Nylon 1012 and preparation method thereof

Abstract

The invention relates to a preparation method of nylon 1012, which comprises the following steps: (1) uniformly mixing dodecanedioic acid, decamethylene diamine and a catalyst, placing in a reaction kettle, and enabling the reaction to be always in an inert atmosphere; (2) slowly heating to 130-140 DEG C, stirring and reacting for a period of time, sequentially heating to 150-160 DEG C and 170-180 DEG C, and stirring and reacting for a period of time; then raising the temperature to 210-220 DEG C, slowly introducing gas for maintaining an inert atmosphere, and stirring to react for a period of time; and (3) stopping heating, closing a gas outlet valve, introducing gas for maintaining an inert atmosphere, discharging, cooling, granulating, and drying to obtain the nylon 1012. According to the invention, dodecanedioic acid and decamethylene diamine are used as raw materials, nylon 1012 is prepared at one step under normal pressure, and the defects of low catalyst activity, high reaction pressure, wide molecular weight distribution and the like in the prior art are overcome.

Description

Technical Field

[0001] The invention belongs to the technical field of synthetic fibers, and particularly relates to long carbon chain nylon 1012 and a preparation method thereof. Background Art

[0002] Nylon, also known as polyamide, is a general term for a class of polymers containing amide groups (-NHCO-) ​​within the repeating units of the macromolecular backbone, abbreviated as PA. Nylon possesses numerous excellent properties, including high toughness, wear and impact resistance, fatigue resistance, chemical resistance, self-lubrication, and a low coefficient of friction. Currently, nylon is primarily used in the manufacture of various engineering plastics, textile and apparel fibers, and also in films, adhesives, and coatings. Its diverse properties underpin its widespread use, maintaining its leading position among engineering plastics. Generally, nylon molecules with a carbon chain length of at least 10 between the two amide groups are referred to as long-chain nylons, such as nylon 11, nylon 12, and nylon 1012.

[0003] Currently, the production of short-chain nylons, such as nylon 6 and nylon 66, still far outpaces other nylons, accounting for approximately 90% of the entire nylon industry. However, due to the high amide bond density of short-chain nylons, they have high water absorption, resulting in poor dimensional stability, flexibility, and electrical properties in finished products, significantly limiting their application and development. Long-chain nylons, on the other hand, possess the common properties of general nylons. Their low amide bond density allows for low water absorption, excellent toughness, and superior insulation properties. Their finished products offer excellent dimensional stability and precision, making them ideal for use in a variety of humid and high-precision environments, filling this gap in nylon's performance. Currently, long-chain nylons are widely used in various fields, including electronics, automotive, aerospace, marine, adhesives, and powder coatings.

[0004] Most existing methods for preparing long-chain nylons use a salt-forming followed by polycondensation. This method is complex and expensive, making it unsuitable for industrial production. Furthermore, the salt-forming process often uses ethanol as a solvent, which is environmentally unfriendly and poses safety risks.

[0005] CN106750264A discloses a bio-based long carbon chain polyamide and a synthesis method thereof, comprising: (1) adding 1,12-dodecanediamine and 1,9-azelaic acid to deionized water and stirring to prepare a mixed solution; (2) adding the mixed solution to a reactor, and then replacing the atmosphere in the reactor with an inert atmosphere; under stirring, the mixed solution is subjected to a melt polycondensation reaction in the reactor to synthesize bio-based polyazelazyl dodecanediamine; the 1,9-azelaic acid is bio-based 1,9-azelaic acid; the melt polycondensation reaction is carried out in three stages, the temperature of the first stage reaction is 90-120°C, the stirring rate is 100-120°C, and the stirring rate is 100-120°C. The method comprises the following steps: stirring at a stirring rate of 400 r / min, a pressure in the reactor of 0 MPa, and continuously discharging water vapor from the reactor during the reaction. When the amount of discharged water vapor reaches 100% of the total volume of the initially added water, the exhaust is stopped; the temperature of the second stage reaction is 150-190°C, the stirring rate is 150-350 r / min, and the water vapor is continuously discharged from the reactor during the reaction. The pressure in the reactor is maintained at 0 MPa, and the reaction time is 1-6 hours; the temperature of the third stage reaction is 200-240°C, the stirring rate is 50-200 r / min, the reactor is sealed, the pressure in the reactor is -0.1 MPa, and the reaction time is 20-200 minutes. The method directly mixes the two monomers in water and adds them to the polymerization reactor, performs a salt-forming reaction while heating, and then directly performs a melt polycondensation reaction under normal pressure. However, the first stage still involves adding a large amount of deionized water to form salt, and at the same time, slowly discharging the added water near the boiling point of water, which takes a long time; the temperature in the second stage is too low, the activity of the chain end functional groups decreases in the middle stage of the reaction, the reaction activity decreases, and the reaction rate is low; the air outlet valve is directly connected to the atmosphere, and the temperature fluctuations in the kettle easily suck back air, causing the product to oxidize and yellow, and the product molecular weight decreases.

[0006] CN106866958A discloses a long carbon chain aliphatic nylon PA1111 material, the preparation method of which is as follows: (1) 117-120 parts of undecane dicarboxylic acid, 100 parts of undecane diamine, 0.06-0.12 parts of a catalyst, 0.64-1.08 parts of an antioxidant, and 1.16-3.48 parts of a molecular weight regulator are uniformly mixed, and then 160-250 parts of deionized water are added to a reactor and stirred, and the mixture is repeatedly replaced with an inert gas 3-5 times, with the inert gas reserved as a protective gas; (2) After the feeding is completed, heating is started, and after reaching the required temperature, constant temperature reaction is carried out to completely salt the polymerization monomer; (3) After the insulation is completed, the temperature is continued to be raised, and after reaching the required pressure, the system is kept in a constant pressure state by releasing the water in the system. After the temperature is raised to the required temperature, the pressure is slowly released until it reaches normal pressure, the temperature is maintained and the center temperature of the reactor is maintained at the required temperature, the preheating discharge port is reduced in speed, inert gas is injected, the discharge port is opened to discharge the material, and the material is pelletized after cooling and dried to obtain the long carbon chain aliphatic nylon PA1111 material. In fact, this method still adopts the method of first salting and then polycondensation, and does not fundamentally overcome the cumbersome process of the traditional two-step nylon polymerization method.

[0007] CN112280032A discloses a one-step polymerization method for preparing long carbon chain nylon, which specifically comprises the following steps: (1) placing 100 parts by weight of a dibasic acid, 50.9 to 140 parts by weight of a diamine, 50 to 80 parts by weight of a solvent, 1 to 2 parts by weight of an antioxidant, and 0.6 to 1 part by weight of a catalyst in a reactor, repeatedly replacing the gas in the reactor with an inert gas, and reserving the inert gas as a protective gas; (2) heating the reactor to 140 to 160° C., and conducting a constant temperature reaction for 0.5 to 10 minutes; 1h; (3) then heating the reactor to 190-200°C, the pressure inside the reactor reaches 1.2-2MPa, and the reaction is carried out at constant pressure for 1-2h; slowly releasing the gas to normal pressure, controlling the release time to be 1-1.5h; (4) then heating the reactor to 240-260°C, evacuating the reactor, and continuing the reaction for 1-3h; (5) stopping heating, filling the reactor with inert gas to return to normal pressure, and then continuing to fill the reactor with inert gas to release the material, cooling it, and pelletizing it. After drying, the long carbon chain nylon material is obtained. This method requires the reaction to be carried out under high pressure, which is not safe; the reaction temperature is relatively high, and the energy consumption is high. Summary of the Invention

[0008] In response to the shortcomings of the prior art, the present invention provides a method for preparing nylon 1012. The present invention uses dodecane dicarboxylic acid and decanediamine as raw materials to prepare nylon 1012 in a single step under normal pressure, overcoming the shortcomings of the prior art, such as low catalyst activity, high pressure required for the reaction, and a wide molecular weight distribution.

[0009] The present invention provides a method for preparing nylon 1012, comprising the following steps:

[0010] (1) mixing dodecanedioic acid, decanediamine, and a catalyst and placing them in a reaction vessel so that the reaction is always under an inert atmosphere;

[0011] (2) first slowly heating to 130-140°C and stirring for a period of time, then successively heating to 150-160°C and 170-180°C and stirring for a period of time; then heating to 210-220°C and slowly introducing a gas to maintain an inert atmosphere and stirring for a period of time;

[0012] (3) Stop heating, close the gas outlet valve, introduce gas to maintain an inert atmosphere to discharge the material, cool it down and pelletize it, and then dry it to obtain the nylon 1012.

[0013] Furthermore, in step (1), the molar ratio of dodecanedioic acid to decanediamine is 1:1.01-1.03, preferably 1:1.0-1.02.

[0014] Furthermore, in step (1), the catalysts are sodium hypophosphite and HATU, and the mass ratio of sodium hypophosphite to HATU is 1:1-1:5, preferably 1:2-1:5. HATU is 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate.

[0015] Furthermore, the amount of catalyst used in step (1) is 0.1%-0.5% of the total mass of dodecanedioic acid and decanediamine, preferably 0.1%-0.2%.

[0016] Furthermore, the inert atmosphere described in step (1) refers to the introduction of any one or more gases such as nitrogen and inert gas to replace the gas in the reactor to maintain an inert atmosphere, preferably nitrogen.

[0017] Furthermore, when the temperature in step (2) is raised to 130-140° C., the reaction is stirred at 50-150 rpm under normal pressure for 0.5-1.0 h.

[0018] Furthermore, when the temperature in step (2) is raised to 150-160° C., the reaction is stirred at normal pressure and 150-250 rpm for 0.5-1.0 h.

[0019] Furthermore, when the temperature in step (2) is raised to 170-180° C., the reaction is carried out at normal pressure and 150-250 rpm for 0.5-1 h.

[0020] Furthermore, when the temperature in step (2) is raised to 210-220° C., any one or more of nitrogen, inert gas, etc. are introduced to maintain an inert atmosphere, and the reaction is carried out at 150-250 rpm for 1-2 hours.

[0021] Furthermore, in step (3), the outlet valve is closed, nitrogen and inert gas are introduced to discharge the material when the pressure is 0.1-0.2 MPa, the material is cooled, and then pelletized by a pelletizer and dried at 70-80° C. for 48-72 hours.

[0022] The nylon 1012 of the present invention is prepared by the above-mentioned method of the present invention. The nylon 1012 synthesized by the present invention has a narrower molecular weight distribution, more stable mechanical properties, and a whiter color.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] (1) The inventors of this application found in the synthesis of nylon 1012 that in the early stage of the reaction, the viscosity of the system was not high, and sodium hypophosphite could be well dispersed. By introducing a charge acceptor, the carboxyl group was deactivated, reducing the charge density of the carbonyl group, so that the amino group and the carboxyl group could react at a faster reaction speed; but when the reaction proceeded to the later stage, the growth of the molecular chain reduced the activity of the terminal functional group, and the viscosity of the system increased dramatically, making it difficult for sodium hypophosphite to play a catalytic role. In order to solve this problem, the inventors introduced HATU as an auxiliary agent, which, through intramolecular transfer, converted the terminal carboxyl group with weakened reaction ability into an active ester, thereby accelerating the reaction. Through the synergistic effect of the two, the reaction temperature was reduced, the reaction time was shortened, and the product quality was improved.

[0025] (2) The introduced HATU contains phosphate groups, which can simultaneously improve the polymer's regeneration, drying, blending, processing stability and color stability.

[0026] (3) The synthesis reaction is carried out under normal pressure, the synthesis conditions are mild and the safety is high.

[0027] (4) Staged heating is beneficial to the formation of oligomers and prevents the escape of monomers.

[0028] (5) One-step polymerization at normal pressure eliminates multiple steps such as traditional salt formation, prepolymerization and solid phase thickening. The entire process is green and clean, the synthesis process is short, the equipment requirements are low, and it is suitable for industrial production. DETAILED DESCRIPTION

[0029] The following examples further illustrate the preparation method of the present invention and its effects. The examples are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operating processes, but the protection scope of the present invention is not limited to the following examples.

[0030] The experimental methods in the following examples, unless otherwise specified, are all conventional methods in the art. The experimental materials used in the following examples, unless otherwise specified, were purchased from conventional biochemical reagent stores.

[0031] In the embodiment of the present invention, the specific detection and analysis methods involving parameters are as follows:

[0032] The relative molecular mass and distribution were determined by gel permeation chromatography using hexafluoroisopropanol as the solvent, a hexafluoroisopropanol-specific column, polymethyl methacrylate (PMMA) as the standard, a flow rate of 1 mL / min, and a temperature of 40°C.

[0033] Relative viscosity determination: The nylon 1012 products from each reaction stage were dried in a 70°C oven for more than 48 h and then dissolved in 98 wt% concentrated sulfuric acid to a concentration of 0.005 g / mL. The relative viscosity (ηr) was measured using an Ubbelohde viscometer in a constant temperature water bath at 25°C.

[0034] Mechanical Properties Testing: Nylon samples were injection molded into various standard bars using an injection molding machine for tensile testing and elongation at break. Tensile testing was conducted at room temperature in accordance with GB / T 1040-2006, using 5A specimens at a rate of 5 mm / min.

[0035] Example 1

[0036] Weigh 300g of dodecanedicarboxylic acid, 225g of decanediamine, 0.25g of sodium hypophosphite, and 0.75g of HATU, mix thoroughly, and place in a reactor. Close the reactor and purge the atmosphere with nitrogen three times to maintain an inert atmosphere. First, slowly heat the reaction to 130°C and hold the temperature constant for 0.5h with stirring at 100rpm. Then, heat the reaction to 150°C and hold the temperature constant for 0.5h with stirring at 200rpm. Then, heat the reaction to 180°C and hold the temperature constant for 1h with stirring at 150rpm. Finally, heat the reaction to 220°C and slowly purge nitrogen to maintain the inert atmosphere. Continue the reaction at this constant temperature for 1.5h with stirring at 150rpm. Stop heating, close the outlet valve, and purge nitrogen to 0.15MPa. Discharge the product, cool, pelletize, and dry in a 70°C oven for 48h to obtain nylon 1012.

[0037] Testing and analysis revealed a relative viscosity of 2.41, a relative molecular mass of 17123, a molecular weight distribution of 2.05, a tensile strength of 51.2 MPa, and an elongation at break of 253%. The injection-molded strips were whiter and showed no noticeable yellowing.

[0038] Example 2

[0039] Weigh 300g of dodecanedicarboxylic acid, 225g of decanediamine, 0.3g of sodium hypophosphite, and 0.6g of HATU, mix thoroughly, and place in a reactor. Close the reactor and purge the atmosphere with nitrogen three times to maintain an inert atmosphere. First, slowly heat the reaction mixture to 135°C and hold it at this temperature for 0.5h with stirring at 50rpm. Then, heat it to 155°C and hold it at this temperature for 0.5h with stirring at 250rpm. Then, heat it to 175°C and hold it at this temperature for 1h with stirring at 200rpm. Finally, heat it to 210°C and slowly purge nitrogen to maintain the inert atmosphere. Continue the reaction at this temperature for 2.0h with stirring at 250rpm. Stop heating, close the outlet valve, and purge nitrogen to 0.1MPa. Discharge the product, cool it, pelletize it, and dry it in a 75°C oven for 48h to obtain nylon 1012.

[0040] Testing and analysis revealed a relative viscosity of 2.35, a relative molecular mass of 16512, a molecular weight distribution of 2.12, a tensile strength of 48.2 MPa, and an elongation at break of 261%. The injection-molded strips were whiter and showed no noticeable yellowing.

[0041] Example 3

[0042] Weigh 300g of dodecanedicarboxylic acid, 225g of decanediamine, 0.25g of sodium hypophosphite, and 1.25g of HATU, mix thoroughly, and place in a reactor. Close the reactor and purge the atmosphere with nitrogen three times to maintain an inert atmosphere. First, slowly raise the temperature to 140°C and hold the temperature constant for 1.0 hour with stirring at 150 rpm. Then, raise the temperature to 160°C and hold the temperature constant for 1.0 hour with stirring at 150 rpm. Then, raise the temperature to 180°C and hold the temperature constant for 0.5 hour with stirring at 250 rpm. Finally, raise the temperature to 215°C and slowly purge nitrogen to maintain the inert atmosphere. Continue the reaction at this constant temperature for 1.0 hour with stirring at 200 rpm. Stop heating, close the outlet valve, and purge nitrogen to 0.2 MPa. Discharge the product, cool, pelletize, and dry in an 80°C oven for 48 hours to obtain nylon 1012.

[0043] Testing and analysis revealed a relative viscosity of 2.38, a relative molecular mass of 16819, a molecular weight distribution of 1.95, a tensile strength of 52.7 MPa, and an elongation at break of 245%. The injection-molded strips were whiter and showed no noticeable yellowing.

[0044] Example 4

[0045] The same as Example 1, except that the inert gas introduced was argon. Finally, nylon 1012 was obtained.

[0046] Testing and analysis revealed a relative viscosity of 2.36, a relative molecular mass of 16,398, a molecular weight distribution of 2.09, a tensile strength of 48.5 MPa, and an elongation at break of 254%. The injection-molded strips were whiter and showed no noticeable yellowing.

[0047] Comparative Example 1

[0048] The reaction conditions were the same as in Example 1, except that only sodium hypophosphite, equal in mass to the catalyst used in the composite catalyst, was used as the catalyst. Nylon 1012 was produced. Analysis revealed a relative viscosity of 2.11, a relative molecular mass of 14007, a molecular weight distribution of 3.59, a tensile strength of 43.2 MPa, and an elongation at break of 175%. The injection-molded strips were yellowed, indicating significant oxidation.

[0049] Comparative Example 2

[0050] The reaction conditions were the same as in Example 1, except that only sodium hypophosphite (equal in mass to the composite catalyst) was used as the catalyst, and the reaction temperature was raised to 245°C for 2 hours. Nylon 1012 was finally produced. Analysis revealed a relative viscosity of 2.37, a relative molecular mass of 16896, a molecular weight distribution of 3.14, a tensile strength of 49.8 MPa, and an elongation at break of 247%. The injection-molded bars showed a slight yellowing, indicating some oxidation. To achieve similar results as in Example 1, the reaction temperature needed to be increased and the reaction time extended.

[0051] Comparative Example 3

[0052] The reaction conditions were the same as in Example 1, except that only HATU, equal in mass to the composite catalyst, was used as the catalyst. Nylon 1012 was finally produced. Analysis revealed a relative viscosity of 2.08, a relative molecular mass of 12709, a molecular weight distribution of 3.64, a tensile strength of 41.5 MPa, and an elongation at break of 170%.

[0053] Comparative Example 4

[0054] The reaction conditions were the same as in Example 1, except that step (2) was not followed by a staged reaction. The temperature was directly raised to 220°C and the reaction was carried out at 150 rpm for 3 hours. Nylon 1012 was finally produced. Analysis revealed a relative viscosity of 1.82, a relative molecular mass of 10521, a molecular weight distribution of 3.21, a tensile strength of 35.2 MPa, and an elongation at break of 158%.

[0055] Comparative Example 5

[0056] The reaction conditions were the same as in Example 1, except that the temperature was finally raised to 220°C, nitrogen was not introduced to maintain an inert atmosphere, and the reaction was continued at this temperature for 1.5 hours. Nylon 1012 was finally produced. Analysis revealed a relative viscosity of 2.19, a relative molecular mass of 15312, a molecular weight distribution of 2.45, a tensile strength of 44.6 MPa, and an elongation at break of 215%.

Claims

1. A method for preparing nylon 1012, characterized in that The steps include: (1) Mix dodecanedioic acid, decanediamine, and catalyst and place them in a reaction kettle so that the reaction is always under an inert atmosphere; (2) First, slowly raise the temperature to 130-140°C and stir the reaction for a period of time, then raise the temperature to 150-160°C and 170-180°C in sequence and stir the reaction for a period of time; Then, the temperature is raised to 210-220°C, and a gas maintaining an inert atmosphere is slowly introduced, and the reaction is stirred for a period of time; (3) Stop heating, close the outlet valve, introduce gas to maintain an inert atmosphere to discharge the material, pelletize after cooling, and obtain the nylon 1012 after drying.

2. The method according to claim 1, wherein: In step (1), the molar ratio of dodecanedioic acid to decanediamine is 1:1.01-1.03, preferably 1:1.0-1.

02.

3. The method according to claim 1, wherein: In step (1), the catalysts are sodium hypophosphite and HATU, and the mass ratio of sodium hypophosphite to HATU is 1:1-1:5, preferably 1:2-1:

5.

4. The method according to claim 1, wherein: The amount of catalyst used in step (1) is 0.1%-0.5% of the total mass of dodecanedioic acid and decanediamine, preferably 0.1%-0.2%.

5. The method according to claim 1, wherein: The inert atmosphere described in step (1) refers to the introduction of any one or more of nitrogen and inert gases to replace the gas in the reactor to maintain an inert atmosphere, preferably nitrogen.

6. The method according to claim 1, wherein: When the temperature in step (2) is raised to 130-140°C, the reaction is stirred at 50-150 rpm under normal pressure for 0.5-1.0 h.

7. The method according to claim 1, wherein: When the temperature in step (2) is raised to 150-160°C, the reaction is stirred at normal pressure and 150-250 rpm for 0.5-1.0 h.

8. The method according to claim 1, wherein: When the temperature in step (2) is raised to 170-180°C, the reaction is carried out at normal pressure and 150-250 rpm for 0.5-1h.

9. The method according to claim 1, wherein: When the temperature in step (2) is raised to 210-220°C, nitrogen or any one or more inert gases are introduced to maintain an inert atmosphere, and the reaction is carried out at 150-250 rpm for 1-2 hours.

10. The method according to claim 1, wherein: Step (3) Close the outlet valve, introduce nitrogen and inert gas to discharge the material when the pressure is 0.1-0.2 MPa.

11. The method according to claim 1, wherein: Step (3) is cooled, pelletized by a pelletizer, and dried at 70-80°C for 48-72h.

12. A nylon 1012, characterized in that It is prepared by the method according to any one of claims 1 to 11.