl sulfoxide were added to a container, stirred, heated, and refluxed. After the reaction was completed, the mixture was cooled and poured into ice water to precipitate a solid, which was filtered, washed, and purified to obtain product 1; Q2: Under nitrogen protection, product 1 and reduced iron powder are added to a container filled with anhydrous acetic acid, heated and stirred to react, and after the reaction is completed, cooled, filtered, extracted, washed, and dried to obtain product 2; product 2 is added to a container filled with anhydrous acetic acid, and then sodium nitrite solution is added dropwise. After the addition is completed, the reaction is carried out, filtered, washed, and dried to obtain product 3 and product 3' containing an N=N double bond; Q3: Under nitrogen protection, N,N-dimethylformamide and dimethyl sulfoxide were added to a container, followed by the mixture of product 3 and product 3' and potassium carbonate. The mixture was stirred and heated to react. 11-(bromomethyl)tricosane was then added, the mixture was heated to react, cooled, added to cold water, extracted, washed, dried, rotary evaporated, and purified to obtain product 4. Q4: Add concentrated sulfuric acid and concentrated nitric acid to a container, cool, add product 4 dropwise, react in an ice bath, remove from the ice bath and continue the reaction. After the reaction is completed, pour into a mixture of ice and water, stir, extract, wash, dry, rotary evaporate, purify, recrystallize, and vacuum dry to obtain product 5; under nitrogen protection, add product 5 and reduced iron powder to a container filled with anhydrous acetic acid, heat and stir to react, cool, extract, wash, dry, and purify to obtain modified diamine.

[0007] In the above process, the synthetic reaction formula of modified diamine is as follows: The results of mass spectrometry analysis of product 1 were: m / z: 171.99 (100.0%), 172.99 (8.0%), 173.99 (4.6%); the results of mass spectrometry analysis of product 2 were: m / z: 144.05 (100.0%), 145.05 (7.2%); the results of mass spectrometry analysis of product 3 were: m / z: 155.03 (100.0%), 156.03 (7.6%); the results of mass spectrometry analysis of product 3' were: m / z:155.03 (100.0%), 156.03 (7.6%); the results of mass spectrometry analysis of product 4 were: m / z: 491.41 (100.0%), 492.41 (33.0%), 493.41 (5.6%), 492.40 (1.1%); the mass spectrometry analysis results of product 5 were: m / z: 581.38 (100.0%), 582.38 (33.2%), 583.38 (6.8%), 582.37 (1.8%); the mass spectrometry analysis results of modified diamine were: m / z: 521.43 (100.0%), 522.43 (33.1%), 523.43 (5.7%), 522.42 (1.8%).

[0008] Preferably, in Q1, the dosage ratio of 4,7-dibromo-2,1,3-benzothiadiazole, potassium fluoride, cuprous iodide, and dimethyl sulfoxide is (2.78-3.11) g: (1.27-1.45) g: (0.17-0.21) g: (100-200) mL, potassium fluoride is vacuum dried at 120-125° C. for 20-24 h, the reflux reaction temperature is 180-200° C., and the reaction time is 24-36 h.

[0009] Preferably, in Q2, the amount ratio of product 1, reduced iron powder and anhydrous acetic acid is (2.92-3.15) g: (11.4-12.21) g: (100-150) mL, the heating and stirring reaction temperature is 145-155° C., and the reaction time is 3-5 h; the amount ratio of product 2, anhydrous acetic acid and sodium nitrite solution is (2.16-2.48) g: (100-120) mL: (20-30) mL, the concentration of the sodium nitrite solution is 0.078 g / mL, the drop acceleration rate is 1 drop / s, and the reaction time is 6-8 h.

[0010] Preferably, in Q3, the amount ratio of N,N-dimethylformamide, dimethyl sulfoxide, the mixture of product 3 and product 3', potassium carbonate and 11-(bromomethyl)tricosane is (200-250) mL: (5-6.25) mL: (5.54-6.12) g: (5.53-6.08) g: (10.02-10.58) g. After mixing and stirring, the reaction temperature is heated to 80-85°C for 1-1.5 hours. After adding 11-(bromomethyl)tricosane, the reaction temperature is heated to 90-93°C and the reaction time is 10-12 hours.

[0011] Preferably, in Q4, the dosage ratio of concentrated sulfuric acid, concentrated nitric acid and product 4 is (40-50) mL: (40-50) mL: (4.78-5.12) g, the drop rate is 1 drop / s, the ice bath reaction time is 1-2 hours, and the continued reaction time is 6-8 hours; the dosage ratio of product 5, reduced iron and anhydrous acetic acid is (10.09-10.84) g: (1.34-1.68) g: (100-120) mL, the heating and stirring reaction temperature is 100-120°C, and the reaction time is 4-6 hours.

[0012] Preferably, the method for preparing the modified diacid comprises the following steps: S1: 3-iodo-2-hydroxybenzoic acid and methanol are added to a container, followed by slow dropwise addition of thionyl chloride, followed by reflux reaction to obtain intermediate A; thionyl chloride is slowly added dropwise to a mixture of intermediate A and acetic anhydride, followed by heating reaction to obtain intermediate B; S2: Mix the intermediate B and the active copper powder, heat and react under argon protection, and obtain the intermediate C after the reaction. Add the intermediate C to a sodium hydroxide aqueous solution, and then add methanol and tetrahydrofuran, stir and react at room temperature, adjust the pH, cool, filter, wash, dry, and purify to obtain the modified diacid.

[0013] In the above process, the synthetic reaction formula of modified diacid is as follows: The results of mass spectrometry analysis of intermediate A were: m / z: 277.94 (100.0%), 278.95 (8.8%), 279.95(1.0%); the results of mass spectrometry analysis of intermediate B were: m / z: 319.95 (100.0%), 320.96 (11.1%), 321.96(1.4%); the results of mass spectrometry analysis of intermediate C were: m / z: 386.10 (100.0%), 387.10 (21.9%), 388.11(2.3%), 388.10 (1.6%); the results of mass spectrometry analysis of modified diacid were: m / z: 274.05 (100.0%), 275.05(15.5%), 276.05 (2.3%).

[0014] Preferably, in said S1, the amount ratio of 3-iodo-2-hydroxybenzoic acid, methanol and thionyl chloride is (10-12) g: (100-120) mL: (2-2.5) mL, and the reflux reaction time is 4-6 h; the amount ratio of intermediate A, acetic anhydride and thionyl chloride is (10-12) g: (10-12) mL: (0.4-0.6) mL, the heating reaction temperature is 80-85 ° C, and the reaction time is 10-12 h; in said S2, intermediate B and active The dosage ratio of the active copper powder is (10-12) g: (11-12.5) g, the heating reaction temperature is 200-220°C, and the time is 5-8 h; the dosage ratio of the intermediate C, sodium hydroxide aqueous solution, methanol and tetrahydrofuran is (5-7.5) g: (100-120) mL: (60-80) mL: (130-150) mL, the concentration of the sodium hydroxide aqueous solution is 0.79 g / mL, the stirring reaction time is 10-12 h, and the pH is adjusted to 1-1.2.

[0015] Preferably, in the step 1, the molar ratio of the modified diamine to the modified diacid is (0.9-1.2): (0.88-1.21), and the reaction temperature with heating and stirring is 80-100°C; in the step 2, the amount ratio of the light stabilizer to the antioxidant is (0.1-0.4) g: (0.2-0.38) g, and the mixing and stirring time is 30-45 min; in the step 3, the amount ratio of the prepolymer to the mixed material is (8-12) g: (0.12-0.26) g, and the temperature is raised to 250-260°C.

[0016] The weather-resistant polyamide composition is prepared by the above-mentioned preparation method.

[0017] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. The present invention uses the prepared modified diamine and modified diacid as the main raw materials of the polyamide composition, which can make it have excellent weather resistance, mechanical strength and low water absorption.

[0018] 2. The present invention uses the prepared modified diamine as one of the main components of the polyamide composition, which can effectively improve its weather resistance and low water absorption. The benzotriazole group contained in the modified diamine has a wide ultraviolet absorption band and can effectively absorb high-energy ultraviolet photons. After absorption, the harmful ultraviolet light energy is converted into harmless low-heat through efficient and harmless intramolecular proton transfer or vibration relaxation processes and dissipated, thereby improving the weather resistance of the polyamide composition; the fluorine atoms in the modified diamine reduce local polarity, and the long-chain alkyl group provides a strong physical hydrophobic barrier, which synergistically inhibits the interaction and diffusion of the amide bonds of water molecules and reduces its water absorption.

[0019] 3. The present invention uses the prepared modified diacid as one of the main components of the polyamide composition, which can effectively improve its mechanical strength. The biphenyl structure contained in the modified diacid is an extremely strong "rod-shaped" or "plate-shaped" rigid unit. Its introduction into the polymer main chain makes it deform very little when subjected to external force, and can also more effectively bear and transmit stress. At the same time, the rigid biphenyl unit promotes the polymer chains to stack more tightly in the solid state, and can also enhance the π-π stacking interaction between the chains, thereby improving the mechanical strength of the polyamide. DETAILED DESCRIPTION

[0020] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0021] Example 1: This example discloses a method for preparing a modified diamine, comprising the following steps: Q1: Under argon protection, 2.94 g of 4,7-dibromo-2,1,3-benzothiadiazole, 1.36 g of potassium fluoride dried in vacuum at 120°C for 24 h, 0.19 g of cuprous iodide, and 150 mL of dimethyl sulfoxide were added to a container, and the mixture was heated to 180°C with stirring and refluxed for 24 h. After the reaction, the mixture was cooled and poured into ice water to precipitate a solid, which was filtered, washed, and purified to obtain product 1; Q2: Under nitrogen protection, 3.06g of product 1 and 11.82g of reduced iron powder were added to a container containing 125mL of anhydrous acetic acid, heated and stirred at 150℃ for 4h, and after the reaction, cooled, filtered, extracted, washed, and dried to obtain product 2; 2.32g of product 2 was added to a container containing 110mL of anhydrous acetic acid, and then 25mL of sodium nitrite solution with a concentration of 0.078g / mL was added dropwise at a drop rate of 1 drop / s. After the addition was completed, the reaction was carried out for 8h. After the reaction was completed, filtered, washed, and dried to obtain products 3 and product 3'; Q3: Under nitrogen protection, 225 mL of N,N-dimethylformamide and 5.72 mL of dimethyl sulfoxide were added to a container, followed by the addition of 5.82 g of a mixture of product 3 and product 3' and 5.81 g of potassium carbonate. After mixing and stirring, the mixture was heated at 85°C for 1.5 h. Subsequently, 10.3 g of 11-(bromomethyl)tricosane was added, and the mixture was heated at 90°C for 12 h. The mixture was cooled, added to cold water, extracted, washed, dried, rotary evaporated, and purified to obtain product 4. Q4: 45 mL of concentrated sulfuric acid and 45 mL of concentrated nitric acid were added to a container. After cooling, 4.95 g of product 4 was added dropwise at a rate of 1 drop / s. After reacting in an ice bath for 2 h, the ice bath was removed and the reaction was continued for 6 h. After the reaction was completed, the mixture was poured into an ice-water mixture, stirred, extracted, washed, dried, rotary evaporated, purified, recrystallized, and vacuum dried to obtain product 5. Under nitrogen protection, 10.41 g of product 5 and 1.52 g of reduced iron powder were added to a container containing 110 mL of anhydrous acetic acid, heated and stirred at 120°C for 6 h, cooled, extracted, washed, dried, and purified to obtain modified diamine.

[0022] This embodiment discloses a method for preparing a modified diacid, comprising the following steps: S1: 11 g of 3-iodo-2-hydroxybenzoic acid and 110 mL of methanol were added to a container, followed by slow dropwise addition of 2.25 mL of thionyl chloride. The mixture was refluxed for 6 h to obtain intermediate A. 0.5 mL of thionyl chloride was slowly added dropwise to a mixture of 11 g of intermediate A and 11 mL of acetic anhydride. The mixture was heated at 85°C for 10 h to obtain intermediate B. S2: 11 g of intermediate B and 11.75 g of active copper powder were mixed, and the mixture was heated at 220 ° C for 6 h under argon protection. After the reaction, intermediate C was obtained; 6.25 g of intermediate C was added to 110 mL of 0.79 g / mL sodium hydroxide aqueous solution, and then 70 mL of methanol and 140 mL of tetrahydrofuran were added. The mixture was stirred at room temperature for 12 h, the pH was adjusted to 1, cooled, filtered, washed, dried, and purified to obtain the modified diacid.

[0023] This embodiment discloses a method for preparing a weather-resistant polyamide composition, comprising the following steps: Step 1: Add 5.21 g of modified diamine and 2.74 g of modified diacid into a reactor, then add deionized water, heat to 90°C and stir to react to obtain a prepolymer; Step 2: Mix 0.25 g of light stabilizer UV-928 and 0.29 g of antioxidant 1010 and stir for 45 minutes to obtain a mixture; Step 3: Add 10g of prepolymer and 0.19g of the mixed material into a high-pressure reactor, heat to 250°C, and perform vacuum polycondensation reaction. After the reaction is completed, perform rotary evaporation, extrude, and solidify to obtain a weather-resistant polyamide composition.

[0024] Example 2: This example discloses a method for preparing a modified diamine, comprising the following steps: Q1: Under argon protection, 2.78 g of 4,7-dibromo-2,1,3-benzothiadiazole, 1.27 g of potassium fluoride dried in vacuum at 120°C for 24 h, 0.21 g of cuprous iodide, and 200 mL of dimethyl sulfoxide were added to a container, and the mixture was heated to 180°C with stirring and refluxed for 24 h. After the reaction, the mixture was cooled and poured into ice water to precipitate a solid, which was filtered, washed, and purified to obtain product 1; Q2: Under nitrogen protection, 2.92g of product 1 and 11.4g of reduced iron powder were added to a container containing 150mL of anhydrous acetic acid, heated and stirred at 150℃ for 4h, and after the reaction, cooled, filtered, extracted, washed, and dried to obtain product 2; 2.16g of product 2 was added to a container containing 120mL of anhydrous acetic acid, and then 30mL of sodium nitrite solution with a concentration of 0.078g / mL was added dropwise at a drop rate of 1 drop / s. After the addition was completed, the reaction was carried out for 8h. After the reaction was completed, filtered, washed, and dried to obtain products 3 and product 3'; Q3: Under nitrogen protection, 250 mL of N,N-dimethylformamide and 5 mL of dimethyl sulfoxide were added to a container, followed by the addition of 5.54 g of a mixture of product 3 and product 3' and 5.53 g of potassium carbonate. After mixing and stirring, the mixture was heated at 85°C for 1.5 h. Subsequently, 10.02 g of 11-(bromomethyl)tricosane was added, and the mixture was heated at 90°C for 12 h. The mixture was cooled, added to cold water, extracted, washed, dried, rotary evaporated, and purified to obtain product 4. Q4: 40 mL of concentrated sulfuric acid and 50 mL of concentrated nitric acid were added to a container. After cooling, 4.78 g of product 4 was added dropwise at a rate of 1 drop / s. After reacting in an ice bath for 2 h, the ice bath was removed and the reaction was continued for 6 h. After the reaction was completed, the mixture was poured into an ice-water mixture, stirred, extracted, washed, dried, rotary evaporated, purified, recrystallized, and vacuum dried to obtain product 5. Under nitrogen protection, 10.09 g of product 5 and 1.34 g of reduced iron powder were added to a container containing 100 mL of anhydrous acetic acid, heated and stirred at 120°C for 6 h, cooled, extracted, washed, dried, and purified to obtain modified diamine.

[0025] This embodiment discloses a method for preparing a modified diacid, comprising the following steps: S1: 12 g of 3-iodo-2-hydroxybenzoic acid and 100 mL of methanol were added to a container, followed by slow dropwise addition of 2.5 mL of thionyl chloride, and the mixture was refluxed for 6 h to obtain intermediate A. 0.4 mL of thionyl chloride was slowly added dropwise to a mixture of 10 g of intermediate A and 12 mL of acetic anhydride, and the mixture was heated at 85°C for 10 h to obtain intermediate B. S2: 12 g of intermediate B and 12.5 g of active copper powder were mixed, and the mixture was heated at 220 ° C for 6 h under argon protection. After the reaction, intermediate C was obtained; 7.5 g of intermediate C was added to 100 mL of 0.79 g / mL sodium hydroxide aqueous solution, and then 80 mL of methanol and 150 mL of tetrahydrofuran were added. The mixture was stirred at room temperature for 12 h, the pH was adjusted to 1, cooled, filtered, washed, dried, and purified to obtain the modified diacid.

[0026] This embodiment discloses a method for preparing a weather-resistant polyamide composition, comprising the following steps: Step 1: Add 4.55g of modified diamine and 2.31g of modified diacid into a reactor, then add deionized water, heat to 90°C and stir to react to obtain a prepolymer; Step 2: Mix 0.4 g of light stabilizer UV-928 and 0.2 g of antioxidant 1010 and stir for 45 minutes to obtain a mixture; Step 3: Add 8 g of prepolymer and 0.26 g of the mixed material into a high-pressure reactor, heat to 250° C., and perform vacuum polycondensation reaction. After the reaction is completed, perform rotary evaporation, extrude, and solidify to obtain a weather-resistant polyamide composition.

[0027] Example 3: This example discloses a method for preparing a modified diamine, comprising the following steps: Q1: Under argon protection, 3.11 g of 4,7-dibromo-2,1,3-benzothiadiazole, 1.45 g of potassium fluoride dried in vacuum at 120°C for 24 h, 0.17 g of cuprous iodide, and 100 mL of dimethyl sulfoxide were added to a container, and the mixture was heated to 180°C with stirring and refluxed for 24 h. After the reaction, the mixture was cooled and poured into ice water to precipitate a solid, which was filtered, washed, and purified to obtain product 1; Q2: Under nitrogen protection, 3.15g of product 1 and 12.21g of reduced iron powder were added to a container containing 100mL of anhydrous acetic acid, heated and stirred at 150℃ for 4h, and after the reaction, cooled, filtered, extracted, washed, and dried to obtain product 2; 2.48g of product 2 was added to a container containing 100mL of anhydrous acetic acid, and then 20mL of sodium nitrite solution with a concentration of 0.078g / mL was added dropwise at a drop rate of 1 drop / s. After the addition was completed, the reaction was carried out for 8h. After the reaction was completed, filtered, washed, and dried to obtain products 3 and product 3'; Q3: Under nitrogen protection, 200 mL of N,N-dimethylformamide and 6.25 mL of dimethyl sulfoxide were added to a container, followed by the addition of 6.12 g of a mixture of product 3 and product 3' and 6.08 g of potassium carbonate. After mixing and stirring, the mixture was heated at 85°C for 1.5 h. Subsequently, 10.58 g of 11-(bromomethyl)tricosane was added, and the mixture was heated at 90°C for 12 h. The mixture was cooled, added to cold water, extracted, washed, dried, rotary evaporated, and purified to obtain product 4. Q4: 50 mL of concentrated sulfuric acid and 40 mL of concentrated nitric acid were added to a container. After cooling, 5.12 g of product 4 was added dropwise at a rate of 1 drop / s. After reacting in an ice bath for 2 h, the ice bath was removed and the reaction was continued for 6 h. After the reaction was completed, the mixture was poured into an ice-water mixture, stirred, extracted, washed, dried, rotary evaporated, purified, recrystallized, and vacuum dried to obtain product 5. Under nitrogen protection, 10.84 g of product 5 and 1.68 g of reduced iron powder were added to a container containing 120 mL of anhydrous acetic acid, heated and stirred at 120°C for 6 h, cooled, extracted, washed, dried, and purified to obtain modified diamine.

[0028] This embodiment discloses a method for preparing a modified diacid, comprising the following steps: S1: 10 g of 3-iodo-2-hydroxybenzoic acid and 120 mL of methanol were added to a container, followed by slow dropwise addition of 2 mL of thionyl chloride. The mixture was refluxed for 6 h to obtain intermediate A. 0.6 mL of thionyl chloride was slowly added dropwise to a mixture of 12 g of intermediate A and 10 mL of acetic anhydride. The mixture was heated at 85°C for 10 h to obtain intermediate B. S2: 10 g of intermediate B and 11 g of active copper powder were mixed, and the mixture was heated at 220°C for 6 h under argon protection. After the reaction, intermediate C was obtained; 5 g of intermediate C was added to 120 mL of 0.79 g / mL sodium hydroxide aqueous solution, followed by 60 mL of methanol and 130 mL of tetrahydrofuran. The mixture was stirred at room temperature for 12 h, the pH was adjusted to 1, cooled, filtered, washed, dried, and purified to obtain the modified diacid.

[0029] This embodiment discloses a method for preparing a weather-resistant polyamide composition, comprising the following steps: Step 1: Add 6.06g of modified diamine and 3.17g of modified diacid into a reactor, then add deionized water, heat to 90°C and stir to react to obtain a prepolymer; Step 2: Mix 0.1 g of light stabilizer UV-928 and 0.38 g of antioxidant 1010 and stir for 45 minutes to obtain a mixture; Step 3: Add 12 g of prepolymer and 0.12 g of the mixed material into a high-pressure reactor, heat to 250° C., and perform vacuum polycondensation reaction. After the reaction is completed, perform rotary evaporation, extrude, and solidify to obtain a weather-resistant polyamide composition.

[0030] Example 4: This example discloses a method for preparing a modified diamine, comprising the following steps: Q1: Under argon protection, 2.82 g of 4,7-dibromo-2,1,3-benzothiadiazole, 1.32 g of potassium fluoride dried in vacuum at 120°C for 24 h, 0.2 g of cuprous iodide, and 120 mL of dimethyl sulfoxide were added to a container, and the mixture was heated to 180°C with stirring and refluxed for 24 h. After the reaction, the mixture was cooled and poured into ice water to precipitate a solid, which was filtered, washed, and purified to obtain product 1; Q2: Under nitrogen protection, 2.98g of product 1 and 11.68g of reduced iron powder were added to a container containing 110mL of anhydrous acetic acid, heated and stirred at 150°C for 4h, and after the reaction, cooled, filtered, extracted, washed, and dried to obtain product 2; 2.27g of product 2 was added to a container containing 105mL of anhydrous acetic acid, and then 28mL of sodium nitrite solution with a concentration of 0.078g / mL was added dropwise at a drop rate of 1 drop / s. After the addition was completed, the reaction was carried out for 8h. After the reaction was completed, filtered, washed, and dried to obtain products 3 and product 3'; Q3: Under nitrogen, 210 mL of N,N-dimethylformamide and 5.12 mL of dimethyl sulfoxide were added to a container, followed by the addition of 5.71 g of a mixture of product 3 and product 3' and 5.71 g of potassium carbonate. After mixing and stirring, the mixture was heated at 85°C for 1.5 h. Subsequently, 10.16 g of 11-(bromomethyl)tricosane was added, and the mixture was heated at 90°C for 12 h. The mixture was cooled, added to cold water, extracted, washed, dried, rotary evaporated, and purified to obtain product 4. Q4: 42 mL of concentrated sulfuric acid and 42 mL of concentrated nitric acid were added to a container. After cooling, 4.82 g of product 4 was added dropwise at a rate of 1 drop / s. After reacting in an ice bath for 2 h, the ice bath was removed and the reaction was continued for 6 h. After the reaction was completed, the mixture was poured into an ice-water mixture, stirred, extracted, washed, dried, rotary evaporated, purified, recrystallized, and vacuum dried to obtain product 5. Under nitrogen protection, 10.25 g of product 5 and 1.47 g of reduced iron powder were added to a container containing 105 mL of anhydrous acetic acid, heated and stirred at 120°C for 6 h, cooled, extracted, washed, dried, and purified to obtain modified diamine.

[0031] This embodiment discloses a method for preparing a modified diacid, comprising the following steps: S1: 10.5 g of 3-iodo-2-hydroxybenzoic acid and 105 mL of methanol were added to a container, followed by slow dropwise addition of 2.1 mL of thionyl chloride, and the mixture was refluxed for 6 h to obtain intermediate A. 0.45 mL of thionyl chloride was slowly added dropwise to a mixture of 10.5 g of intermediate A and 10.5 mL of acetic anhydride, and the mixture was heated at 85°C for 10 h to obtain intermediate B. S2: 10.5 g of intermediate B and 11.3 g of active copper powder were mixed, and the mixture was heated at 220 ° C for 6 h under argon protection. After the reaction, intermediate C was obtained; 5.2 g of intermediate C was added to 105 mL of 0.79 g / mL sodium hydroxide aqueous solution, and then 65 mL of methanol and 135 mL of tetrahydrofuran were added. The mixture was stirred at room temperature for 12 h, the pH was adjusted to 1, cooled, filtered, washed, dried, and purified to obtain the modified diacid.

[0032] This embodiment discloses a method for preparing a weather-resistant polyamide composition, comprising the following steps: Step 1: Add 4.87 g of modified diamine and 2.68 g of modified diacid into a reactor, then add deionized water, heat to 90°C and stir to react to obtain a prepolymer; Step 2: Mix 0.2 g of light stabilizer UV-928 and 0.27 g of antioxidant 1010 and stir for 45 minutes to obtain a mixture; Step 3: Add 9 g of prepolymer and 0.21 g of the mixed material into a high-pressure reactor, heat to 250° C., and perform vacuum polycondensation reaction. After the reaction is completed, perform rotary evaporation, extrude, and solidify to obtain a weather-resistant polyamide composition.

[0033] Comparative Example 1: Compared with Example 1, in the process of preparing the weather-resistant polyamide composition in Comparative Example 1, hexamethylenediamine was used instead of modified diamine, and other conditions remained unchanged.

[0034] Comparative Example 2: Compared with Example 1, in the process of preparing the weather-resistant polyamide composition in Comparative Example 2, adipic acid was used instead of the modified diacid, and other conditions remained unchanged.

[0035] Performance Testing The weather-resistant polyamide compositions prepared in Examples 1-4 and Comparative Examples 1-2 were subjected to performance tests. The weather resistance of the samples was tested according to GB / T 16422.2-2022, the tensile properties of the samples were tested according to GB / T 1040.2-2022, the bending properties of the samples were tested according to GB / T 9341-2008, and the water absorption properties of the samples were tested according to GB / T 1034-2008. The test results are shown in Table 1: Table 1 As can be seen from the test results in Table 1, the weather resistance, mechanical strength, and water absorption of the polyamide composition can be effectively improved by using the methods of Examples 1-4. By comparing Comparative Example 1 with Examples 1-4, it can be found that when hexamethylenediamine is used instead of the modified diamine, the reduction rate of elongation at break is significantly higher than that of Examples 1-4, indicating that the use of the modified diamine can effectively improve the weather resistance of the material. At the same time, the 24-hour water absorption of Comparative Example 1 is significantly higher than that of Comparative Examples 1-4, indicating that the use of the modified diamine can effectively reduce the water absorption of the material. By comparing Comparative Example 2 with Examples 1-4, it can be found that when adipic acid is used instead of the modified diacid, the tensile strength and flexural strength are significantly reduced, indicating that the addition of the modified diacid can effectively improve the mechanical properties of the material.

[0036] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

[0037] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to specific embodiments. Obviously, many modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a weather-resistant polyamide composition, characterized in that: The following steps are involved: Step 1: Add modified diamine and modified diacid into a reactor, then add deionized water, heat and stir to react, and obtain a prepolymer; Step 2: Mixing and stirring the light stabilizer and the antioxidant to obtain a mixture; Step 3: Add the prepolymer and the mixed material into a high-pressure reactor, increase the temperature, and vacuumize the reactor for polycondensation reaction. After the reaction is completed, perform rotary evaporation, extrusion, and solidification to obtain a weather-resistant polyamide composition.

2. The method for preparing the weather-resistant polyamide composition according to claim 1, wherein The preparation method of the modified diamine comprises the following steps: Q1: Under argon protection, 4,7-dibromo-2,1,3-benzothiadiazole, potassium fluoride, cuprous iodide, and dimethyl sulfoxide were added to a container, stirred, heated, and refluxed. After the reaction was completed, the mixture was cooled and poured into ice water to precipitate a solid, which was filtered, washed, and purified to obtain product 1; Q2: Under nitrogen protection, product 1 and reduced iron powder are added to a container filled with anhydrous acetic acid, heated and stirred to react, and after the reaction is completed, cooled, filtered, extracted, washed, and dried to obtain product 2; product 2 is added to a container filled with anhydrous acetic acid, and then sodium nitrite solution is added dropwise. After the addition is completed, the reaction is carried out, filtered, washed, and dried to obtain product 3 and product 3' containing an N=N double bond; Q3: Under nitrogen protection, N,N-dimethylformamide and dimethyl sulfoxide were added to a container, followed by the mixture of product 3 and product 3' and potassium carbonate. The mixture was stirred and heated to react. 11-(bromomethyl)tricosane was then added, the mixture was heated to react, cooled, added to cold water, extracted, washed, dried, rotary evaporated, and purified to obtain product 4. Q4: Add concentrated sulfuric acid and concentrated nitric acid to a container, cool, add product 4 dropwise, react in an ice bath, remove from the ice bath and continue the reaction. After the reaction is completed, pour into a mixture of ice and water, stir, extract, wash, dry, rotary evaporate, purify, recrystallize, and vacuum dry to obtain product 5; under nitrogen protection, add product 5 and reduced iron powder to a container filled with anhydrous acetic acid, heat and stir to react, cool, extract, wash, dry, and purify to obtain modified diamine.

3. The method for preparing the weather-resistant polyamide composition according to claim 2, wherein In the Q1, the usage ratio of 4,7-dibromo-2,1,3-benzothiadiazole, potassium fluoride, cuprous iodide and dimethyl sulfoxide is (2.78-3.11) g: (1.27-1.45) g: (0.17-0.21) g: (100-200) mL.

4. The method for preparing the weather-resistant polyamide composition according to claim 2, wherein In Q2, the usage ratio of product 1, reduced iron powder and anhydrous acetic acid is (2.92-3.15) g: (11.4-12.21) g: (100-150) mL; the usage ratio of product 2, anhydrous acetic acid and sodium nitrite solution is (2.16-2.48) g: (100-120) mL: (20-30) mL.

5. The method for preparing the weather-resistant polyamide composition according to claim 2, wherein: In Q3, the usage ratio of N,N-dimethylformamide, dimethyl sulfoxide, the mixture of product 3 and product 3', potassium carbonate and 11-(bromomethyl)tricosane is (200-250) mL: (5-6.25) mL: (5.54-6.12) g: (5.53-6.08) g: (10.02-10.58) g.

6. The method for preparing the weather-resistant polyamide composition according to claim 2, wherein: In the Q4, the usage ratio of concentrated sulfuric acid, concentrated nitric acid and product 4 is (40-50) mL: (40-50) mL: (4.78-5.12) g, and the drop acceleration rate is 1 drop / s; the usage ratio of product 5, reduced iron and anhydrous acetic acid is (10.09-10.84) g: (1.34-1.68) g: (100-120) mL.

7. The method for preparing the weather-resistant polyamide composition according to claim 1, wherein: The preparation method of the modified diacid comprises the following steps: S1: 3-iodo-2-hydroxybenzoic acid and methanol are added to a container, followed by slow dropwise addition of thionyl chloride, followed by reflux reaction to obtain intermediate A; thionyl chloride is slowly added dropwise to a mixture of intermediate A and acetic anhydride, followed by heating reaction to obtain intermediate B; S2: Mix the intermediate B and the active copper powder, heat and react under argon protection, and obtain the intermediate C after the reaction. Add the intermediate C to a sodium hydroxide aqueous solution, and then add methanol and tetrahydrofuran, stir and react at room temperature, adjust the pH, cool, filter, wash, dry, and purify to obtain the modified diacid.

8. The method for preparing the weather-resistant polyamide composition according to claim 7, wherein: In S1, the usage ratio of 3-iodo-2-hydroxybenzoic acid, methanol, and thionyl chloride is (10-12) g: (100-120) mL: (2-2.5) mL; the usage ratio of intermediate A, acetic anhydride, and thionyl chloride is (10-12) g: (10-12) mL: (0.4-0.6) mL; and in S2, the usage ratio of intermediate B and active copper powder is (10-12) g: (11-12.5) g. The usage ratio of intermediate C, sodium hydroxide aqueous solution, methanol and tetrahydrofuran is (5-7.5) g: (100-120) mL: (60-80) mL: (130-150) mL.

9. The method for preparing the weather-resistant polyamide composition according to claim 1, wherein: In the step 1, the molar ratio of the modified diamine to the modified diacid is (0.9-1.2): (0.88-1.21); in the step 2, the amount ratio of the light stabilizer to the antioxidant is (0.1-0.4) g: (0.2-0.38) g; and in the step 3, the amount ratio of the prepolymer to the mixed material is (8-12) g: (0.12-0.26) g.

10. A weather-resistant polyamide composition prepared by the method for preparing a weather-resistant polyamide composition according to any one of claims 1 to 9.

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