Bio-based long-carbon-chain nylon based on pentamethylene diamine and preparation method of bio-based long-carbon-chain nylon

Abstract

The invention relates to bio-based long-carbon-chain nylon based on pentamethylene diamine and a preparation method thereof.The bio-based long-carbon-chain nylon is prepared through the following steps that A, pentamethylene diamine and binary acid are subjected to a water bath reaction, and precursor salt is prepared; and B, adding the precursor salt and a reaction aid into a reaction kettle to perform a prepolymerization reaction under the condition of a catalyst through a melt polycondensation method, and then performing a final polymerization reaction to obtain the catalyst. The mechanical property test result of the prepared bio-based long carbon chain nylon shows that the yield strength of the bio-based long carbon chain nylon is 54-60 MPa, the elongation at break can reach 219-255%, and the bio-based long carbon chain nylon has certain strength and good toughness; and the non-isothermal crystallization activation energy [delta] E is-144.09 to-216.79 KJ / mol.

Description

Technical Field

[0001] The present application relates to the technical field of polymer materials, and in particular to a bio-based long carbon chain nylon based on pentamethylenediamine and a preparation method thereof. Background Art

[0002] With the improvement of human living standards and the rapid development of industrial production, the demand for high-performance polymer materials in various regions of the world continues to expand, and the performance requirements are becoming increasingly higher. Nylon firmly occupies the top position among the five major engineering plastics with its excellent comprehensive performance. At present, the vast majority of nylon products are petroleum-based materials. Due to the widespread concern of people about global warming and the depletion of oil resources, the development of sustainable green synthesis processes has become the most promising alternative to traditional petroleum-based chemical synthesis processes

[90] . Against this background, bio-based nylon has developed rapidly in recent years. Long-chain dibasic acids produced mainly from castor oil are widely used to prepare bio-based nylon and have a long history of development. As a major producer of castor oil, my country has a very mature high-temperature cracking technology for producing long-chain dibasic acid monomers and launched its own unique bio-based PA1010 in the last century. In addition to the oil-based monomer preparation route, the sugar route using glucose, starch, cellulose and other sugar substances as raw materials to prepare monomers through microbial fermentation has also made major breakthroughs. Bio-based nylons including PA56 have flourished and have become an indispensable and important member of the nylon family.

[0003] Pentamethylenediamine is a common alkaloid widely found in organisms. As a key intermediate in the synthesis of bio-based nylon, pentamethylenediamine has experienced rapid development in the past decade. Microbial fermentation technology has achieved significant breakthroughs, leading to continued increases in production capacity and decreasing costs. This has facilitated the rapid development of pentamethylenediamine-based bio-based nylon. As the largest pentamethylenediamine producer in China and abroad, Shanghai Kaisai Biotechnology Co., Ltd. has fully commercialized PA56 fiber and launched related modified products. These products have gained widespread recognition for their excellent performance and comfortable feel, even being considered an alternative to the petroleum-based PA66. Currently, Kaisai Biotechnology is continuously expanding production capacity, with construction of a 100,000-ton production line underway. At the same time, the new bio-based long-chain nylon based on pentamethylenediamine is also a bio-based product with great development potential. In addition to the characteristics of general nylon, long-carbon chain nylon also has the advantages of low water absorption, good flexibility, good electrical insulation, and low-temperature resistance. It is widely used in engineering and civil fields. Due to the restriction of the key raw material hexamethylenediamine, most of the long-carbon chain nylons such as PA610 and PA612 in my country still need to be imported or monopolized by foreign companies. They are always facing force majeure such as high premiums and insufficient supply. Therefore, the development of new bio-based long-carbon chain nylon with independent intellectual property rights and excellent performance is of great significance for my country to break through the overseas monopoly and promote the development of domestic nylon new materials. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a bio-based long carbon chain nylon based on pentamethylenediamine and a preparation method thereof.

[0005] The present invention is achieved through the following technical solutions:

[0006] The present invention provides a method for preparing bio-based long carbon chain nylon based on pentamethylenediamine, comprising the following steps:

[0007] A. reacting pentamethylenediamine and dibasic acid in a water bath to prepare a precursor salt;

[0008] B. The precursor salt prepared in step A is subjected to a melt polycondensation method. Under catalyst conditions, the precursor salt and a reaction aid are added to a reactor for a prepolymerization reaction, and then a final polymerization reaction is carried out to prepare a bio-based long carbon chain nylon.

[0009] Preferably, in step A, the dibasic acid is selected from at least one of sebacic acid, dodecanedioic acid, and tridecanedioic acid.

[0010] Preferably, in step A, the molar ratio of pentamethylenediamine to dibasic acid is 1:1.

[0011] Preferably, in step A, the reaction temperature of the water bath reaction is 50° C. and the reaction time is 30-60 min.

[0012] Preferably, in step B, the catalyst is sodium hypophosphite;

[0013] Preferably, in step B, the amount of the catalyst added is 0.1 wt% of the precursor salt.

[0014] Preferably, in step B, the reaction aid is hexafluoroisopropanol or deuterated sulfuric acid.

[0015] Preferably, in step B, the reaction temperature of the prepolymerization reaction is 170-180° C. and the reaction time is 1 hour.

[0016] Preferably, in step B, the reaction temperature of the final polymerization reaction is 200-220° C., and the reaction time is 2-3 h.

[0017] The present invention also provides a bio-based long carbon chain nylon based on pentamethylenediamine prepared by the aforementioned method.

[0018] Compared with the prior art, the present invention has the following positive effects:

[0019] This invention synthesizes a series of bio-based long-chain nylons by reacting the bio-based monomer pentamethylenediamine with a long-chain dibasic acid. Mechanical property testing results show that the bio-based long-chain nylons have a yield strength between 54 and 60 MPa and an elongation at break of 219 to 255%, demonstrating both strength and toughness. Furthermore, their non-isothermal crystallization activation energy, ΔE, ranges from -144.09 to -216.79 kJ / mol. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0021] Figure 1 FT-IR spectra of bio-based long carbon chain nylon (PA510, PA512, PA513) prepared in Examples 1-3;

[0022] Figure 2 NMR spectra of bio-based long carbon chain nylon (PA510, PA512, PA513) prepared in Examples 1-3; wherein, Figure 2 (a) is the hydrogen spectrum, Figure 2 (a) is the carbon spectrum. DETAILED DESCRIPTION

[0023] Unless otherwise indicated, implied from the context, or customary in the art, all parts and percentages in this application are based on weight. Where applicable, the contents of any patents, patent applications, or publications referred to in this application are incorporated herein by reference in their entirety, and their equivalent patent families are also incorporated by reference. If the definition of a specific term disclosed in the prior art is inconsistent with any definition provided in this application, the definition of the term provided in this application shall prevail.

[0024] Numerical ranges in this application are approximate values, so unless otherwise stated, they may include numerical values ​​outside the range. Numerical ranges include all numerical values ​​from the lower limit to the upper limit increased by 1 unit, provided that there is an interval of at least 2 units between any lower value and any higher value. For example, if the recorded component, physical or other properties (such as molecular weight, melt index, etc.) are 100 to 1000, it is meant that all individual numerical values ​​are clearly enumerated, such as 100, 101, 102, etc., and all subranges, such as 100 to 166, 155 to 170, 198 to 200, etc. For a range comprising a numerical value less than 1 or comprising a fraction greater than 1 (such as 1.1, 1.5, etc.), 1 unit is appropriately considered to be 0.0001, 0.001, 0.01 or 0.1. For a range comprising a single digit less than 10 (such as 1 to 5), 1 unit is typically considered to be 0.1. These are merely specific examples of what is intended, and all possible combinations of values ​​between the lowest and highest values ​​recited are considered to be expressly stated in this application. It should also be noted that the terms "first," "second," etc. herein do not limit the order of precedence, but are only used to distinguish substances of different structures.

[0025] When used with respect to chemical compounds, unless expressly stated otherwise, the singular includes all isomeric forms and vice versa (e.g., "hexane" includes all isomers of hexane, individually or collectively). In addition, nouns using "a," "an," or "the" also include their plural forms unless expressly stated otherwise.

[0026] The terms "comprising", "including", "having" and their derivatives do not exclude the presence of any other components, steps or processes and are irrelevant to whether these other components, steps or processes are disclosed in this application. To eliminate any doubt, all compositions using the terms "comprising", "including", or "having" in this application may include any additional additives, excipients or compounds unless expressly stated otherwise. In contrast, the term "essentially consisting of" excludes any other components, steps or processes from the scope of any description of the term below, except those necessary for operational performance. The term "consisting of" does not include any components, steps or processes that are not specifically described or listed. Unless expressly stated otherwise, the term "or" refers to the listed members alone or in any combination thereof.

[0027] Example

[0028] The following examples will be used to clearly and completely describe the technical solutions of the present application. Unless otherwise specified, all reagents and raw materials used can be purchased from commercial sources. The experimental methods in the following examples, where specific conditions are not specified, were performed according to conventional methods and conditions, or selected according to the product specifications.

[0029] Example 1

[0030] This embodiment provides a method for preparing bio-based long carbon chain nylon based on pentamethylenediamine. The specific preparation steps are as follows:

[0031] 1) Weigh appropriate amounts of pentamethylenediamine and sebacic acid in a molar ratio of 1:1, add 500 mL of anhydrous ethanol to a three-necked flask, add the weighed sebacic acid to the flask, place the flask in a water bath, turn on the water bath heating and stirring, and slowly raise the temperature to 50°C to completely dissolve the sebacic acid in the ethanol; slowly add the weighed pentamethylenediamine to the sebacic acid solution within 30 minutes. Too fast addition will cause violent boiling and agglomeration. With the addition of pentamethylenediamine, the system gradually turns into a clear and transparent yellow solution. After continuing the reaction for 30 minutes, stop heating, and cool the obtained nylon salt solution at room temperature for 12 hours to precipitate white crystalline salt. Wash the precipitated crystalline salt with anhydrous ethanol and filter it. After repeating three times, place it in a vacuum oven and dry it at 30°C for 12 hours to obtain dry white PA510 salt powder.

[0032] 2) Weigh an appropriate amount of PA510 salt powder and dissolve it in deionized water to prepare a PA510 salt solution with a mass fraction of approximately 60%, add 0.1w% sodium hypophosphite as a catalyst, and additionally add 1-2‰ of diamine monomer as loss compensation. The nylon salt solution and reaction aids hexafluoroisopropanol and deuterated sulfuric acid are stirred evenly and then added to a glass reactor; the reactor is placed in an electric constant temperature oil bath, fixed with a device, and high-purity nitrogen is continuously introduced to purge the container to expel all oxygen, with a nitrogen purge flow rate of 50 mL / min; stirring and heating are started, and the temperature is raised to 180°C and then heated at a constant temperature for 1 hour to carry out a prepolymerization reaction. After the reaction is completed, the temperature is continued to be raised to 220°C and the constant temperature reaction is carried out for 3 hours to carry out a final polymerization reaction. After the reaction is completed, the nylon melt is quickly taken out and placed in a cold water tank. After cooling and shaping, it is crushed and dried to obtain a translucent PA510 nylon.

[0033] Example 2

[0034] This embodiment provides a method for preparing bio-based long carbon chain nylon based on pentamethylenediamine. The specific preparation steps are as follows:

[0035] 1) Weigh appropriate amounts of pentamethylenediamine and dodecanedioic acid in a molar ratio of 1:1 and set aside. Add 500 mL of anhydrous ethanol to a three-necked flask, add the weighed dodecanedioic acid to the flask, place the flask in a water bath, turn on the water bath for heating and stirring, and slowly raise the temperature to 50° C. to completely dissolve the dodecanedioic acid in the ethanol; slowly add the weighed pentamethylenediamine to the dodecanedioic acid solution over 30 minutes. Too rapid addition will cause violent boiling and agglomeration. With the addition of pentamethylenediamine, the system gradually turns into a clear and transparent yellow solution. Continue the reaction for 30 minutes and then stop heating. Cool the obtained nylon salt solution at room temperature for 12 hours to precipitate white crystalline salt. Wash the precipitated crystalline salt with anhydrous ethanol and filter it. After repeating this three times, place it in a vacuum oven at 30° C. and dry it for 12 hours to obtain dry white PA512 salt powder.

[0036] 2) Weigh an appropriate amount of PA512 salt powder and dissolve it in deionized water to prepare a PA512 salt solution with a mass fraction of approximately 60%, add 0.1w% sodium hypophosphite as a catalyst, and additionally add 1-2‰ of diamine monomer as loss compensation. The nylon salt solution and reaction aids hexafluoroisopropanol and deuterated sulfuric acid are stirred evenly and then added to a glass reactor; the reactor is placed in an electric constant temperature oil bath, fixed with a device, and high-purity nitrogen is continuously introduced to purge the container to expel all oxygen, with a nitrogen purge flow rate of 50 mL / min; stirring and heating are started, and the temperature is raised to 180°C and then heated at a constant temperature for 1 hour to carry out a prepolymerization reaction. After the reaction is completed, the temperature is continued to be raised to 220°C and the constant temperature reaction is carried out for 3 hours to carry out a final polymerization reaction. After the reaction is completed, the nylon melt is quickly taken out and placed in a cold water tank. After cooling and shaping, it is crushed and dried to obtain a translucent PA512 nylon.

[0037] Example 3

[0038] This embodiment provides a method for preparing bio-based long carbon chain nylon based on pentamethylenediamine. The specific preparation steps are as follows:

[0039] 1) Weigh appropriate amounts of pentamethylenediamine and tridecanedioic acid in a molar ratio of 1:1 and set aside. Add 500 mL of anhydrous ethanol to a three-necked flask, add the weighed tridecanedioic acid to the flask, place the flask in a water bath, turn on the water bath for heating and stirring, and slowly raise the temperature to 50° C. to completely dissolve the tridecanedioic acid in the ethanol; slowly add the weighed pentamethylenediamine to the tridecanedioic acid solution over 30 minutes. Too rapid addition will cause violent boiling and agglomeration. With the addition of pentamethylenediamine, the system gradually turns into a clear and transparent yellow solution. Continue the reaction for 30 minutes and then stop heating. Cool the obtained nylon salt solution at room temperature for 12 hours to precipitate white crystalline salt. Wash the precipitated crystalline salt with anhydrous ethanol and filter it. After repeating this three times, place it in a vacuum oven at 30° C. and dry it for 12 hours to obtain dry white PA513 salt powder.

[0040] 2) Weigh an appropriate amount of PA513 salt powder and dissolve it in deionized water to prepare a PA513 salt solution with a mass fraction of approximately 60%. Add 0.1w% sodium hypophosphite as a catalyst, and additionally add 1-2‰ of diamine monomer as loss compensation. Stir the nylon salt solution and reaction aids hexafluoroisopropanol and deuterated sulfuric acid until uniformly distributed, and then add the mixture to a glass reactor. Place the reactor in an electric constant temperature oil bath, fix the device and continuously introduce high-purity nitrogen to purge the container to expel all oxygen. The nitrogen purge flow rate is 50 mL / min. Stir and heat are started, and the temperature is raised to 180°C and then heated at a constant temperature for 1 hour to perform a prepolymerization reaction. After the reaction is completed, the temperature is continuously raised to 220°C and the reaction is carried out at a constant temperature for 3 hours to perform a final polymerization reaction. After the reaction is completed, the nylon melt is quickly removed and placed in a cold water tank. After cooling and shaping, it is crushed and dried to obtain a translucent PA513 nylon.

[0041] Performance testing:

[0042] (1) Infrared absorption spectroscopy (FT-IR) test

[0043] Weigh appropriate amounts of PA510 nylon, PA512 nylon, and PA513 nylon pellets prepared in Examples 1-3, set the upper and lower plate temperatures of the hot press at 250°C, wrap each nylon pellet with polytetrafluoroethylene film, and hot-press to prepare thin sheets. Infrared testing of the sheet samples was performed using the ATR method. The infrared spectrum test range was 400-4000 cm -1 , with a resolution of 4cm -1 .

[0044] The FT-IR spectrum obtained by the test is as follows Figure 1 As shown in the figure, it can be seen that the infrared spectra of the three PA5X are relatively close.

[0045] (2) H NMR spectrum ( 1 H NMR) test, carbon spectrum ( 13C NMR) testing

[0046] Using tetramethylsilane (TMS) as the internal standard, a small amount of PA510 nylon, PA512 nylon, and PA513 nylon prepared in Examples 1-3 was dissolved in D2SO4. An appropriate amount of the sample solution was transferred to a clean NMR tube for analysis by NMR spectrometry. The instrument was set to scan 128 times at a frequency of 600 MHz.

[0047] Tested 1 H NMR and 13 C NMR results are as follows Figure 2 shown.

[0048] (3) Differential scanning calorimetry (DSC) test

[0049] A small amount of PA510 nylon, PA512 nylon, and PA513 nylon prepared in Examples 1-3 were weighed and placed in a crucible. Under a nitrogen atmosphere, the temperature was raised from 50°C to 300°C at a heating rate of 10°C / min. After holding for 5 minutes, the temperature was lowered to 50°C at a cooling rate of 10°C / min, held for 2 minutes, and finally raised to 300°C at a rate of 10°C / min. The nitrogen purge rate was 60 mL / min.

[0050] The tests showed that the melting temperatures (Tm) of PA510 nylon, PA512 nylon and PA513 nylon were 214°C, 209°C and 204°C respectively.

[0051] (4) Mechanical properties test

[0052] The prepared PA5X resin pellets were vacuum-dried at 100°C for 8 hours. The pellets were then fully melted using a micro double-cone extruder with the upper and lower platens set at 225°C and a rotational speed of 15 rpm. The melt was then extruded into the barrel of an injection molding machine. A WZS10D micro-injection molding machine was used under the following processing conditions: a barrel temperature of 225°C, a mold temperature of 70°C, and a pressure of 0.8 MPa. Tensile, flexural, and notched impact bars were prepared using different molds. The mechanical properties of the PA5X bars were then tested using a UTM-1422 (JJ-TEST, China). All samples had a strictly standardized size of 80 × 5.5 × 2 mm³. Mechanical strength tests were conducted according to GB / T 1040.1-2018. The tensile test was conducted at a measurement speed of 10 mm / min³ for the plate specimens. Flexural strength samples were tested according to GB / T 9341-2008. Tensile tests were conducted at a speed of 2 mm / min⁻¹ and a deflection of 6 mm for plate specimens. Notched impact strength samples were tested according to GB / T 9341-2008. Each sample was tested five times, and the average value was calculated.

[0053] The mechanical properties test results are shown in Table 1.

[0054] Table 1

[0055]

[0056] As can be seen from the results in Table 1, the tensile strength of PA510, PA512, and PA513 is between 54 and 60 MPa, which can meet the requirements of engineering plastics. The elongation at break of the three nylons all reaches more than 200%, and they all have good toughness. The flexural strength and notched impact strength of PA510 are significantly better than those of PA512 and PA513. The main reason is that as the length of the dibasic acid chain increases, the amide bond density decreases, the intermolecular force weakens, and the material crystallinity decreases, so the material strength will be reduced.

[0057] (5) Non-isothermal crystallization behavior test

[0058] Appropriate amounts of PA510 nylon, PA512 nylon, and PA513 nylon were weighed and dried in a vacuum oven at 80°C for 8 hours. The dried samples were placed in a crucible and each sample was divided into 5 groups. Under a nitrogen atmosphere, the temperature of all samples was reduced at a rate of 20°C / min to 250°C and kept warm for 5 minutes to fully melt the samples. Then, the temperatures of the 5 groups of samples were reduced to room temperature at different cooling rates of 5, 10, 20, 30, and 40°C / min, respectively, to obtain cooling curves.

[0059] The Kissinger equation was used to calculate the non-isothermal crystallization activation energy ΔE of PA510, PA512, and PA513. After fitting, a good linear relationship was found. The calculated ΔE were -144.09 KJ / mol, -216.79 KJ / mol, and -160.60 KJ / mol, respectively.

[0060] The above description of the embodiments is intended to facilitate understanding and application of the present application by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without expending any creative effort. Therefore, the present application is not limited to the embodiments described herein, and improvements and modifications made by those skilled in the art based on the disclosure of this application without departing from the scope and spirit of this application are within the scope of this application.

Claims

1. A method for preparing bio-based long carbon chain nylon based on pentamethylenediamine, characterized in that: The following steps are involved: A. reacting pentamethylenediamine and dibasic acid in a water bath to prepare a precursor salt; B. The precursor salt prepared in step A is subjected to a melt polycondensation method. Under catalyst conditions, the precursor salt and a reaction aid are added to a reactor for a prepolymerization reaction, and then a final polymerization reaction is carried out to prepare a bio-based long carbon chain nylon.

2. The method for preparing bio-based long carbon chain nylon based on pentamethylenediamine according to claim 1, characterized in that: In step A, the dibasic acid is selected from at least one of sebacic acid, dodecanedioic acid, and tridecanedioic acid.

3. The method for preparing bio-based long carbon chain nylon based on pentamethylenediamine according to claim 1, characterized in that: In step A, the molar ratio of pentamethylenediamine to dibasic acid is 1:

1.

4. The method for preparing bio-based long carbon chain nylon based on pentamethylenediamine according to claim 1, characterized in that: In step A, the reaction temperature of the water bath reaction is 50° C. and the reaction time is 30-60 min.

5. The method for preparing bio-based long carbon chain nylon based on pentamethylenediamine according to claim 1, characterized in that: In step B, the catalyst is sodium hypophosphite.

6. The method for preparing bio-based long carbon chain nylon based on pentamethylenediamine according to claim 1 or 5, characterized in that: In step B, the amount of the catalyst added is 0.1 wt% of the precursor salt.

7. The method for preparing bio-based long carbon chain nylon based on pentamethylenediamine according to claim 1, characterized in that: In step B, the reaction aids are hexafluoroisopropanol and deuterated sulfuric acid.

8. The method for preparing bio-based long carbon chain nylon based on pentamethylenediamine according to claim 1, characterized in that: In step B, the reaction temperature of the prepolymerization reaction is 170-180° C. and the reaction time is 1 hour.

9. The method for preparing bio-based long carbon chain nylon based on pentamethylenediamine according to claim 1, characterized in that: In step B, the reaction temperature of the final polymerization reaction is 200-220° C. and the reaction time is 2-3 hours.

10. A bio-based long carbon chain nylon based on pentamethylenediamine prepared according to the method according to any one of claims 1 to 9.

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