Bio-based nylon 12 and preparation method thereof

Abstract

The invention provides bio-based nylon 12 and a preparation method thereof. The preparation method comprises the following steps: a) adding 12-amino dodecanoic acid inner salt, a catalyst, an antioxidant and a molecular weight regulator into a reaction kettle, filling inert shielding gas into the reaction kettle, and carrying out prepolymerization reaction to obtain a prepolymer; b) performing condensation polymerization on the prepolymer obtained in the step a) to obtain a condensation polymer; and c) sequentially carrying out melt blending, extrusion, cooling and granulation on the polycondensate obtained in the step b) to obtain the bio-based nylon 12. Compared with the prior art, the preparation method provided by the invention has the advantages that the bio-based nylon monomer 12-amino dodecanoic acid inner salt is adopted as a raw material and is matched with other raw material components, polymerization is carried out under specific process steps, overall better interaction is realized, and the prepared ultra-high molecular weight full bio-based nylon 12 is high in product molecular weight, free of coking and good in comprehensive performance.

Description

Technical Field

[0001] The present invention relates to the technical field of nylon preparation, and more specifically, to a bio-based nylon 12 and a preparation method thereof. Background Art

[0002] Nylon 12 is a long carbon chain nylon containing a long subunit unit chain. It has a low amide group density and is currently the lowest density nylon. At the same time, it has the advantages of low water absorption, good dimensional stability, good low-temperature toughness, oil resistance and wear resistance. It has been widely used in automotive fuel pipes, chemical petroleum pipelines, wire and cable sheaths and other fields.

[0003] There are two main routes for the synthesis of nylon 12: the first is to form it through ring-opening polymerization of laurolactam, in which the laurolactam monomer comes from butadiene. The preparation process route is long, and its ring-opening speed is much lower than that of caprolactam. At the same time, it requires a high temperature of more than 300°C, resulting in a high cost of the obtained nylon 12; the second process route is to polymerize 12-aminododecanoic acid as a monomer. Compared with the ring-opening method of laurolactam, the reaction conditions of this process are mild, but the molecular weight of the nylon 12 resin obtained by this method is small. This is because the 12-aminododecanoic acid monomer has high reactivity, melting and polycondensation are carried out simultaneously, and the reaction is difficult to control. It is not only difficult to obtain a high molecular weight nylon resin, but also the molecular weight distribution is poor. The obtained product is easy to coke and decompose, and it is difficult to obtain a high-quality qualified product. In addition, the raw materials for the preparation of nylon 12 are all from petrochemical products, and there is no relevant research and report on bio-based nylon 12. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a bio-based nylon 12 and a preparation method thereof. The monomers in the preparation method provided by the present invention are derived from bio-based components, and the prepared bio-based nylon 12 has a high molecular weight, no coking, and good comprehensive performance.

[0005] The present invention provides a method for preparing bio-based nylon 12, comprising the following steps:

[0006] a) adding 12-aminododecanoic acid inner salt, a catalyst, an antioxidant and a molecular weight regulator into a reaction kettle, and filling the reaction kettle with an inert protective gas to carry out a prepolymerization reaction to obtain a prepolymer;

[0007] b) subjecting the prepolymer obtained in step a) to a polycondensation reaction to obtain a polycondensate;

[0008] c) subjecting the polycondensate obtained in step b) to melt blending, extrusion, cooling and granulation in sequence to obtain bio-based nylon 12.

[0009] Preferably, the 12-aminododecanoic acid inner salt in step a) is obtained from a bio-based method and is prepared by polysaccharide fermentation.

[0010] Preferably, the catalyst in step a) is selected from one or more of phosphoric acid, phosphorous acid, sodium phosphite, sodium hypophosphite and pyrophosphorous acid.

[0011] Preferably, the antioxidant in step a) is selected from one or more of IRGANOX1010, IRGANOX1076, IRGANOX1035, IRGANOX245, IRGANOX1098, IRGANOX1135 and IRGANOX1520.

[0012] Preferably, the molecular weight regulator in step a) is a carboxylic acid or a diamine; the carboxylic acid is selected from one or more of 1,3-propanedioic acid, 1,4-butanedioic acid, 1,6-hexanedioic acid, 1,7-heptanedioic acid, 1,8-octanedioic acid, 1,9-nonanedioic acid, 1,10-decanedioic acid, 1,11-undecanedioic acid, 1,12-dodecanediamine, 1,13-tridecanediamine, 1,14-tetradecanediamine, 1,15-pentadecanedioic acid and 1,16-hexadecanediamine; the diamine is selected from one or more of 1,10-decanediamine, 1,11-undecanedioic acid, 1,12-dodecanediamine, 1,14-tetradecanediamine and 1,16-diaminohexadecane.

[0013] Preferably, the mass ratio of the 12-aminododecanoic acid inner salt, the catalyst, the antioxidant and the molecular weight regulator in step a) is 100:(0.05-1.5):(0.03-1):(0.15-5).

[0014] Preferably, the prepolymerization reaction in step a) is carried out at a temperature of 200° C. to 260° C., a pressure of 0.2 MPa to 1.5 MPa, and a time of 0.5 h to 4 h.

[0015] Preferably, the process of carrying out the polycondensation reaction in step b) is specifically as follows:

[0016] The prepolymer is transferred to a polycondensation kettle, and the stirring of the polycondensation kettle is started. The kettle temperature of the polycondensation kettle is pre-heated to 280°C ~ 340°C, and the pressure of the polycondensation kettle is adjusted to 0.5MPa ~ 1.0MPa. The reaction time is 0.1h ~ 3h, and then the pressure of the polycondensation kettle is reduced to normal pressure, and the reaction is carried out for 20min ~ 45min. Negative pressure is started, the pressure is -10KPa ~ -20KPa, and the reaction is carried out for 1h ~ 2h. The vacuum pressure is evacuated to -30KPa ~ -50KPa, and the reaction is continued for 0.5h ~ 2h to obtain a polycondensate.

[0017] Preferably, the process of melt blending, extrusion, cooling and granulation in step c) is specifically as follows:

[0018] The polycondensate is pumped into a twin-screw co-rotating extruder, and starting from the die head, the vacuum degree of each zone of the screw is adjusted to 30Pa-200Pa, the temperature of each zone of the screw is 185°C-240°C, and the residence time is 2min-4min. The material melt is extruded into a water tank at the die head for cooling, and then drawn into strips and pelletized to obtain bio-based nylon 12.

[0019] The present invention also provides a bio-based nylon 12, which is prepared by the preparation method described in the above technical solution.

[0020] The present invention provides a bio-based nylon 12 and a preparation method thereof; the preparation method comprises the following steps: a) adding 12-aminododecanoic acid inner salt, a catalyst, an antioxidant and a molecular weight regulator into a reactor, charging the reactor with an inert protective gas, performing a prepolymerization reaction, and obtaining a prepolymer; b) performing a polycondensation reaction on the prepolymer obtained in step a) to obtain a polycondensate; c) performing melt blending, extrusion, cooling and granulation on the polycondensate obtained in step b) in sequence to obtain bio-based nylon 12. Compared with the prior art, the preparation method provided by the present invention uses the bio-based nylon monomer 12-aminododecanoic acid inner salt as a raw material, cooperates with other raw material components, performs polymerization under specific process steps, realizes overall good interaction, and obtains ultra-high molecular weight all-bio-based nylon 12, which has high molecular weight, no coking, and good comprehensive performance.

[0021] At the same time, the preparation method provided by the present invention has simple process, easy-to-operate steps, mild and easy-to-control conditions, no pollution, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A physical picture of bio-based nylon 12 obtained by the preparation method provided in Example 1 of the present invention;

[0023] Figure 2 GPC results of bio-based nylon 12 obtained by the preparation method provided in Example 1 of the present invention;

[0024] Figure 3 This is a physical picture of the nylon 12 resin obtained by the preparation method provided in Comparative Example 1. DETAILED DESCRIPTION

[0025] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] The present invention provides a method for preparing bio-based nylon 12, comprising the following steps:

[0027] a) adding 12-aminododecanoic acid inner salt, a catalyst, an antioxidant and a molecular weight regulator into a reaction kettle, and filling the reaction kettle with an inert protective gas to carry out a prepolymerization reaction to obtain a prepolymer;

[0028] b) subjecting the prepolymer obtained in step a) to a polycondensation reaction to obtain a polycondensate;

[0029] c) subjecting the polycondensate obtained in step b) to melt blending, extrusion, cooling and granulation in sequence to obtain bio-based nylon 12.

[0030] The invention provides a method for preparing bio-based long carbon chain nylon, which adopts the process steps of melt prepolymerization, polycondensation and screw viscosity enhancement to realize the preparation of bio-based nylon 12 for the first time. The preparation method solves the problems of low molecular weight and poor comprehensive performance of products obtained by the traditional one-pot method through multi-step reactions, and avoids the problem of low molecular weight caused by the high reaction activity of traditional dodecaaminocarboxylic acid.

[0031] The invention firstly adds 12-aminododecanoic acid inner salt, a catalyst, an antioxidant and a molecular weight regulator into a reaction kettle, fills the reaction kettle with inert protective gas, performs prepolymerization reaction and obtains a prepolymer.

[0032] In the present invention, the 12-aminododecanoic acid inner salt is preferably obtained from a bio-based method and prepared by polysaccharide fermentation.

[0033] In the present invention, the catalyst is preferably selected from one or more of phosphoric acid, phosphorous acid, sodium phosphite, sodium hypophosphite and pyrophosphorous acid, more preferably phosphoric acid, phosphorous acid, sodium phosphite, sodium hypophosphite or pyrophosphorous acid. The present invention has no particular restrictions on the source of the catalyst, and commercially available products known to those skilled in the art can be used.

[0034] In the present invention, the antioxidant is preferably selected from one or more of IRGANOX1010, IRGANOX1076, IRGANOX1035, IRGANOX245, IRGANOX1098, IRGANOX1135 and IRGANOX1520, more preferably IRGANOX1010, IRGANOX1076, IRGANOX1035, IRGANOX245, IRGANOX1135 or IRGANOX1520. The present invention has no particular limitation on the source of the antioxidant, and commercially available products well known to those skilled in the art may be used.

[0035] In the present invention, the molecular weight regulator is preferably a carboxylic acid or a diamine; wherein the carboxylic acid is preferably selected from one or more of 1,3-propanedioic acid, 1,4-butanedioic acid, 1,6-hexanedioic acid, 1,7-heptanedioic acid, 1,8-octanedioic acid, 1,9-nonanedioic acid, 1,10-decanedioic acid, 1,11-undecane dicarboxylic acid, 1,12-dodecane dicarboxylic acid, 1,13-tridecane dicarboxylic acid, 1,14-tetradecane dicarboxylic acid, 1,15-pentadecanedioic acid and 1,16-hexadecane dicarboxylic acid; the diamine is preferably selected from one or more of 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, 1,14-tetradecanediamine and 1,16-diaminohexadecane. In a preferred embodiment of the present invention, the molecular weight regulator is 1,4-butanediol, 1,6-hexanediol, 1,10-decanedioic acid, 1,11-undecanediamine, 1,14-tetradecanediamine or 1,16-diaminohexadecane. The present invention has no particular limitation on the source of the molecular weight regulator, and commercially available products known to those skilled in the art can be used.

[0036] In the present invention, the mass ratio of the 12-aminododecanoic acid inner salt, the catalyst, the antioxidant and the molecular weight regulator is preferably 100: (0.05-1.5): (0.03-1): (0.15-5), and more preferably 100: (0.05-1.2): (0.03-0.8): (0.15-3.5).

[0037] In the present invention, the inert protective gas is preferably nitrogen, carbon dioxide or argon; the present invention has no particular limitation on its source.

[0038] In the present invention, the temperature of the prepolymerization reaction is preferably 200°C to 260°C, the pressure is preferably 0.2MPa to 1.5MPa, and the time is preferably 0.5h to 4h; the prepolymerization process is preferably carried out under stirring conditions, and a prepolymerization kettle stirring device such as a propeller stirrer or a turbine stirrer well known to those skilled in the art can be used.

[0039] After obtaining the prepolymer, the present invention performs a polycondensation reaction on the obtained prepolymer to obtain a polycondensate.

[0040] In the present invention, the process of carrying out the polycondensation reaction is preferably specifically as follows:

[0041] The prepolymer is transferred to a polycondensation kettle, and the stirring of the polycondensation kettle is started. The kettle temperature of the polycondensation kettle is preheated to 280°C to 340°C, and the pressure of the polycondensation kettle is adjusted to 0.5MPa to 1.0MPa, and the reaction time is 0.1h to 3h. Then, the pressure of the polycondensation kettle is reduced to normal pressure, and the reaction is carried out for 20min to 45min. A negative pressure is started, and the pressure is -10KPa to -20KPa. The reaction is carried out for 1h to 2h, and the vacuum pressure is evacuated to -30KPa to -50KPa. The reaction is continued for 0.5h to 2h to obtain a polycondensate;

[0042] More preferably:

[0043] The prepolymer is transferred to a polycondensation kettle, and the stirring of the polycondensation kettle is started. The kettle temperature of the polycondensation kettle is pre-heated to 280°C ~ 340°C, and the pressure of the polycondensation kettle is adjusted to 0.5MPa ~ 1.0MPa. The reaction time is 0.5h ~ 3h, and then the pressure of the polycondensation kettle is reduced to normal pressure, and the reaction is carried out for 20min ~ 45min. A negative pressure is started, the pressure is -10KPa ~ -20KPa, and the reaction is carried out for 1h ~ 2h. The vacuum pressure is evacuated to -30KPa ~ -50KPa, and the reaction is continued for 0.5h ~ 2h to obtain a polycondensate.

[0044] After obtaining the polycondensate, the present invention sequentially subjectes the obtained polycondensate to melt blending, extrusion, cooling and granulation to obtain bio-based nylon 12.

[0045] In the present invention, the process of melt blending, extrusion, cooling and granulation is preferably specifically as follows:

[0046] The polycondensate is pumped into a twin-screw co-rotating extruder, and starting from the die head, the vacuum degree of each zone of the screw is adjusted to 30Pa-200Pa, the temperature of each zone of the screw is 185°C-240°C, and the residence time is 2min-4min. The material melt is extruded into a water tank at the die head for cooling, and then drawn into strips and pelletized to obtain bio-based nylon 12.

[0047] In the present invention, the polycondensation reactor is preferably charged with inert protective gas to a constant pressure, and the polycondensate is pumped into a twin-screw co-rotating extruder at a constant rate.

[0048] In a preferred embodiment of the present invention, the vacuum degree of each zone of the screw is adjusted to 50Pa-100Pa, or 80Pa-150Pa, or 30Pa-100Pa, or 60Pa-200Pa, or 100Pa-160Pa; the temperature of each zone of the screw is adjusted to 185°C, 190°C, 200°C, 220°C, 230°C, 220°C, 215°C, 210°C, or 190°C, 195°C, 210°C, 230°C, 230°C, 215°C, 215°C, 200°C, or 195°C, 200°C, 215°C, 220°C, 230°C, 23 0℃, 220℃, 220℃, or 195℃, 200℃, 220℃, 225℃, 225℃, 220℃, 210℃, 205℃, or 185℃, 190℃, 200℃, 220℃, 220℃, 210℃, 210℃, 195℃, or 210℃, 210℃, 220℃, 240℃, 240℃, 230℃, 220℃, 210℃; after all process parameters are stable, detect the consistency of the resin melt index, and adjust relevant parameters according to the resin characteristics requirements, and control the molecular weight to 20000-35000 to obtain qualified nylon 12.

[0049] The preparation method provided by the present invention adopts the bio-based nylon monomer 12-aminododecanoic acid inner salt as a raw material, cooperates with other raw material components, and performs polymerization under specific process steps to achieve overall good interaction. The ultra-high molecular weight all-bio-based nylon 12 prepared has high molecular weight, no coking, and good comprehensive performance. At the same time, the preparation method provided by the present invention has a simple process, easy steps to operate, mild conditions, easy control, no pollution, and has broad application prospects.

[0050] The present invention also provides a bio-based nylon 12, which is prepared by the preparation method described in the above technical solution.

[0051] The bio-based nylon 12 product provided by the invention has no coking, narrow normal molecular weight distribution and excellent comprehensive performance.

[0052] The present invention provides a bio-based nylon 12 and a preparation method thereof; the preparation method comprises the following steps: a) adding 12-aminododecanoic acid inner salt, a catalyst, an antioxidant and a molecular weight regulator into a reactor, charging the reactor with an inert protective gas, performing a prepolymerization reaction, and obtaining a prepolymer; b) performing a polycondensation reaction on the prepolymer obtained in step a) to obtain a polycondensate; c) performing melt blending, extrusion, cooling and granulation on the polycondensate obtained in step b) in sequence to obtain bio-based nylon 12. Compared with the prior art, the preparation method provided by the present invention uses the bio-based nylon monomer 12-aminododecanoic acid inner salt as a raw material, cooperates with other raw material components, performs polymerization under specific process steps, realizes overall good interaction, and obtains ultra-high molecular weight all-bio-based nylon 12, which has high molecular weight, no coking, and good comprehensive performance.

[0053] At the same time, the preparation method provided by the present invention has simple process, easy-to-operate steps, mild and easy-to-control conditions, no pollution, and has broad application prospects.

[0054] In order to further illustrate the present invention, the following examples are used to provide a detailed description. The raw materials used in the following examples of the present invention are all commercially available; among them, the 12-aminododecanoic acid inner salt used is from a bio-based method and is prepared by polysaccharide fermentation.

[0055] Example 1

[0056] The first step is to add 5.8 kg of 12-aminododecanoic acid inner salt, 2.9 g of catalyst phosphoric acid, 1.7 g of antioxidant IRGANOX1010 and 8.7 g of molecular weight regulator 1,4-succinic acid into the reactor, fill the reactor with nitrogen, heat the reactor to 200°C, control the pressure in the reactor at 1.5 MPa, start the prepolymerization reactor to stir, and the reaction time is 4 hours to obtain a prepolymer;

[0057] The second step is to transfer the prepolymer material into the polycondensation kettle, start the polycondensation kettle stirring, preheat the kettle temperature to 280°C, adjust the polycondensation kettle pressure to 1.0MPa, and the reaction time is 3h. Then, reduce the polycondensation kettle pressure to normal pressure, react for 45min, start negative pressure, the pressure is -10KPa, react for 2h, evacuate the pressure to -30KPa, and continue to react for 2h to obtain a polycondensate;

[0058] The third step is to charge nitrogen into the polymerization kettle, and pump the polycondensate into the twin-screw co-rotating extruder at a constant rate of 80 ml / min. Starting from the die head, the vacuum degree of each zone of the screw is adjusted to 50-100 Pa, respectively. The temperature of each zone of the screw is 185°C, 190°C, 200°C, 220°C, 230°C, 220°C, 215°C, 210°C, and the residence time is 2 min. The extruded material melt is cooled in a water tank at the die head, drawn into strips, and pelletized to obtain bio-based nylon 12; see the actual picture for details. Figure 1 shown.

[0059] Example 2

[0060] The first step is to add 4.5 kg of 12-aminododecanoic acid inner salt, 54.1 g of phosphorous acid as a catalyst, 36.2 g of antioxidant IRGANOX1076 and 157.5 g of molecular weight regulator 1,6-adipic acid into a reactor, fill the reactor with argon, heat the reactor to 260° C., control the pressure in the reactor at 0.2 MPa, start stirring the prepolymerization reactor, and react for 0.5 h to obtain a prepolymer;

[0061] The second step is to transfer the prepolymer material into the polycondensation kettle, start the polycondensation kettle stirring, preheat the kettle temperature to 340°C, adjust the polycondensation kettle pressure to 0.5MPa, and the reaction time is 0.5h. Then, reduce the polycondensation kettle pressure to normal pressure, react for 20min, start negative pressure, the pressure is -20KPa, react for 1h, evacuate the pressure to -50KPa, and continue to react for 0.5h to obtain a polycondensate;

[0062] The third step is to fill argon into the polymerization kettle and pump the condensation polymer into the twin-screw co-rotating extruder at a constant rate of 120 ml / min. Starting from the die head, the vacuum degree of each zone of the screw is adjusted to 80-150 Pa, respectively. The temperature of each zone of the screw is 190°C, 195°C, 210°C, 230°C, 230°C, 215°C, 215°C, 200°C, and the residence time is 3 min. The extruded material melt is cooled in a water trough at the die head, drawn into strips, and pelletized to obtain bio-based nylon 12.

[0063] Example 3

[0064] The first step is to add 6.4 kg of 12-aminododecanoic acid inner salt, 53.8 g of sodium phosphite catalyst, 28.8 g of antioxidant IRGANOX1035 and 140.8 g of molecular weight regulator 1,10-decanedioic acid into a reactor, fill the reactor with carbon dioxide gas, heat the reactor to 220° C., control the pressure in the reactor at 0.5 MPa, start the prepolymerization reactor and stir, the reaction time is 1 hour, and obtain a prepolymer;

[0065] The second step is to transfer the prepolymer material to the polycondensation kettle, start the polycondensation kettle stirring, preheat the kettle temperature to 300°C, adjust the polycondensation kettle pressure to 0.8MPa, and the reaction time is 1.5h. Then, reduce the polycondensation kettle pressure to normal pressure, react for 30min, start negative pressure, the pressure is -15KPa, react for 1.5h, evacuate the pressure to -40KPa, and continue to react for 1h to obtain a polycondensate;

[0066] The third step is to charge carbon dioxide into the polymerization kettle and pump the condensation polymer into the twin-screw co-rotating extruder at a constant rate of 100 ml / min. Starting from the die head, the vacuum degree of each zone of the screw is adjusted to 30-100 Pa, respectively. The temperature of each zone of the screw is 195°C, 200°C, 215°C, 220°C, 230°C, 230°C, 220°C, 220°C, and the residence time is 2 min. The extruded material melt is cooled in a water trough at the die head, drawn into strips, and pelletized to obtain bio-based nylon 12.

[0067] Example 4

[0068] The first step is to add 3.7 kg of 12-aminododecanoic acid inner salt, 35.2 g of catalyst sodium hypophosphite, 20.4 g of antioxidant IRGANOX245 and 105.8 g of molecular weight regulator 1,11-undecanediamine into a reactor, fill the reactor with argon, heat the reactor to 240° C., control the pressure in the reactor at 1.2 MPa, start the prepolymerization reactor and stir, the reaction time is 2 h, and obtain a prepolymer;

[0069] The second step is to transfer the prepolymer material into the polycondensation kettle, start the polycondensation kettle stirring, preheat the kettle temperature to 300°C, adjust the polycondensation kettle pressure to 0.8MPa, and the reaction time is 2h. Then, reduce the polycondensation kettle pressure to normal pressure, react for 35min, start negative pressure, the pressure is -18KPa, react for 1h, evacuate the pressure to -35KPa, and continue to react for 1.5h to obtain a polycondensate;

[0070] The third step is to fill argon into the polymerization kettle and pump the condensation polymer into the twin-screw co-rotating extruder at a constant rate of 95 ml / min. Starting from the die head, the vacuum degree of each zone of the screw is adjusted to 80-150 Pa, respectively. The temperature of each zone of the screw is 195°C, 200°C, 220°C, 225°C, 225°C, 220°C, 210°C, 205°C, and the residence time is 3 min. The extruded material melt is cooled in a water trough at the die head, drawn into strips, and pelletized to obtain bio-based nylon 12.

[0071] Example 5

[0072] The first step is to add 4.6 kg of 12-aminododecanoic acid inner salt, 11.5 g of catalyst pyrophosphorous acid, 4.2 g of antioxidant IRGANOX1135 and 110.6 g of molecular weight regulator 1,14-tetradecanediamine into a reactor, fill the reactor with nitrogen, heat the reactor to 210° C., control the pressure in the reactor at 0.7 MPa, start the prepolymerization reactor and stir, the reaction time is 2.5 h, and obtain a prepolymer;

[0073] The second step is to transfer the prepolymer material into the polycondensation kettle, start the polycondensation kettle stirring, preheat the kettle temperature to 295°C, adjust the polycondensation kettle pressure to 0.6MPa, and the reaction time is 2.5h. Then, reduce the polycondensation kettle pressure to normal pressure, react for 30min, start negative pressure, the pressure is -15KPa, react for 2h, evacuate the pressure to -45KPa, and continue to react for 1h to obtain a polycondensate;

[0074] The third step is to fill argon into the polymerization kettle and pump the condensation polymer into the twin-screw co-rotating extruder at a constant rate of 115 ml / min. Starting from the die head, the vacuum degree of each zone of the screw is adjusted to 60-200 Pa, respectively. The temperature of each zone of the screw is 185°C, 190°C, 200°C, 220°C, 220°C, 210°C, 210°C, 195°C, and the residence time is 4 minutes. The extruded material melt is cooled in a water trough at the die head, drawn into strips, and pelletized to obtain bio-based nylon 12.

[0075] Example 6

[0076] The first step is to add 7.5 kg of 12-aminododecanoic acid inner salt, 65.2 g of phosphorous acid as a catalyst, 48.7 g of antioxidant IRGANOX1520 and 220 g of molecular weight regulator 1,16-diaminohexadecane into a reactor, fill the reactor with argon, heat the reactor to 230° C., control the pressure in the reactor at 1 MPa, start stirring the prepolymerization reactor, and react for 3 hours to obtain a prepolymer;

[0077] The second step is to transfer the prepolymer material into the polycondensation kettle, start the polycondensation kettle stirring, preheat the kettle temperature to 310°C, adjust the polycondensation kettle pressure to 0.8MPa, and the reaction time is 2.5h. Then, reduce the polycondensation kettle pressure to normal pressure, react for 45min, start negative pressure, the pressure is -14KPa, react for 1.5h, evacuate the pressure to -45KPa, and continue the reaction for 1h to obtain a polycondensate;

[0078] The third step is to fill argon into the polymerization kettle and pump the condensation polymer into the twin-screw co-rotating extruder at a constant rate of 90 ml / min. Starting from the die head, the vacuum degree of each zone of the screw is adjusted to 100-160 Pa, respectively. The temperature of each zone of the screw is 210°C, 210°C, 220°C, 240°C, 240°C, 230°C, 220°C, 210°C, and the residence time is 2 min. The extruded material melt is cooled in a water trough at the die head, drawn into strips, and pelletized to obtain bio-based nylon 12.

[0079] Comparative Example 1

[0080] 5.8 kg of 12-aminododecanoic acid, 18.6 kg of deionized water, 2.9 g of sodium hypophosphite, 1.7 g of antioxidant IRGANOX1135 and 8.7 g of molecular weight regulator 1,10-decanedioic acid were added to the reactor, nitrogen was charged into the reactor, the reactor was heated to 190°C, the pressure in the reactor was controlled at 1.5 MPa, and the reaction was carried out for 4 hours; the pressure of the reactor was gradually reduced to normal pressure, the temperature was controlled at 220°C, the reaction was continued for 0.5 hours, and then negative pressure was started, the pressure was controlled at -10 KPa, the reaction was carried out for 2 hours, and the resin was directly poured out to obtain nylon 12 resin; see the actual picture for details. Figure 3 .

[0081] Comparative Example 2

[0082] 3kg of lauryl lactam, 2kg of deionized water, 45g of molecular weight regulator 1,10-decanedioic acid, 2.9g of catalyst sodium phosphite, and 1.7g of antioxidant IRGANOX1076 were filled into the reactor with argon, and the temperature was raised to 220°C. The pressure in the reactor was controlled at 0.8MPa and the reaction was carried out for 3h. After the reactor system was depressurized to normal pressure, the reactor temperature was raised to 240°C, and the pressure was evacuated to -30KPa. The reaction was carried out for 4.5h, and the discharged material was water-cooled and pelletized to obtain nylon 12 resin.

[0083] Related performance test methods:

[0084] (1) Relative viscosity:

[0085] Add 1g of nylon resin to 80ml of 98% sulfuric acid, stir in a 35℃ water bath to completely dissolve the nylon and prepare a solution. Place the solution in an Ubbelohde viscometer and place it in a 25℃ constant temperature bath for 10 minutes, then measure the rate of decline t. Similarly measure the rate of decline t0 of 98% sulfuric acid and calculate the relative viscosity according to the following formula. Relative viscosity = t / t0.

[0086] (2) Mechanical properties:

[0087] In the injection molding machine, the temperature rises to 340°C, the nylon resin is melted, and the injection pressure is 600kgf / cm 2The injection molded samples were obtained under the conditions of 2.0s injection time and 100°C mold temperature, and the mechanical strength test was carried out in an absolutely dry state.

[0088] (3) Molecular weight and its distribution:

[0089] 10 mg of sample nylon 12 resin was dissolved in 10 g of hexafluoroisopropanol to prepare a nylon solution for GPC testing.

[0090] The test results are shown in Table 1 below.

[0091] Table 1 Performance test results of polymers

[0092]

[0093]

[0094] The experimental results show that the tensile strength of the bio-based nylon 12 resin prepared by the preparation method provided by the present invention is 51-58 MPa, and the elongation at break is 185-210%, which is much higher than the tensile strength of 1.8 MPa and the elongation at break of 10% of the comparative example 1, and also much higher than the tensile strength of 45 MPa and the elongation at break of 74% of the comparative example 2; from the appearance of the nylon 12 resin provided by the present invention ( Figure 1 ) and Comparative Example 1 ( Figure 3 ), the preparation method provided by the present invention can obtain a product with a certain degree of transparency and a pelletizable appearance, while the nylon 12 resin obtained in Comparative Example 1 has a coking phenomenon, and the mechanical properties become very poor. In addition, the number average molecular weight of the product prepared by the present invention can reach 24.2-26.3 kg / mol, while the comparative example obtains a low molecular weight resin, the molecular weight of which is only 0.86-0.94 kg / mol. This is because the present invention can achieve efficient synthesis of nylon 12 resin, while the comparative example accelerates the coking of the resin, fails to obtain a polymer material, and the related properties are also poor.

[0095] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing bio-based nylon 12, comprising the following steps: a) adding 12-aminododecanoic acid inner salt, a catalyst, an antioxidant and a molecular weight regulator into a reaction kettle, and filling the reaction kettle with an inert protective gas to carry out a prepolymerization reaction to obtain a prepolymer; b) subjecting the prepolymer obtained in step a) to a polycondensation reaction to obtain a polycondensate; c) subjecting the polycondensate obtained in step b) to melt blending, extrusion, cooling and granulation in sequence to obtain bio-based nylon 12.

2. The preparation method according to claim 1, characterized in that: The 12-aminododecanoic acid inner salt in step a) is obtained from a bio-based method and is prepared by polysaccharide fermentation.

3. The preparation method according to claim 1, characterized in that: The catalyst in step a) is selected from one or more of phosphoric acid, phosphorous acid, sodium phosphite, sodium hypophosphite and pyrophosphorous acid.

4. The preparation method according to claim 1, characterized in that: The antioxidant in step a) is selected from one or more of IRGANOX1010, IRGANOX1076, IRGANOX1035, IRGANOX245, IRGANOX1098, IRGANOX1135 and IRGANOX1520.

5. The preparation method according to claim 1, characterized in that: In step a), the molecular weight regulator is a carboxylic acid or a diamine; the carboxylic acid is selected from one or more of 1,3-propanedioic acid, 1,4-butanedioic acid, 1,6-hexanedioic acid, 1,7-heptanedioic acid, 1,8-octanedioic acid, 1,9-nonanedioic acid, 1,10-decanedioic acid, 1,11-undecane dicarboxylic acid, 1,12-dodecane dicarboxylic acid, 1,13-tridecane dicarboxylic acid, 1,14-tetradecane dicarboxylic acid, 1,15-pentadecanedioic acid and 1,16-hexadecane dicarboxylic acid; the diamine is selected from one or more of 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, 1,14-tetradecanediamine and 1,16-diaminohexadecane.

6. The preparation method according to claim 1, characterized in that: The mass ratio of the 12-aminododecanoic acid inner salt, the catalyst, the antioxidant and the molecular weight regulator in step a) is 100: (0.05-1.5): (0.03-1): (0.15-5).

7. The preparation method according to claim 1, characterized in that: The temperature of the prepolymerization reaction in step a) is 200° C. to 260° C., the pressure is 0.2 MPa to 1.5 MPa, and the time is 0.5 h to 4 h.

8. The preparation method according to claim 1, characterized in that: The process of carrying out the polycondensation reaction in step b) is specifically as follows: The prepolymer is transferred to a polycondensation kettle, and the stirring of the polycondensation kettle is started. The kettle temperature of the polycondensation kettle is pre-heated to 280°C ~ 340°C, and the pressure of the polycondensation kettle is adjusted to 0.5MPa ~ 1.0MPa. The reaction time is 0.1h ~ 3h, and then the pressure of the polycondensation kettle is reduced to normal pressure, and the reaction is carried out for 20min ~ 45min. Negative pressure is started, the pressure is -10KPa ~ -20KPa, and the reaction is carried out for 1h ~ 2h. The vacuum pressure is evacuated to -30KPa ~ -50KPa, and the reaction is continued for 0.5h ~ 2h to obtain a polycondensate.

9. The preparation method according to claim 1, characterized in that: The process of melt blending, extrusion, cooling and granulation in step c) is specifically as follows: The polycondensate is pumped into a twin-screw co-rotating extruder, and starting from the die head, the vacuum degree of each zone of the screw is adjusted to 30Pa-200Pa, the temperature of each zone of the screw is 185°C-240°C, and the residence time is 2min-4min. The material melt is extruded into a water tank at the die head for cooling, and then drawn into strips and pelletized to obtain bio-based nylon 12.

10. A bio-based nylon 12, characterized in that: The preparation method is described in any one of claims 1 to 9.

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