High-toughness low-melting-point nylon resin, and preparation method and application thereof

Abstract

The application discloses a high-toughness low-melting-point nylon resin and a preparation method and application thereof. The high-toughness low-melting-point nylon resin is mainly prepared from the following components: long carbon chain dibasic acid, long carbon chain diamine, amino acid containing an ether bond, a catalyst and an end-capping agent, and water is used as a reaction medium. The preparation method comprises the following steps: (1) adding the long carbon chain dibasic acid, the long carbon chain diamine and water into a reaction kettle, and stirring to form a salt at room temperature; (2) adding the amino acid containing the ether bond, the catalyst and the end-capping agent, replacing air in the reaction kettle with an inert gas and filling the inert gas, and then performing a polycondensation reaction, and after filling the inert gas again, discharging the product. The high-toughness low-melting-point nylon resin is used in the technical field of automobile oil pipes, water pipes or energy storage equipment hoses. The high-toughness low-melting-point nylon resin has high toughness, low melting point and low water absorption, is diversified in products and is easy to process. The product obtained by the method has few by-products, the production process is simple, and the method is suitable for industrialized continuous production.

Description

Technical Field

[0001] This invention relates to a nylon resin, its preparation method, and its application, specifically to a high-toughness, low-melting-point nylon resin, its preparation method, and its application. Background Technology

[0002] Polyamide (PA), commonly known as nylon, is a resin obtained by the condensation polymerization of diacids and diamines or amino acids. It is a general term for resins whose molecular chains contain repeating amide groups. Nylon is the most produced, most diverse, widely used, and best-performing basic resin among the five major general-purpose engineering plastics. Nylon's leading position among the five engineering plastics is primarily due to its numerous superior properties, particularly in mechanical, chemical, and thermal properties. After more than 70 years of development, the application of nylon has expanded from spun fibers to films, engineering plastics, and other fields.

[0003] Low-melting-point nylon refers to modified products with a melting point lower than that of conventional nylon. Due to the presence of polar amide groups in its molecular chain, it exhibits excellent bonding properties to many polar materials and possesses advantages such as a narrow melting range, high softening point, rapid curing, resistance to dry cleaning with organic solvents, and no environmental pollution during use. Therefore, it has been widely used in hot melt adhesives, nonwoven fabrics, and engineering plastics. Currently, methods for synthesizing low-melting-point nylon include random copolymerization, blending, and other modification methods. Among these, random copolymerization modification is the most commonly used method for preparing low-melting-point nylon. Its main characteristics are relatively simple process and excellent results, making it widely applicable in hot melt adhesives and fiber spinning. However, it suffers from problems such as poor heat resistance of the comonomer, leading to polymer yellowing, high monomer residue, and the inability to simultaneously maintain mechanical properties.

[0004] CN102492135A discloses a method for synthesizing dimer acid-type nylon hot melt adhesive, which uses dimer acid, aliphatic dicarboxylic acid, and aliphatic diamine as raw materials, and adds a catalyst, an aqueous solution of alcohol, and additives to prepare low-melting-point nylon. However, the use of dimer acid in the formulation results in a yellowish color in the final product.

[0005] CN109970969A discloses a method for preparing ternary copolymer low-melting-point nylon. This low-melting-point nylon is mainly copolymerized from 2,4-diaminotoluene, aliphatic diamine, aliphatic diacid, and caprolactam (molar percentages are 10-38%, 10-38%, 35-48%, and 5-30%, respectively), and its melting point is between 70 and 150°C. Although the preparation method is simple and easy to operate, the amino group of 2,4-diaminotoluene is directly attached to the benzene ring, resulting in low reactivity and affecting the molecular weight of the low-melting-point nylon. In addition, the presence of caprolactam can easily lead to a certain amount of residual monomers and oligomers in the final product, which limits its application areas.

[0006] CN109722020A discloses an ultra-tough nylon composite material toughened with an amino-functionalized polyolefin elastomer and its preparation method. The ultra-tough nylon composite material is composed of 50-97 parts of nylon resin, 2-50 parts of amino-functionalized polyolefin elastomer, and 0-0.8 parts of antioxidant. Although its preparation process does not require the addition of peroxy crosslinking agents and polar monomers, effectively avoiding side reactions such as crosslinking and degradation during processing, the prepared high-toughness nylon composite material has good processing performance, tensile strength, and toughness. However, due to the poor compatibility between the amino-functionalized polyolefin elastomer and the nylon matrix, while improving the toughness of the nylon resin, other properties are inevitably sacrificed, and a significant reduction in the melting point of the nylon resin cannot be achieved, thus failing to balance the performance of all aspects.

[0007] In summary, there is an urgent need to find a high-toughness, low-melting-point nylon resin with high toughness, low melting point, low water absorption, diversified products, easy processing and applications, as well as a preparation method for a high-toughness, low-melting-point nylon resin with few by-products, simple production process, and suitable for continuous industrial production. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a high-toughness, low-melting-point nylon resin and its applications that are highly tough, have a low melting point, low water absorption, diversified products, and are easy to process.

[0009] The further technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a method for preparing high-toughness, low-melting-point nylon resin with fewer by-products, simple production process, and suitable for industrial continuous production.

[0010] The technical solution adopted by the present invention to solve its technical problem is as follows: a high-toughness, low-melting-point nylon resin, mainly made of the following components: long-chain dicarboxylic acid, long-chain diamine, amino acid containing ether bonds, catalyst and end-capping agent, and water as the reaction medium.

[0011] The inventive concept of this invention is as follows: The amide bonds in the nylon molecular chain have a significant impact on its thermal properties. Without amide bonds, its chemical structure is equivalent to polyethylene, with no hydrogen bonding between molecules, relying solely on weak van der Waals forces for interaction. In this case, nylon is merely a polymer with a melting point of 120°C, while nylon 6 has a melting point as high as approximately 220°C. Therefore, the presence of amide bonds increases the melting point of nylon. Reducing the proportion of amide bonds and increasing the number of carbon atoms between each amide bond can, to some extent, lower the melting point of nylon; for example, nylon 12 has a melting point of approximately 178°C. Based on the factors influencing the melting point of nylon, reducing the melting point should focus on the intermolecular forces, rigidity, regularity, and hydrogen bonding of the nylon molecular chains. This invention uses long-chain dicarboxylic acids and long-chain diamines as the main matrix, and introduces a certain proportion of amino acids containing ethoxy (i.e., ether bonds) repeating units as copolymerization modification components to disrupt the regularity of nylon molecular chains, reduce the hydrogen bond density and crystallinity between nylon molecular chains, thereby achieving the purpose of lowering the melting point of nylon resin and improving the toughness of nylon resin; at the same time, due to the long carbon chain structure of the matrix molecules, its macroscopic properties exhibit high impact resistance and low water absorption.

[0012] Preferably, the molar ratio of the long-chain dicarboxylic acid to the long-chain diamine is 1:1.0 to 1.10.

[0013] Preferably, the amounts of the ether-containing amino acid, catalyst, end-capping agent, and water are 10.0–30.0%, 0.18–0.42% (more preferably 0.18–0.30%), 0.3–0.8% (more preferably 0.3–0.6%), and 40–50% of the total mass of the long-chain dicarboxylic acid and the long-chain diamine, respectively.

[0014] Preferably, the long-chain dicarboxylic acid has the general structural formula HOOC-(CH2). n -COOH, where n is an integer from 8 to 16. More preferably, the long-chain dicarboxylic acid includes one or more of sebacic acid, dodecanoic acid, or octadecanoic acid.

[0015] Preferably, the long-chain diamine has the general structural formula NH2-(CH2). n -NH2, where n = an integer from 10 to 18. More preferably, the long-chain diamine includes one or more of decanediamine, dodecanediamine, or octadecanediamine.

[0016] Preferably, the ether-containing amino acid includes 1-amino-3,6,9,12-tetraoxopentadecane-15-acid, 1-amino-3,6,9,12,15-pentaoxoctadecane-18-acid, 1-amino-3,6,9,12,15,18-hexaoxotetradecane-21-acid, and 1-amino-3,6,9,12,15,18,21-heptaoxotetradecane-24-acid. One or more of the following: 1-amino-3,6,9,12,15,18,21,24-octaoxoheptadecane-27-acid, 1-amino-3,6,9,12,15,18,21,24,27-nonoxatritane-30-acid, or 1-amino-3,6,9,12,15,18,21,24,27,30-decaoxatritane-33-acid.

[0017] Preferably, the catalyst comprises one or more of sodium hypophosphite, potassium hypophosphite, calcium hypophosphite, or magnesium hypophosphite. The catalyst catalyzes the polycondensation reaction between a diacid and a diamine.

[0018] Preferably, the end-capping agent comprises a monoamino or monocarboxyl organosilicon, one or more of Shin-Etsu modified silicone oils KF-864, KF-865, KF-868, or X-22-3701E. The end-capping agent is monofunctional, and its function is to achieve end-capping, control the molecular weight, and obtain nylon resin with the desired molecular weight.

[0019] This invention allows for the control of the melting point of nylon resin between 122 and 160°C by adjusting the type and content of the copolymer components, thereby enabling the customization of product performance to meet the specific application requirements of various applications.

[0020] The technical solution adopted by the present invention to further solve its technical problem is as follows: A method for preparing high-toughness, low-melting-point nylon resin, comprising the following steps:

[0021] (1) Add long-chain dicarboxylic acid, long-chain diamine and water to a reaction vessel and stir at room temperature to form a salt to obtain a nylon salt solution;

[0022] (2) Add the amino acid containing ether bond, catalyst and end-capping agent to the nylon salt solution obtained in step (1), replace the air in the reactor with inert gas and fill it with inert gas, carry out polycondensation reaction, fill it with inert gas again, discharge the material, and obtain high toughness low melting point nylon resin.

[0023] Preferably, in step (2), the specific reaction process of the polycondensation reaction is as follows: first, a heating and pressure holding reaction is carried out, then the gas is slowly released and a second heating and pressure holding reaction is carried out, then the gas is released to normal pressure, the water in the system is discharged, and a vacuum is gradually drawn to carry out a decompression reaction.

[0024] Preferably, the single-stage heating and pressure-holding reaction refers to heating to 210–220°C and maintaining the pressure inside the reactor at 2.0–2.5 MPa for 1.5–2.0 hours. The purpose of the single-stage heating and pressure-holding reaction is mainly pre-polymerization to form oligomers.

[0025] Preferably, the slow venting and secondary heating and pressure holding reaction refers to: continuing to heat to 240-250°C, slowly venting during the heating process to maintain the pressure inside the reactor at 1.0-1.5 MPa (more preferably 1.1-1.3 MPa), and reacting for 1.0-2.0 h (more preferably 1.3-1.8 h). The purpose of the secondary heating and pressure holding reaction is mainly to carry out the chain growth reaction, remove water from the system and water generated by the condensation reaction, promote the reaction in the forward direction, and gradually increase the molecular weight.

[0026] Preferably, the stepwise vacuuming for the decompression reaction refers to: first, evacuating to -0.01 to -0.03 MPa and holding the pressure for 15 to 25 minutes; then evacuating to -0.03 to -0.05 MPa and holding the pressure for 15 to 25 minutes; finally, evacuating to -0.05 to -0.07 MPa and holding the pressure for 12 to 30 minutes. The vacuum level of each subsequent evacuation is greater than the previous one. Before stepwise vacuuming, releasing gas to atmospheric pressure can further remove moisture from the system. The purpose of stepwise vacuuming is to further remove water generated during the post-condensation reaction, i.e., the decompression reaction, promoting the reaction in the forward direction and further increasing the molecular weight. The initial vacuum level is relatively low to avoid the reaction becoming too vigorous, which could cause the extracted moisture and oligomers to clog the vacuum pipes. The vacuum level is gradually increased subsequently to remove as much moisture as possible, obtaining nylon resin with the desired molecular weight.

[0027] More preferably, the stepwise vacuuming for decompression reaction refers to: first, vacuuming to -0.01 to -0.02 MPa, then holding the pressure for 20 to 25 minutes; then, vacuuming to -0.03 to -0.04 MPa, then holding the pressure for 20 to 25 minutes; and finally, vacuuming to -0.05 to -0.06 MPa, then holding the pressure for 20 to 30 minutes.

[0028] Preferably, before the polycondensation reaction, the air in the reactor is replaced with inert gas 3 to 4 times and then filled with inert gas to 0.1 to 0.2 MPa.

[0029] Preferably, after the polycondensation reaction, an inert gas is introduced to a pressure of 0.2–0.3 MPa.

[0030] Preferably, the inert gas includes one or more of carbon dioxide, nitrogen, argon, or helium. The inert gas used in this invention is a high-purity gas with a purity ≥ 99.999%.

[0031] The technical solution adopted by the present invention to further solve its technical problem is as follows: the high-toughness, low-melting-point nylon resin is used in the technical fields of automotive oil pipes, water pipes or energy storage equipment hoses, etc.

[0032] The beneficial effects of this invention are as follows:

[0033] (1) The high-toughness, low-melting-point nylon resin of this invention has the characteristics of high toughness, low melting point, low water absorption, diversified products, and easy processing. Among them, the relative viscosity is as high as 2.52, the tensile strength reaches 47MPa, the elongation at break is as high as 382%, the flexural strength reaches 68MPa, and the notched impact strength is as high as 32kJ / m 2 With a melting point as low as 122℃ and a water absorption rate as low as 0.36%, it can replace imported high-performance nylon resin and be used in technical fields such as automotive oil pipes, water pipes, or energy storage equipment hoses.

[0034] (2) The product obtained by the method of the present invention has few by-products, the production process is simple, and it is suitable for industrial continuous production. Detailed Implementation

[0035] The present invention will be further described below with reference to the embodiments.

[0036] The inert gases used in the embodiments and comparative examples of this invention are high-purity gases with a purity of ≥99.999%; the raw materials or chemical reagents used in the embodiments of this invention, unless otherwise specified, are obtained through conventional commercial channels.

[0037] Examples 1-8 of a high-toughness, low-melting-point nylon resin

[0038] Examples 1-8 of a high-toughness, low-melting-point nylon resin are prepared from the following components: long-chain dicarboxylic acid, long-chain diamine, amino acid containing ether bonds, catalyst and end-capping agent, with water as the reaction medium; the components and their amounts are shown in Table 1.

[0039] The components and dosages of Comparative Examples 1 and 2 are shown in Table 1.

[0040] Table 1. Components and dosages of the high-toughness, low-melting-point nylon resin of the present invention in Examples 1-8 and Comparative Examples 1 and 2.

[0041]

[0042] Note: " / " in the table indicates that it has not been added.

[0043] Example 1: A method for preparing high-toughness, low-melting-point nylon resin

[0044] (1) Add 2.022 kg (10.00 mol) of long-chain dicarboxylic acid sebacic acid, 1.730 kg (10.04 mol) of long-chain diamine decanediamine and 1.501 kg of water (water / (dicarboxylic acid + diamine) = 40%, the same below) to the reaction vessel, stir at room temperature to form salt, and obtain nylon 1010 salt solution;

[0045] (2) 375.2 g of ether-containing amino acid 1-amino-3,6,9,12-tetraoxopentadecane-15-acid, 7.5 g of catalyst sodium hypophosphite, and 15.0 g of end-capping agent Shin-Etsu modified silicone oil KF-864 were added to the nylon 1010 salt solution obtained in step (1). The air in the reactor was replaced three times with high-purity nitrogen and then filled with high-purity nitrogen to 0.2 MPa. Then, a polycondensation reaction was carried out: the temperature was first raised to 212 ℃ and the pressure inside the reactor was maintained at 2.0 MPa. A first heating and pressure holding reaction was carried out for 1.5 h. The temperature was then raised to 250 ℃. During the heating process, the gas was slowly released to maintain the pressure inside the reactor at 1.2 MPa. A second heating and pressure holding reaction was carried out for 1.3 h. After h, the pressure inside the reactor was released to atmospheric pressure. After the water in the system was discharged, a vacuum pump was used to gradually evacuate the reactor for a reduced pressure reaction: first, the pressure was evacuated to -0.02 MPa and then maintained for 20 min; then, the pressure was evacuated to -0.04 MPa and maintained for 20 min; finally, the pressure was evacuated to -0.06 MPa and maintained for 30 min; then, high-purity nitrogen was introduced to 0.2 MPa, and the material was discharged to obtain high-toughness, low-melting-point nylon resin.

[0046] Example 2: A method for preparing a high-toughness, low-melting-point nylon resin

[0047] (1) Add 2.022 kg (10.00 mol) of long-chain dicarboxylic acid sebacic acid, 2.012 kg (10.04 mol) of long-chain diamine dodecanediamine and 1.614 kg of water (40%) to the reaction vessel and stir at room temperature to form a salt solution, thus obtaining a nylon 1210 salt solution;

[0048] (2) 403.4 g of ether-containing amino acid 1-amino-3,6,9,12-tetraoxopentadecane-15-acid, 7.8 g of catalyst sodium hypophosphite, and 16.0 g of end-capping agent Shin-Etsu modified silicone oil KF-864 were added to the nylon 1210 salt solution obtained in step (1). The air in the reactor was replaced three times with high-purity nitrogen and then filled with high-purity nitrogen to 0.2 MPa. The polycondensation reaction was then carried out: the temperature was first raised to 215 ℃ and the pressure inside the reactor was maintained at 2.2 MPa for a first heating and pressure holding reaction of 1.7 h. The temperature was then raised to 246 ℃, and the gas was slowly released during the heating process to maintain the pressure inside the reactor at 1.1 MPa. A second heating and pressure holding reaction was carried out for 1.5 h. After h, the pressure inside the reactor was released to atmospheric pressure. After the water in the system was discharged, a vacuum pump was used to gradually evacuate the reactor for a reduced pressure reaction: first, the pressure was evacuated to -0.02 MPa and then maintained for 20 min; then, the pressure was evacuated to -0.04 MPa and maintained for 20 min; finally, the pressure was evacuated to -0.06 MPa and maintained for 30 min; then, high-purity nitrogen was introduced to 0.2 MPa, and the material was discharged to obtain high-toughness, low-melting-point nylon resin.

[0049] Example 3: A method for preparing high-toughness, low-melting-point nylon resin

[0050] (1) Add 2.300 kg (10.00 mol) of long-chain dicarboxylic acid dodecanoic acid, 2.014 kg (10.05 mol) of long-chain diamine dodecanoic acid and 1.726 kg of water (40%) to a reaction vessel and stir at room temperature to form a salt solution, thus obtaining a nylon 1212 salt solution.

[0051] (2) 431.4 g of ether-containing amino acid 1-amino-3,6,9,12-tetraoxopentadecane-15-acid, 7.9 g of catalyst sodium hypophosphite, and 16.2 g of end-capping agent Shin-Etsu modified silicone oil KF-864 were added to the nylon 1212 salt solution obtained in step (1). The air in the reactor was replaced three times with high-purity nitrogen and then filled with high-purity nitrogen to 0.2 MPa. The polycondensation reaction was then carried out: the temperature was first raised to 216 ℃ and the pressure inside the reactor was maintained at 2.2 MPa for a first heating and pressure holding reaction of 1.8 h. The temperature was then raised to 245 ℃, and the gas was slowly released during the heating process to maintain the pressure inside the reactor at 1.1 MPa. A second heating and pressure holding reaction was carried out for 1.6 h. After h, the pressure inside the reactor was released to atmospheric pressure. After the water in the system was discharged, a vacuum pump was used to gradually evacuate the reactor for a reduced pressure reaction: first, the pressure was evacuated to -0.02 MPa and then maintained for 20 min; then, the pressure was evacuated to -0.04 MPa and maintained for 20 min; finally, the pressure was evacuated to -0.06 MPa and maintained for 30 min; then, high-purity nitrogen was introduced to 0.2 MPa, and the material was discharged to obtain high-toughness, low-melting-point nylon resin.

[0052] Example 4: A method for preparing a high-toughness, low-melting-point nylon resin

[0053] (1) Add 3.145 kg (10.00 mol) of long-chain dicarboxylic acid octadecanoic acid, 2.859 kg (10.05 mol) of long-chain diamine octadecanoic acid and 3.002 kg of water (50%) to the reaction vessel and stir at room temperature to form a salt solution, thus obtaining a nylon 1818 salt solution;

[0054] (2) 600.4 g of ether-containing amino acid 1-amino-3,6,9,12-tetraoxopentadecane-15-acid, 13.0 g of catalyst sodium hypophosphite, and 25.0 g of end-capping agent Shin-Etsu modified silicone oil KF-868 were added to the nylon 1818 salt solution obtained in step (1). The air in the reactor was replaced three times with high-purity nitrogen and then filled with high-purity nitrogen to 0.2 MPa. The polycondensation reaction was then carried out: the temperature was first raised to 218 ℃ and the pressure inside the reactor was maintained at 2.5 MPa. The reaction was carried out for 2.0 h with a first heating and pressure holding process. The temperature was then raised to 241 ℃. During the heating process, the gas was slowly released to maintain the pressure inside the reactor at 1.3 MPa. The reaction was then carried out for 1.8 h with a second heating and pressure holding process. After h, the pressure inside the reactor was released to atmospheric pressure. After the water in the system was discharged, a vacuum pump was used to gradually evacuate the reactor for a reduced pressure reaction: first, the pressure was evacuated to -0.02 MPa and then maintained for 20 min; then, the pressure was evacuated to -0.04 MPa and maintained for 20 min; finally, the pressure was evacuated to -0.06 MPa and maintained for 30 min; then, high-purity nitrogen was introduced to 0.2 MPa, and the material was discharged to obtain high-toughness, low-melting-point nylon resin.

[0055] Example 5: A method for preparing a high-toughness, low-melting-point nylon resin

[0056] (1) Add 2.300 kg (10.00 mol) of long-chain dicarboxylic acid dodecanoic acid, 2.014 kg (10.05 mol) of long-chain diamine dodecanoic acid and 1.726 kg of water (40%) to a reaction vessel and stir at room temperature to form a salt solution, thus obtaining a nylon 1212 salt solution.

[0057] (2) 647.1 g of ether-containing amino acid 1-amino-3,6,9,12-tetraoxoctadecano-15-acid, 8.0 g of catalyst magnesium hypophosphite and 16.5 g of end-capping agent Shin-Etsu modified silicone oil KF-865 were added to the nylon 1212 salt solution obtained in step (1), and the subsequent operations were the same as step (2) of Example 3 of the present invention.

[0058] Example 6: A method for preparing a high-toughness, low-melting-point nylon resin

[0059] (1) Add 2.300 kg (10.00 mol) of long-chain dicarboxylic acid dodecanoic acid, 2.014 kg (10.05 mol) of long-chain diamine dodecanoic acid and 1.726 kg of water (40%) to a reaction vessel and stir at room temperature to form a salt solution, thus obtaining a nylon 1212 salt solution.

[0060] (2) Add 862.8 g of ether-containing amino acid 1-amino-3,6,9,12-tetraoxoctadecano-15-acid, 8.3 g of catalyst magnesium hypophosphite and 16.8 g of end-capping agent Shin-Etsu modified silicone oil KF-865 to the nylon 1212 salt solution obtained in step (1), and the subsequent operations are the same as step (2) of Example 3 of the present invention.

[0061] Example 7: A method for preparing a high-toughness, low-melting-point nylon resin

[0062] (1) Add 2.300 kg (10.00 mol) of long-chain dicarboxylic acid dodecanoic acid, 2.014 kg (10.05 mol) of long-chain diamine dodecanoic acid and 1.726 kg of water (40%) to a reaction vessel and stir at room temperature to form a salt solution, thus obtaining a nylon 1212 salt solution.

[0063] (2) Add 1078.5 g of ether-containing amino acid 1-amino-3,6,9,12,15,18-hexaoxodocosane-21-acid, 9.0 g of catalyst magnesium hypophosphite and 18.0 g of end-capping agent Shin-Etsu modified silicone oil KF-865 to the nylon 1212 salt solution obtained in step (1), and the subsequent operations are the same as step (2) of Example 3 of the present invention.

[0064] Example 8: A method for preparing a high-toughness, low-melting-point nylon resin

[0065] (1) Add 2.300 kg (10.00 mol) of long-chain dicarboxylic acid dodecanoic acid, 2.014 kg (10.05 mol) of long-chain diamine dodecanoic acid and 1.726 kg of water (40%) to a reaction vessel and stir at room temperature to form a salt solution, thus obtaining a nylon 1212 salt solution.

[0066] (2) 1294.2 g of ether-containing amino acid 1-amino-3,6,9,12,15,18,21,24,27-nonoxatriane-30-acid, 10.0 g of catalyst magnesium hypophosphite, and 20.0 g of end-capping agent Shin-Etsu modified silicone oil X-22-3701E were added to the nylon 1212 salt solution obtained in step (1). The subsequent operations were the same as step (2) of Example 3 of the present invention.

[0067] Application Examples of a High-Toughness, Low-Melting-Point Nylon Resin 1-8

[0068] Examples 1-8 of high-toughness, low-melting-point nylon resins were applied to the fields of automotive oil pipes, water pipes, or energy storage equipment hoses.

[0069] Comparative Example 1

[0070] The only difference between Comparative Example 1 and Method Example 1 is that in step (2), 375.2 g of 1-amino-3,6,9,12-tetraoxopentadecane-15-acid is not added, and 15.0 g of Shin-Etsu modified silicone oil KF-864 is replaced with 15.0 g of benzoic acid. The rest is the same as in Method Example 1 of this invention.

[0071] Comparative Example 2

[0072] The only difference between Comparative Example 1 and Method Example 1 is that the molar ratio of 2.022 kg (10.00 mol) of the long-chain dicarboxylic acid sebacic acid and 1.981 kg (11.50 mol) of the long-chain diamine decanediamine is 1:1.15. The rest is the same as in Method Example 1 of this invention.

[0073] To evaluate the relative viscosity, mechanical properties, heat resistance, and water absorption properties of the high-toughness, low-melting-point nylon resins of Examples 1-8 and Comparative Examples 1 and 2 of the present invention, tests were conducted under the following conditions:

[0074] Relative viscosity test conditions: The samples of the examples and comparative examples were placed in a vacuum drying oven at 120℃ for 4 hours and a concentrated sulfuric acid solution with a concentration of 0.010 g / mL was prepared. The solution was tested using an automatic viscometer in accordance with the standard GB / T 38138-2019.

[0075] Tensile strength and elongation at break test conditions: The tensile specimens were placed in a constant temperature and humidity chamber for 24 hours and tested using a testing machine in accordance with standard GB / T 1040.2-2006;

[0076] Bending strength test conditions: The bending specimen was placed in a constant temperature and humidity chamber for 24 hours and tested using a testing machine in accordance with standard GB / T 9341-2008;

[0077] Notched impact strength test conditions: The impact specimen was placed in a constant temperature and humidity chamber for 24 hours and tested using a testing machine in accordance with standard GB / T 1043.1-2008;

[0078] Melting point test conditions: Weigh 5-10 mg of the sample from the examples and comparative examples, heat the sample to 340℃ for 3 min under high-purity nitrogen protection, quench it with liquid nitrogen, then heat the quenched sample to 350℃, cool it to room temperature, and then heat it to 350℃ again. The heating rate is 10℃ / min, referring to standard GB / T 19466.3-2004.

[0079] Water absorption test conditions: The samples of the examples and comparative examples were dried in an oven at 100°C and cooled in the oven. The tests were conducted in accordance with the standard ASTM D570-98.

[0080] The results are shown in Table 2.

[0081] Table 2. Comparison of performance data of the high-toughness, low-melting-point nylon resin of the present invention in Examples 1-8 and Comparative Examples 1 and 2.

[0082]

[0083] As shown in Table 2, the high-toughness, low-melting-point nylon resins obtained in Examples 1-8 of the present invention have a relative viscosity as high as 2.52, a tensile strength of 47 MPa, an elongation at break of 382%, a flexural strength of 68 MPa, and a notched impact strength of 32 kJ / m. 2 The high-toughness, low-melting-point nylon resin obtained in Example 1 of this invention has a melting point as low as 122℃ and a water absorption rate as low as 0.36%. Compared with Comparative Example 1, the high-toughness, low-melting-point nylon resin obtained in Example 1 maintains high mechanical strength while significantly improving elongation at break and notched impact strength, with a melting point reduction of nearly 20%. In Comparative Example 2, the molar ratio of long-chain dicarboxylic acid to long-chain diamine exceeds the range of 1:1.0 to 1.10, resulting in a lower relative viscosity of the obtained nylon resin and a significant reduction in overall performance parameters. Furthermore, the method of this invention has the characteristics of fewer by-products, simple production process, and suitability for continuous industrial production. The obtained high-toughness, low-melting-point nylon resin can replace imported high-performance nylon resins and can be used in technical fields such as automotive oil pipes, water pipes, or energy storage equipment hoses.

Claims

1. A high-toughness, low-melting-point nylon resin, characterized in that, It is mainly composed of the following components: long-chain dicarboxylic acid, long-chain diamine, ether-containing amino acid, catalyst, and capping agent, with water as the reaction medium; the molar ratio of the long-chain dicarboxylic acid to the long-chain diamine is 1:1.0–1.10; the amounts of the ether-containing amino acid and the capping agent are 10.0–30.0% and 0.3–0.8% of the total mass of the long-chain dicarboxylic acid and the long-chain diamine, respectively; the general structural formula of the long-chain dicarboxylic acid is HOOC-(CH2). n -COOH, where n = an integer from 8 to 16; the general structural formula of the long-chain diamine is NH2-(CH2). n -NH2, where n = an integer from 10 to 18; the ether-containing amino acids include 1-amino-3,6,9,12-tetraoxopentadecane-15-acid, 1-amino-3,6,9,12,15-pentaoxoctadecane-18-acid, 1-amino-3,6,9,12,15,18-hexaoxotetradecane-21-acid, 1-amino-3,6,9,12,15,18,21-heptaoxotetradecane-24-acid, 1-amino-3,6,9,12,15,18,21-heptaoxotetradecane-24-acid, 1-amino-3,6,9,12,1... The end-capping agent comprises one or more of the following: 5,18,21,24-octaoxoheptadecano-27-acid, 1-amino-3,6,9,12,15,18,21,24,27-nonoxatritane-30-acid, or 1-amino-3,6,9,12,15,18,21,24,27,30-decaoxatritane-33-acid; 2. The high-toughness, low-melting-point nylon resin according to claim 1, characterized in that: The amounts of catalyst and water used are 0.18–0.42% and 40–50% of the total mass of long-chain dicarboxylic acid and long-chain diamine, respectively.

3. The high-toughness, low-melting-point nylon resin according to claim 1 or 2, characterized in that: The catalyst includes one or more of sodium hypophosphite, potassium hypophosphite, calcium hypophosphite, or magnesium hypophosphite.

4. A method for preparing the high-toughness, low-melting-point nylon resin as described in any one of claims 1 to 3, characterized in that, Includes the following steps: (1) Add long-chain dicarboxylic acid, long-chain diamine and water to a reaction vessel and stir at room temperature to form a salt to obtain a nylon salt solution; (2) Add the amino acid containing ether bond, catalyst and end-capping agent to the nylon salt solution obtained in step (1), replace the air in the reactor with inert gas and fill it with inert gas, carry out polycondensation reaction, fill it with inert gas again, discharge the material, and obtain high toughness low melting point nylon resin.

5. The method for preparing high-toughness, low-melting-point nylon resin according to claim 4, characterized in that: In step (2), the specific reaction process of the polycondensation reaction is as follows: first, a heating and pressure holding reaction is carried out, followed by slow gas release and a second heating and pressure holding reaction, then gas release to atmospheric pressure, water in the system is discharged, and a vacuum is gradually drawn for a decompression reaction; the first heating and pressure holding reaction refers to: heating to 210-220℃ and maintaining the pressure inside the reactor at 2.0-2.5MPa for 1.5-2.0h; the slow gas release and second heating and pressure holding reaction refers to: continuing to heat to 240-250℃, slowly releasing gas during the heating process to maintain the pressure inside the reactor at 1.0-1.5MPa for 1.0-2.0h; the gradual vacuuming reaction refers to: The step-by-step vacuum reduction reaction refers to: first, evacuating to -0.01 to -0.03 MPa, maintaining the pressure for 15 to 25 minutes; then evacuating to -0.03 to -0.05 MPa, maintaining the pressure for 15 to 25 minutes; finally, evacuating to -0.05 to -0.07 MPa, maintaining the pressure for 12 to 30 minutes. Before the polycondensation reaction, the air in the reactor is replaced with inert gas 3 to 4 times and then filled with inert gas to 0.1 to 0.2 MPa. After the polycondensation reaction, inert gas is filled to 0.2 to 0.3 MPa. The inert gas includes one or more of nitrogen, argon, or helium.

6. The application of a high-toughness, low-melting-point nylon resin as described in any one of claims 1 to 3, characterized in that: The high-toughness, low-melting-point nylon resin is used in the field of automotive oil pipes, water pipes, or energy storage equipment hoses.

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