A novel method for the low temperature green preparation of glutaric / succinic based aliphatic nylons

Abstract

The application belongs to the field of nylon polymers, and particularly relates to a novel method for preparing glutaric acid / succinic acid-based aliphatic nylon at low temperature in a green manner, and specifically comprises the following steps: (1) mixing aliphatic diamine, glutaric acid and / or succinic acid, water and a catalyst in a polymerization kettle according to a certain proportion, and ensuring that the reaction system is sealed and in an oxygen-free environment; when the interior of the polymerization kettle reaches a predetermined temperature and the pressure rises to a first predetermined pressure, maintaining the temperature and pressure for a certain time; then releasing the gas to a second predetermined pressure within a certain time, and maintaining the temperature at the second predetermined pressure for a period of time, and discharging to obtain a powdered nylon prepolymer; (2) placing the powdered nylon prepolymer into a solid-phase post-polymerization reactor, heating the system to a predetermined temperature under vacuum, and maintaining the temperature and pressure for a certain time, and obtaining a nylon polymer with a higher viscosity. The method for preparing glutaric acid / succinic acid-based aliphatic nylon has a temperature lower than the melting point of the polymer in all reaction stages, and a large amount of water and a low polymerization temperature reduce the cyclization reaction of glutaric acid / succinic acid in the polymerization process, so that a nylon product with a high viscosity can be obtained.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of nylon polymer preparation, and particularly relates to a novel method for low-temperature green preparation of glutaric acid / succinic acid-based aliphatic nylon. BACKGROUND

[0002] Polyamide, commonly known as nylon, is a general term for a kind of high molecular polymer containing amide bond repeating structure in the main chain. Due to its good mechanical properties, excellent wear resistance and chemical resistance, it is widely used in many fields such as automobile parts, electronics and electrical appliances, aerospace, medical applications, etc. With the sustainable development of society, people have put forward urgent demand for high-performance, functional and green and environmentally friendly polyamides.

[0003] Glutaric acid, also known as 1,3-propane dicarboxylic acid and gum acid, and succinic acid, also known as succinic acid and 1,2-ethane dicarboxylic acid. These two kinds of dibasic acids are very important organic chemical synthesis raw materials, which can react with dibasic amine to prepare nylon. However, when succinic acid and glutaric acid are polymerized with dibasic amine, five-membered ring and six-membered ring imides are easily formed, which leads to the termination of polymerization reaction, the molecular weight of the polymerization product is low, and the performance cannot meet the application requirements. The higher the temperature, the more significant the ring formation phenomenon. Therefore, there is no industrialized nylon 65 product on the market.

[0004] The technical breakthrough of inhibiting ring formation reaction and improving the molecular weight of the polymerization product can not only expand the application field of succinic acid and glutaric acid, but also increase the new varieties of high-performance nylon and improve its added value.

[0005] Patents CN111253568A, CN112920401A, and papers - synthesis and performance characterization of nylon 65, synthesis and performance research of bio-based polyamide 55 (PA55), synthesis and structure research of copolyamide PA5T / 54, etc. all study the preparation of nylon by polymerizing glutaric acid / succinic acid with diamine. Patent CN111253568A reports a method for preparing nylon 65 polymer, including the following steps: (1) glutaric acid is dissolved in S1 solvent to prepare a glutaric acid solution; hexamethylene diamine is dissolved after heating and then dissolved in S2 solvent to prepare a hexamethylene diamine solution; (2) the hexamethylene diamine solution is added dropwise to the glutaric acid solution in a 40-80℃ water bath and stirred to prepare nylon 65 salt and refine it; (3) the refined nylon 65 salt is prepared into a salt solution and then added to a reactor, which is protected by inert gas, and the reaction is carried out at 150-190℃ and a pressure of 1.2-1.8MPa; the pressure in the reactor is reduced to normal pressure, and the condensation is carried out at 200-250℃, and finally vacuum is applied to obtain nylon 65 polymer. In this patent, the salt needs to be formed before polymerization, and organic solvents are used during the salt formation process, which puts higher requirements on safety production and solvent recovery; in patent CN112920401A, the authors use a melt polymerization method for polymerization. Including the following steps: the nylon 65 salt synthesized by the method disclosed in patent (CN108285532B) is placed in a normal pressure reaction vessel, inert gas is introduced to isolate the system from oxygen, the temperature of the system is increased from room temperature to the pre-polymerization temperature (above the melting point temperature of nylon 65 salt) at a certain heating rate, the solid salt is melted, after a certain time of heat preservation, the temperature is increased to the polymerization temperature (near the melting point temperature of nylon 65), and then reacted for a certain time to obtain nylon 65. In this patent (CN112920401A), the reaction is carried out under inert atmosphere at normal pressure. This patent has the following problems: (1) Claim 1(1) indicates that the reaction is carried out at a certain heating rate to 160-200℃ for melt pre-polymerization. Under this condition, the nylon 65 salt will decompose and be carried out of the reactor by the flowing inert gas, causing loss of reactants, imbalance of acid-amine molar ratio, and environmental pollution. (2) The pre-polymer is melt-reacted at 220-260℃, and the melting point of nylon 65 is around 245℃, so the polymerization reaction temperature is higher than its melting point. Under this condition, a large amount of cyclization reaction will occur. Imbalance of carboxyl and amine groups in the pre-polymer and cyclization of the molecular chain end groups will cause the final product to have a lower molecular weight and poor mechanical properties. As shown in the patent specification

[0068] , the maximum tensile strength of the product sample is only 6.42MPa; in the paper "Synthesis and Performance Characterization of Nylon 65" by Shao Zi Hua, the authors obtained nylon 65 polymer by melt polymerization of nylon 65 salt followed by solid-phase polymerization, and the relative viscosity of the nylon 65 polymer was only 2.1, which is still relatively low, and the paper does not discuss the effect of cyclization reaction on the molecular chain of the polymerization product.According to its reaction conditions, the reason for the low viscosity is most likely due to the cyclization reaction preventing the growth of the nylon 65 molecular chain, resulting in a relatively low viscosity. In reference [4] (Synthesis and performance study of bio-based polyamide 55 (PA55)), the authors used melt polymerization followed by solid-state polymerization and direct solid-state polymerization to polymerize nylon 55 and finally obtained a nylon 55 polymer with a relative viscosity of 2.26. The product viscosity was still low. In order to further improve the product viscosity, the method of adding a third monomer for copolymerization was used to obtain a copolymer product with a maximum viscosity of 2.79, but its melting point was significantly lower than that of the nylon 55 polymer. In reference (Synthesis and structural study of copolyamide PA5T / 54), the authors used the direct solid-state polymerization method of nylon 5T / 54 salt to prepare a semi-aromatic nylon PA5T / 54 with a higher molecular weight. The main feature of this method is that the nylon salt is polymerized in the solid state, which can obtain a product with a higher molecular weight. The preparation of the copolymer studied in this literature has a low proportion of succinic acid, which is prone to cyclization reaction, in the reaction monomer. At the same time, this method requires strict control of reaction conditions and high-level reaction equipment.

[0006] This shows that currently, glutaric acid and succinic acid, as monomers for nylon polymerization, are typically used to first prepare nylon salts, which are then used to produce nylon products through melt polymerization. During melt polymerization, the reaction temperature is higher than the melting points of the nylon salts and the products. This higher reaction temperature leads to cyclization reactions, resulting in lower molecular weights for the products, which do not yet meet the requirements for industrial production as high-performance materials. Summary of the Invention

[0007] The purpose of this invention is to provide a novel low-temperature, green method for preparing glutaric acid / succinic acid-based aliphatic nylon. This method does not require the prior preparation of nylon salts. In the presence of water, the reactants, dicarboxylic acid and diamine, undergo prepolymerization and solid-state postpolymerization reactions at temperatures below the melting point of the nylon polymer product, thereby producing high-quality, high-viscosity nylon products.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A novel method for the low-temperature, green preparation of glutaric acid / succinic acid-based aliphatic nylon includes the following steps:

[0010] (1) Aliphatic diamine, diacid, water and catalyst are added to a polymerization reactor in a certain proportion and mixed. The reaction system is sealed and in an oxygen-free environment. When the inside of the polymerization reactor is heated to a predetermined temperature of 180-220℃ and the pressure rises to the first predetermined pressure of 0.9-2.2MPa, the temperature and pressure are maintained for 0.5-1.5h. Then, the gas is released to the second predetermined pressure of 0.3-0.9MPa within 0.5-2h, and the temperature is maintained for 0.5-1.5h. The material is discharged to obtain powdered nylon prepolymer. The diacid is one or a combination of two of glutaric acid and succinic acid.

[0011] (2) Place the powdered nylon prepolymer into a solid-phase post-polymerization reactor, heat the system to a predetermined temperature of 200-240℃ under vacuum conditions, keep it at the temperature and pressure for 4-20h, and then discharge the material at a temperature below 50℃ to obtain the powdered nylon polymer.

[0012] This invention discloses a novel method for the low-temperature preparation of glutaric acid / succinic acid-based aliphatic nylon. The method primarily involves conducting a polymerization reaction under conditions below the melting point of the nylon product and in the presence of water, resulting in a high-viscosity polymerized product. The principle is based on in-depth analysis of the macromolecular chain growth mechanism during nylon polymerization using glutaric acid and succinic acid as reactants. It was discovered that during the condensation polymerization of glutaric acid or succinic acid with diamines, in addition to the main reaction where the carboxyl and amine groups react to form amide bonds and nylon macromolecules, the terminal carboxyl groups also undergo a dehydration reaction with adjacent amide groups on the macromolecular chain, forming six- or five-membered cyclic imide units. This caps the macromolecular chain, rendering it inactive and preventing further chain growth, which is the main reason for the low molecular weight of the product. Based on the principle that high temperatures favor imide cyclization and the reaction mechanism involving the removal of water molecules during cyclization, this invention proposes a technical route for conducting condensation polymerization under low-temperature and aqueous conditions to inhibit cyclization and promote nylon macromolecular chain growth, thereby obtaining a higher molecular weight nylon product.

[0013] As a further preferred embodiment of the present invention, in step (1), the amount of water used is (10-100) wt% of the weight of the diamine and dicarboxylic acid raw materials;

[0014] As a further preferred embodiment of the present invention, in step (1), the diamine is one or a mixture of two or more of butanediamine, pentapentinediamine, hexanediamine, decanedine, dodecanediamine, tridecanediamine, and tetradecanediamine.

[0015] As a further preferred embodiment of the present invention, in step (1), in order to increase the degree of reaction between the diamine and the diacid and obtain a product with a higher molecular weight, the molar ratio of the two should be made as close as possible. Preferably, the molar ratio of the diamine and the diacid is 0.99-1.02:1, more preferably 1.01:1.

[0016] As a further preferred embodiment of the present invention, to better control the degree of polymerization reaction, the catalyst is preferably one or a mixture of two or more of the following: phosphorous acid, sodium hypophosphite, triphenyl phosphate, H10, stannous chloride, potassium iodide, and copper acetate, and the amount of catalyst used is (0.05-0.5) wt% of the total mass of the nylon salt.

[0017] In step (1) of this invention, the predetermined temperature for the prepolymerization stage is 180-220℃, the predetermined pressure is 0.9-2.2MPa, and the holding time is 0.5-1.5h. During the prepolymerization process, the reaction temperature is lower than the melting point of the polymer product. Under the conditions of a large amount of water and the predetermined temperature, the reactants are in a liquid state. Since the equilibrium constant of the reaction between amine and carboxyl groups is about 300, the amidation reaction can still proceed even in the presence of water, but the end-group conversion rate is low and the molecular weight of the product is not high. Low temperature and water can inhibit the cyclization reaction, which is beneficial to the solid-state polymerization reaction in step (2).

[0018] The venting time during the prepolymerization stage is 0.5-2 hours, the venting pressure is 0.3-0.9 MPa, and the holding time at the predetermined pressure is 0.5-1.5 hours. The purpose of venting to the predetermined pressure in this invention is to reduce moisture content, promote the polymerization reaction towards the product direction, improve monomer conversion, and obtain a prepolymer with a higher molecular weight. When the prepolymerization reaction reaches the predetermined time, the discharge valve is opened to discharge the material. Because the pressure drops sharply when the prepolymer product is discharged from the reactor, the moisture instantly vaporizes, resulting in a powdery product.

[0019] In step (2), the solid-state post-polymerization temperature is 200-240℃, the reaction time is 4-20h, and the pressure is 1-100Pa. Under the predetermined reaction temperature and pressure conditions, the solid-state post-polymerization reaction occurs at a temperature lower than the melting point of the prepolymer. In solid-state reactions, the macromolecular chains have weak mobility, and the probability of the terminal carboxyl groups reacting with adjacent amide groups to form cyclic imides is low. Simultaneously, the powder state of the material and the vacuum conditions facilitate the diffusion of the reaction byproduct water, further increasing the molecular weight of the nylon. The reaction temperature and reaction time depend on the type of nylon, the required molecular weight of the product, and the vacuum level.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) By using a lower reaction temperature and maintaining a certain water content in the system during the prepolymerization process, the reaction between glutaric acid / succinic acid and diamine can be effectively suppressed, which is conducive to the growth of nylon macromolecular chains and thus obtains nylon products with higher molecular weight.

[0022] (2) The nylon polymer is discharged as powder during the prepolymerization stage, and remains in powder form during the solid-phase polymerization stage. This process is beneficial for suppressing cyclization side reactions and for removing moisture from byproducts, thus shortening the reaction time and improving polymerization efficiency. The nylon material prepared by this technology has a high molecular weight, which meets the material performance requirements of engineering fields. Attached Figure Description

[0023] Figure 1 The image shows the FT-IR image of nylon 65 obtained in Example 1.

[0024] Figure 2 The nylon 65 obtained in Example 1 1 H-NMR spectrum. Detailed Implementation Plan

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described below in conjunction with specific embodiments.

[0026] Example 1

[0027] This embodiment presents a novel method for the low-temperature, green preparation of glutaric acid / succinic acid-based aliphatic nylon, comprising the following steps:

[0028] (1) Add 705g hexamethylenediamine, 795g glutaric acid, 750g water and 3g sodium hypophosphite into a polymerization reactor and seal it. Replace the air in the polymerization reactor three times with an inert gas (nitrogen) to make the polymerization reactor an oxygen-free environment; first raise the temperature inside the reactor to 200℃, at which point the first predetermined pressure is 1.5MPa, keep it at the temperature and pressure for 0.5h, then release the gas to the second predetermined pressure of 0.6MPa after 1.5h, and keep it at the second predetermined pressure of 0.6MPa for 1h, then discharge the material to obtain powdered nylon 65 prepolymer;

[0029] (2) Place the powdered nylon 65 prepolymer into the solid-phase post-polymerization reactor and seal it. Replace the gas in the solid-phase post-polymerization reactor with inert gas three times, turn on the vacuum system, pump the absolute pressure inside the equipment to 1-100 Pa, raise the internal temperature of the reactor to 220℃, and keep it at the temperature and pressure for 6 hours. Then, cool it down to below 50℃ and discharge the material to finally obtain the powdered nylon 65 polymer.

[0030] Example 2

[0031] This embodiment presents a novel method for the low-temperature, green preparation of glutaric acid / succinic acid-based aliphatic nylon, comprising the following steps:

[0032] (1) Add 699g of pentanediamine, 801g of succinic acid, 750g of water and 3g of sodium hypophosphite into a polymerization reactor and seal it. Replace the air in the polymerization reactor three times with an inert gas (nitrogen) to make the polymerization reactor an oxygen-free environment. First raise the temperature inside the reactor to 200℃, at which point the first predetermined pressure is 1.5MPa. Maintain the temperature and pressure for 0.5h, then release the gas to the second predetermined pressure of 0.6MPa after 1.5h, and maintain the temperature at the second predetermined pressure of 0.6MPa for 1h. Discharge the material to obtain powdered nylon 54 prepolymer.

[0033] (2) Place the powdered nylon 54 prepolymer into the solid-phase post-polymerization reactor and seal it. Replace the gas in the solid-phase post-polymerization reactor with inert gas three times, turn on the vacuum system, pump the absolute pressure inside the equipment to 1-100Pa, raise the internal temperature of the reactor to 220℃, and keep it at the temperature and pressure for 6 hours. Then, cool it down to below 50℃ and discharge the material to finally obtain the powdered nylon 54 polymer.

[0034] Example 3

[0035] This embodiment presents a novel method for the low-temperature, green preparation of glutaric acid / succinic acid-based aliphatic nylon, comprising the following steps:

[0036] (1) Add 657g of pentanediamine, 843g of glutaric acid, 750g of water and 3g of sodium hypophosphite into a polymerization reactor and seal it. Replace the air in the polymerization reactor three times with an inert gas (nitrogen) to make the polymerization reactor an oxygen-free environment. First raise the temperature inside the reactor to 200℃, at which point the first predetermined pressure is 1.5MPa. Maintain the temperature and pressure for 0.5h, then release the gas to the second predetermined pressure of 0.6MPa after 1.5h, and maintain the temperature at the second predetermined pressure of 0.6MPa for 1h. Discharge the material to obtain powdered nylon 55 prepolymer.

[0037] (2) Place the powdered nylon 55 prepolymer into the solid-phase post-polymerization reactor and seal it. Replace the gas in the solid-phase post-polymerization reactor with inert gas three times, turn on the vacuum system, pump the absolute pressure inside the equipment to 1-100Pa, raise the internal temperature of the reactor to 220℃, and keep it at the temperature and pressure for 6 hours. Then, cool it down to below 50℃ and discharge the material to finally obtain the powdered nylon 55 polymer.

[0038] Example 4

[0039] This embodiment presents a novel method for the low-temperature preparation of green glutaric acid / succinic acid-based aliphatic nylon. The only difference between this method and Example 1 is the molar ratio of diamine to diacid. All other process parameters are the same as in Example 1. In this embodiment, the molar ratio of diamine to diacid is 1:0.99.

[0040] Example 5

[0041] This embodiment presents a novel low-temperature green method for preparing glutaric acid / succinic acid-based aliphatic nylon. The only difference between this embodiment and Example 1 is the molar ratio of diamine to diacid. All other process parameters are the same as in Example 1. In this embodiment, the molar ratio of diamine to diacid is 1:1.02.

[0042] Example 6

[0043] This embodiment presents a novel method for the low-temperature, green preparation of glutaric acid / succinic acid-based aliphatic nylon. The only difference between this method and Example 1 is the reaction temperature during the prepolymerization stage. All other process parameters are the same as in Example 1. In this embodiment, the reaction temperature during the prepolymerization stage is 180°C.

[0044] Example 7

[0045] This embodiment presents a novel method for the low-temperature, green preparation of glutaric acid / succinic acid-based aliphatic nylon. The only difference between this embodiment and Example 1 is the reaction temperature during the prepolymerization stage. All other process parameters are the same as in Example 1. In this embodiment, the reaction temperature during the prepolymerization stage is 220°C.

[0046] Example 8

[0047] This embodiment presents a novel method for the low-temperature green preparation of glutaric acid / succinic acid-based aliphatic nylon. The only difference between this method and Example 1 is the gas release time during the prepolymerization stage. All other process parameters are the same as in Example 1. In this embodiment, the gas release time during the prepolymerization stage is 0.5 h.

[0048] Example 9

[0049] This embodiment presents a novel method for the low-temperature green preparation of glutaric acid / succinic acid-based aliphatic nylon. The only difference between this method and Example 1 is the gas release time during the prepolymerization stage. All other process parameters are the same as in Example 1. In this embodiment, the gas release time during the prepolymerization stage is 2 hours.

[0050] Example 10

[0051] This embodiment presents a novel method for the low-temperature green preparation of glutaric acid / succinic acid-based aliphatic nylon. The only difference between this method and Example 1 is the second predetermined pressure in the prepolymerization stage. All other process parameters are the same as in Example 1. In this embodiment, the second predetermined pressure in the prepolymerization stage is 0.3 MPa.

[0052] Example 11

[0053] This embodiment presents a novel method for the low-temperature green preparation of glutaric acid / succinic acid-based aliphatic nylon. The only difference between this method and Example 1 is the second predetermined pressure in the prepolymerization stage. All other process parameters are the same as in Example 1. In this embodiment, the second predetermined pressure in the prepolymerization stage is 0.5 MPa.

[0054] Example 12

[0055] This embodiment presents a novel method for the low-temperature green preparation of glutaric acid / succinic acid-based aliphatic nylon. The only difference between this method and Example 1 is the second predetermined pressure in the prepolymerization stage. All other process parameters are the same as in Example 1. In this embodiment, the second predetermined pressure in the prepolymerization stage is 0.9 MPa.

[0056] Example 13

[0057] This embodiment presents a novel method for the low-temperature green preparation of glutaric acid / succinic acid-based aliphatic nylon. The only difference between this method and Example 1 is the holding time under the second predetermined pressure during the prepolymerization stage. All other process parameters are the same as in Example 1. In this embodiment, the holding time under the second predetermined pressure during the prepolymerization stage is 0.5 h.

[0058] Example 14

[0059] This embodiment presents a novel method for the low-temperature green preparation of glutaric acid / succinic acid-based aliphatic nylon. The only difference between this method and Example 1 is the holding time under the second predetermined pressure during the prepolymerization stage. All other process parameters are the same as in Example 1. In this embodiment, the holding time under the second predetermined pressure during the prepolymerization stage is 1.5 hours.

[0060] Example 15

[0061] This embodiment presents a novel method for the low-temperature, green preparation of glutaric acid / succinic acid-based aliphatic nylon. The only difference between this method and Example 1 is the polymerization temperature during the post-solid-phase polymerization stage. All other process parameters are the same as in Example 1. In this embodiment, the polymerization temperature during the post-solid-phase polymerization stage is 200°C.

[0062] Example 16

[0063] This embodiment presents a novel method for the low-temperature, green preparation of glutaric acid / succinic acid-based aliphatic nylon. The only difference between this method and Example 1 is the polymerization temperature during the post-solid-phase polymerization stage. All other process parameters are the same as in Example 1. In this embodiment, the polymerization temperature during the post-solid-phase polymerization stage is 240°C.

[0064] Example 17

[0065] This embodiment presents a novel method for the low-temperature, green preparation of glutaric acid / succinic acid-based aliphatic nylon. The only difference between this method and Example 1 is the polymerization reaction time in the post-solid phase polymerization stage. Other process parameters are the same as in Example 1. In this embodiment, the polymerization reaction time in the post-solid phase polymerization stage is 4 hours.

[0066] Example 18

[0067] This embodiment presents a novel method for the low-temperature, green preparation of glutaric acid / succinic acid-based aliphatic nylon. The only difference between this method and Example 1 is the polymerization reaction time in the post-solid-phase polymerization stage. Other process parameters are the same as in Example 1. In this embodiment, the polymerization reaction time in the post-solid-phase polymerization stage is 8 hours.

[0068] Example 19

[0069] This embodiment presents a novel method for the low-temperature, green preparation of glutaric acid / succinic acid-based aliphatic nylon. The only difference between this method and Example 1 is the polymerization reaction time in the post-solid-phase polymerization stage. Other process parameters are the same as in Example 1. In this embodiment, the polymerization reaction time in the post-solid-phase polymerization stage is 20 hours.

[0070] Comparative Example 1

[0071] This comparative example is the same as Example 1, except that the temperature in the prepolymerization stage is different. In this comparative example, the reaction temperature in the prepolymerization stage is 260°C.

[0072] Comparative Example 2

[0073] This comparative example is the same as Example 1, except that the polymerization time in the post-solid phase polymerization stage is different. In this comparative example, the polymerization time in the post-solid phase polymerization stage is 2 hours.

[0074] Comparative Example 3

[0075] This comparative example is the same as Example 1, except that the polymerization temperature in the post-solid phase polymerization stage is different. In this comparative example, the polymerization temperature in the post-solid phase polymerization stage is 180°C.

[0076] Comparative Example 4

[0077] This comparative example is the same as Example 1, except that the second predetermined pressure in the prepolymerization stage is different. In this comparative example, the second predetermined pressure in the prepolymerization stage is 0 MPa.

[0078] Experimental Example 1

[0079] To illustrate the effects of the present invention, Example 1 is used as an example to perform FT-IR and... 1 H-NMR testing, the test results are as follows Figures 1-2 As shown.

[0080] Figure 1 Middle, 3301cm -1 It is the NH stretching vibration peak, 2931 cm⁻¹. -1 and 2858cm -1 It is the characteristic absorption peak of CH2, at 1634 cm⁻¹. -1 It is the C=O stretching vibration peak (a characteristic absorption peak of the amide I band), 1538 cm⁻¹. -1It is a combined absorption peak of NH bending vibration and CN stretching vibration (characteristic absorption peak of amide II band), 1267 cm⁻¹ -1 It is a combined absorption peak of the stretching vibration of CN and the bending vibration of CN (characteristic absorption peak of amide III band), 934 cm⁻¹ -1 and 688cm -1 These are characteristic absorption peaks of amide IV and amide V bands, at 1725 cm⁻¹. -1 It is the stretching vibration peak of the carbonyl C=O group of imide.

[0081] Figure 2 The chemical shifts of H in nylon 65 polymer under different conditions are shown in the figure.

[0082] The above experimental results show that the present invention successfully prepared nylon 65 polymer.

[0083] Experiment Example 2

[0084] In this experimental example, the physical properties of the products obtained in Examples 1-19 and Comparative Examples 1-4 were analyzed. The test reactors and test standards used are shown in the table below.

[0085] Table 1 Test Items, Reactors, and Standards

[0086]

[0087]

[0088] Examples 1-3 reflect the physical properties of different glutaric acid / succinic acid-based aliphatic nylons prepared, and the specific results are shown in Table 2.

[0089] Table 2. Properties of the nylon polymers obtained in Examples 1-3

[0090] Item Example 1 Example 2 Example 3 Sample Nylon 65 Nylon 54 Nylon 55 Relative viscosity 2.63 2.47 2.52 T d 5％ / ℃]] 373 305 408 T m / ℃]] 252 275 241 Cyclization rate 1％ 1.4％ 1.2％

[0091] As shown in Table 2, the relative viscosity of the prepared glutaric acid / succinic acid-based aliphatic nylon can reach above 2.4 and the cyclization rate is about 1%.

[0092] Example 1 and Example 4-5 reflect the effect of different acid-amine molar ratios of raw materials on the physical properties of nylon polymers. The specific results are shown in Table 3.

[0093] Table 3. Properties of Nylon 65 polymers obtained in Examples 1 and 4-5

[0094] Item Example 1 Example 4 Example 5 Acid / amine feed ratio 1:1.01 1:0.99 1:1.02 Relative viscosity 2.63 2.54 2.59 T d 5％ / ℃]] 373 373 371 T m / ℃]] 252 251 251 Cyclization rate 1％ 1.1％ 1％

[0095] Table 3 shows that when the molar ratio of acid to amine is around 1:1, the relative viscosity of nylon 65 increases with the increase of the amine ratio. m Td 5％ And the cyclization rate remains basically unchanged.

[0096] Examples 1 and 6-7 reflect the effect of the reaction temperature during the prepolymerization stage on the physical properties of nylon 65 polymer. The specific results are shown in Table 4.

[0097] Table 4. Properties of the Nylon 65 polymer obtained in Example 1, after processes 6-7

[0098]

[0099]

[0100] Table 4 shows that when the reaction temperature in the prepolymerization stage increases from 180℃ to 220℃, the relative viscosity of nylon 65 first increases and then decreases, while the cyclization rate increases with increasing temperature. m and T d 5％ Basically unchanged.

[0101] Examples 1 and 8-9 reflect the effect of different outgassing times during the prepolymerization stage on the physical properties of nylon 65 polymer. The specific results are shown in Table 5.

[0102] Table 5. Properties of the Nylon 65 polymer obtained in Example 1, Steps 8-9

[0103] Item Example 1 Example 8 Example 9 Degassing time in prepolymerization stage / h 1.5 0.5 2 Relative viscosity 2.63 2.55 2.64 T d 5％ / ℃]] 373 372 373 T m / ℃]] 252 251 252 Cyclization rate 1％ 0.9％ 1.3％

[0104] As shown in Table 5, when the prepolymerization stage degassing time is extended from 0.5 h to 2 h, the relative viscosity of nylon 65 first increases and then tends to stabilize, while the cyclization rate gradually increases. m and T d 5％ Basically unchanged.

[0105] Examples 1 and 10-12 reflect the effect of the second predetermined pressure in the prepolymerization stage on the physical properties of nylon 65 polymer. The specific results are shown in Table 6.

[0106] Table 6. Properties of Nylon 65 polymer obtained in Example 1 after 10-12 steps

[0107]

[0108] As shown in Table 6, with the increase of the second predetermined pressure in the prepolymerization stage, the relative viscosity of Nylon 65 first increases and then decreases, the cyclization rate gradually decreases, and T... m and T d 5％ Basically unchanged.

[0109] Examples 1 and 13-14 reflect the effect of the second predetermined pressure holding time in the prepolymerization stage on the physical properties of nylon 65 polymer. The specific results are shown in Table 7.

[0110] Table 7. Properties of Nylon 65 polymer obtained in Example 1, Sections 13-14

[0111]

[0112]

[0113] As shown in Table 7, with the increase of the holding time under the second predetermined pressure in the prepolymerization stage, the relative viscosity first increases and then decreases, the cyclization rate gradually increases, and Tm and Td... 5％ Basically unchanged.

[0114] Examples 1 and 15-16 reflect the effect of reaction temperature during the solid-state polymerization stage on the physical properties of nylon 65 polymer. The specific results are shown in Table 8.

[0115] Table 8. Properties of Nylon 65 polymer obtained in Example 1, after 15-16.

[0116] Item Example 1 Example 15 Example 16 Temperature of post-solid-state polymerization / °C 220 200 240 Relative viscosity 2.63 2.42 2.56 T d 5％ / ℃]] 373 372 372 Tm / °C 252 249 251 Cyclization rate 1％ 0.9％ 1.8％

[0117] As shown in Table 8, when the solid-state polymerization temperature increases from 200℃ to 240℃, the relative viscosity of Nylon 65 first increases and then decreases, the cyclization rate gradually increases, and Tm and Td... 5％ Basically unchanged.

[0118] Examples 1 and 17-19 reflect the effect of reaction time during the solid-state polymerization stage on the physical properties of nylon 65 polymer. The specific results are shown in Table 9.

[0119] Table 9. Properties of Nylon 65 polymers obtained in Example 1 of Examples 17-19

[0120]

[0121] As shown in Table 9, when the post-solid-state polymerization time is extended from 4 h to 20 h, the relative viscosity of Nylon 65 increases with time, the cyclization rate gradually increases, and Tm and Td... 5％ Basically unchanged.

[0122] Example 1: The physical properties of the nylon 65 polymers prepared in Comparative Examples 1-4 were characterized, and the results are shown in Table 10.

[0123] Table 10. Properties of Nylon 65 polymers obtained in Examples 1 and Comparative Examples 1-4

[0124] Item Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Relative viscosity 2.63 2.01 2.22 2.13 2.19 T d 5％ / ℃]] 373 370 371 371 372 T m / ℃]] 252 247 249 249 249 Cyclization rate 1％ 3.4％ 0.9％ 0.8％ 2.1％

[0125] Comparative Example 1, with a prepolymerization stage reaction temperature of 260℃, employed a melt polymerization followed by solid-state polymerization method, achieving a relative viscosity of 2.01 and a cyclization rate of 3.4%. Comparative Example 2, with a shorter solid-state polymerization reaction time of only 2 hours, exhibited a relatively higher relative viscosity of 2.22. Comparative Example 3, with a solid-state polymerization reaction temperature of 180℃, achieved a relative viscosity of 2.13. Comparative Example 4, after a second pressurization to atmospheric pressure, achieved a relative viscosity of 2.19 and a cyclization rate of 2.1%.

[0126] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application. Those skilled in the art should consider the specification as a whole, and the technical solutions in the various embodiments can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A novel method for the low-temperature, green preparation of glutaric acid / succinic acid-based aliphatic nylon, characterized in that, Includes the following steps: (1) Aliphatic diamine, diacid, water and catalyst are added to a polymerization reactor in a certain proportion and mixed. The reaction system is sealed and in an oxygen-free environment. When the inside of the polymerization reactor is heated to a predetermined temperature of 180-220℃ and the pressure rises to the first predetermined pressure of 0.9-2.2MPa, the temperature and pressure are maintained for 0.5-1.5h. Then, the gas is released to the second predetermined pressure of 0.3-0.9MPa within 0.5-2h, and the temperature is maintained for 0.5-1.5h. The material is discharged to obtain powdered nylon prepolymer. The diacid is one or a combination of two of glutaric acid and succinic acid. (2) The powdered nylon prepolymer is placed in a solid-phase post-polymerization reactor. Under vacuum conditions, the system is heated to a predetermined temperature of 200-240℃ and kept at the temperature and pressure for 4-20 hours. The material is discharged when the temperature drops to below 50℃ to obtain powdered glutaric acid / succinic acid aliphatic nylon polymer.

2. The novel method for low-temperature green preparation of glutaric acid / succinic acid-based aliphatic nylon according to claim 1, characterized in that, In step (1), the amount of water used is (10-100)wt% of the weight of the diamine and diacid raw materials.

3. The novel method for low-temperature green preparation of glutaric acid / succinic acid-based aliphatic nylon according to claim 1, characterized in that, In step (1), the aliphatic diamine includes, but is not limited to, one or a mixture of two or more of butanediamine, pentanediamine, hexanediamine, decanediamine, dodecanediamine, tridecanediamine, and tetradecanediamine.

4. The novel method for low-temperature green preparation of glutaric acid / succinic acid-based aliphatic nylon according to claim 1, characterized in that, In step (1), the molar ratio of the diamine to the dicarboxylic acid is (0.99-1.02):

1.

5. The novel method for low-temperature green preparation of glutaric acid / succinic acid-based aliphatic nylon according to claim 1, characterized in that, In step (1), the catalyst is one or a mixture of two or more of sodium hypophosphite, phosphorous acid, triphenyl phosphate, H10, stannous chloride, and copper acetate, and the amount of catalyst used is (0.05-0.5) wt% of the total mass of the diamine and diacid raw materials.

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