A novel bio-based furan copolyamide and preparation method thereof

Abstract

The invention discloses a novel bio-based furan copolyamide and a preparation method thereof, and belongs to the technical field of polyamide preparation. The above method comprises: reacting a slightly excessive amount of diamine and 2,5-furandicarboxylic acid dimethyl ester to obtain an active nylon segment with different repeating units; determining the molecular weight of the nylon active segment; then calculating a dibasic acid with an equal molar ratio to the nylon segment, and adding raw materials such as a catalyst, an antioxidant and a stabilizer to a reactor to complete polymerization. The present invention breaks through in structural design, so that the furan monomer first exists stably in the molecular chain, and then is subsequently polymerized, and a bio-based furan copolyamide with high molecular weight, high transparency, high strength and high toughness is obtained by accurately controlling the segment structure and the content of the furan ring.

Description

Technical Field

[0001] The invention relates to the technical field of polyamide synthesis, in particular to a novel bio-based furan copolyamide and a preparation method thereof. Background Art

[0002] Polyamide (PA) is widely used in mechanical engineering, medical devices and the automotive industry due to its good thermal properties, mechanical properties and chemical resistance. Nowadays, most of the monomers for the preparation of polyamide come from petroleum resources, such as the commercialized polydecamethylene terephthalate PA10T produced from terephthalic acid (TPA). Considering the shortage of petroleum resources and fossil raw materials, the development of renewable biomass raw materials to produce bio-based monomers to synthesize bio-based polyamide has become a new research hotspot in recent years.

[0003] 2,5-Furandicarboxylic acid (FDCA) is the only aromatic compound among the 12 bio-based platform compounds produced from sugars screened by the U.S. Department of Energy. FDCA can be used to obtain a variety of furan derivatives with application potential through oxidation, reduction and amidation reactions. The molecular structure of FDCA contains an aromatic ring, which has fewer carbon atoms than the benzene ring and weaker aromaticity than the benzene ring. Its structural characteristics and structural properties are similar to those of the compound TPA extracted from traditional petrochemical resources. It is a good substitute for petroleum-based terephthalic acid / phthalic acid, so it is rated by the U.S. Department of Energy as one of the most valuable and promising biomass platform substances. Furan-based polymers even have better thermodynamic properties than TPA polymers. Therefore, more and more researchers use FDCA and its derivatives to synthesize furan-based polyamides. However, in the prior art, most researchers' research on furan-based polyamides mainly focuses on its synthesis. The performance data of the obtained polymers are limited, and the obtained products are not stable, have low molecular weight, and have poor mechanical properties. Decarboxylation during high temperature, breakage of furan rings and deactivation of active end groups of oligomers are the main reasons for the low molecular weight of bio-based furan polyamides. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the present invention provides a novel bio-based furan copolyamide and a preparation method thereof. The present invention reacts 2,5-furandicarboxylic acid dimethyl ester with a slightly excess of diamine to obtain amino-terminated active nylon segments with different repeating units, and then reacts the active nylon segments with dibasic acids to obtain a novel bio-based furan copolyamide with a regular structure; the obtained bio-based furan copolyamide has the characteristics of high molecular weight, high transparency, excellent mechanical properties and the like.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] In one aspect, the present invention provides a method for preparing a novel bio-based furan copolyamide, comprising:

[0007] (1) Preparation of amino-terminated products by amide ester exchange between dimethyl 2,5-furandicarboxylate and diamine X

[0008] The nylon active chain segments with different repeating units serve as monomers for subsequent polymerization;

[0009] (2) Dissolving the amino-terminated active nylon segments having different repeating units obtained in (1)

[0010] The molecular weight is titrated in a polar solvent using a dilute hydrochloric acid solution of a certain concentration to obtain the actual molecular weight of the nylon active chain segment;

[0011] (3) Equimolar amino-terminated nylon active segments with different repeating units and dibasic acids

[0012] Y, a catalyst, a stabilizer, an antioxidant and an appropriate amount of water are added into a high-temperature and high-pressure reactor, and then melt polycondensation is performed to obtain a bio-based furan copolyamide with regular segments, high molecular weight, high transparency, high strength and high toughness.

[0013] Preferably, in step (1), the diamine X is one of 1,3-propylenediamine, 1,4-butylenediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine and p-phenylenediamine;

[0014] Furthermore, in the step (1), the amino-terminated nylon active chain segments with different repeating units are: when the molar ratio of dimethyl 2,5-furandicarboxylate to diamine X is 1:2-1:2.1, an active nylon chain segment (XFX) with a repeating unit of 1 is obtained. (1) When the molar ratio of dimethyl 2,5-furandicarboxylate to diamine X is 2:3-2:3.15, an active nylon segment (XFX) having a repeating unit of 2 is obtained. (2) When the molar ratio of dimethyl 2,5-furandicarboxylate to diamine X is 3:4-3:4.2, an active nylon segment (XFX) having a repeating unit of 3 is obtained. (3) diamine);

[0015] Furthermore, the structural formula of the amino-terminated nylon active chain segment with different repeating units in step (1) is as follows:

[0016] The repeating unit is 1:

[0017]

[0018] The repeating unit is 2:

[0019]

[0020] The repeating unit is 3:

[0021]

[0022] Wherein, X is one of a linear aliphatic diamine C3-C12 and p-phenylenediamine; Y is one of a linear aliphatic diacid C3-C12 and cis-1,4-cyclohexanedicarboxylic acid.

[0023] Furthermore, the step (1) is specifically as follows: adding dimethyl 2,5-furandicarboxylate and a slightly excess amount of diamine X into a glass kettle equipped with a mechanical stirrer and a condensing device, heating to 120° C. for reaction for 2 hours under nitrogen flow, i.e., normal pressure, during which a large amount of methanol is produced, then heating to 160-190° C. for reaction for 1-2 hours, then heating to 210° C. for reaction for 0.5 hours, during which only a small amount of methanol is produced, and finally reacting in vacuum at -0.07 MPa for 15 minutes to remove the remaining small molecules, thereby obtaining amino-terminated active nylon segments with different repeating units.

[0024] Preferably, in step (2), the polar solvent is one of hexafluoroisopropanol and trifluoroethanol, and the concentration of dilute hydrochloric acid is 0.05-0.1 mol / L.

[0025] Furthermore, the step (2) is specifically as follows: 0.2-0.4 g of the nylon active chain segment is placed in a 100 mL beaker, 30-50 mL of a polar solvent is added and stirred for 0.5-2 h to dissolve, and then placed in an automatic potentiometric titrator and titrated with a certain concentration of dilute hydrochloric acid solution while stirring to obtain the actual molecular weight of the nylon active chain segment.

[0026] Preferably, in step (3), the dibasic acid Y is one of 1,3-propanedioic acid, 1,4-succinic acid, 1,5-pentanedioic acid, 1,6-hexanedioic acid, 1,7-pimelic acid, 1,8-octanedioic acid, 1,9-nonanedioic acid, 1,10-decanedioic acid, 1,11-undecanedioic acid, 1,12-dodecanedicarboxylic acid and cis-1,4-cyclohexanedicarboxylic acid.

[0027] Preferably, in step (3), the catalyst is one or more of sodium hypophosphite, titanium isopropoxide, titanium citrate, triphenyl phosphite and 1,5,7-triazabicyclo[4.4.0]dec-5-ene; and the antioxidant is antioxidant 1010 and / or antioxidant 1098.

[0028] Preferably, in step (3), the amount of the catalyst is 2‰ of the total mass of the nylon active chain segment and the dibasic acid, and the amount of the antioxidant is 1‰ of the total mass of the nylon active chain segment and the dibasic acid.

[0029] Furthermore, in the step (3), the specific steps for preparing the bio-based furan copolyamide are: calculating the molar number of the nylon active chain segment by the actual molecular weight of the nylon active chain segment titrated in (2). Then, equimolar nylon active chain segments and dibasic acid Y as well as catalyst, stabilizer, antioxidant and appropriate amount of water are added to a high temperature and high pressure reactor, firstly the air is replaced by nitrogen, then the temperature is raised to 5-10°C above the melting point of dibasic acid Y and stabilized for 0.5-2h, then the reaction is carried out at 190-220°C for 2h, then the small molecules existing in the system are slowly released at 220-230°C, then the reaction is carried out at 230°C and 0MPa for 1-2h, and finally the reaction is carried out at 240-250°C and -0.09Mpa for 1h-2h to complete the polymerization. The system is restored to normal pressure, the reactor is opened, the bio-based furan copolyamide is quickly taken out and placed in deionized water, and then the bio-based furan copolyamide product is placed in a 60°C forced air drying oven and dried for 24h.

[0030] On the other hand, the present invention also provides a novel bio-based furan copolyamide prepared by the above method, the general structural formula of which is as follows:

[0031] The repeating unit is 1:

[0032]

[0033] The repeating unit is 2:

[0034]

[0035] The repeating unit is 3:

[0036]

[0037] Wherein, X is one of linear aliphatic diamine C3-C12 and p-phenylenediamine; Y is one of linear aliphatic diacid C3-C12 and cis-1,4-cyclohexanedicarboxylic acid.

[0038] The number average molecular weight of the prepared copolyamide is ≥18000 g / mol, the relative viscosity is ≥2.0, Td-5% is ≥370°C, Td-max is ≥430°C, and the amorphous bio-based furan copolyamide has excellent transparency.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] (1) The present invention first reacts an unstable furan monomer with a diamine X to obtain a stable amino-terminated nylon active hard segment having different repeating units. By this means, the high-temperature decarboxylation and terminal deactivation of dimethyl 2,5-furandicarboxylate can be suppressed, and the furan ring content can be controlled.

[0041] (2) The present invention prepares a novel bio-based furan copolyamide with a regular structure by reacting nylon active segments with other dibasic acids Y. By introducing other monomer units, it is possible to obtain properties that are superior to many bio-based furan random copolymers or even bio-based furan homopolymers. The invention solves the problems of the current bio-based furan polyamides, such as the difficulty in increasing the molecular weight, low molecular weight, many side reactions, and wide molecular weight distribution, thereby preparing a bio-based furan copolyamide with regular segments, high molecular weight, high transparency, and high strength and toughness. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 The FTIR spectrum of the nylon active segment with 1 amino-terminated repeating unit prepared in Example 1 of the present invention;

[0043] Figure 2 FTIR spectrum of the bio-based furan copolyamide prepared by using an active nylon segment having a repeating unit of 1 in Example 1 of the present invention;

[0044] Figure 3 The DSC curve of the bio-based furan copolyamide prepared by using an active nylon segment having a repeating unit of 1 in Example 1 of the present invention;

[0045] Figure 4 This is the TG curve of the bio-based furan copolyamide prepared by using an active nylon segment with a repeating unit of 1 in Example 1 of the present invention. DETAILED DESCRIPTION

[0046] In order to make the technical problems to be solved, technical solutions and advantages of the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0047] In the present invention, the materials and reagents used can be obtained from commercial sources unless otherwise specified.

[0048] The present invention provides a novel bio-based furan copolyamide and a preparation method thereof, and specific embodiments are as follows.

[0049] Example 1

[0050] A method for preparing a novel bio-based furan copolyamide comprises:

[0051] (1) 128.9 parts of dimethyl 2,5-furandicarboxylate and 170 parts of hexamethylenediamine were added to a glass kettle equipped with a magnetic stirring device and a condensing device, and the temperature was raised to 120°C for reaction for 2 hours under nitrogen flow, i.e., normal pressure. During this stage, a large amount of methanol was produced. The temperature was then raised to 160°C for reaction for 1 hour, then raised to 180°C for reaction for 2 hours, and then raised to 210°C for reaction for 0.5 hours. Only a small amount of methanol was produced during these three temperature stages. Finally, the reaction was carried out in vacuum at -0.07 MPa for 15 minutes to remove the remaining small molecules, thereby obtaining an amino-terminated active nylon segment (6F6 (1) diamine).

[0052] (2) Add 0.3 parts of 6F6 (1) The diamine was dissolved in 30 mL of hexafluoroisopropanol, stirred until dissolved, and titrated with 0.05 mol / L dilute hydrochloric acid solution using an automatic potentiometric titrator to obtain 6F6 (1) The actual average molecular weight of the diamine is 373 g / mol.

[0053] (3) 79.81 copies of 6F6 (1) Diamine and 31.27 parts of adipic acid, 0.222 parts of catalyst, 0.111 parts of antioxidant, and 0.111 parts of stabilizer were added to a high-temperature and high-pressure reactor. The air was first replaced by nitrogen, and then the temperature was raised to 5-10°C above the melting point of adipic acid, that is, 160°C for 1 hour, followed by reaction at 220°C for 2 hours, and then the small molecules in the system were slowly released at 220°C; then the reaction was carried out at 230°C and 0MPa for 1 hour, and finally at 240°C and -0.09Mpa for 1 hour to complete the polymerization. The system was restored to normal pressure, the reactor was opened, the bio-based furan copolyamide was quickly taken out and placed in deionized water, and then the bio-based furan copolyamide product was placed in a 60°C forced air drying oven for 24 hours.

[0054] Figure 1 The amino-terminated repeating unit of nylon active segment 6F6 prepared in Example 1 is 1 (1) FTIR spectrum of 3500cm -1 The presence of the characteristic NH peaks of the left and right terminal groups and amide bands I, II, and III indicates the successful synthesis of the amino-terminated nylon active chain segments.

[0055] Figure 2 Bio-based furan copolyamide PA6F6 prepared in Example 1 of the present invention (1) FTIR spectrum of 6. 3300cm -1 Nearby peaks: stretching vibration of hydrogen bond NH in amide group; 2930cm -1 and 2860cm -1 Nearby peaks: asymmetric and symmetric CH stretching vibration peaks; amide I band 1640cm-1 Nearby peaks: C=O stretching vibration of amide group; amide II band 1530 cm -1 Nearby peaks: NH bending vibration; amide III band 1280 cm - Nearby peaks: CNH combined absorption peak.

[0056] Figure 3 Bio-based furan copolyamide PA6F6 prepared in Example 1 of the present invention (1) DSC curve of 6. The glass transition temperature gradually increases with the increase of furan ring content, that is, the increase of the number of repeating units. Melting peaks and crystallization peaks are observed from the second DSC heating curve and the cooling curve, indicating that the bio-based furan copolyamide is an amorphous polyamide.

[0057] Figure 4 Bio-based furan copolyamide PA6F6 prepared in Example 1 of the present invention (1) TG curve of PA6F66. From the TG curve, we can see that the bio-based furan copolyamide has only one weight loss process, indicating that the two structural units are completely copolymerized. Moreover, the Td-5% of PA6F66 is ≥375℃ and the Td-max is ≥430℃, indicating that it has good thermal stability.

[0058] Example 2

[0059] A method for preparing a novel bio-based furan copolyamide comprises:

[0060] (1) 184.15 parts of dimethyl 2,5-furandicarboxylate and 183 parts of hexamethylenediamine were added to a glass kettle equipped with a magnetic stirring device and a condensing device, and the temperature was raised to 120°C for reaction for 2 hours under nitrogen flow, i.e., normal pressure. During this stage, a large amount of methanol was produced. The temperature was then raised to 160°C for reaction for 1 hour, then raised to 190°C for reaction for 2 hours, and then raised to 210°C for reaction for 0.5 hours. Only a small amount of methanol was produced during these three temperature stages. Finally, the reaction was carried out in vacuum at -0.07 MPa for 15 minutes to remove the remaining small molecules, thereby obtaining an amino-terminated active nylon segment (6F6 (2) diamine).

[0061] (2) Add 0.3 parts of 6F6 (2) The diamine was dissolved in 30 mL of hexafluoroisopropanol, stirred until dissolved, and titrated with 0.05 mol / L dilute hydrochloric acid solution using an automatic potentiometric titrator to obtain 6F6 (2) The actual average molecular weight of the diamine is 575 g / mol.

[0062] (3) 114.51 copies of 6F6 (2)Diamine, 29.09 parts of adipic acid, 0.286 parts of catalyst, 0.143 parts of antioxidant, 0.143 parts of stabilizer and 7.18 parts of deionized water were added to a high temperature and high pressure reactor. The air was first replaced by nitrogen, and then the temperature was raised to 5-10°C above the melting point of adipic acid, that is, 160°C for 1 hour, and then reacted at 220°C for 2 hours, and then the small molecules in the system were slowly released at 220°C; then reacted at 230°C and 0MPa for 1 hour, and finally reacted at 250°C and -0.09Mpa for 1 hour to complete the polymerization. The system was restored to normal pressure, the reactor was opened, the bio-based furan copolyamide was quickly taken out and placed in deionized water, and then the bio-based furan copolyamide product was placed in a 60°C forced air drying oven for 24 hours.

[0063] Example 3

[0064] A method for preparing a novel bio-based furan copolyamide comprises:

[0065] (1) 184.15 parts of dimethyl 2,5-furandicarboxylate and 161.5 parts of hexamethylenediamine were added to a glass kettle equipped with a magnetic stirring device and a condensing device, and the temperature was raised to 120° C. for reaction for 2 h under nitrogen flow, i.e., normal pressure. During this stage, a large amount of methanol was produced. The temperature was then raised to 190° C. for reaction for 2 h, and then raised to 210° C. for reaction for 0.5 h. During these three temperature stages, only a small amount of methanol was produced. Finally, the reaction was carried out in a vacuum at -0.07 MPa for 15 min to remove the remaining small molecules, thereby obtaining an amino-terminated active nylon segment (6F6 (3) diamine).

[0066] (2) Add 0.3 parts of 6F6 (3) The diamine was dissolved in 30 mL of hexafluoroisopropanol, stirred until dissolved, and titrated with 0.05 mol / L dilute hydrochloric acid solution using an automatic potentiometric titrator to obtain 6F6 (3) The actual average molecular weight of the diamine is 833 g / mol.

[0067] (3) 120 copies of 6F6 (3)Diamine, 21.05 parts of adipic acid, 0.282 parts of catalyst, 0.141 parts of antioxidant, 0.141 parts of stabilizer and 7.05 parts of deionized water were added to a high temperature and high pressure reactor. The air was first replaced by nitrogen, and then the temperature was raised to 5-10°C above the melting point of adipic acid, that is, 160°C for 1 hour, and then reacted at 230°C for 2 hours, and then the small molecules in the system were slowly released at 230°C; then reacted at 240°C and 0MPa for 1 hour, and finally reacted at 250°C and -0.09Mpa for 1 hour to complete the polymerization. The system was restored to normal pressure, the reactor was opened, the bio-based furan copolyamide was quickly taken out and placed in deionized water, and then the bio-based furan copolyamide product was placed in a 60°C forced air drying oven for 24 hours.

[0068] Example 4

[0069] A method for preparing a novel bio-based furan copolyamide comprises:

[0070] (1)-(2) Same as Example 1, 6F6 (1) The molecular weight of the diamine is 373 g / mol;

[0071] (3) 85 copies of 6F6 (1) Diamine and 52.41 parts of dodecanedioic acid, 0.274 parts of catalyst, 0.137 parts of antioxidant, and 0.137 parts of stabilizer were added to a high-temperature and high-pressure reactor. The air was first replaced by nitrogen, and then the temperature was raised to 5-10°C above the melting point of dodecanedioic acid, that is, 140°C for 1 hour, followed by reaction at 220°C for 2 hours, and then the small molecules in the system were slowly released at 220°C; then the reaction was carried out at 230°C and 0MPa for 1 hour, and finally at 240°C and -0.09Mpa for 1 hour to complete the polymerization. The system was restored to normal pressure, the reactor was opened, the bio-based furan copolyamide was quickly taken out and placed in deionized water, and then the bio-based furan copolyamide product was placed in a 60°C forced air drying oven for 24 hours.

[0072] Example 5

[0073] A method for preparing a novel bio-based furan copolyamide comprises:

[0074] (1)-(2) Same as Example 2, 6F6 (2) The molecular weight of the diamine is 575 g / mol;

[0075] (3) 125 copies of 6F6 (2)Diamine and 49.9 parts of dodecanedioic acid, 0.350 parts of catalyst, 0.175 parts of antioxidant, 0.175 parts of stabilizer and 8.74 parts of deionized water were added to a high temperature and high pressure reactor, and then the temperature was raised to 5-10°C above the melting point of dodecanedioic acid, that is, 140°C for stabilization for 1 hour, followed by reaction at 220°C for 2 hours, and then the small molecules in the system were slowly released at 220°C; then the reaction was carried out at 230°C and 0MPa for 1 hour, and finally at 240°C and -0.09Mpa for 1 hour to complete the polymerization. The system was restored to normal pressure, the reactor was opened, the bio-based furan copolyamide was quickly taken out and placed in deionized water, and then the bio-based furan copolyamide product was placed in a 60°C forced air drying oven for 24 hours.

[0076] Example 6

[0077] A method for preparing a novel bio-based furan copolyamide comprises:

[0078] (1)-(2) Same as Example 3, 6F6 was obtained (3) The molecular weight of the diamine is 833 g / mol;

[0079] (3) 100 copies of 6F6 (3) Diamine and 27.61 parts of dodecanedioic acid, 0.254 parts of catalyst, 0.127 parts of antioxidant, 0.127 parts of stabilizer and 6.38 parts of deionized water were added to a high temperature and high pressure reactor, and then the temperature was raised to 5-10°C above the melting point of dodecanedioic acid, that is, 140°C for stabilization for 1 hour, followed by reaction at 220°C for 2 hours, and then the small molecules in the system were slowly released at 220°C; then the reaction was carried out at 230°C and 0MPa for 1 hour, and finally at 240°C and -0.09Mpa for 1 hour to complete the polymerization. The system was restored to normal pressure, the reactor was opened, the bio-based furan copolyamide was quickly taken out and placed in deionized water, and then the bio-based furan copolyamide product was placed in a 60°C forced air drying oven for 24 hours.

[0080] Example 7

[0081] A method for preparing a novel bio-based furan copolyamide comprises:

[0082] (1) 128.9 parts of dimethyl 2,5-furandicarboxylate and 253.33 parts of decanediamine were added to a glass kettle equipped with a magnetic stirring device and a condensing device, and the temperature was raised to 140°C for reaction for 2 hours under nitrogen flow, i.e., normal pressure. During this stage, a large amount of methanol was produced. The temperature was then raised to 180°C for reaction for 2 hours, and then raised to 220°C for reaction for 0.5 hours. Only a small amount of methanol was produced during these three temperature stages. Finally, the reaction was carried out in a vacuum at -0.07 MPa for 15 minutes to remove the remaining small molecules, thereby obtaining an amino-terminated active nylon segment (10F10 (1) diamine).

[0083] (2) Mix 3 parts 0.3 parts 10F10 (1) The diamine was dissolved in 30 mL of hexafluoroisopropanol, stirred until dissolved, and titrated with 0.05 mol / L dilute hydrochloric acid solution using an automatic potentiometric titrator to obtain 10F10 (1) The actual average molecular weight of the diamine is 470 g / mol.

[0084] (3) 90 portions of 10F10 (1) Diamine and 27.9 parts of adipic acid, 0.235 parts of catalyst, 0.117 parts of antioxidant, and 0.117 parts of stabilizer were added to a high-temperature and high-pressure reactor. The air was first replaced by nitrogen, and then the temperature was raised to 5-10°C above the melting point of adipic acid, that is, 160°C for 1 hour, followed by reaction at 220°C for 2 hours, and then the small molecules in the system were slowly released at 220°C; then the reaction was carried out at 230°C and 0MPa for 1 hour, and finally at 240°C and -0.09Mpa for 1 hour to complete the polymerization. The system was restored to normal pressure, the reactor was opened, the bio-based furan copolyamide was quickly taken out and placed in deionized water, and then the bio-based furan copolyamide product was placed in a 60°C forced air drying oven for 24 hours.

[0085] Example 8

[0086] A method for preparing a novel bio-based furan copolyamide comprises:

[0087] (1) 184.15 parts of dimethyl 2,5-furandicarboxylate and 271.43 parts of decanediamine were added to a glass kettle equipped with a magnetic stirring device and a condensing device, and the temperature was raised to 140°C for reaction for 2 hours under nitrogen flow, i.e., normal pressure. During this stage, a large amount of methanol was produced. The temperature was then raised to 190°C for reaction for 2 hours, and then raised to 220°C for reaction for 0.5 hours. Only a small amount of methanol was produced during these three temperature stages. Finally, the reaction was carried out in a vacuum at -0.07 MPa for 15 minutes to remove the remaining small molecules, thereby obtaining an amino-terminated active nylon segment having two repeating units (10F10 (2) diamine).

[0088] (2) Mix 3 parts 0.3 parts 10F10 (2) The diamine was dissolved in 30 mL of hexafluoroisopropanol, stirred until dissolved, and titrated with 0.05 mol / L dilute hydrochloric acid solution using an automatic potentiometric titrator to obtain 10F10 (2) The actual average molecular weight of the diamine is 773 g / mol.

[0089] (3) 113 portions of 10F10 (2)Diamine, 21.8 parts of adipic acid, 0.268 parts of catalyst, 0.134 parts of antioxidant, 0.134 parts of stabilizer and 6.74 parts of deionized water were added to a high temperature and high pressure reactor. The air was first replaced by nitrogen, and then the temperature was raised to 5-10°C above the melting point of adipic acid, i.e. 160°C for 1h, followed by reaction at 220°C for 2h, and then the small molecules in the system were slowly released at 220°C; then the reaction was carried out at 230°C and 0MPa for 1h, and finally at 240°C and -0.09Mpa for 1h to complete the polymerization. The system was restored to normal pressure, the reactor was opened, the bio-based furan copolyamide was quickly taken out and placed in deionized water, and then the bio-based furan copolyamide product was placed in a 60°C forced air drying oven for 24h.

[0090] Example 9

[0091] A method for preparing a novel bio-based furan copolyamide comprises:

[0092] (1) 184.15 parts of dimethyl 2,5-furandicarboxylate and 239.55 parts of hexamethylenediamine were added to a glass kettle equipped with a magnetic stirring device and a condensing device, and the temperature was raised to 140°C for reaction for 2 hours under nitrogen flow, i.e., normal pressure. During this stage, a large amount of methanol was produced. The temperature was then raised to 200°C for reaction for 2 hours, and then raised to 220°C for reaction for 0.5 hours. Only a small amount of methanol was produced during these three temperature stages. Finally, the reaction was carried out in a vacuum at -0.07 MPa for 15 minutes to remove the remaining small molecules, thereby obtaining an amino-terminated active nylon segment having three repeating units (10F10 (3) diamine).

[0093] (2) Mix 3 parts 0.3 parts 10F10 (3) The diamine was dissolved in 30 mL of hexafluoroisopropanol, stirred until dissolved, and titrated with 0.05 mol / L dilute hydrochloric acid solution using an automatic potentiometric titrator to obtain 10F10 (3) The actual average molecular weight of the diamine is 1034 g / mol

[0094] (3) 130 portions of 10F10 (3)Diamine and 18.11 parts of adipic acid, 0.296 parts of catalyst, 0.148 parts of antioxidant, 0.148 parts of stabilizer and 7.40 parts of deionized water were added to a high temperature and high pressure reactor, and the air was first replaced by nitrogen, and then the temperature was raised to 5-10°C above the melting point of adipic acid, that is, 160°C for 1 hour, and then reacted at 220°C for 2 hours, and then the small molecules in the system were slowly released at 220°C; then reacted at 230°C and 0MPa for 1 hour, and finally reacted at 240°C and -0.09Mpa for 1 hour to complete the polymerization. The system was restored to normal pressure, the reactor was opened, the bio-based furan copolyamide was quickly taken out and placed in deionized water, and then the bio-based furan copolyamide product was placed in a 60°C forced air drying oven for 24 hours.

[0095] Example 10

[0096] A method for preparing a novel bio-based furan copolyamide comprises:

[0097] (1)-(2) Same as Example 7, 10F10 was obtained (1) The molecular weight of the diamine is 470 g / mol;

[0098] (3) 100 portions of 10F10 (1) Diamine and 48.93 parts of dodecanedioic acid, 0.296 parts of catalyst, 0.148 parts of antioxidant, and 0.148 parts of stabilizer were added to a high-temperature and high-pressure reactor. The air was first replaced by nitrogen, and then the temperature was raised to 5-10°C above the melting point of adipic acid, that is, 160°C for 1 hour, followed by reaction at 220°C for 2 hours, and then the small molecules in the system were slowly released at 220°C; then the reaction was carried out at 230°C and 0MPa for 1 hour, and finally at 240°C and -0.09Mpa for 1 hour to complete the polymerization. The system was restored to normal pressure, the reactor was opened, the bio-based furan copolyamide was quickly taken out and placed in deionized water, and then the bio-based furan copolyamide product was placed in a 60°C forced air drying oven for 24 hours.

[0099] Embodiment 11

[0100] A method for preparing a novel bio-based furan copolyamide comprises:

[0101] (1)-(2) Same as Example 8, 10F10 was obtained (2) The molecular weight of the diamine is 773 g / mol;

[0102] (3) 120 portions of 10F10 (2)Diamine and 35.70 parts of dodecanedioic acid, 0.312 parts of catalyst, 0.156 parts of antioxidant, 0.156 parts of stabilizer and 7.79 parts of deionized water were added to a high temperature and high pressure reactor, and the air was first replaced by nitrogen, and then the temperature was raised to 5-10°C above the melting point of adipic acid, that is, 160°C for 1 hour, and then reacted at 220°C for 2 hours, and then the small molecules in the system were slowly released at 220°C; then reacted at 230°C and 0MPa for 1 hour, and finally reacted at 240°C and -0.09Mpa for 1 hour to complete the polymerization. The system was restored to normal pressure, the reactor was opened, the bio-based furan copolyamide was quickly taken out and placed in deionized water, and then the bio-based furan copolyamide product was placed in a 60°C forced air drying oven for 24 hours.

[0103] Example 12

[0104] A method for preparing a novel bio-based furan copolyamide comprises:

[0105] (1)-(2) Same as Example 9, 10F10 was obtained (3) The molecular weight of the diamine is 1034 g / mol;

[0106] (3) 150 portions of 10F10 (3) Diamine and 32.36 parts of dodecanedioic acid, 0.366 parts of catalyst, 0.183 parts of antioxidant, 0.183 parts of stabilizer and 9.13 parts of deionized water were added to a high temperature and high pressure reactor, and the air was first replaced by nitrogen, and then the temperature was raised to 5-10°C above the melting point of adipic acid, that is, 160°C for 1 hour, and then reacted at 220°C for 2 hours, and then the small molecules in the system were slowly released at 220°C; then reacted at 230°C and 0MPa for 1 hour, and finally reacted at 240°C and -0.09Mpa for 1 hour to complete the polymerization. The system was restored to normal pressure, the reactor was opened, the bio-based furan copolyamide was quickly taken out and placed in deionized water, and then the bio-based furan copolyamide product was placed in a 60°C forced air drying oven for 24 hours.

[0107] To further illustrate the beneficial effects of the present invention, a comparative example is constructed as follows:

[0108] Comparative Example 1

[0109] A method for preparing polyamide, comprising:

[0110] 128.9 parts of dimethyl 2,5-furandicarboxylate and 89.47 parts of hexamethylenediamine, 0.436 parts of catalyst, 0.218 parts of antioxidant, and 0.218 parts of stabilizer were placed in a high-temperature and high-pressure reactor, and the air was first replaced by nitrogen, and then the temperature was raised to 130°C for 2 hours, and then reacted at 170°C for 1 hour, and then reacted at 220°C for 2 hours, and then the small molecules in the system were slowly released at 220°C; then reacted at 230°C and 0MPa for 1 hour, and finally reacted at 240°C and -0.09Mpa for 1 hour to complete the polymerization. The system was restored to normal pressure, the reactor was opened, the bio-based furan polyamide was quickly taken out and placed in deionized water, and then the bio-based furan polyamide product was placed in a 60°C forced air drying oven for 24 hours.

[0111] Comparative Example 2

[0112] A method for preparing polyamide, comprising:

[0113] 128.9 parts of dimethyl 2,5-furandicarboxylate and 154.27 parts of dodecanediamine, as well as 0.566 parts of catalyst, 0.283 parts of antioxidant, and 0.283 parts of stabilizer were placed in a high-temperature and high-pressure reactor, and the air was first replaced by nitrogen, and then the temperature was raised to 120°C for 2h, and then reacted at 160°C for 1h, and then reacted at 200°C for 2h, and then the small molecules in the system were slowly released at 200°C; then reacted at 220°C and 0MPa for 1h, and finally reacted at 230°C and -0.09Mpa for 1h to complete the polymerization. The system was restored to normal pressure, the reactor was opened, the bio-based furan polyamide was quickly taken out and placed in deionized water, and then the bio-based furan polyamide product was placed in a 60°C forced air drying oven for 24h.

[0114] Comparative Example 3

[0115] A method for preparing polyamide, comprising:

[0116] 184.15 parts of dimethyl 2,5-furandicarboxylate, 232.4 parts of hexamethylenediamine, 146.14 parts of adipic acid, 1.126 parts of catalyst, 0.563 parts of antioxidant, 0.563 parts of stabilizer and 28.15 parts of deionized water were added to a high temperature and high pressure reactor, and the air was first replaced by nitrogen, and then the temperature was raised to 5-10°C above the melting point of adipic acid, that is, 160°C for 1 hour, and then reacted at 220°C for 2 hours, and then the small molecules in the system were slowly released at 220°C; then reacted at 230°C and 0MPa for 1 hour, and finally reacted at 250°C and -0.09Mpa for 1 hour to complete the polymerization. The system was restored to normal pressure, the reactor was opened, the bio-based furan copolyamide was quickly taken out and placed in deionized water, and then the bio-based furan copolyamide product was placed in a 60°C forced air drying oven for 24 hours.

[0117] Comparative Example 4

[0118] 184.15 parts of dimethyl 2,5-furandicarboxylate, 174.3 parts of hexamethylenediamine, 73.07 parts of adipic acid, 0.864 parts of catalyst, 0.432 parts of antioxidant, 0.432 parts of stabilizer and 21.57 parts of deionized water were added into a high temperature and high pressure reactor. The other conditions were the same as those of Comparative Example 3.

[0119] Comparative Example 5

[0120] 184.15 parts of dimethyl 2,5-furandicarboxylate, 154.93 parts of hexamethylenediamine, 48.71 parts of adipic acid, 0.774 parts of catalyst, 0.387 parts of antioxidant, 0.387 parts of stabilizer and 19.35 parts of deionized water were added into a high temperature and high pressure reactor. The other conditions were the same as those of Comparative Example 3.

[0121] Comparative Example 6

[0122] In step (1) of this comparative example, the molar ratio of dimethyl 2,5-furandicarboxylate to diamine is 1:2.3, and the other conditions are the same as those in Example 1.

[0123] Comparative Example 7

[0124] In step (1) of this comparative example, the molar ratio of dimethyl 2,5-furandicarboxylate to diamine is 1:1.7, and the other conditions are the same as those in Example 1.

[0125] Comparative Example 8

[0126] In step (1) of this comparative example, the molar ratio of dimethyl 2,5-furandicarboxylate to diamine is 1:1.5, and the other conditions are the same as those in Example 1.

[0127] The polyamides prepared in the examples of the present invention and the comparative examples were subjected to performance tests, and the specific test characterization methods are as follows.

[0128] (1) Fourier transform infrared spectroscopy (FTIR): The ATR method was used to test the copolyamide at 4000-650 cm -1 Scan within the range, the number of times is 32.

[0129] (2) Differential Scanning Calorimetry (DSC): 7-10 mg of the copolyamide was placed in an aluminum crucible and tested under a nitrogen atmosphere. The temperature was raised from 30°C to 300°C at a rate of 10°C / min, kept constant for 2 min to eliminate the history, then lowered from 300°C to 30°C at a rate of 10°C / min, and finally raised from 30°C to 300°C at a rate of 10°C / min.

[0130] (3) Thermogravimetric Analyzer (TGA): 7-10 mg of the copolyamide was placed in an aluminum crucible and tested under a nitrogen atmosphere. The temperature was raised from 30°C to 800°C at a rate of 10°C / min.

[0131] (4) Tensile properties: With reference to the injection molded tensile specimens of GB / T 1040, the copolyamide was subjected to a tensile test on a universal testing machine at a tensile rate of 5 mm / min.

[0132] (5) Gel Permeation Chromatography (GPC): 3-5 mg of copolyamide was dissolved in the mobile phase HFIP. After dissolution, the solution was filtered using a syringe and a filter. 20 μL of the solution was tested at 40°C to obtain the molecular weight of the material.

[0133] The specific test results are shown in Table 1-2.

[0134] Table 1

[0135]

[0136]

[0137] As can be seen from Table 1, the present invention first reacts the unstable furan monomer with the diamine X to obtain a stable amino-terminated nylon active hard segment with different repeating units. By this means, the high-temperature decarboxylation and end group deactivation of 2,5-furandicarboxylic acid dimethyl ester can be suppressed, and the content of the furan ring can be controlled. Then, it can be seen from Examples 1-12 that the nylon active segment reacts with other dibasic acids Y to prepare a new bio-based furan copolyamide with a regular structure. By introducing other monomer units, more excellent properties of the bio-based furan homopolymer can be obtained, and the obtained bio-based furan copolyamide has good uniformity and structural regularity.

[0138] Table 2

[0139]

[0140] From Table 1-2, by comparing Examples 1-12 and Comparative Example 1-2, it can be found that the obtained bio-based furan copolyamide has better thermal stability and mechanical properties than the bio-based furan polyamide homopolymer, especially the tensile strength, breaking strength and elongation at break are greatly improved.

[0141] By comparing Examples 1-12 and Comparative Examples 3-5, it can be found that the bio-based copolyamide obtained by the two-step method has better mechanical properties and thermal stability than the bio-based copolyamide obtained by the one-step method. This is because the addition of dimethyl 2,5-furandicarboxylate in the one-step method cannot ensure its good stability at high temperatures, and is prone to side reactions such as decarboxylation and inactivation of active end groups of oligomers, resulting in poor molecular weight and mechanical properties.

[0142] In Comparative Examples 6-8, when preparing the nylon active chain segments, the excessive amount of diamine added will cause too much deviation between the actual molecular weight and the theoretical molecular weight of the nylon active chain segments, and a large amount of diamine residues in the nylon active chain segments are not easy to remove, which will make it impossible to accurately calculate the subsequent acid-amine molar ratio and the alternating structure of the copolyamide. Therefore, the subsequent polymerization and data acquisition are not carried out.

[0143] In summary, the present invention can reduce the occurrence of side reactions of furan monomers such as high-temperature decarboxylation and oligomer end group deactivation by reacting unstable furan monomers with dibasic acid X to obtain stable amino-terminated nylon active hard segments with different repeating units. At the same time, a regular bio-based furan copolyamide can be prepared by controlling the content of furan rings. The prepared bio-based furan copolyamide has high molecular weight, high heat resistance, and high strength and toughness mechanical properties.

[0144] The above is a preferred embodiment of the present invention. For ordinary technicians in this technical field, without departing from the principles of the present invention, making several improvements and modifications should also be regarded as within the protection scope of the present invention.

Claims

1. A method for preparing a novel bio-based furan copolyamide, characterized in that: include: (1) Under nitrogen protection, dimethyl 2,5-furandicarboxylate and diamine are added to a glass kettle, and the temperature is raised for multiple reactions to obtain amino-terminated active nylon segments with different repeating units; The molar ratio of dimethyl 2,5-furandicarboxylate to diamine is 1:2-1:2.1; or, the molar ratio of dimethyl 2,5-furandicarboxylate to diamine X is 2:3-2:3.15; or, the molar ratio of dimethyl 2,5-furandicarboxylate to diamine X is 3:4-3:4.2; (2) dissolving the active nylon chain segment obtained in step (1) in a polar solvent, and then titrating the molecular weight with a dilute hydrochloric acid solution to obtain the actual molecular weight of the nylon active chain segment; (3) adding the active nylon segment and dibasic acid obtained in step (1) together with a catalyst, an antioxidant, a stabilizer and an appropriate amount of water into a high-temperature and high-pressure reactor, replacing the air with nitrogen, and then obtaining a bio-based furan copolyamide by melt polycondensation; The molar ratio of the active nylon segment to the dibasic acid is 1:1; In the step (1), the diamine is one of 1,3-propylenediamine, 1,4-butylenediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine and p-phenylenediamine; The dibasic acid in step (3) is one of 1,3-propanedioic acid, 1,4-succinic acid, 1,5-pentanedioic acid, 1,6-hexanedioic acid, 1,7-pimelic acid, 1,8-octanedioic acid, 1,9-nonanedioic acid, 1,10-decanedioic acid, 1,11-undecanedioic acid, 1,12-dodecanedicarboxylic acid and cis-1,4-cyclohexanedicarboxylic acid.

2. The preparation method according to claim 1, characterized in that: In the step (2), the polar solvent is hexafluoroisopropanol or trifluoroethanol; and the solubility of the dilute hydrochloric acid is 0.05-0.1 mol / L.

3. The preparation method according to claim 2, characterized in that: In the step (3), the catalyst is one or more of sodium hypophosphite, titanium isopropoxide, titanium citrate, triphenyl phosphite and 1,5,7-triazabicyclo[4.4.0]dec-5-ene; and the antioxidant is antioxidant 1010 and / or antioxidant 1098.

4. The preparation method according to claim 3, characterized in that: The step (1) specifically comprises: adding dimethyl 2,5-furandicarboxylate and a diamine in a defined molar ratio into a glass kettle equipped with a mechanical stirrer and a condenser, heating to 120° C. for reaction for 2 h under nitrogen circulation, i.e., normal pressure, then heating to 160-190° C. for reaction for 1-2 h, then heating to 210° C. for reaction for 0.5 h, and finally reacting in vacuum at -0.07 Mpa for 15 min, thereby obtaining amino-terminated active nylon segments having different repeating units.

5. The preparation method according to claim 4, characterized in that: The step (2) is specifically as follows: 0.2-0.4 g of the nylon active chain segment is placed in a 100 mL beaker, 30-50 mL of a polar solvent is added and stirred for 0.5-2 h to dissolve, and then the mixture is placed in an automatic potentiometric titrator and titrated with a dilute hydrochloric acid solution of a certain concentration while stirring to obtain the actual molecular weight of the nylon active chain segment.

6. The preparation method according to claim 5, characterized in that: In the step (3), the amount of the catalyst is 2‰ of the total mass of the nylon active chain segment and the dibasic acid; the amount of the antioxidant is 1‰ of the total mass of the nylon active chain segment and the dibasic acid.

7. The preparation method according to claim 6, characterized in that: The step (3) is specifically as follows: calculating the molar number of the nylon active chain segment according to the actual molecular weight of the nylon active chain segment titrated in (2); then adding equal moles of the nylon active chain segment and the dibasic acid as well as the catalyst, stabilizer, antioxidant and appropriate amount of water into a high temperature and high pressure reactor, first replacing the air with nitrogen, then heating to 5-10° C. above the melting point of the dibasic acid and stabilizing for 0.5-2 h, then reacting at 190-220° C. for 2 h, then slowly releasing the small molecules in the system at 220-230° C., then reacting at 230° C. and 0 MPa for 1-2 h, and finally reacting at 240-250° C. and -0.09 MPa for 1 h-2 h to complete the polymerization; restoring the system to normal pressure, opening the reactor, quickly taking out the bio-based furan copolyamide and placing it in deionized water, and then placing the bio-based furan copolyamide product in a 60° C. forced air drying oven and drying it for 24 h.

8. A novel bio-based furan copolyamide, characterized in that: It is prepared by the method according to any one of claims 1 to 7.

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