One-step preparation of bio-based nylon 12 derivatives and preparation method and application thereof

Abstract

This application discloses a one-step preparation of a bio-based nylon 12 derivative, its preparation method, and application, belonging to the technical field of polyamide materials. The method comprises the following steps: (1) pre-modification: mixing an aromatic dibasic acid, an alicyclic diamine, and a reaction aid A in a preparation tank and heating the mixture to form a pre-modified system; (2) batching: adding bio-based 12-aminododecanoic acid, a flexible segment monomer, a reaction aid B, and water to the pre-modified system and stirring and mixing them uniformly; (3) feeding: pressing the mixture in the preparation tank into a polymerization kettle by nitrogen pressurization; (4) polymerization. This application achieves a one-step process (i.e., in the same reactor) to obtain a nylon 12 derivative with high transparency and excellent mechanical properties by pre-modifying the product before the polymerization reaction and adding a flexible segment and a reaction aid system, while optimizing the process flow and precisely controlling key nodes.

Description

Technical Field

[0001] The present application relates to a bio-based nylon 12 derivative prepared in one step, a preparation method thereof, and an application thereof, and belongs to the technical field of polyamide materials. Background Art

[0002] Nylon 12 (PA12) is a typical long-carbon-chain aliphatic nylon with low water absorption, low density, good dimensional stability, and excellent low-temperature impact resistance. It is widely used in automotive, chemical and petroleum pipelines, hydraulic transmission systems, electronics, electrical appliances, plastic alloys, and aerospace and military equipment. However, as a semi-crystalline material, PA12's inherent structure results in a distinct distribution of crystalline and amorphous regions, a high degree of molecular regularity, and a high degree of crystallinity. This results in poor transparency, limiting its use in applications requiring optical transparency or decorative properties.

[0003] On the other hand, if highly transparent nylon products are to have good mechanical strength and toughness, they need to be modified and toughened. However, traditional toughening methods often destroy the regularity of the main chain, resulting in defects such as poor compatibility, uneven structure, and precipitation of impurities, which leads to decreased transparency of the polymerization system, increased yellowing, and even reduced mechanical properties and thermal stability.

[0004] Chinese patent CN113549319B discloses a transparent toughened nylon 12 alloy material and its preparation method. By introducing a two-component polymerized long carbon chain nylon and a small amount of hyperbranched resin into PA12, a certain degree of intermolecular amide exchange occurs during the melt blending process, thereby regulating crystallization behavior and improving transparency. Although this method can improve the transparency and impact resistance of PA12 to a certain extent, the following problems still exist:

[0005] 1. Limited structural regulation mechanism: This method relies on physical blending and amide exchange reaction to achieve crystallization behavior perturbation. Its structural construction is uncontrollable, and the resulting product has a wide molecular weight distribution and a disordered crystal phase, which easily leads to product performance fluctuations.

[0006] 2. Limited compatibility of raw materials: Different polyamide molecular segments have different polarity, chain length, and crystallization rates, which can easily cause phase separation or reduced transparency. Especially in large-scale continuous production, consistency is difficult to ensure.

[0007] In addition, most of this method and other existing technologies rely on later physical mixing (twin-screw extrusion) for modification, and cannot achieve dynamic regulation of the polymer structure during the polycondensation stage. Regarding the process of nylon 12 polymerization, such as Chinese patent CN107312170B - a process for preparing nylon 12 using long-chain amino acids as monomers, its polymerization stage basically requires three steps to complete, with a long production cycle and difficulty in continuous production.

[0008] Therefore, there is an urgent need to provide a preparation method for bio-based nylon 12 derivatives that can be continuously produced, has a stable and controllable process, and has balanced transparency and toughness optimization, so as to meet the industrialization demand for a new generation of environmentally friendly high-performance polyamide materials. Summary of the Invention

[0009] To address the above-mentioned issues, a one-step method for preparing bio-based nylon 12 derivatives, as well as a preparation method and application thereof, are provided. By pre-modifying the nylon 12 derivatives before the polymerization reaction and introducing stable amorphous segments, and adding flexible segments and a reaction aid system, the process flow is optimized and key nodes are precisely controlled. Ultimately, a one-step process (i.e., in the same reactor) is achieved to obtain nylon 12 derivatives with high transparency and excellent mechanical properties by polymerization using bio-based 12-aminododecanoic acid as the core monomer. The prepared products have high transparency, good toughness, and are environmentally friendly. They can meet the application requirements of electronic and electrical housings, food packaging, and shoe sole materials requiring high transparency and high toughness.

[0010] According to one aspect of the present application, a one-step method for preparing a bio-based nylon 12 derivative is provided, comprising the following steps:

[0011] (1) Pre-modification: The aromatic dibasic acid, alicyclic diamine and reaction aid A are mixed and heated in a preparation tank to form a pre-modified system;

[0012] (2) Ingredients: Add bio-based 12-aminododecanoic acid, flexible segment monomer, reaction aid B and water to the above pre-modified system and stir to mix evenly;

[0013] (3) Feeding: The mixture in the preparation tank is pressed into the polymerization reactor by nitrogen pressure;

[0014] (4) Aggregation: The following operations are performed in sequence through the control system:

[0015] i. Increase temperature and pressure: Start stirring, increase temperature to 175-185°C, increase pressure to 0.8-1.6 MPa, and react for 1-2 hours;

[0016] ii. Constant temperature and pressure: Maintain the temperature no higher than 185°C, keep the pressure stable, gradually drain the moisture, and the temperature of the material will automatically rise after the water is drained. The material temperature should not exceed 200°C. When the material temperature rises to a certain temperature, the pressure will be reduced in stages, but the pressure must always be maintained at no less than 0.8MPa;

[0017] iii. Temperature increase and pressure reduction: The material temperature is gradually increased, the pressure is reduced to normal pressure, and the temperature is controlled at 230-250℃;

[0018] iv. Constant temperature and pressure: The temperature remains constant and nitrogen is purged for 0.5-1h;

[0019] v. Constant temperature vacuum: Keep the temperature constant and evacuate to 0.06-0.09 MPa;

[0020] vi. Nitrogen pressurization: The polymer melt is discharged through nitrogen pressurization, and the bio-based nylon 12 derivative product is obtained by water-cooling and pelletizing.

[0021] Among them, the reaction aid A includes a catalyst and polyethylene glycol, and the addition amounts are 0.002-0.01% and 3-5% of the total mass of the raw materials of the pre-modified system respectively; the reaction aid B includes a catalyst, an antioxidant and a molecular weight regulator, and the addition amounts are 0.01-0.04%, 0.05-0.15% and 0.2-0.5% of the total mass of the raw materials of the reaction system respectively.

[0022] Specifically, the polymerization kettle of the present application is equipped with a dedicated feed tank, which can immediately pressurize the mixed raw material mixture at an appropriate temperature into the polymerization kettle in the production state using nitrogen, thereby achieving seamless intermittent polymerization and continuous production. The control system used in step (4) is a DCS control system.

[0023] Furthermore, the present application uses 12-aminododecanoic acid as the core monomer for a polymerization reaction. During the development of a one-step method for preparing bio-based nylon 12 using 12-aminododecanoic acid as a monomer, the inventors of the present application discovered that there are two core problems in the polymerization process of 12-aminododecanoic acid:

[0024] The first problem is that when the temperature rises to near the melting point, polymerization reaction will occur rapidly. At this time, if the pressure and temperature are not properly controlled, it will cause either explosion or depolymerization, affecting the transparency of the product.

[0025] Therefore, in the second stage of polymerization, that is, the constant temperature and pressure holding stage, the present application first accurately controls the polymerization dehydration temperature to be no higher than 185°C, maintains the pressure stable and controls the drainage time, so that in this stage it is in a solid-liquid coexistence state, the lattice gap is expanded, and the water molecules are efficiently diffused. At the same time, the pressure is controlled to maintain the presence of liquid water to avoid premature vaporization leading to volume expansion and destruction of the material structure. At the same time, due to the enthalpy change of the polycondensation reaction, heat will be released during the water removal process, the material temperature will automatically rise, and melt polymerization will begin. In order to further remove moisture and other impurities to increase viscosity and avoid yellowing, the present application is to limit the temperature to reach the trigger temperature before gradually reducing the pressure, and maintain the minimum pressure at above 0.8MPa. At this time, the melt stability is maintained by high pressure, and the reverse reaction of polycondensation is suppressed, so that the material can be stably polymerized and the water molecules can be fully discharged.

[0026] The second problem, which is also the most significant feature that distinguishes it from other nylons, is that due to its extremely fast polymerization speed, many small molecules do not have time to be discharged from the polymer system. As the viscosity increases in the later stages of polymerization, the discharge becomes slower and slower, ultimately leading to uneven viscosity, too wide a molecular weight distribution, poor mechanical properties, and even inability to properly draw strands and pelletize.

[0027] In this regard, the present application blows in an appropriate amount of nitrogen in the fourth stage of polymerization (constant temperature and normal pressure stage), and controls the initial flow rate of nitrogen to be higher than the final flow rate. The initial high flow rate causes the nitrogen to form turbulence on the surface of the melt, forming a vortex peeling boundary layer, accelerating the removal of free small molecules (water, oligomers, other organic matter, etc.), the mid-term transition flow continuously removes residual substances at the grain boundaries, and the late laminar flow maintains the stability of the material state.

[0028] In addition, to address issues such as monomer compatibility during the polymerization process, this application first uses a pre-modification process to react aromatic dibasic acids with alicyclic diamines to form a complex structural unit with a rigid aromatic ring + sterically hindered cyclohexyl group. This unit has good interchain entanglement, which is conducive to stable embedding in the main chain. At the same time, this structure is difficult to form regular hydrogen bond arrangement and lattice stacking in the main chain, thereby effectively interfering with the crystallinity of the chain segments, reducing the crystallinity of the main chain, and creating a structural foundation for improved transparency. In this structure, the aromatic ring introduces conjugated planar polarity, which can enhance the intermolecular forces between the chain segments, thereby increasing the glass transition temperature and fracture ductility, achieving a dual improvement in thermal stability and toughness. Polyethylene glycol (PEG) not only serves as a dispersion medium, but also "wraps" the primary polymer particles with flexible chain segments during the reaction process, preventing them from prematurely long chaining or cross-linking, improving the uniformity of the pre-modified system, and providing a controllable starting state for subsequent polymerization.

[0029] Optionally, the mass ratio of the bio-based 12-aminododecanoic acid to the aromatic dibasic acid, the alicyclic diamine, the soft segment monomer and water is 1:(0.03-0.08):(0.03-0.08):(0.10-0.15):(0.2-0.5), respectively.

[0030] Optionally, in step (1), the aromatic dibasic acid is isophthalic acid or terephthalic acid, and the alicyclic diamine is 4,4′-diaminodicyclohexylmethane; in step (2), the flexible segment monomer is polycaprolactone diol; specifically, the polyethylene glycol is PEG-400.

[0031] This application introduces a polycaprolactone diol flexible chain segment (PCL-diol), which effectively disrupts the crystallinity of the polyamide backbone and slows grain growth, thereby improving light transmittance. The PCL-diol terminal hydroxyl groups react with the carboxyl groups in the polyamide to form a block structure, thereby maintaining the ductility of the backbone while constructing a flexible microphase structure, significantly improving the material's elongation at break and impact resistance. Furthermore, the PCL segment exhibits excellent polarity transition capability, improving segment compatibility between aromatic, alicyclic, and aliphatic monomers, reducing the risk of phase separation, enhancing the structural stability and optical uniformity of the polymerization system, and enhancing the transparency and thermoforming properties of the final product.

[0032] In step (1), the reaction temperature is 80-100°C and the reaction time is 30-60 min. In step (3), the nitrogen pressure is increased by 0.2-0.5 MPa to pressurize the suspension into the polymerization kettle.

[0033] Optionally, in the constant temperature and pressure holding stage of step (4), the polymerization dehydration time is 2-3.5 h, the trigger temperature for staged pressure reduction is 195° C., and the pressure reduction rate is 0.05-0.1 MPa / min.

[0034] Optionally, in the constant temperature and pressure stage of step (4), the nitrogen purge flow rate is 0.5-1.5 L / min, and the initial flow rate is higher than the final flow rate.

[0035] Specifically, in the constant temperature and normal pressure stage of step (4), the nitrogen purge includes three gradient stages in sequence: a. 0-20 min, flow rate 1.5 L / min; b. 20-40 min, flow rate 1.0 L / min; c. 40-60 min, flow rate 0.6 L / min.

[0036] Preferably, the molecular weight regulator comprises adipic acid and acetic acid in a mass ratio of 3:1.

[0037] Specifically, by using adipic acid and limiting it to the primary modifier, the carboxylic acid group of adipic acid acts as a Bronsted acid, proton-activating the amino group and reducing the nucleophilic activation energy of the amino group. The protonated amino group is more likely to attack the carboxylic acid carbonyl oxygen, forming an amide bond. This can assist in catalyzing and accelerating polycondensation in the early stages of the polymerization reaction, stabilize the reaction in the middle stages, promote increased monomer conversion, and achieve efficient chain termination and end-capping in the later stages of polymerization, effectively controlling the molecular weight distribution. Limiting its proportion can maintain linear control of molecular weight while promoting the effective removal of water molecules. In addition, when used in combination with acetic acid, it can also inhibit oligomer formation to a certain extent, further optimizing the molecular weight distribution.

[0038] Optionally, the catalyst in reaction aid A and reaction aid B is any one of phosphoric acid, sodium phosphite and sodium hypophosphite; the antioxidant is one or more of antioxidant 1010, antioxidant H10 and antioxidant 1098.

[0039] Optionally, the temperature rise and pressure reduction phase of step (4) lasts for 1-1.5 h; the constant temperature vacuum phase lasts for 30-60 min; and the nitrogen pressurization phase lasts for 10-15 min, with a pressure of 0.2-0.5 MPa.

[0040] According to another aspect of the present application, a bio-based nylon 12 derivative prepared by the above-mentioned preparation method is also provided, wherein the bio-based nylon 12 derivative has a light transmittance of not less than 90% and an elongation at break of not less than 120%.

[0041] According to another aspect of the present application, the use of the bio-based nylon 12 derivative prepared by the above preparation method is also provided. The bio-based nylon 12 derivative can be used for electrical appliance housings, food packaging materials, sports shoe soles or support sheets.

[0042] The beneficial effects of this application include but are not limited to:

[0043] 1. The one-step method for preparing bio-based nylon 12 derivatives disclosed herein integrates the entire polymerization process into a single polymerization kettle through the six-stage full-process control of a feed tank combined with a polymerization kettle. This encompasses multiple steps, including pre-modification, batching, and polymerization, enabling efficient, one-step continuous production. This method avoids the tedious physical blending and post-modification processes required in traditional modification methods, thereby improving production efficiency.

[0044] 2. According to the one-step method for preparing bio-based nylon 12 derivatives disclosed herein, pre-modification allows aromatic dibasic acids to react with alicyclic diamines to form stable amorphous regulatory structural units, disrupting the inherent crystallinity of PA12 and improving the material's transparency and toughness. Furthermore, polycaprolactone diol (PCL-diol) is used as a flexible segment monomer, with terminal hydroxyl groups reacting with the nylon 12 backbone to form a block structure. This effectively improves the polyamide's ductility and impact resistance while avoiding loss of transparency. Pre-modification also ensures good compatibility among the monomers in the polymerization reaction, avoiding defects such as macromolecular inhomogeneity and phase separation.

[0045] 3. The one-step method for preparing bio-based nylon 12 derivatives disclosed herein achieves a balanced ratio between the polymer's main chain and flexible domains by limiting the mass ratio of the raw materials. This effectively enhances the material's optical and mechanical properties, ensuring a balance between high transparency and toughness. Furthermore, the reaction rate and molecular weight are effectively controlled during the polymerization process.

[0046] 4. According to the one-step method for preparing bio-based nylon 12 derivatives disclosed herein, precise control of parameters such as temperature, pressure, and reaction time during the polymerization process ensures reaction uniformity and stability. During the constant temperature and pressure holding stage, the timing of pressure reduction is controlled by setting a trigger temperature, thereby avoiding premature pressure degradation that could cause excessive polymerization or coking. The staged pressure reduction effectively prevents premature vaporization of water vapor, which could cause material expansion and chain breakage. DETAILED DESCRIPTION

[0047] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0048] Unless otherwise defined, all professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. The reagents and raw materials used in the present invention can be purchased through conventional channels. Unless otherwise specified, the reagents and raw materials used in the present invention are used in accordance with conventional methods in the art or in accordance with the product instructions. In addition, any methods and materials similar to or equivalent to those described herein can be applied to the present invention. The preferred embodiments and materials described in this patent are for illustrative purposes only.

[0049] The bio-based 12-aminododecanoic acid used in this application is a commercially available product derived from bioresources such as plant oils, such as castor oil. This application utilizes a commercially available polymerization reactor equipped with a dual heating system, including an outer jacket and inner coil, and a reaction preparation tank. The water used in the preparation method is high-purity water or desalted water, and normal pressure refers to standard atmospheric pressure. The amount of bio-based 12-aminododecanoic acid used in the examples of this application is 5 kg.

[0050] Example 1 Bio-based nylon 12 derivative-1#

[0051] The preparation method of bio-based nylon 12 derivative-1# comprises the following steps:

[0052] (1) Pre-modification: The aromatic dibasic acid, alicyclic diamine and reaction aid A are mixed and heated in a preparation tank to form a pre-modified system;

[0053] (2) Ingredients: Add bio-based 12-aminododecanoic acid, flexible segment monomer, reaction aid B and water to the above pre-modified system and stir to mix evenly;

[0054] (3) Feeding: The mixture in the preparation tank is pressed into the polymerization reactor by nitrogen pressure;

[0055] (4) Aggregation: The following operations are performed in sequence through the control system:

[0056] i. Temperature and pressure increase: start stirring, raise the temperature to 180°C, increase the pressure to 1.2MPa, and react for 1.5h;

[0057] ii. Constant temperature and pressure: Maintain the temperature no higher than 185°C, keep the pressure stable, gradually drain the moisture, and the temperature of the material will automatically rise after the water is drained. The material temperature should not exceed 200°C. When the material temperature rises to a certain temperature, the pressure will be reduced in stages, but the pressure must always be maintained at no less than 0.8MPa;

[0058] iii. Temperature increase and pressure reduction: The material temperature is gradually increased, the pressure is reduced to normal pressure, and the temperature is controlled at 240°C;

[0059] iv. Constant temperature and pressure: The temperature remains constant and nitrogen is purged for 0.6 hours;

[0060] v. Constant temperature vacuum: keep the temperature constant and evacuate to 0.06 MPa;

[0061] vi. Nitrogen pressurization: The polymer melt is discharged by nitrogen pressurization, and the water-cooled strands are pelletized to obtain the bio-based nylon 12 derivative 1#;

[0062] Among them, reaction aid A includes catalyst and polyethylene glycol, and the addition amounts are 0.005% and 4% of the total raw material mass of the pre-modification system respectively; reaction aid B includes catalyst, antioxidant and molecular weight regulator, and the addition amounts are 0.02%, 0.1% and 0.3% of the total raw material mass of the reaction system respectively.

[0063] The mass ratios of bio-based 12-aminododecanoic acid to aromatic dibasic acid, alicyclic diamine, soft segment monomer, and water are 1:0.05:0.05:0.12:0.2, respectively;

[0064] In step (1), the aromatic dibasic acid is isophthalic acid, and the alicyclic diamine is 4,4′-diaminodicyclohexylmethane; in the pre-modification of step (1), the reaction temperature is 90°C, the reaction time is 45 min, and the stirring rate is 100 rpm; in step (2), the flexible segment monomer is polycaprolactone diol; the polyethylene glycol is PEG-400, and the stirring rate is 100 rpm.

[0065] In step (3), nitrogen was pressurized to 0.3 MPa to force the suspension into the polymerization vessel. In step (4), the constant temperature and pressure stage, the nitrogen purge flow rate in the first half was 1.2 L / min, which was 0.5 L / min higher than the purge flow rate in the second half. The molecular weight regulator included adipic acid and acetic acid in a mass ratio of 3:1. The catalyst in reaction aids A and B was sodium phosphite; the antioxidant was antioxidant 1010.

[0066] During the constant temperature and pressure holding stage of step (4), the polymerization and dehydration time was 3 hours, the trigger temperature for the staged pressure reduction was 195°C, and the pressure reduction rate was 0.08 MPa / min. The temperature increase and pressure reduction stage of step (4) lasted 1.2 hours; the constant temperature and vacuum stage lasted 45 minutes; and the nitrogen pressurization stage lasted 12 minutes at a pressure of 0.3 MPa.

[0067] Example 2 Bio-based nylon 12 derivative-2#

[0068] The preparation method of bio-based nylon 12 derivative-2# comprises the following steps:

[0069] (1) Pre-modification: The aromatic dibasic acid, alicyclic diamine and reaction aid A are mixed and heated in a preparation tank to form a pre-modified system;

[0070] (2) Ingredients: Add bio-based 12-aminododecanoic acid, flexible segment monomer, reaction aid B and water to the above pre-modified system and stir to mix evenly;

[0071] (3) Feeding: The mixture in the preparation tank is pressed into the polymerization reactor by nitrogen pressure;

[0072] (4) Aggregation: The following operations are performed in sequence through the control system:

[0073] i. Temperature and pressure increase: start stirring, raise the temperature to 175°C, increase the pressure to 1.6 MPa, and react for 2 hours;

[0074] ii. Constant temperature and pressure: Maintain the temperature no higher than 185°C, keep the pressure stable, gradually drain the moisture, and the temperature of the material will automatically rise after the water is drained. The material temperature should not exceed 200°C. When the material temperature rises to a certain temperature, the pressure will be reduced in stages, but the pressure must always be maintained at no less than 0.8MPa;

[0075] iii. Temperature increase and pressure reduction: The material temperature is gradually increased, the pressure is reduced to normal pressure, and the temperature is controlled at 230°C;

[0076] iv. Constant temperature and pressure: The temperature remains constant and nitrogen is purged for 1 hour;

[0077] v. Constant temperature vacuum: keep the temperature constant and evacuate to 0.09 MPa;

[0078] vi. Nitrogen pressurization: The polymer melt is discharged through nitrogen pressurization, and the bio-based nylon 12 derivative 2# is obtained by water-cooling and pelletizing.

[0079] Among them, reaction aid A includes catalyst and polyethylene glycol, and the addition amounts are 0.01% and 5% of the total raw material mass of the pre-modification system respectively; reaction aid B includes catalyst, antioxidant and molecular weight regulator, and the addition amounts are 0.04%, 0.15% and 0.5% of the total raw material mass of the reaction system respectively.

[0080] The mass ratios of bio-based 12-aminododecanoic acid to aromatic dibasic acid, alicyclic diamine, soft segment monomer, and water are 1:0.08:0.08:0.15:0.5, respectively;

[0081] In step (1), the aromatic dibasic acid is terephthalic acid, and the alicyclic diamine is 4,4′-diaminodicyclohexylmethane; in the pre-modification of step (1), the reaction temperature is 100°C, the reaction time is 30 min, and the stirring rate is 100 rpm; in step (2), the flexible segment monomer is polycaprolactone diol; the polyethylene glycol is PEG-400, and the stirring rate is 100 rpm.

[0082] In step (3), nitrogen is pressurized to 0.5 MPa to pressurize the suspension into the polymerization vessel. In step (4), the constant temperature and normal pressure stage, the nitrogen purge flow rate in the first half is 1.2 L / min, which is 0.5 L / min higher than the purge flow rate in the second half. The molecular weight regulator includes adipic acid and acetic acid in a mass ratio of 3:1. The catalyst in reaction aids A and B is phosphoric acid; the antioxidant is antioxidant H10.

[0083] During the constant temperature and pressure holding stage of step (4), the polymerization and dehydration time was 3.5 hours, the trigger temperature for the staged pressure reduction was 195°C, and the pressure reduction rate was 0.1 MPa / min. The temperature increase and pressure reduction stage of step (4) lasted 1.5 hours; the constant temperature and vacuum stage lasted 60 minutes; and the nitrogen pressurization stage lasted 15 minutes at a pressure of 0.2 MPa.

[0084] Example 3 Bio-based nylon 12 derivative-3#

[0085] The preparation method of bio-based nylon 12 derivative-3# comprises the following steps:

[0086] (1) Pre-modification: The aromatic dibasic acid, alicyclic diamine and reaction aid A are mixed and heated in a preparation tank to form a pre-modified system;

[0087] (2) Ingredients: Add bio-based 12-aminododecanoic acid, flexible segment monomer, reaction aid B and water to the above pre-modified system and stir to mix evenly;

[0088] (3) Feeding: The mixture in the preparation tank is pressed into the polymerization reactor by nitrogen pressure;

[0089] (4) Aggregation: The following operations are performed in sequence through the control system:

[0090] i. Temperature and pressure increase: Start stirring, raise the temperature to 185°C, increase the pressure to 0.8 MPa, and react for 1 hour;

[0091] ii. Constant temperature and pressure: Maintain the temperature no higher than 185°C, keep the pressure stable, gradually drain the moisture, and the temperature of the material will automatically rise after the water is drained. The material temperature should not exceed 200°C. When the material temperature rises to a certain temperature, the pressure will be reduced in stages, but the pressure must always be maintained at no less than 0.8MPa;

[0092] iii. Temperature increase and pressure reduction: The material temperature is gradually increased, the pressure is reduced to normal pressure, and the temperature is controlled at 230°C;

[0093] iv. Constant temperature and pressure: The temperature remains constant and nitrogen is purged for 0.5h;

[0094] v. Constant temperature vacuum: keep the temperature constant and evacuate to 0.06 MPa;

[0095] vi. Nitrogen pressurization: The polymer melt is discharged by nitrogen pressurization, and the water-cooled strands are pelletized to obtain the bio-based nylon 12 derivative 3#;

[0096] Among them, reaction aid A includes catalyst and polyethylene glycol, and the addition amounts are 0.01% and 3% of the total mass of raw materials of the pre-modification system respectively; reaction aid B includes catalyst, antioxidant and molecular weight regulator, and the addition amounts are 0.01%, 0.05% and 0.2% of the total mass of raw materials of the reaction system respectively.

[0097] The mass ratios of bio-based 12-aminododecanoic acid to aromatic dibasic acid, alicyclic diamine, soft segment monomer, and water are 1:0.03:0.03:0.10:0.2, respectively;

[0098] In step (1), the aromatic dibasic acid is isophthalic acid, and the alicyclic diamine is 4,4′-diaminodicyclohexylmethane; in the pre-modification of step (1), the reaction temperature is 80°C, the reaction time is 60 min, and the stirring rate is 100 rpm; in step (2), the flexible segment monomer is polycaprolactone diol; the polyethylene glycol is PEG-400, and the stirring rate is 100 rpm.

[0099] In step (3), nitrogen was pressurized to 0.2 MPa to force the suspension into the polymerization vessel. In step (4), the constant temperature and pressure stage, the nitrogen purge flow rate in the first half was 1.0 L / min, which was 0.5 L / min higher than the purge flow rate in the second half. The molecular weight regulator included adipic acid and acetic acid in a mass ratio of 3:1. The catalyst in reaction aids A and B was sodium hypophosphite; the antioxidant was antioxidant 1098.

[0100] During the constant temperature and pressure holding stage of step (4), the polymerization and dehydration time is 2 hours, the trigger temperature for the staged pressure reduction is 195°C, and the pressure reduction rate is 0.05 MPa / min. The temperature increase and pressure reduction stage of step (4) lasts for 1 hour; the constant temperature and vacuum stage lasts for 60 minutes; and the nitrogen pressurization stage lasts for 15 minutes at a pressure of 0.5 MPa.

[0101] Example 4 Bio-based nylon 12 derivative-4#

[0102] The preparation method of bio-based nylon 12 derivative-4# comprises the following steps:

[0103] (1) Pre-modification: The aromatic dibasic acid, alicyclic diamine and reaction aid A are mixed and heated in a preparation tank to form a pre-modified system;

[0104] (2) Ingredients: Add bio-based 12-aminododecanoic acid, flexible segment monomer, reaction aid B and water to the above pre-modified system and stir to mix evenly;

[0105] (3) Feeding: The mixture in the preparation tank is pressed into the polymerization reactor by nitrogen pressure;

[0106] (4) Aggregation: The following operations are performed in sequence through the control system:

[0107] i. Temperature and pressure increase: start stirring, raise the temperature to 180°C, increase the pressure to 1.0 MPa, and react for 1.5 hours;

[0108] ii. Constant temperature and pressure: Maintain the temperature no higher than 185°C, keep the pressure stable, gradually drain the moisture, and the temperature of the material will automatically rise after the water is drained. The material temperature should not exceed 200°C. When the material temperature rises to a certain temperature, the pressure will be reduced in stages, but the pressure must always be maintained at no less than 0.8MPa;

[0109] iii. Temperature increase and pressure reduction: The material temperature is gradually increased, the pressure is reduced to normal pressure, and the temperature is controlled at 240°C;

[0110] iv. Constant temperature and pressure: The temperature remains constant and nitrogen is purged for 0.8h;

[0111] v. Constant temperature vacuum: keep the temperature constant and evacuate to 0.08 MPa;

[0112] Nitrogen pressurization: The polymer melt is discharged through nitrogen pressurization, and the bio-based nylon 12 derivative 4# is obtained by water-cooling and pelletizing.

[0113] Among them, reaction aid A includes catalyst and polyethylene glycol, and the addition amounts are 0.005% and 4% of the total raw material mass of the pre-modification system respectively; reaction aid B includes catalyst, antioxidant and molecular weight regulator, and the addition amounts are 0.02%, 0.08% and 0.3% of the total raw material mass of the reaction system respectively.

[0114] The mass ratios of bio-based 12-aminododecanoic acid to aromatic dibasic acid, alicyclic diamine, soft segment monomer, and water are 1:0.05:0.05:0.12:0.3, respectively;

[0115] In step (1), the aromatic dibasic acid is terephthalic acid, and the alicyclic diamine is 4,4′-diaminodicyclohexylmethane; in the pre-modification of step (1), the reaction temperature is 90°C, the reaction time is 40 min, and the stirring rate is 100 rpm; in step (2), the flexible segment monomer is polycaprolactone diol; the polyethylene glycol is PEG-400, and the stirring rate is 100 rpm.

[0116] In step (3), nitrogen was pressurized to 0.3 MPa to pressurize the suspension into the polymerization vessel. In step (4), the constant temperature and pressure stage, the nitrogen purge included three gradient stages: a. 0-20 min, flow rate 1.5 L / min; b. 20-40 min, flow rate 1.0 L / min; c. 40-60 min, flow rate 0.6 L / min. The molecular weight regulator included adipic acid and acetic acid in a mass ratio of 3:1. The catalyst in reaction aids A and B was sodium phosphite; the antioxidant was antioxidant H10.

[0117] During the constant temperature and pressure holding stage of step (4), the polymerization and dehydration time was 3.0 h, the trigger temperature for the staged pressure reduction was 195°C, and the pressure reduction rate was 0.08 MPa / min. The temperature increase and pressure reduction stage of step (4) lasted 1.2 h; the constant temperature and vacuum stage lasted 45 min; and the nitrogen pressurization stage lasted 12 min at a pressure of 0.3 MPa.

[0118] Example 5 Bio-based nylon 12 derivative-5#

[0119] The preparation method of bio-based nylon 12 derivative-5# comprises the following steps:

[0120] (1) Pre-modification: The aromatic dibasic acid, alicyclic diamine and reaction aid A are mixed and heated in a preparation tank to form a pre-modified system;

[0121] (2) Ingredients: Add bio-based 12-aminododecanoic acid, flexible segment monomer, reaction aid B and water to the above pre-modified system and stir to mix evenly;

[0122] (3) Feeding: The mixture in the preparation tank is pressed into the polymerization reactor by nitrogen pressure;

[0123] (4) Aggregation: The following operations are performed in sequence through the control system:

[0124] i. Temperature and pressure increase: start stirring, raise the temperature to 180°C, increase the pressure to 1.2MPa, and react for 1.5h;

[0125] ii. Constant temperature and pressure: Maintain the temperature no higher than 185°C, keep the pressure stable, gradually drain the moisture, and the temperature of the material will automatically rise after the water is drained. The material temperature should not exceed 200°C. When the material temperature rises to a certain temperature, the pressure will be reduced in stages, but the pressure must always be maintained at no less than 0.8MPa;

[0126] iii. Temperature increase and pressure reduction: The material temperature is gradually increased, the pressure is reduced to normal pressure, and the temperature is controlled at 240°C;

[0127] iv. Constant temperature and pressure: The temperature remains constant and nitrogen is purged for 0.6 hours;

[0128] v. Constant temperature vacuum: keep the temperature constant and evacuate to 0.06 MPa;

[0129] vi. Nitrogen pressurization: The polymer melt is discharged through nitrogen pressurization, and the water-cooled strands are cut into pellets to obtain the bio-based nylon 12 derivative 5#;

[0130] Among them, reaction aid A includes catalyst and polyethylene glycol, and the addition amounts are 0.005% and 4% of the total raw material mass of the pre-modification system respectively; reaction aid B includes catalyst, antioxidant and molecular weight regulator, and the addition amounts are 0.02%, 0.1% and 0.3% of the total raw material mass of the reaction system respectively.

[0131] The mass ratios of bio-based 12-aminododecanoic acid to aromatic dibasic acid, alicyclic diamine, soft segment monomer, and water are 1:0.05:0.05:0.12:0.2, respectively;

[0132] In step (1), the aromatic dibasic acid is isophthalic acid, and the alicyclic diamine is 4,4′-diaminodicyclohexylmethane; in the pre-modification of step (1), the reaction temperature is 90°C, the reaction time is 45 min, and the stirring rate is 100 rpm; in step (2), the flexible segment monomer is polycaprolactone diol; the polyethylene glycol is PEG-400, and the stirring rate is 100 rpm.

[0133] In step (3), nitrogen was pressurized to 0.3 MPa to pressurize the suspension into the polymerization vessel. In step (4), the constant temperature and pressure stage was maintained at a constant nitrogen purge flow rate of 0.8 L / min. The molecular weight regulators included adipic acid and acetic acid in a mass ratio of 3:1. The catalyst in reaction aids A and B was sodium phosphite; the antioxidant was antioxidant 1010.

[0134] During the constant temperature and pressure holding stage of step (4), the polymerization and dehydration time was 3 hours, the trigger temperature for the staged pressure reduction was 195°C, and the pressure reduction rate was 0.08 MPa / min. The temperature increase and pressure reduction stage of step (4) lasted 1.2 hours; the constant temperature and vacuum stage lasted 45 minutes; and the nitrogen pressurization stage lasted 12 minutes at a pressure of 0.3 MPa.

[0135] Example 6 Bio-based nylon 12 derivative-6#

[0136] The preparation method of bio-based nylon 12 derivative-6# comprises the following steps:

[0137] (1) Pre-modification: The aromatic dibasic acid, alicyclic diamine and reaction aid A are mixed and heated in a preparation tank to form a pre-modified system;

[0138] (2) Ingredients: Add bio-based 12-aminododecanoic acid, flexible segment monomer, reaction aid B and water to the above pre-modified system and stir to mix evenly;

[0139] (3) Feeding: The mixture in the preparation tank is pressed into the polymerization reactor by nitrogen pressure;

[0140] (4) Aggregation: The following operations are performed in sequence through the control system:

[0141] i. Temperature and pressure increase: start stirring, raise the temperature to 180°C, increase the pressure to 1.0 MPa, and react for 1.5 hours;

[0142] ii. Constant temperature and pressure: Maintain the temperature no higher than 185°C, keep the pressure stable, gradually drain the moisture, and the temperature of the material will automatically rise after the water is drained. The material temperature should not exceed 200°C. When the material temperature rises to a certain temperature, the pressure will be reduced in stages, but the pressure must always be maintained at no less than 0.8MPa;

[0143] iii. Temperature increase and pressure reduction: The material temperature is gradually increased, the pressure is reduced to normal pressure, and the temperature is controlled at 240°C;

[0144] iv. Constant temperature and pressure: The temperature remains constant and nitrogen is purged for 0.8h;

[0145] v. Constant temperature vacuum: keep the temperature constant and evacuate to 0.08 MPa;

[0146] Nitrogen pressurization: The polymer melt is discharged through nitrogen pressurization, and the bio-based nylon 12 derivative 6# is obtained by water-cooling and pelletizing.

[0147] Among them, reaction aid A includes catalyst and polyethylene glycol, and the addition amounts are 0.005% and 4% of the total raw material mass of the pre-modification system respectively; reaction aid B includes catalyst, antioxidant and molecular weight regulator, and the addition amounts are 0.02%, 0.08% and 0.3% of the total raw material mass of the reaction system respectively.

[0148] The mass ratios of bio-based 12-aminododecanoic acid to aromatic dibasic acid, alicyclic diamine, soft segment monomer, and water are 1:0.05:0.05:0.02:0.3, respectively;

[0149] In step (1), the aromatic dibasic acid is terephthalic acid, and the alicyclic diamine is 4,4′-diaminodicyclohexylmethane; in the pre-modification of step (1), the reaction temperature is 90°C, the reaction time is 40 min, and the stirring rate is 100 rpm; in step (2), the flexible segment monomer is polycaprolactone diol; the polyethylene glycol is PEG-400, and the stirring rate is 100 rpm.

[0150] In step (3), nitrogen was pressurized to 0.3 MPa to pressurize the suspension into the polymerization vessel. In step (4), the constant temperature and pressure stage, the nitrogen purge included three gradient stages: a. 0-20 min, flow rate 1.5 L / min; b. 20-40 min, flow rate 1.0 L / min; c. 40-60 min, flow rate 0.6 L / min. The molecular weight regulator included adipic acid and acetic acid in a mass ratio of 3:1. The catalyst in reaction aids A and B was sodium phosphite; the antioxidant was antioxidant H10.

[0151] During the constant temperature and pressure holding stage of step (4), the polymerization and dehydration time was 3.0 h, the trigger temperature for the staged pressure reduction was 195°C, and the pressure reduction rate was 0.08 MPa / min. The temperature increase and pressure reduction stage of step (4) lasted 1.2 h; the constant temperature and vacuum stage lasted 45 min; and the nitrogen pressurization stage lasted 12 min at a pressure of 0.3 MPa.

[0152] Comparative Example 1: Comparison of bio-based nylon 12 derivative-1#

[0153] The difference between Comparative Example 1 and Example 1 is that in Comparative Example 1, no pre-modification is performed, and the raw materials are directly mixed and then polymerized.

[0154] Comparative Example 2: Comparison of bio-based nylon 12 derivative-2#

[0155] The difference between Comparative Example 2 and Example 1 is that no soft segment monomer is used in the raw materials of Comparative Example 2.

[0156] Comparative Example 3: Comparison of bio-based nylon 12 derivative-3#

[0157] The difference between Comparative Example 3 and Example 1 is that in the constant temperature and pressure holding stage of step (4) in Comparative Example 3, the pressure is reduced in stages when the material temperature reaches 230°C.

[0158] Comparative Example 4: Comparison of bio-based nylon 12 derivatives-4#

[0159] The difference between Comparative Example 4 and Example 1 is that in the constant temperature and pressure holding stage of step (4) in Comparative Example 4, the pressure is finally reduced to 0.4 MPa.

[0160] Experimental example

[0161] 1. The molecular weight and distribution of bio-based nylon 12 derivatives 1#-6# prepared in Examples 1-6 were tested;

[0162] 2. The mechanical and optical properties of the bio-based nylon 12 derivatives 1#-6# prepared in Examples 1-6 and the comparative bio-based nylon 12 derivatives 1#-4# prepared in Comparative Examples 1-4 were tested. Table 1 lists the test items and methods, Table 2 shows the molecular weight and its distribution, and Table 3 shows the experimental data.

[0163] Table 1 Experimental test items and methods

[0164]

[0165] Table 2 Molecular weight and distribution of Examples 1-6

[0166]

[0167] Table 3 Experimental data

[0168]

[0169] From the above results, it can be seen that the bio-based nylon 12 derivatives prepared using the raw materials and methods specified in this application have uniform molecular weight distribution, high transmittance, and good mechanical properties. The samples in Examples 1-4 all have excellent properties of transmittance ≥90% and elongation at break ≥120%, and the haze is well controlled and the crystallinity is less than 15%.

[0170] A high light transmittance of ≥90% makes it easy to observe the contents when used as electrical housings and food packaging materials, meeting the transparency requirements of these materials. A break elongation of ≥120% also meets the high toughness requirements of shoe soles or sole support plates, making it suitable for use as a shock-absorbing and support structure in high-end sports shoe soles. These results demonstrate that the product prepared in this application can meet the current market demand for high transparency and high mechanical properties of nylon 12 derivatives.

[0171] While Example 5 still met the transmittance requirement of ≥90%, its haze increased to 11.5%, its tensile and impact properties slightly decreased, and its crystallinity increased (16.3%). This was attributed to insufficient nitrogen purge, with a small amount of residual monomer. Example 6 also exhibited a low level of soft segment addition, low elongation at break, high crystallinity, and a more regular structure, indicating insufficient flexibility control.

[0172] Comparative Example 1 had no pre-modification and poor transparency. The reason for this was that the reaction activity of the various monomers varied greatly, forming a heterogeneous chain structure with poor compatibility. Furthermore, the regularity of the PA12 molecular chain was not destroyed, resulting in a fast crystallization rate and large grains, which led to severe haze and decreased transmittance. Comparative Example 2 did not add a flexible segment monomer and had poor mechanical properties. The reason for this was that the segments had poor slippage and deformation capabilities, resulting in insufficient ductility before fracture. Comparative Example 3 had a too high pressure-reduction trigger temperature, resulting in poor transparency and mechanical properties. The reason for this was that the polyamide main chain was sensitive to heat and could potentially undergo thermal degradation or reaction reversal. Comparative Example 4 had a low pressure during the constant temperature and pressure holding stage, resulting in poor transparency and mechanical properties. The reason for this was that the polycondensation process was unstable and the segments were prone to depolymerization.

[0173] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A one-step method for preparing a bio-based nylon 12 derivative, characterized in that: The following steps are involved: (1) Pre-modification: The aromatic dibasic acid, alicyclic diamine and reaction aid A are mixed and heated in a preparation tank to form a pre-modified system; (2) Ingredients: Add bio-based 12-aminododecanoic acid, flexible segment monomer, reaction aid B and water to the above pre-modified system and stir to mix evenly; (3) Feeding: The mixture in the preparation tank is pressed into the polymerization reactor by nitrogen pressure; (4) Aggregation: The following operations are performed in sequence through the control system: i. Increase temperature and pressure: Start stirring, increase temperature to 175-185°C, increase pressure to 0.8-1.6 MPa, and react for 1-2 hours; ii. Constant temperature and pressure: Maintain the temperature no higher than 185°C, keep the pressure stable, and gradually drain the moisture. The temperature of the material will automatically rise after the water is drained. The material temperature will not exceed 200°C. When the material temperature rises to a certain temperature, the pressure will be reduced in stages. The trigger temperature for staged pressure reduction is 195°C, but the pressure must always be maintained at no less than 0.8MPa. iii. Temperature increase and pressure reduction: The material temperature is gradually increased, the pressure is reduced to normal pressure, and the temperature is controlled at 230-250℃; iv. Constant temperature and pressure: The temperature remains constant and nitrogen is purged for 0.5-1h; v. Constant temperature vacuum: Keep the temperature constant and evacuate to 0.06-0.09 MPa; vi. Nitrogen pressurization: The polymer melt is discharged through nitrogen pressurization, and the bio-based nylon 12 derivative product is obtained by water-cooling and pelletizing. Among them, the reaction aid A includes a catalyst and polyethylene glycol, and the addition amounts are 0.002-0.01% and 3-5% of the total mass of the raw materials of the pre-modified system respectively; the reaction aid B includes a catalyst, an antioxidant and a molecular weight regulator, and the addition amounts are 0.01-0.04%, 0.05-0.15% and 0.2-0.5% of the total mass of the raw materials of the reaction system respectively.

2. The preparation method according to claim 1, characterized in that The mass ratios of the bio-based 12-aminododecanoic acid to the aromatic dibasic acid, the alicyclic diamine, the flexible segment monomer and water are 1:(0.03-0.08):(0.03-0.08):(0.10-0.15):(0.2-0.5) respectively.

3. The preparation method according to claim 1, characterized in that In step (1), the aromatic dibasic acid is isophthalic acid or terephthalic acid, and the alicyclic diamine is 4,4′-diaminodicyclohexylmethane; in step (2), the flexible segment monomer is polycaprolactone diol; In step (1), the reaction temperature for the pre-modification is 80-100°C and the reaction time is 30-60 min. In step (3), the mixture is pressurized into a polymerization reactor with nitrogen at a pressure of 0.2-0.5 MPa.

4. The preparation method according to claim 1, characterized in that In the constant temperature and pressure holding stage of step (4), the polymerization dehydration time is 2-3.5 h, and the pressure reduction rate is 0.05-0.1 MPa / min.

5. The preparation method according to claim 1, characterized in that In the constant temperature and pressure stage of step (4), the nitrogen purge flow rate is 0.5-1.5 L / min, and the initial flow rate is higher than the final flow rate.

6. The preparation method according to claim 1, characterized in that Molecular weight regulators include adipic acid and acetic acid.

7. The preparation method according to claim 1, characterized in that The catalyst in the reaction aid A and the reaction aid B is any one of phosphoric acid, sodium phosphite and sodium hypophosphite; The antioxidant is one or more of antioxidant 1010, antioxidant H10 and antioxidant 1098.

8. The preparation method according to claim 1, characterized in that The temperature rise and pressure reduction phase of step (4) lasts for 1-1.5 hours; the constant temperature vacuum phase lasts for 30-60 minutes; and the nitrogen pressurization phase lasts for 10-15 minutes, with a pressure of 0.2-0.5 MPa.

9. A bio-based nylon 12 derivative prepared by the method according to any one of claims 1 to 8, characterized in that: The bio-based nylon 12 derivative has a light transmittance of not less than 90% and an elongation at break of not less than 120%.

10. The use of the bio-based nylon 12 derivative according to claim 9, characterized in that: The bio-based nylon 12 derivative can be used for electrical appliance housings, food packaging materials, shoe soles or shoe sole support sheets.

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