A method for preparing a fully bio-based polyamide

Abstract

The application belongs to the technical field of polymers, and provides a preparation method of a full-bio-based polyamide. After mixing the full-bio-based polyamide salt and water, concentration is performed, and after water removal and concentration, the system is continuously heated to enter a prepolymerization stage and a solid-phase tackification stage, both of which are performed under a closed condition without water vapor discharge, so as to ensure the stability of the diacid and the diamine in the system and avoid the loss of the diamine. After the reaction is stable, the polyamide is obtained. The method has high repeatability and stability, and the end group content difference of the polyamides obtained under the same production condition and in different production batches is small, and the maximum deviation value of the end amino group is less than or equal to 10%. The method is particularly suitable for intermittent production equipment, and the equipment investment cost is greatly reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polymer, more particularly, to a preparation method of full-bio-based polyamide. BACKGROUND

[0002] The full-bio-based polyamide is prepared by using bio-based raw materials, which meets the environmental protection requirements, and the traditional petroleum-based polyamide is gradually replaced by the bio-based polyamide. The full-bio-based polyamide is mainly used for synthetic fibers. In order to meet the dyeing and printing requirements of various blended knitted garments, the fibers need to be dyed in various styles. The dyeing efficiency of the fibers is related to the end groups of the polyamide. The end groups of the polyamide contain carboxyl and amino groups, among which the end amino group has a greater impact on the dyeing efficiency. This is because the acid dyes currently used on the market contain hydrophilic groups of sodium sulfonate groups (-SO3Na), which can be combined with the end amino groups (-NH + ) of the polyamide fibers through ionic bonds or electrostatic forces to provide better dyeability and brighter colors. However, during the production of the polyamide, especially in batch production, the polyamide salt is not very stable. At slightly higher temperatures, the diamines in the polyamide salt will be lost with the evaporation of water vapor. The higher the polymerization temperature, the more serious the loss of diamines (for example, when the temperature is higher than 180℃, the volatilization of diamines is intensified), thereby causing the imbalance between the diamines and the diacids, and thus the end group content of the polyamide resin in different production batches is quite different, resulting in unstable fiber dyeing effect.

[0003] Therefore, it is urgent to develop a preparation method of polyamide, which can reduce the difference in the end group content of the polyamide in different production batches and improve the stability of the end group content of the polyamide product. SUMMARY

[0004] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application provides a preparation method of full-bio-based polyamide. The method provided by the present application can reduce the difference in the end groups of the full-bio-based polyamide in different production batches, the maximum deviation of the end amino groups between different production batches is within 10%, and the stability of the end group content of the full-bio-based polyamide is improved.

[0005] The first aspect of the present application provides a preparation method of full-bio-based polyamide.

[0006] Specifically, the preparation method of full-bio-based polyamide comprises the following steps:

[0007] (1) mixing the full-bio-based polyamide salt and water, concentrating to obtain a concentrate;

[0008] (2) in a closed environment, heating, the concentrate is subjected to a prepolymerization reaction, and the full-bio-based polyamide prepolymer is obtained by cooling and drying;

[0009] (3) in a closed environment, the temperature is raised, and the dried polyamide prepolymer is solid-phase tackified to prepare the full-bio-based polyamide.

[0010] The full-bio-based polyamide salt is mixed with water, and the purpose of adding water is to ensure the flowability of the polyamide salt, and then concentrated to remove the water initially added and the water generated during the polymerization reaction. After the water vapor is removed, the temperature is raised to enter the prepolymerization stage and the solid-phase tackification stage. Although the temperatures of the two stages are high, the system is closed, and no water vapor is discharged, so the content of the diacid and diamine in the system is stable, and the loss of diamine is avoided. After the reaction is stable, the full-bio-based polyamide is obtained. The method has high repeatability, and the end group content of the full-bio-based polyamides produced in different batches has small differences and high stability.

[0011] Preferably, in step (1), the temperature is raised to 100-180°C for concentration. The low temperature during the concentration process reduces the volatilization of the diamine.

[0012] Preferably, in step (2), the temperature is raised to 180-260°C, and the concentrate is subjected to prepolymerization and isothermal for 0.5-1h.

[0013] Preferably, in step (3), the temperature is raised to 180-260°C, and the dried polyamide prepolymer is subjected to solid-phase tackification and isothermal for 4-24h.

[0014] Preferably, in step (1), the mass ratio of the full-bio-based polyamide salt to water is (0.5-1.5):(0.5-1.5)

[0015] Further preferably, in step (1), the mass ratio of the full-bio-based polyamide salt to water is 1:1.

[0016] Preferably, in step (1), when the mass of the water after the water vapor is liquefied reaches 85-110% of the total mass of the full-bio-based polyamide salt, the concentration is stopped.

[0017] Preferably, in step (1), the full-bio-based polyamide salt includes at least one of full-bio-based polyamide 56 salt, full-bio-based polyamide 510 salt, full-bio-based polyamide 512 salt, full-bio-based polyamide 513 salt, full-bio-based polyamide 66 salt, full-bio-based polyamide 610 salt, full-bio-based polyamide 612 salt, full-bio-based polyamide 613 salt, full-bio-based polyamide 1010 salt, full-bio-based polyamide 1012 salt, full-bio-based polyamide 1013 salt, full-bio-based polyamide 1212 salt, and full-bio-based polyamide 1213 salt.

[0018] Preferably, in step (1), the raw materials for preparing the full-bio-based polyamide salt include a full-bio-based diamine and a full-bio-based diacid.

[0019] Preferably, the molar ratio of the full-bio-based diamine and the full-bio-based diacid is (1-2):(1-2).

[0020] Further preferably, the molar ratio of the full-bio-based diamine and the full-bio-based diacid is 1:1.

[0021] Preferably, the bio-based diamine is at least one of a bio-based butanediamine, a bio-based pentanediamine, a bio-based decanediamine, a bio-based dodecanediamine, a bio-based hexanediamine, a bio-based undecanediamine, and a bio-based tridecanediamine.

[0022] Further preferably, the bio-based diamine is at least one of a bio-based pentanediamine, a bio-based decanediamine, and a bio-based dodecanediamine.

[0023] Preferably, the bio-based diacid is at least one of a bio-based pentanedioic acid, a bio-based hexanedioic acid, a bio-based decanedioic acid, a bio-based dodecanedioic acid, a bio-based undecanedioic acid, a bio-based tridecanedioic acid, and a bio-based itaconic acid.

[0024] Further preferably, the bio-based diacid is at least one of a bio-based decanedioic acid, a bio-based dodecanedioic acid, and a bio-based itaconic acid.

[0025] Preferably, in step (1), the mass of water after the water vapor discharged in the concentration process is liquefied into water reaches 85-110% of the total mass of the full-bio-based polyamide salt, and then the concentration exhaust is stopped.

[0026] Preferably, in step (2), the specific concentration viscosity of the full-bio-based polyamide prepolymer is 0.1-0.8.

[0027] Preferably, in step (3), the specific concentration viscosity of the full-bio-based polyamide is 0.8-3.

[0028] Preferably, in step (3), before the solid-phase viscosity enhancement, vacuum is first extracted to 30-100 Pa at 20-50 ℃.

[0029] Further preferably, in step (3), before the solid-phase viscosity enhancement, vacuum is first extracted to 50-60 Pa at 20-50 ℃.

[0030] Preferably, in step (3), the closed environment is an environment that is closed and has stirring conditions.

[0031] Preferably, in step (3), the solid-phase thickening is carried out in one of the following devices: a vertical reactor, a horizontal reactor, a rotary drum, a vertical single-cone dryer, or a double-cone dryer. Devices such as vertical reactors, horizontal reactors, rotary drums, vertical single-cone dryers, and double-cone dryers can provide a closed environment with stirring conditions.

[0032] A second aspect of the present invention provides an application of a method for preparing a fully bio-based polyamide.

[0033] Application of a fully bio-based polyamide preparation method in the field of synthetic fiber preparation.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] This invention involves mixing a fully bio-based polyamide salt with water, concentrating the mixture to remove water, and then further heating it to enter the prepolymerization and solid-phase thickening stages. Both stages are conducted under closed conditions to prevent the release of water vapor, ensuring the stability of the diacid and diamine in the system and preventing the loss of the diamine. After the reaction stabilizes, polyamide is obtained. This method exhibits high repeatability and stability, with minimal differences in the end-group content of polyamide from different production batches under the same production conditions; the maximum deviation of the terminal amino groups is ≤10%. The method provided by this invention is particularly suitable for batch production equipment, significantly reducing equipment investment costs. Furthermore, this invention uses bio-based raw materials to produce fully bio-based polyamide, making it more environmentally friendly and preventing pollution. Detailed Implementation

[0036] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0037] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0038] Example 1

[0039] A method for preparing a fully bio-based polyamide includes the following steps:

[0040] (1) Weigh 2.04 kg of bio-based pentanediamine, 4.04 kg of bio-based sebacic acid and 6.08 kg of deionized water to prepare a 50% bio-based polyamide 510 salt solution (the mass of bio-based polyamide 510 salt is 6.08 kg). Heat the solution to 180°C and concentrate it. After cooling the discharged water vapor, weigh the water obtained until the weight of the water reaches 6.38 kg (at this time, the weight of the water is 105% of the total mass of bio-based polyamide 510 salt). Then stop the concentration.

[0041] (2) Under closed conditions, continue to heat up to 200℃ for reaction, keep warm for 30 min, cool, discharge the material to obtain bio-based polyamide 510 prepolymer, and then dry at 120℃ for 4 h;

[0042] (3) Add the prepolymer to the drum and evacuate it to 50 Pa. Then, in a sealed environment, heat the dried bio-based polyamide 510 prepolymer to 200 °C and keep it at that temperature for 6 hours to perform solid-phase thickening and obtain the fully bio-based polyamide 510 resin.

[0043] Example 2

[0044] A method for preparing a fully bio-based polyamide includes the following steps:

[0045] (1) Weigh 2.04 kg of bio-based pentanediamine, 4.6 kg of bio-based dodecanoic acid and 6.64 kg of deionized water to prepare a 50% bio-based polyamide 512 salt solution (the mass of bio-based polyamide 512 salt is 6.64 kg). Heat the solution to 160℃ and concentrate it. After cooling the discharged water vapor, weigh the water obtained until the weight of the water reaches 7.17 kg (at this time, the weight of the water is 108% of the total mass of bio-based polyamide 512 salt). Then stop the concentration.

[0046] (2) Under closed conditions, continue to heat up to 220℃ for reaction, keep warm for 60 min, cool, discharge the material to obtain bio-based polyamide 512 prepolymer, and then dry at 120℃ for 4 h.

[0047] (3) Add the prepolymer to the drum and evacuate it to 50 Pa. Then, in a sealed environment, heat the dried bio-based polyamide 512 prepolymer to 180°C and keep it at that temperature for 10 hours to perform solid-phase thickening and obtain the fully bio-based polyamide 512 resin.

[0048] Example 3

[0049] A method for preparing a fully bio-based polyamide includes the following steps:

[0050] (1) Weigh 6 kg of bio-based polyamide 1010 salt and 6 kg of deionized water, mix them, heat to 160°C and concentrate. After cooling the discharged water vapor, weigh the water obtained until the weight of the water reaches 6 kg (at this time the weight of the water is 100% of the total weight of bio-based polyamide salt 1010) and then stop the concentration.

[0051] (2) Under closed conditions, continue to heat up to 240℃ for reaction, keep warm for 60 min, cool, discharge the material to obtain bio-based polyamide 1010 prepolymer, and then dry at 120℃ for 4 h.

[0052] (3) Add the prepolymer to the drum and evacuate it to 50 Pa. Then, in a sealed environment, heat the dried bio-based polyamide 1010 prepolymer to 180°C and keep it at that temperature for 10 hours to perform solid-phase thickening and obtain the fully bio-based polyamide 1010 resin.

[0053] Comparative Example 1

[0054] A method for preparing a fully bio-based polyamide includes the following steps:

[0055] (1) Weigh 2.04 kg of bio-based pentanediamine, 4.04 kg of bio-based sebacic acid and 6.08 kg of deionized water and mix them to prepare a 50% bio-based polyamide 510 salt solution. Heat the solution to 180°C and concentrate it. After cooling the discharged water vapor, weigh the water until the weight of the water reaches 4.86 kg (at this time, the weight of the water is 80% of the total mass of the bio-based polyamide 510 salt).

[0056] (2) Continue heating to 240℃, maintain this temperature and continue to discharge water vapor (non-sealed conditions), cool the discharged water vapor and weigh the water until the weight of the water reaches 6.38kg (at this time the weight of the water is 105% of the total mass of bio-based polyamide 510 salt), cool, discharge the material, and obtain bio-based polyamide 510 prepolymer, and then dry at 120℃ for 4h.

[0057] (3) Add the prepolymer to the drum and evacuate it to 50 Pa. Then, in a sealed environment, heat the dried bio-based polyamide 510 prepolymer to 200 °C and keep it at that temperature for 6 hours to perform solid-phase thickening and obtain the fully bio-based polyamide 510 resin.

[0058] Comparative Example 2

[0059] A method for preparing a fully bio-based polyamide differs from Example 1 in step (3), specifically as follows:

[0060] The bio-based polyamide 510 prepolymer obtained in Example 1 was added to a drum, and a vacuum was continuously drawn to maintain a vacuum degree of 50 Pa. Then, in a non-sealed environment, the temperature was raised to 200°C and held for 6 hours to carry out solid-phase thickening, thereby obtaining the fully bio-based polyamide 510 resin.

[0061] Product effectiveness test

[0062] The methods of each of the above examples and comparative examples were repeated 10 times to obtain polyamides. The terminal amino content of different batches of polyamides was tested, and the average value and deviation of the terminal amino content were calculated. The results are shown in Table 1.

[0063] Table 1. Average values ​​and deviations of terminal amino groups from different batches.

[0064]

[0065] As shown in the table above, the terminal amine content of the polyamides produced by the methods in Examples 1-3 of this invention is small, indicating that after the improvement of this invention, the terminal amine content of the polyamides obtained from different production batches using the same production method is stable, and the method has good repeatability. However, Comparative Examples 1 and 2 were not carried out in a closed environment during the prepolymerization and solid-phase thickening stages, respectively, and were conducted at higher temperatures (above 180°C). The diamine evaporated and was lost significantly at high temperatures, resulting in poor method stability and large terminal amine content deviations between different batches of polyamide.

Claims

1. A method for preparing a fully bio-based polyamide, characterized in that, Includes the following steps: (1) Mix the fully bio-based polyamide salt with water and concentrate it to obtain a concentrate; (2) Under a closed environment, the temperature is raised, the concentrate undergoes a prepolymerization reaction, and after cooling, a fully bio-based polyamide prepolymer is obtained and dried; (3) In a closed environment, the polyamide prepolymer is heated and dried to undergo solid-phase thickening to obtain the fully bio-based polyamide; In step (1), the temperature is raised to 100-180℃ for concentration; In step (2), the temperature is raised to 180-260℃, and the concentrate undergoes a prepolymerization reaction, which is maintained for 0.5-1h. In step (3), the temperature is raised to 180-260℃, and the dried polyamide prepolymer is subjected to solid-phase thickening and kept at the temperature for 4-24 hours.

2. The preparation method according to claim 1, characterized in that, In step (1), the all-bio-based polyamide salt includes at least one of all-bio-based polyamide 56 salt, all-bio-based polyamide 510 salt, all-bio-based polyamide 512 salt, all-bio-based polyamide 513 salt, all-bio-based polyamide 66 salt, all-bio-based polyamide 610 salt, all-bio-based polyamide 612 salt, all-bio-based polyamide 613 salt, all-bio-based polyamide 1010 salt, all-bio-based polyamide 1012 salt, all-bio-based polyamide 1013 salt, all-bio-based polyamide 1212 salt, and all-bio-based polyamide 1213 salt.

3. The preparation method according to claim 1, characterized in that, In step (1), the mass ratio of the fully bio-based polyamide salt to water is (0.5-1.5):(0.5-1.5).

4. The preparation method according to claim 1, characterized in that, In step (2), the specific viscosity of the fully bio-based polyamide prepolymer is 0.1-0.

8.

5. The preparation method according to claim 1, characterized in that, In step (3), the specific viscosity of the fully bio-based polyamide is 0.8-3.

6. The preparation method according to claim 1, characterized in that, In step (3), before the solid phase thickening, a vacuum is first drawn at 20-30℃ to 30-100Pa.

7. The application of the method for preparing the fully bio-based polyamide according to any one of claims 1-6 in the field of synthetic fiber preparation.

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