Novel low-temperature green method for preparing glutaric acid / succinic acid aliphatic nylon

Abstract

The invention belongs to the field of nylon polymers, and particularly relates to a novel low-temperature green preparation method of glutaric acid / succinic acid aliphatic nylon, which specifically comprises the following steps: (1) putting aliphatic diamine, glutaric acid and / or succinic acid, water and a catalyst into a polymerization kettle according to a certain proportion, mixing, and ensuring that a reaction system is sealed and is in an oxygen-free environment, when the inside of the polymerization kettle reaches a preset temperature and the pressure rises to a first preset pressure, keeping the temperature and the pressure for a certain time; deflating to a second preset pressure within a certain time, preserving heat for a period of time under the second preset pressure, and discharging to obtain a powdery nylon prepolymer; and (2) putting the powdery nylon prepolymer into a solid-phase post-polymerization reactor, heating the system to a preset temperature under a vacuum condition, and keeping the temperature and the pressure for a certain time to obtain the high-viscosity nylon polymer. The glutaric acid / succinic acid aliphatic nylon prepared by the method has the advantages that the temperature in all reaction stages is lower than the melting point of the polymer, the cyclization reaction of glutaric acid / succinic acid in the polymerization process is reduced by a large amount of water and lower polymerization temperature, and a high-viscosity nylon product can be obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of nylon polymer preparation, and in particular relates to a new method for preparing glutaric acid / succinic acid-based aliphatic nylon in a low-temperature and green manner. Background Art

[0002] Polyamide, commonly known as nylon, is a general term for high molecular polymers with a repeating amide bond 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 automotive parts, electronics and electrical, aerospace, and medical applications. With the sustainable development of society, people have an urgent need for high-performance, functional and green polyamides.

[0003] Glutaric acid, also known as 1,3-propanedicarboxylic acid, gum acid; succinic acid, also known as succinic acid, 1,2-ethanedicarboxylic acid. Both dibasic acids are very important organic chemical synthesis raw materials, which can react with diamines to prepare nylon. However, when succinic acid and glutaric acid are polymerized with diamines, they are easy to form five-membered rings and six-membered cyclic imides, resulting in the termination of the 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 cyclization phenomenon. Therefore, there is no industrial nylon 65 product available.

[0004] The technological breakthrough of inhibiting cyclization reaction and increasing the molecular weight of the polymerization product can not only expand the application areas 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, etc. and papers - Synthesis and performance characterization of nylon 65, synthesis and performance study of bio-based polyamide 55 (PA55), synthesis and structural study of copolyamide PA5T / 54, etc. have studied the preparation of nylon by polymerization of glutaric acid / succinic acid and diamines. Patent CN111253568A reports a method for preparing nylon 65 polymer, which includes the following steps: (1) dissolving glutaric acid in S1 solvent to prepare glutaric acid solution; heating and dissolving hexamethylenediamine and then dissolving it in S2 solvent to prepare hexamethylenediamine solution; (2) adding the hexamethylenediamine solution dropwise into the glutaric acid solution in a 40-80°C water bath and stirring to prepare nylon 65 salt and purify it; (3) adding the refined nylon 65 salt to a reactor to prepare a salt solution, and reacting at 150-190°C and a pressure of 1.2-1.8 MPa under inert gas protection; reducing the pressure in the reactor to normal pressure, and polycondensing at 200-250°C, and finally evacuating to obtain nylon 65 polymer. In this patent, it is necessary to form salt first and then polymerize, and an organic solvent is used in the salt formation process, which puts forward higher requirements for safe production and solvent recovery; in patent CN112920401A, the author uses melt polymerization to polymerize. It includes the following steps: the nylon 65 salt synthesized by the method disclosed in patent (CN108285532B) is placed in a normal pressure reaction container, an inert gas is introduced to isolate the system from oxygen, the system temperature is increased from room temperature to the prepolymerization temperature (above the melting point of nylon 65 salt) at a certain heating rate, the solid salt is melted, and after a certain period of insulation reaction, the temperature is increased to the polymerization temperature (near the melting point of nylon 65), and then reacted for a certain period of time to obtain nylon 65. In this patent (CN112920401A), the reaction is a normal pressure melt reaction in an inert atmosphere. This patent has the following problems: (1) Claim 1 (1) shows that the reaction is melt prepolymerized at a certain heating rate to 160-200°C. Under these conditions, nylon 65 salt will decompose and be carried out of the reactor by the flowing inert gas, resulting in loss of reaction materials, imbalance of acid-amine molar ratio and environmental pollution. (2) The prepolymer melts at 220-260°C. Since the melting point of nylon 65 is around 245°C, the polymerization temperature is higher than its melting point. Under these conditions, a large number of cyclization reactions will occur. The imbalance of the molar ratio of carboxyl and amine groups in the prepolymer and the cyclization of the molecular chain end groups will both result in a low molecular weight of the final product. The mechanical properties are poor. As shown in the patent specification

[0068] , the maximum tensile strength of the product prepared from the sample is only 6.42MPa; in Shao Zihua's document "Synthesis of Nylon 65 and Characterization of Its Properties", the author obtains a nylon 65 polymer with a relative viscosity of only 2.1 at most by melt polymerization and solid phase polymerization of nylon 65 salt, which is still relatively low. The paper also does not explore the effect of cyclization on the molecular chain of its polymer product.According to the reaction conditions, the reason for the low viscosity is probably that the cyclization reaction prevents the growth of the nylon 65 molecular chain, resulting in a low relative viscosity. In reference [4] (Synthesis and performance study of bio-based polyamide 55 (PA55)), the authors used melt polymerization followed by solid phase polymerization and direct solid phase polymerization to polymerize nylon 55, and finally obtained a nylon 55 polymer with a maximum relative viscosity of 2.26. The product viscosity was still low. In order to further increase the product viscosity, a copolymer with a maximum viscosity of 2.79 was obtained by adding a third monomer for copolymerization, but its melting point was significantly lower than that of nylon 55 polymer. In reference (Synthesis and structural study of copolyamide PA5T / 54), the authors used a nylon 5T / 54 salt direct solid phase polymerization method to prepare a relatively high molecular weight semi-aromatic nylon PA5T / 54. The main feature of this method is that the nylon salt undergoes a polymerization reaction in the solid state to obtain a relatively high molecular weight product. In the preparation of the copolymer studied in this document, the proportion of succinic acid, which is prone to cyclization reaction, in the reaction monomers was relatively low. At the same time, this method has strict control over the reaction conditions and has high requirements for the reaction equipment.

[0006] It can be seen that currently, glutaric acid and succinic acid are used as nylon polymerization monomers, and nylon salts are usually prepared first, and nylon products are prepared by melt polymerization of nylon salts. In the melt polymerization process, the reaction temperature is higher than the melting point of nylon salts and products. The higher reaction temperature will lead to the occurrence of cyclization reaction. Under this condition, the molecular weight of the product is relatively low, which cannot meet the requirements of industrial production for use as high-performance materials. Summary of the invention

[0007] The purpose of the present invention is to provide a new low-temperature green method for preparing glutaric acid / succinic acid-based aliphatic nylon, which method does not require the pre-preparation of nylon salt. In the presence of water, the reaction monomer dibasic acid and diamine are prepolymerized and solid-phase post-polymerized at a temperature lower than the melting point of the nylon polymerization product to prepare a high-quality, high-viscosity nylon product.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] A new method for preparing glutaric acid / succinic acid-based aliphatic nylon at low temperature and in a green manner comprises the following steps:

[0010] (1) adding aliphatic diamine, dibasic acid, water and catalyst into a polymerization kettle in a certain proportion and mixing, and ensuring that the reaction system is sealed and oxygen-free, heating the inside of the polymerization kettle to a predetermined temperature of 180-220° C., and when the pressure rises to a first predetermined pressure of 0.9-2.2 MPa, maintaining the temperature and pressure for 0.5-1.5 h; then venting to a second predetermined pressure of 0.3-0.9 MPa within 0.5-2 h, maintaining the temperature for 0.5-1.5 h, and discharging to obtain a powdered nylon prepolymer; the dibasic acid is one or a combination of glutaric acid and succinic acid;

[0011] (2) placing a powdered nylon prepolymer into a solid phase post-polymerization reactor, heating the system to a predetermined temperature of 200-240° C. under vacuum conditions, maintaining the temperature and pressure for 4-20 hours, cooling the system to below 50° C., and discharging the system to obtain a powdered nylon polymer.

[0012] The invention discloses a novel method for preparing glutaric acid / succinic acid-based aliphatic nylon at low temperature, which mainly involves carrying out polymerization reaction under the condition of lower than the melting point of nylon product and in the presence of water to obtain a polymer product with higher viscosity. The principle is that, through in-depth analysis of the macromolecular chain growth mechanism in the nylon polymerization process with glutaric acid and succinic acid as reaction monomers, it is found that when glutaric acid or succinic acid undergoes condensation polymerization reaction with diamine, in addition to the main reaction of carboxyl group and amine group reacting to form amide bond to form nylon macromolecule, the terminal carboxyl group and the adjacent amide group on the macromolecular chain will also undergo dehydration reaction to form six-membered or five-membered cyclic imide units to end the macromolecular chain, so that the macromolecular chain loses its reaction activity and the macromolecular chain no longer grows, which is the main reason for the low molecular weight of the product. Based on the reaction mechanism that high temperature is conducive to the occurrence of imide cyclization reaction and the removal of water molecules in the cyclization reaction, the invention proposes a technical route of carrying out condensation polymerization reaction under low temperature and water presence conditions to inhibit the occurrence of cyclization reaction and promote the growth of nylon macromolecular chain, thereby obtaining a nylon product with higher molecular weight.

[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 dibasic acid raw materials;

[0014] As further preferred embodiment of the present invention, in step (1), the diamine is one or a mixture of two or more of butanediamine, pentanediamine, hexanediamine, decanediamine, 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 dibasic acid and obtain a product with a higher molecular weight, the molar ratio of the two should be as close as possible. Preferably, the molar ratio of the diamine and the dibasic acid is 0.99-1.02:1, more preferably 1.01:1.

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

[0017] In step (1) of the present invention, the predetermined temperature of the prepolymerization stage is 180-220°C, the first predetermined pressure is 0.9-2.2MPa, and the heat preservation and pressure holding time is 0.5-1.5h. During the prepolymerization process, the reaction temperature is lower than the melting point of the polymer product. In the presence of a large amount of water and the predetermined temperature conditions, the reaction material is in a liquid state. Since the equilibrium constant of the reaction between the amine group and the carboxyl group is about 300, although there is water, the amidation reaction can still proceed, but the end group conversion rate is low and the product molecular weight is not high. Low temperature and water can inhibit the cyclization reaction, which is conducive to the solid phase polymerization reaction in step (2).

[0018] The degassing time in the prepolymerization stage is 0.5-2h, the degassing to a predetermined pressure is 0.3-0.9MPa, and the holding time under the predetermined pressure is 0.5-1.5h. The purpose of degassing to a predetermined pressure in the present invention is to reduce the moisture content, promote the polymerization reaction to move toward the product direction, improve the monomer conversion rate, 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. When the prepolymer product is discharged from the reactor, the pressure drops suddenly, and the moisture is instantly gasified, so that the product is in a powder state.

[0019] In step (2), the solid phase post-polymerization temperature is 200-240° C., the reaction time is 4-20 hours, and the pressure is 1-100 Pa. Under the predetermined reaction temperature and pressure conditions, the temperature is lower than the melting point of the prepolymer and the solid phase post-polymerization reaction occurs. The solid-state reaction macromolecular chain has weak mobility, and the probability of the terminal carboxyl group reacting with the adjacent amide group to form a cyclic imide end-capping is low. At the same time, the powder state of the material and the vacuum condition are conducive to the diffusion of the reaction by-product water, so that the molecular weight of the nylon is further increased. The reaction temperature and reaction time are determined according to the type of nylon, the product molecular weight requirement and the vacuum degree.

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

[0021] (1) The present invention uses a relatively low reaction temperature and maintains a certain water content in the system during the prepolymerization process, which can effectively inhibit the reaction between glutaric acid / succinic acid and diamine, which is beneficial to the growth of nylon macromolecular chains, thereby obtaining a nylon product with a higher molecular weight;

[0022] (2) The material in the prepolymerization stage is in the form of powdered nylon polymer, and the material in the solid phase post-polymerization stage is in the form of powder, which is beneficial for inhibiting the cyclization side reaction and discharging the by-product water, shortening the reaction time and improving the polymerization efficiency. The nylon material prepared by this technology has a higher molecular weight and can meet the requirements of the material performance in the engineering field. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 FT-IR graph of nylon 65 obtained in Example 1;

[0024] Figure 2 The nylon 65 obtained in Example 1 1 H-NMR spectrum. Specific implementation plan

[0025] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described below in conjunction with specific implementation methods.

[0026] Example 1

[0027] A new method for preparing glutaric acid / succinic acid-based aliphatic nylon at low temperature and in a green manner in this embodiment comprises the following steps:

[0028] (1) 705 g of hexamethylenediamine, 795 g of glutaric acid, 750 g of water and 3 g of sodium hypophosphite are placed in a polymerization kettle and sealed. The air in the polymerization kettle is replaced with an inert gas (nitrogen) three times to make the polymerization kettle an oxygen-free environment; the temperature in the kettle is first raised to 200° C., at which time the first predetermined pressure is 1.5 MPa, and the temperature is maintained for 0.5 h, and then the air is released to the second predetermined pressure of 0.6 MPa after 1.5 h, and the temperature is maintained at the second predetermined pressure of 0.6 MPa for 1 h, and the material is discharged to obtain a powdered nylon 65 prepolymer;

[0029] (2) Powdered nylon 65 prepolymer is placed in a solid phase post-polymerization reactor and sealed. The gas in the solid phase post-polymerization reactor is replaced with an inert gas three times, the vacuum system is turned on, the absolute pressure inside the equipment is evacuated to 1-100 Pa, the temperature inside the reactor is raised to 220°C, and the temperature and pressure are maintained for 6 hours, and the temperature is lowered to below 50°C before discharging, and finally a powdered nylon 65 polymer is obtained.

[0030] Example 2

[0031] A new method for preparing glutaric acid / succinic acid-based aliphatic nylon at low temperature and in a green manner in this embodiment comprises the following steps:

[0032] (1) 699 g of pentamethylenediamine, 801 g of succinic acid, 750 g of water and 3 g of sodium hypophosphite are placed in a polymerization kettle and sealed. The air in the polymerization kettle is replaced with an inert gas (nitrogen) three times to make the polymerization kettle an oxygen-free environment. The temperature in the kettle is first raised to 200°C, at which time the first predetermined pressure is 1.5 MPa, and the temperature is maintained for 0.5 h. After 1.5 h, the air is released to the second predetermined pressure of 0.6 MPa, and the temperature is maintained at the second predetermined pressure of 0.6 MPa for 1 h. The material is discharged to obtain a powdered nylon 54 prepolymer.

[0033] (2) Powdered nylon 54 prepolymer is placed in a solid phase post-polymerization reactor and sealed. The gas in the solid phase post-polymerization reactor is replaced with an inert gas three times, the vacuum system is turned on, the absolute pressure inside the equipment is evacuated to 1-100 Pa, the temperature inside the reactor is raised to 220°C, and the temperature and pressure are maintained for 6 hours, and the temperature is lowered to below 50°C before discharging, and finally a powdered nylon 54 polymer is obtained.

[0034] Example 3

[0035] A new method for preparing glutaric acid / succinic acid-based aliphatic nylon at low temperature and in a green manner in this embodiment comprises the following steps:

[0036] (1) 657 g of pentamethylenediamine, 843 g of glutaric acid, 750 g of water and 3 g of sodium hypophosphite are placed in a polymerization kettle and sealed. The air in the polymerization kettle is replaced with an inert gas (nitrogen) three times to make the polymerization kettle an oxygen-free environment. The temperature in the kettle is first raised to 200° C., at which time the first predetermined pressure is 1.5 MPa, and the temperature is maintained for 0.5 h. After 1.5 h, the air is released to a second predetermined pressure of 0.6 MPa, and the temperature is maintained at the second predetermined pressure of 0.6 MPa for 1 h. The material is discharged to obtain a powdered nylon 55 prepolymer.

[0037] (2) Powdered nylon 55 prepolymer is placed in a solid phase post-polymerization reactor and sealed. The gas in the solid phase post-polymerization reactor is replaced with inert gas three times, the vacuum system is turned on, the absolute pressure inside the equipment is evacuated to 1-100 Pa, the temperature inside the reactor is raised to 220°C, and the temperature and pressure are maintained for 6 hours, and the temperature is lowered to below 50°C and the material is discharged, and finally a powdered nylon 55 polymer is obtained.

[0038] Example 4

[0039] The new method for preparing green glutaric acid / succinic acid-based aliphatic nylon at low temperature in this embodiment is different from that in Example 1 only in that the molar ratio of the diamine to the dibasic acid is different. The other process parameters are the same as those in Example 1. In this embodiment, the molar ratio of the diamine to the dibasic acid is 1:0.99.

[0040] Example 5

[0041] The present embodiment is a new method for preparing glutaric acid / succinic acid-based aliphatic nylon at a low temperature and in a green manner. The difference from the embodiment 1 is that the molar ratio of the diamine to the dibasic acid is different. The other process parameters are the same as those of the embodiment 1. In the present embodiment, the molar ratio of the diamine to the dibasic acid is 1:1.02.

[0042] Example 6

[0043] The present embodiment is a new method for preparing glutaric acid / succinic acid-based aliphatic nylon at a low temperature and in a green manner. The difference from the embodiment 1 is only in the reaction temperature in the prepolymerization stage. The other process parameters are the same as those in the embodiment 1. In the present embodiment, the reaction temperature in the prepolymerization stage is 180°C.

[0044] Example 7

[0045] The present embodiment is a new method for preparing glutaric acid / succinic acid-based aliphatic nylon at a low temperature and in a green manner. The difference from the embodiment 1 is only in the reaction temperature in the prepolymerization stage. The other process parameters are the same as those in the embodiment 1. In the present embodiment, the reaction temperature in the prepolymerization stage is 220°C.

[0046] Example 8

[0047] The new method for preparing glutaric acid / succinic acid-based aliphatic nylon at a low temperature and in a green manner in this embodiment is different from that in Example 1 only in that the degassing time in the prepolymerization stage is different. The other process parameters are the same as those in Example 1. In this embodiment, the degassing time in the prepolymerization stage is 0.5 h.

[0048] Example 9

[0049] The new method for preparing glutaric acid / succinic acid-based aliphatic nylon at a low temperature and in a green manner in this embodiment is different from that in Example 1 only in that the degassing time in the prepolymerization stage is different. The other process parameters are the same as in Example 1. In this embodiment, the degassing time in the prepolymerization stage is 2 hours.

[0050] Example 10

[0051] The new method for preparing glutaric acid / succinic acid-based aliphatic nylon at a low temperature and in a green manner in this embodiment is different from that in Example 1 only in that the second predetermined pressure in the prepolymerization stage is different, and the 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] Embodiment 11

[0053] The new method for preparing glutaric acid / succinic acid-based aliphatic nylon at a low temperature and in a green manner in this embodiment is different from that in Example 1 only in that the second predetermined pressure in the prepolymerization stage is different, and the other process parameters are the same as those in Example 1. In this embodiment, the second predetermined pressure in the prepolymerization stage is 0.5 MPa.

[0054] Example 12

[0055] The new method for preparing glutaric acid / succinic acid-based aliphatic nylon at a low temperature and in a green manner in this embodiment is different from that in Example 1 only in that the second predetermined pressure in the prepolymerization stage is different, and the 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] The new method for preparing glutaric acid / succinic acid-based aliphatic nylon at a low temperature and in a green manner in this embodiment is different from that in Example 1 only in that the holding time at the second predetermined pressure in the prepolymerization stage is different. The other process parameters are the same as in Example 1. In this embodiment, the holding time at the second predetermined pressure in the prepolymerization stage is 0.5 h.

[0058] Embodiment 14

[0059] The new method for preparing glutaric acid / succinic acid-based aliphatic nylon at a low temperature and in a green manner in this embodiment is different from that in Example 1 only in that the holding time at the second predetermined pressure in the prepolymerization stage is different. Other process parameters are the same as in Example 1. In this embodiment, the holding time at the second predetermined pressure in the prepolymerization stage is 1.5 hours.

[0060] Embodiment 15

[0061] The present embodiment is a new low-temperature green method for preparing glutaric acid / succinic acid-based aliphatic nylon, which is different from the embodiment 1 only in that the polymerization temperature in the solid phase post-polymerization stage is different, and the other process parameters are the same as the embodiment 1. In the present embodiment, the polymerization temperature in the solid phase post-polymerization stage is 200°C.

[0062] Example 16

[0063] The present embodiment is a new low-temperature green method for preparing glutaric acid / succinic acid-based aliphatic nylon, which is different from the embodiment 1 only in that the polymerization temperature in the solid phase post-polymerization stage is different, and the other process parameters are the same as the embodiment 1. In the present embodiment, the polymerization temperature in the solid phase post-polymerization stage is 240°C.

[0064] Embodiment 17

[0065] The new method for preparing glutaric acid / succinic acid-based aliphatic nylon at a low temperature and in a green manner in this embodiment is different from that in Example 1 only in that the polymerization reaction time in the solid phase post-polymerization stage is different, and the other process parameters are the same as in Example 1. In this embodiment, the polymerization reaction time in the solid phase post-polymerization stage is 4 hours.

[0066] Embodiment 18

[0067] The new method for preparing glutaric acid / succinic acid-based aliphatic nylon at a low temperature and in a green manner in this embodiment is different from that in Example 1 only in that the polymerization reaction time in the solid phase post-polymerization stage is different, and the other process parameters are the same as in Example 1. In this embodiment, the polymerization reaction time in the solid phase post-polymerization stage is 8 hours.

[0068] Embodiment 19

[0069] The present embodiment is a new method for preparing glutaric acid / succinic acid-based aliphatic nylon at a low temperature and in a green manner. The difference from the present embodiment 1 is only in the polymerization reaction time of the solid phase post-polymerization stage. The other process parameters are the same as those of the present embodiment 1. The polymerization reaction time of the solid phase post-polymerization stage in the present embodiment is 20 hours.

[0070] Comparative Example 1

[0071] This comparative example is the same as Example 1, except that the temperature in the system during the prepolymerization stage is different. In this comparative example, the reaction temperature during 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 solid phase post-polymerization stage is different. In this comparative example, the polymerization time in the solid phase post-polymerization stage is 2 h.

[0074] Comparative Example 3

[0075] This comparative example is the same as Example 1, except that the polymerization temperature in the solid phase post-polymerization stage is different. In this comparative example, the polymerization temperature in the solid phase post-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 effect of the present invention, taking Example 1 as an example, the nylon 65 polymer prepared therefrom was subjected to FT-IR and 1 H-NMR test, the test results are as follows Figure 1-2 shown.

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

[0081] Figure 2 The chemical shifts of H in nylon 65 polymer under different environments are shown in FIG.

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

[0083] Experimental Example 2

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

[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 Physical properties of nylon polymers obtained in Examples 1-3

[0090] project Example 1 Example 2 Example 3 sample Nylon 65 Nylon 54 Nylon 55 Relative viscosity 2.63 2.47 2.52 <![CDATA[T d 5％ / ℃]]> 373 305 408 <![CDATA[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, Implementation 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 Physical properties of nylon 65 polymers obtained in Example 1 and Examples 4-5

[0094] project 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 <![CDATA[T d 5％ / ℃]]> 373 373 371 <![CDATA[T m / ℃]]> 252 251 251 Cyclization rate 1％ 1.1％ 1％

[0095] It can be seen from Table 3 that when the molar ratio of acid to amine is around 1:1, the relative viscosity of nylon 65 increases with the increase of amine ratio, T m , Td 5％ The cyclization rate remained basically unchanged.

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

[0097] Table 4 Physical properties of nylon 65 polymer obtained by implementing Example 1 and 6-7

[0098]

[0099]

[0100] It can be seen from Table 4 that when the reaction temperature in the prepolymerization stage increases from 180°C to 220°C, the relative viscosity of nylon 65 increases first and then decreases, and the cyclization rate increases with the increase of temperature. m and T d 5％ Basically unchanged.

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

[0102] Table 5 Physical properties of nylon 65 polymer obtained by implementing 8-9 in Example 1

[0103] project 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 <![CDATA[T d 5％ / ℃]]> 373 372 373 <![CDATA[T m / ℃]]> 252 251 252 Cyclization rate 1％ 0.9％ 1.3％

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

[0105] Example 1 and Examples 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 Physical properties of nylon 65 polymer obtained by implementing 10-12 Example 1

[0107]

[0108] It can be seen from Table 6 that 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] Example 1 and Examples 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 Physical properties of nylon 65 polymer obtained by implementing 13-14 Example 1

[0111]

[0112]

[0113] It can be seen from Table 7 that with the increase of the holding time of the second predetermined pressure in the prepolymerization stage, the relative viscosity first increases and then decreases, the cyclization rate gradually increases, and the T m and T d 5％ Basically unchanged.

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

[0115] Table 8 Physical properties of nylon 65 polymer obtained by implementing 15-16 Example 1

[0116] project Example 1 Embodiment 15 Example 16 Solid phase post polymerization temperature / ℃ 220 200 240 Relative viscosity 2.63 2.42 2.56 <![CDATA[T d 5％ / ℃]]> 373 372 372 T m / ℃ 252 249 251 Cyclization rate 1％ 0.9％ 1.8％

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

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

[0119] Table 9 Physical properties of nylon 65 polymer obtained by implementing 17-19 Example 1

[0120]

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

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

[0123] Table 10 Physical properties of nylon 65 polymers obtained in Example 1 and Comparative Examples 1-4

[0124] project 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 <![CDATA[T d 5％ / ℃]]> 373 370 371 371 372 <![CDATA[T m / ℃]]> 252 247 249 249 249 Cyclization rate 1％ 3.4％ 0.9％ 0.8％ 2.1％

[0125] The reaction temperature of the prepolymerization stage of Comparative Example 1 is 260°C, which is a method of melt polymerization followed by solid phase postpolymerization. The relative viscosity is 2.01 and the cyclization rate is 3.4%. The reaction time of the solid phase postpolymerization of Comparative Example 2 is shorter, only 2h, and the relative viscosity is 2.22. The solid phase postpolymerization reaction temperature of Comparative Example 3 is 180°C, and the relative viscosity is 2.13. Comparative Example 4 is pressurized twice to normal pressure, the relative viscosity is 2.19, and the cyclization rate is 2.1%.

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

Claims

1. A new method for preparing glutaric acid / succinic acid-based aliphatic nylon at low temperature and in a green manner, characterized in that: The steps include: (1) adding aliphatic diamine, dibasic acid, water and catalyst into a polymerization kettle in a certain proportion and mixing, and ensuring that the reaction system is sealed and oxygen-free, heating the inside of the polymerization kettle to a predetermined temperature of 180-220° C., and when the pressure rises to a first predetermined pressure of 0.9-2.2 MPa, maintaining the temperature and pressure for 0.5-1.5 h; then venting to a second predetermined pressure of 0.3-0.9 MPa within 0.5-2 h, maintaining the temperature for 0.5-1.5 h, and discharging to obtain a powdered nylon prepolymer; the dibasic acid is one or a combination of glutaric acid and succinic acid; (2) placing a powdered nylon prepolymer into a solid phase post-polymerization reactor, heating the system to a predetermined temperature of 200-240° C. under vacuum conditions, maintaining the temperature and pressure for 4-20 hours, cooling the system to below 50° C., and discharging the system to obtain a powdered glutaric acid / succinic acid-based aliphatic nylon polymer.

2. The novel method for preparing glutaric acid / succinic acid-based aliphatic nylon at low temperature and in a green manner 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 dibasic acid raw materials.

3. The novel method for preparing glutaric acid / succinic acid-based aliphatic nylon at low temperature and in a green manner 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 diamine, such as diamine, amine, hexamethylenediamine, diamine, dodecanediamine, tridecanediamine and tetradecanediamine.

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

1.

5. The novel method for preparing glutaric acid / succinic acid-based aliphatic nylon at low temperature and in a green manner 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 cupric acetate, and the amount of the catalyst is (0.05-0.5) wt% of the total mass of the diamine and dibasic acid raw materials.

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