Continuous preparation method of long-carbon-chain nylon intermediate, preparation system and application of long-carbon-chain nylon intermediate

Abstract

The invention discloses a method for continuously preparing a long-carbon-chain nylon intermediate, a preparation system and application thereof. The continuous preparation method comprises the following steps: in a protective atmosphere, conveying raw materials for preparing the long-carbon-chain nylon intermediate into a melting device for melting, then continuously conveying the melted materials into a first polymerization device for primary polymerization reaction, and then conveying the materials into a second polymerization device for secondary polymerization reaction to obtain the long-carbon-chain nylon intermediate. According to the method and the device for continuously preparing the long carbon chain nylon intermediate, the problem that an existing method cannot realize continuous production is solved in a targeted manner, the method can be used for guiding and extremely easily realizing industrial continuous production, and the method not only realizes continuous production of the long carbon chain nylon intermediate, but also is simple to operate and low in cost. The prepared long-carbon-chain nylon intermediate is narrow in molecular weight distribution, so that a long-carbon-chain nylon product with narrow molecular weight distribution can be subsequently prepared, and the product quality is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of long carbon chain nylon preparation, further, to a method for continuous preparation of long carbon chain nylon intermediates, a system for preparing the same and applications thereof. BACKGROUND

[0002] Long carbon chain nylon generally refers to nylon with a methylene length of more than 10 carbons in the chain segment, including nylon 11, nylon 12, nylon 1212, nylon 1012, nylon 1313, etc. From the chain structure of long carbon chain nylon resin, the methylene in the macromolecular chain is relatively long, and the amide group density is low. Therefore, long carbon chain nylon has high toughness and softness, low water absorption, high dimensional stability and other characteristics that conventional nylon 6 and nylon 66 do not have, in addition to general properties of nylon such as lubricity, wear resistance, pressure resistance and easy processability.

[0003] CN115947937A discloses a method for producing high-viscosity long carbon chain nylon by intermittent method, comprising the following steps: step S1, placing diacid, diamine, deionized water and antioxidant in a reaction kettle, and maintaining the pressure of the reaction kettle by discharging steam from the reaction kettle during the reaction; step S2, transporting the long carbon chain nylon in the reaction kettle to a first viscosity increaser for polymerization, and staying for 30-90 minutes; step S3, transporting the long carbon chain nylon in the first viscosity increaser to a second viscosity increaser for continuous polymerization to obtain high-viscosity long carbon chain nylon particles.

[0004] CN101881458B discloses a process for preparing nylon 1212, comprising the following steps: first, distilling refined dodecanedinitrile; second, distilling refined dodecanediamine, and then forming the obtained dodecanediamine into sheet-shaped solid in a tablet machine; third, synthesizing nylon 1212, and cutting the nylon 1212 resin after cooling.

[0005] CN113698288B discloses a new method and a matching device for continuously preparing powdered nylon salt, which comprises the following steps: 1) replacing the air in the system with inert gas, heating the neutralization reactor, the salt solution temporary storage tank, the solution delivery pump and the solution delivery pipeline, and at the same time, turning on the heating switch of the spray drying equipment and heating the high-temperature air delivery pipeline; 2) continuously adding diamin, diacid, catalyst and solvent into the neutralization reactor in a certain proportion, with a residence time of 10-20 min, and the obtained nylon salt solution enters the salt solution temporary storage tank and adjusts the pH; 3) the adjusted nylon salt solution is sent into the drying tower of the spray drying equipment by the solution delivery pump, and after the action of high-temperature air, the solvent becomes steam and escapes, and the powdered nylon salt is obtained.

[0006] CN113881036A discloses a method for preparing long-chain nylon and the resulting nylon. The method includes the following steps: Step 1, preparing nylon salt using diacid and diamine as raw materials; Step 2, mixing the raw materials including the nylon salt, water, catalyst, and molecular weight regulator, and polymerizing to obtain the long-chain nylon; wherein the weight ratio of nylon salt to water is 1:(0.7~2.5). Step 2 can be carried out by batch polymerization or solid-state post-condensation polymerization, preferably under a protective atmosphere.

[0007] CN109180931B discloses a method for preparing long-chain nylon PA1313. The method uses 1,13-tridecanoic acid as a raw material, which is nitrified and amination to produce 1,13-tridecanoic acid diamine. Then, using 1,13-tridecanoic acid diamine and 1,13-tridecanoic acid as raw materials and water as a solvent, PA1313 salt is prepared. PA1313 salt and water are added to a polymerization reactor in a certain proportion and melt polymerized to obtain PA1313 with a certain molecular weight.

[0008] Currently published patents concerning the production of long-chain nylon resins are all based on intermittent methods, and the basic operating procedures or equipment for production preparation are limited to laboratory or pilot-scale research. There are very few reports on continuous or industrial production methods and apparatus for long-chain nylon, and the operating procedures are complex. Therefore, there is a need to provide a method and apparatus for the continuous preparation of long-chain nylon intermediates. Summary of the Invention

[0009] To address the problems in existing technologies, this invention proposes a method, system, and application for the continuous preparation of long-chain nylon intermediates. The method and apparatus for the continuous preparation of long-chain nylon intermediates of this invention specifically solve the problem of the inability to achieve continuous production using existing methods. It can be used to guide and is easily implemented for industrial-scale continuous production. Furthermore, the method of this invention not only achieves continuous production of long-chain nylon intermediates but is also simple to operate, and the prepared long-chain nylon intermediates have a narrow molecular weight distribution, which is beneficial for subsequent production of long-chain nylon products with a narrow molecular weight distribution, thus improving product quality.

[0010] One objective of this invention is to provide a method for the continuous preparation of long-chain nylon intermediates, comprising the following steps:

[0011] Under a protective atmosphere, the raw materials for preparing long-chain nylon intermediates are fed into a melting device for melting. The molten material is then continuously fed into a first polymerization device for a first polymerization reaction, and then into a second polymerization device for a second polymerization reaction to obtain the long-chain nylon intermediate.

[0012] In the method for continuous preparation of long-chain nylon intermediates according to the present invention, preferably, it includes the following steps:

[0013] a) Under a protective atmosphere, long-chain nylon salt, antioxidant, catalyst and molecular weight regulator are fed into a powder conveying device and mixed thoroughly before being fed together into a melting device. Solvent is also fed into the melting device.

[0014] b) The molten material in the melting device is sent to the first polymerization device for a primary polymerization reaction;

[0015] c) The reacted material from the first polymerization unit is sent to the second polymerization unit for a secondary polymerization reaction to obtain a long-chain nylon intermediate.

[0016] In the method for continuous preparation of long-chain nylon intermediates according to the present invention, preferably,

[0017] In step a),

[0018] Under a protective atmosphere, long-chain nylon salt is first fed into a powder conveying device; then antioxidants, catalysts, and molecular weight regulators are fed into the powder conveying device. After the above materials are fully mixed in the powder conveying device, they are sent together to the melting device, while the solvent is sent directly to the melting device.

[0019] In the method for continuous preparation of long-chain nylon intermediates according to the present invention, preferably,

[0020] Step a) includes the following steps:

[0021] a1) Under a protective atmosphere, long-chain nylon salt is fed into the powder silo;

[0022] a2) The long-chain nylon salt in the powder silo is first fed into the powder conveying device through the hopper of the powder conveying device;

[0023] a3) Then, the antioxidant, catalyst and molecular weight regulator are fed into the mixing section of the powder conveying device. After the above materials are fully mixed in the powder conveying device, they are sent to the melting device together. The solvent is sent directly to the melting device. According to the material conveying direction of the powder conveying device, the hopper of the powder conveying device is in front and the mixing section of the powder conveying device is in the back.

[0024] Preferably,

[0025] The long-chain nylon salt is fed intermittently and / or continuously into the powder silo, preferably continuously; and / or,

[0026] Long-chain nylon salts from the powder silo are intermittently and / or continuously fed into the hopper of the powder conveying device, preferably continuously; and / or,

[0027] Antioxidants, catalysts, and molecular weight regulators are introduced separately into the mixing section of the powder conveying device and / or mixed before entering the mixing section of the powder conveying device, preferably mixed before entering the mixing section of the powder conveying device; and / or,

[0028] The solvent is water.

[0029] In the method for continuous preparation of long-chain nylon intermediates according to the present invention, preferably,

[0030] The protective gas in the protective atmosphere is selected from at least one of nitrogen, carbon dioxide, or argon, preferably carbon dioxide; and / or,

[0031] The oxygen content in the protective atmosphere does not exceed 10 ppm; preferably 2–8 ppm; and / or,

[0032] The long-chain nylon salt is a solid powder, selected from commonly used long-chain nylon salts in the prior art, and prepared using common methods. Preferably, the long-chain nylon salt is a long-chain nylon salt generated by the reaction of a diacid and a diamine, wherein the molar ratio of diacid structural units to diamine structural units in the long-chain nylon salt is 0.995 to 1.005; more preferably, the pH value of the long-chain nylon salt solution generated by the reaction of a diacid and a diamine is 6.8 to 7.2.

[0033] In the technical solution of this invention, controlling the pH value can prevent the molecular weight distribution from being too large.

[0034] More preferably,

[0035] The dicarboxylic acid is selected from C10 to C20 dicarboxylic acids; and / or,

[0036] The diamine is selected from C10 to C20 diamines.

[0037] In the method for continuous preparation of long-chain nylon intermediates according to the present invention, preferably,

[0038] In the raw materials for preparing long-chain nylon intermediates, the mass ratio of long-chain nylon salt: antioxidant: catalyst: molecular weight regulator is 1:0.0001~0.01:0.0001~0.01:0.0001~0.01, preferably 1:0.0005~0.005:0.0005~0.005:0.0005~0.005; and / or,

[0039] In the melting apparatus, the molar ratio of long-chain nylon salt to water is 1:0.5–5, preferably 1:1–3; and / or,

[0040] The operating pressure of the melting device is 0.1–0.9 MPaG, preferably 0.2–0.5 MPaG; and / or,

[0041] The temperature of the melting device is 120–180°C, preferably 130–160°C;

[0042] The melting device may or may not emit gas, preferably it does not emit gas.

[0043] More preferably, in the technical solution of the present invention, after the preparation of the long carbon chain nylon intermediate is continuously and stably operated, there is always molten liquid in the melting device. The mass ratio of the solid material conveyed from the powder conveying device to the melting device to the molten material contained in the melting device is 1:3 to 20, preferably 1:5 to 15, so that the raw material can be melted almost instantly when it enters the melting device.

[0044] In the method for continuous preparation of long-chain nylon intermediates according to the present invention, preferably,

[0045] The temperature for the primary polymerization reaction is 190–235°C, preferably 200–227°C; and / or,

[0046] The pressure of a single polymerization reaction is 1.2–3.0 MPaG, preferably 1.5–2.5 MPaG; and / or,

[0047] The time for one polymerization reaction is 0.5 to 5 hours, preferably 1 to 4 hours.

[0048] In the method for continuous preparation of long-chain nylon intermediates according to the present invention, preferably,

[0049] The temperature for the secondary polymerization reaction is 210–260°C, preferably 220–250°C; and / or,

[0050] The pressure for the secondary polymerization reaction is -0.09 to 0.15 MPaG, preferably -0.05 to 0.05 MPaG; and / or,

[0051] The secondary polymerization reaction takes 0.5 to 5 hours, preferably 1 to 3 hours.

[0052] In the technical solution of the present invention, the number average molecular weight of the prepared long carbon chain nylon intermediate is 6000-16000, preferably 7000-15000;

[0053] The molecular weight distribution range of the prepared long-chain nylon intermediate is 2.0 to 2.8, preferably 2.1 to 2.6; more preferably 2.1 to 2.3.

[0054] A second objective of this invention is to provide a system for the continuous preparation of long-chain nylon intermediates, comprising:

[0055] The assembly consists of a powder conveying device, a melting device, a molten material conveying device, a first polymerization device, a first polymerization device discharge conveying device, a second polymerization device, and optionally a second polymerization device discharge conveying device, all connected in sequence. The melting device is also equipped with a solvent inlet. The powder conveying device is equipped with a feed pipeline for the raw materials used to prepare long-chain nylon intermediates.

[0056] The method described in the preferred embodiment of the present invention is prepared using the system described above.

[0057] In the system for continuous preparation of long-chain nylon intermediates according to the present invention, preferably,

[0058] The system also includes a powder silo and an additive mixing device. The powder silo is equipped with an inert gas pipeline and a long-chain nylon salt feed pipeline. The outlet of the powder silo is connected to the hopper of the powder conveying device. The additive mixing device is equipped with separate and / or mixed feed pipelines for antioxidants, catalysts, and molecular weight regulators. The outlet of the additive mixing device is connected to the inlet of the mixing section of the powder conveying device. According to the material conveying direction of the powder conveying device, the hopper of the powder conveying device is located in front, and the mixing section of the powder conveying device is located behind.

[0059] Preferably, a rotary discharge valve is also provided between the powder silo and the hopper of the powder conveying device;

[0060] More preferably, the rotary discharge valve is connected to the hopper of the powder conveying device by a flexible hose.

[0061] In the system for continuous preparation of long-chain nylon intermediates according to the present invention, preferably,

[0062] The connecting pipeline between the powder conveying device and the discharge conveying device of the second polymerization unit is a jacketed pipe and / or a heat tracing pipe, preferably a jacketed pipe; and / or,

[0063] The powder conveying device is selected from a screw conveyor; preferably, the powder hopper of the screw conveyor is equipped with a weighing scale; and / or, the screw conveyor is a single screw or a twin screw, preferably a twin screw; and / or

[0064] The melting device is selected from a melting kettle; and / or,

[0065] The first polymerization apparatus is selected from the first polymerization reactor; and / or,

[0066] The second polymerization apparatus is selected from the second polymerization reactor;

[0067] Preferably, the melting vessel, the first polymerization vessel, and the second polymerization vessel are each independently provided with at least one of a stirring paddle and a jacket; more preferably, the stirring paddle is selected from at least one of an anchor type, a frame type, or a ribbon type stirring paddle.

[0068] In the technical solution of the present invention, the melting kettle, the first polymerization kettle, and the second polymerization kettle can be selected from kettles commonly used in the prior art that can achieve the above-mentioned melting or polymerization functions.

[0069] In the system for continuous preparation of long-chain nylon intermediates according to the present invention, preferably,

[0070] The molten material conveying device is a molten material discharge conveying pump; and / or,

[0071] The first polymerization unit discharge conveying device is a first polymerization reactor discharge conveying pump; and / or,

[0072] The discharge conveying device of the second polymerization unit is the discharge conveying pump of the second polymerization reactor;

[0073] Preferably, the molten material discharge conveying device, the first polymerization device discharge conveying device, and the second polymerization device discharge conveying device are each independently selected from gear pumps;

[0074] More preferably, the gear pump is equipped with a heat tracing jacket and / or a heating module.

[0075] In the system for continuous preparation of long-chain nylon intermediates according to the present invention, preferably,

[0076] The melting apparatus is also equipped with gas pipelines for the introduction of inert gas and / or the discharge of non-condensable gas; and / or,

[0077] The melting device is also equipped with a sight glass; and / or

[0078] The melting device is also equipped with a level gauge; and / or,

[0079] Preferably,

[0080] The gas pipeline of the melting device is equipped with a pressure gauge and a pressure regulating valve; and / or,

[0081] The level gauge is preferably a radar level gauge.

[0082] In the technical solution of the present invention, the melting device introduces inert gas and / or discharges non-condensable gas depending on the operation of the device, so as to maintain the required pressure balance; the first polymerization device and the second polymerization device do not require inert gas, the polymerization reaction will generate gas, and the generated gas will be automatically discharged to the outside through the pressure regulating valve according to the pressure inside the vessel, so as to maintain the stability of the pressure inside the vessel.

[0083] A third objective of this invention is to provide an application of the long-chain nylon intermediate prepared by the method described in any one of the objectives of this invention or by the system described in the second objective of this invention in the preparation of long-chain nylon.

[0084] The long-chain nylon intermediate prepared according to this invention is further used in conventional thickening equipment such as a twin-screw extruder to increase the molecular weight of the long-chain nylon, thereby preparing long-chain nylon products. The long-chain nylon intermediate of this invention has a narrow molecular weight distribution and high product quality, which is beneficial for preparing long-chain nylon products with a narrow molecular weight distribution and high product quality.

[0085] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values; these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. In the following, various technical solutions can, in principle, be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein.

[0086] Compared with the prior art, the present invention has at least the following advantages:

[0087] In existing technologies, the preparation of long-chain nylon intermediates or raw materials for long-chain nylon is carried out in a single reactor. Because the pressure requirements differ at each polymerization stage during the preparation of long-chain nylon intermediates or raw materials, pressure relief and temperature adjustment are necessary, resulting in discontinuous production. Furthermore, the direct entry of materials into the reactor leads to a low filling coefficient due to the low bulk density of the powder. In contrast, this invention continuously feeds the powder into the melting reactor, melts it, and then continuously feeds it into the polymerization reactor, solving the problem of low filling coefficient in the polymerization reactor caused by the low bulk density of the powder. Simultaneously, the continuous transport of the molten raw materials allows for staged polymerization reactions, resolving the issues of variable pressure operation and continuity in the equipment.

[0088] The method of this invention not only realizes the continuous production of long-chain nylon intermediates, but also has simple operation and can produce long-chain nylon intermediates with a narrow molecular weight distribution, which is beneficial for the subsequent production of long-chain nylon products with a narrow molecular weight distribution and improves product quality. Attached Figure Description

[0089] Figure 1 This is a schematic diagram of the continuous preparation system for long-chain nylon intermediates according to the present invention.

[0090] V1 - Powder silo; X1 - Powder conveying device; V2 - Additive preparation device; R1 - Melting device; R2 - First polymerization device; R3 - Second polymerization device; P1 - Melting device discharge conveying device; P2 - First polymerization device discharge conveying device; P3 - Second polymerization device discharge conveying device;

[0091] 101 - Non-condensable gas stream; 102 - Solvent stream; 103 - Melting unit discharge stream; 104 - Raw material stream; 105 - Melting unit jacket discharge stream; 106 - Melting unit jacket feed stream; 107 - First polymerization unit feed stream; 108 - First polymerization unit discharge stream; 109 - First polymerization unit gas phase stream; 110 - First polymerization unit jacket discharge stream; 111 - First polymerization reactor jacket feed stream; 112 - Second polymerization unit feed stream; 113 - Second polymerization unit discharge stream; 114 - Nylon product feed stream; 115 - Second polymerization unit gas phase stream; 116 - Second polymerization unit jacket discharge stream; 117 - Second polymerization unit jacket feed stream; 118 - Additive feed stream; 119 - Inert gas stream; 120 - Long-chain nylon salt; 121 - Mixed additives.

[0092] Figure 1 In the process, under the protection of inert gas stream 119, long-chain nylon salt 120 is fed into powder silo V1. Powder silo V1 then uses a rotary valve to feed the long-chain nylon salt into the hopper of powder conveying device X1. Antioxidant, catalyst, and molecular weight regulator are then mixed as mixing aid 121 by aid mixing device V2 and fed into the mixing section of powder conveying device as aid feed stream 118. After being fully mixed by the powder conveying device (such as a screw), they are sent to melting device R1 as raw material stream 104. Melting device R1 is equipped with an exhaust port for discharging non-condensable gas streams. 101. The melting device R1 is provided with a feed inlet for solvent stream 102 (e.g., water as the solvent); the discharge stream 103 of the melting device is used as the feed stream 107 of the first polymerization device and is transported to the first polymerization device R2 through the discharge conveyor P1 of the melting device; the discharge stream 108 of the first polymerization device is used as the feed stream 112 of the second polymerization device and is transported to the second polymerization device R3 through the discharge conveyor P2 of the first polymerization device; the discharge stream 113 of the second polymerization device is used as the feed stream 114 of the nylon product and is transported to the nylon product production device (e.g., a twin-screw extruder) through the discharge conveyor P3 of the second polymerization device.

[0093] In addition, the melting device R1 is a melting kettle; the first polymerization device R2 and the second polymerization device R3 are polymerization kettles; the melting device R1 is equipped with a jacket for controlling the temperature, and the temperature is controlled by the material flow 105 from the jacket of the melting device and the material flow 106 from the jacket of the melting device.

[0094] The first polymerization unit R2 is equipped with a temperature control jacket, and the temperature is controlled by the discharge stream 110 and the feed stream 111 of the first polymerization unit jacket. The first polymerization unit R2 is also equipped with a pressure regulating valve, which automatically discharges the gaseous stream 109 of the first polymerization unit to the outside to maintain the pressure inside the reactor.

[0095] The second polymerization unit R3 is equipped with a temperature control jacket, and the temperature is controlled by the discharge stream 116 of the second polymerization unit jacket and the feed stream 117 of the first polymerization unit jacket. The second polymerization unit R3 is also equipped with a pressure regulating valve, which automatically discharges the gaseous stream 115 of the second polymerization unit to the outside to maintain stable pressure inside the reactor. Detailed Implementation

[0096] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0097] It should also be noted that the various specific technical features described in the following embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the various possible combinations will not be described separately in this invention.

[0098] Furthermore, various embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention. The resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0099] Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, such as those that can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0100]

Example 1

[0101] like Figure 1 The system shown is for the continuous preparation of long-chain nylon intermediates according to the present invention, comprising: a powder conveying device X1, a melting device R1, a molten material conveying device P1, a first polymerization device R2, a first polymerization device discharge conveying device P2, a second polymerization device R3, and optionally a second polymerization device discharge conveying device P3 connected in sequence; the melting device is further provided with a solvent inlet (water in this embodiment); the powder conveying device is provided with a feed line for the raw materials for preparing long-chain nylon intermediates;

[0102] The system also includes a powder silo V1 and an additive preparation device V2. The powder silo is equipped with an inert gas pipeline and a long-chain nylon salt feed pipeline. The outlet of the powder silo is connected to the hopper of the powder conveying device. The additive preparation device is equipped with separate and / or mixed feed pipelines for antioxidants, catalysts, and molecular weight regulators. The outlet of the additive preparation device is connected to the inlet of the mixing section of the powder conveying device. According to the material conveying direction of the powder conveying device, the hopper of the powder conveying device is located in front, and the mixing section of the powder conveying device is located behind. A rotary discharge valve is also provided between the powder silo and the hopper of the powder conveying device. The rotary discharge valve is connected to the hopper of the powder conveying device by a flexible hose.

[0103] The connecting pipeline between the powder conveying device and the discharge conveying device of the second polymerization device is a jacketed pipe;

[0104] The powder conveying device is selected from a twin-screw conveyor; preferably, the powder hopper of the twin-screw conveyor is equipped with a weighing scale.

[0105] The melting device is selected from a melting kettle; the first polymerization device is selected from a first polymerization kettle; the second polymerization device is selected from a second polymerization kettle; the melting kettle, the first polymerization kettle and the second polymerization kettle are all equipped with a stirring paddle and a jacket; the stirring paddle is an anchor-type stirring paddle.

[0106] The molten material conveying device is a molten material discharge conveying pump; the first polymerization unit discharge conveying device is a first polymerization reactor discharge conveying pump; the second polymerization unit discharge conveying device is a second polymerization reactor discharge conveying pump; and the molten material discharge conveying device, the first polymerization unit discharge conveying device, and the second polymerization unit discharge conveying device are all selected from gear pumps; the gear pump is equipped with a heat tracing jacket.

[0107] The specific system process material conveying process is as follows:

[0108] Figure 1In the process, under the protection of inert gas stream 119, long-chain nylon salt 120 is fed into powder silo V1. Powder silo V1 then uses a rotary valve to feed the long-chain nylon salt into the hopper of powder conveying device X1. Antioxidant, catalyst, and molecular weight regulator are then mixed as mixing aid 121 by aid mixing device V2 and fed into the mixing section of powder conveying device as aid feed stream 118. After thorough mixing by the powder conveying device (e.g., screw), the mixture is sent to melting device R1 as raw material stream 104. Melting device R1 is equipped with an exhaust port for discharging... Non-condensable gas stream 101; melting device R1 has an inlet for solvent stream 102 (e.g., water as solvent); melt output stream 103 is used as feed stream 107 for the first polymerization device and is conveyed to the first polymerization device R2 via melt output conveyor P1; first polymerization device output stream 108 is used as feed stream 112 for the second polymerization device and is conveyed to the second polymerization device R3 via first polymerization device output conveyor P2; second polymerization device output stream 113 is used as feed stream 114 for nylon products and is conveyed to the nylon product production device via second polymerization device output conveyor P3.

[0109] In addition, the melting device R1 is a melting kettle; the first polymerization device R2 and the second polymerization device R3 are polymerization kettles; the melting device R1 is equipped with a jacket for controlling the temperature, and the temperature is controlled by the material flow 105 from the jacket of the melting device and the material flow 106 from the jacket of the melting device.

[0110] The first polymerization unit R2 is equipped with a temperature control jacket, and the temperature is controlled by the discharge stream 110 and the feed stream 111 of the first polymerization unit jacket. The first polymerization unit R2 is also equipped with a pressure regulating valve, which automatically discharges the gaseous stream 109 of the first polymerization unit to the outside to maintain the pressure inside the reactor.

[0111] The second polymerization unit R3 is equipped with a temperature control jacket, and the temperature is controlled by the discharge stream 116 of the second polymerization unit jacket and the feed stream 117 of the first polymerization unit jacket. The second polymerization unit R3 is also equipped with a pressure regulating valve, which automatically discharges the gaseous stream 115 of the second polymerization unit to the outside to maintain stable pressure inside the reactor.

[0112]

Example 2

[0113] The system for continuous preparation of long-chain nylon intermediates as described in Example 1, specifically the method for continuous preparation of long-chain nylon intermediates, includes the following steps:

[0114] a) Under a protective atmosphere, long-chain nylon salt, antioxidant, catalyst, and molecular weight regulator in a mass ratio of 1:0.005:0.001:0.005 are fed into a powder conveying device and thoroughly mixed before being fed into a melting device. Water is also fed into the melting device. The protective gas in the protective atmosphere is selected from argon. The oxygen content in the protective atmosphere is ≤10ppm.

[0115] The long-chain nylon salt is a solid powder, preferably a long-chain nylon salt formed by the reaction of a diacid and a diamine, wherein the molar ratio of diacid structural units to diamine structural units in the long-chain nylon salt molecule is 0.999, and the pH value of the long-chain nylon salt solution formed by the reaction of the diacid and the diamine is 7.01; the diacid is selected from C12 diacids; the diamine is selected from C12 diamines;

[0116] In the melting device, the molar ratio of long-chain nylon salt to water is 1:2;

[0117] The operating pressure of the melting device is 0.32 MPaG;

[0118] The temperature of the melting device is 145°C;

[0119] Once the device is running stably, the mass ratio of the solid material conveyed from the powder conveying device to the melting device to the molten material contained in the melting device is 1:10.

[0120] b) The molten material in the melting device is sent to the first polymerization device for a primary polymerization reaction; the temperature of the primary polymerization reaction is 215°C; the pressure of the primary polymerization reaction is 2.0 MPaG; and the time of the primary polymerization reaction is 4 hours.

[0121] c) The material after reaction in the first polymerization unit is sent to the second polymerization unit for secondary polymerization to obtain a long-chain nylon intermediate; the temperature of the secondary polymerization reaction is 250℃; the pressure of the secondary polymerization reaction is 0.0MPaG; and the time of the secondary polymerization reaction is 4h.

[0122]

Example 3

[0123] The system for continuous preparation of long-chain nylon intermediates as described in Example 1, specifically the method for continuous preparation of long-chain nylon intermediates, includes the following steps:

[0124] a) Under a protective atmosphere, long-chain nylon salt, antioxidant, catalyst, and molecular weight regulator in a mass ratio of 1:0.005:0.001:0.005 are fed into a powder conveying device and thoroughly mixed before being fed into a melting device. Water is also fed into the melting device. The protective gas in the protective atmosphere is selected from nitrogen. The oxygen content in the protective atmosphere is ≤10ppm.

[0125] The long-chain nylon salt is a solid powder, preferably a long-chain nylon salt generated by the reaction of a diacid and a diamine, wherein the molar ratio of diacid structural units to diamine structural units in the long-chain nylon salt molecule is 0.999, and the pH value of the long-chain nylon salt solution generated by the reaction of the diacid and the diamine is 7.01; the diacid is selected from C10 diacids; the diamine is selected from C12 diamines;

[0126] In the melting device, the molar ratio of long-chain nylon salt to water is 1:2;

[0127] The operating pressure of the melting device is 0.30 MPaG;

[0128] The temperature of the melting device is 140°C;

[0129] Once the device is running stably, the mass ratio of the solid material conveyed from the powder conveying device to the melting device to the molten material contained in the melting device is 1:10.

[0130] b) The molten material in the melting device is sent to the first polymerization device for a primary polymerization reaction; the temperature of the primary polymerization reaction is 213°C; the pressure of the primary polymerization reaction is 2.0 MPaG; and the time of the primary polymerization reaction is 4 hours.

[0131] c) The material after reaction in the first polymerization unit is sent to the second polymerization unit for secondary polymerization to obtain a long-chain nylon intermediate; the temperature of the secondary polymerization reaction is 250℃; the pressure of the secondary polymerization reaction is 0.0MPaG; and the time of the secondary polymerization reaction is 4h.

[0132]

Example 4

[0133] The system for continuous preparation of long-chain nylon intermediates as described in Example 1, specifically the method for continuous preparation of long-chain nylon intermediates, includes the following steps:

[0134] a) Under a protective atmosphere, long-chain nylon salt, antioxidant, catalyst, and molecular weight regulator in a mass ratio of 1:0.005:0.001:0.005 are fed into a powder conveying device and thoroughly mixed before being fed into a melting device. Water is also fed into the melting device. The protective gas in the protective atmosphere is selected from argon. The oxygen content in the protective atmosphere is ≤10ppm.

[0135] The long-chain nylon salt is a solid powder, preferably a long-chain nylon salt generated by the reaction of a diacid and a diamine, wherein the molar ratio of diacid structural units to diamine structural units in the long-chain nylon salt molecule is 1.005, and the pH value of the long-chain nylon salt solution generated by the reaction of the diacid and the diamine is 6.85; the diacid is selected from C12 diacids; the diamine is selected from C12 diamines;

[0136] In the melting device, the molar ratio of long-chain nylon salt to water is 1:2;

[0137] The operating pressure of the melting device is 0.33 MPaG;

[0138] The temperature of the melting device is 147°C;

[0139] Once the device is running stably, the mass ratio of the solid material conveyed from the powder conveying device to the melting device to the molten material contained in the melting device is 1:10.

[0140] b) The molten material in the melting device is sent to the first polymerization device for a primary polymerization reaction; the temperature of the primary polymerization reaction is 217°C; the pressure of the primary polymerization reaction is 2.0 MPaG; and the time of the primary polymerization reaction is 4 hours.

[0141] c) The material after reaction in the first polymerization unit is sent to the second polymerization unit for secondary polymerization to obtain a long-chain nylon intermediate; the temperature of the secondary polymerization reaction is 250℃; the pressure of the secondary polymerization reaction is 0.01MPaG; and the time of the secondary polymerization reaction is 4h.

[0142]

Example 5

[0143] The system for continuous preparation of long-chain nylon intermediates as described in Example 1, specifically the method for continuous preparation of long-chain nylon intermediates, includes the following steps:

[0144] a) Under a protective atmosphere, long-chain nylon salt, antioxidant, catalyst, and molecular weight regulator in a mass ratio of 1:0.005:0.001:0.005 are fed into a powder conveying device and thoroughly mixed before being fed into a melting device. Water is also fed into the melting device. The protective gas in the protective atmosphere is selected from carbon dioxide. The oxygen content in the protective atmosphere is ≤10ppm.

[0145] The long-chain nylon salt is a solid powder, preferably a long-chain nylon salt generated by the reaction of a diacid and a diamine, wherein the molar ratio of diacid structural units to diamine structural units in the long-chain nylon salt molecule is 1.005, and the pH value of the long-chain nylon salt solution generated by the reaction of the diacid and the diamine is 6.85; the diacid is selected from C12 diacids; the diamine is selected from C12 diamines;

[0146] In the melting device, the molar ratio of long-chain nylon salt to water is 1:2;

[0147] The operating pressure of the melting device is 0.32 MPaG;

[0148] The temperature of the melting device is 145°C;

[0149] Once the device is running stably, the mass ratio of the solid material conveyed from the powder conveying device to the melting device to the molten material contained in the melting device is 1:10.

[0150] b) The molten material in the melting device is sent to the first polymerization device for a primary polymerization reaction; the temperature of the primary polymerization reaction is 215°C; the pressure of the primary polymerization reaction is 2.0 MPaG; and the time of the primary polymerization reaction is 4 hours.

[0151] c) The material after reaction in the first polymerization unit is sent to the second polymerization unit for secondary polymerization to obtain a long-chain nylon intermediate; the temperature of the secondary polymerization reaction is 250℃; the pressure of the secondary polymerization reaction is 0.0MPaG; and the time of the secondary polymerization reaction is 4h.

[0152]

Example 6

[0153] The system for continuous preparation of long-chain nylon intermediates as described in Example 1, specifically the method for continuous preparation of long-chain nylon intermediates, includes the following steps:

[0154] a) Under a protective atmosphere, long-chain nylon salt, antioxidant, catalyst, and molecular weight regulator in a mass ratio of 1:0.005:0.001:0.005 are fed into a powder conveying device and thoroughly mixed before being fed into a melting device. Water is also fed into the melting device. The protective gas in the protective atmosphere is selected from carbon dioxide. The oxygen content in the protective atmosphere is ≤10ppm.

[0155] The long-chain nylon salt is a solid powder, preferably a long-chain nylon salt generated by the reaction of a diacid and a diamine, wherein the molar ratio of diacid structural units to diamine structural units in the long-chain nylon salt molecule is 0.995, and the pH value of the long-chain nylon salt solution generated by the reaction of the diacid and the diamine is 7.15; the diacid is selected from C12 diacids; the diamine is selected from C12 diamines;

[0156] In the melting device, the molar ratio of long-chain nylon salt to water is 1:2;

[0157] The operating pressure of the melting device is 0.32 MPaG;

[0158] The temperature of the melting device is 145°C;

[0159] Once the device is running stably, the mass ratio of the solid material conveyed from the powder conveying device to the melting device to the molten material contained in the melting device is 1:10.

[0160] b) The molten material in the melting device is sent to the first polymerization device for a primary polymerization reaction; the temperature of the primary polymerization reaction is 215°C; the pressure of the primary polymerization reaction is 2.0 MPaG; and the time of the primary polymerization reaction is 4 hours.

[0161] c) The material after reaction in the first polymerization unit is sent to the second polymerization unit for secondary polymerization to obtain a long-chain nylon intermediate; the temperature of the secondary polymerization reaction is 250℃; the pressure of the secondary polymerization reaction is 0.0MPaG; and the time of the secondary polymerization reaction is 4h.

[0162]

Example 7

[0163] The system for continuous preparation of long-chain nylon intermediates as described in Example 1, specifically the method for continuous preparation of long-chain nylon intermediates, includes the following steps:

[0164] a) Under a protective atmosphere, long-chain nylon salt, antioxidant, catalyst, and molecular weight regulator in a mass ratio of 1:0.005:0.001:0.005 are fed into a powder conveying device and thoroughly mixed before being fed into a melting device. Water is also fed into the melting device. The protective gas in the protective atmosphere is selected from carbon dioxide. The oxygen content in the protective atmosphere is ≤10ppm.

[0165] The long-chain nylon salt is a solid powder, preferably a long-chain nylon salt formed by the reaction of a diacid and a diamine, wherein the molar ratio of diacid structural units to diamine structural units in the long-chain nylon salt molecule is 0.996, and the pH value of the long-chain nylon salt solution formed by the reaction of the diacid and the diamine is 7.14; the diacid is selected from C12 diacids; the diamine is selected from C12 diamines;

[0166] In the melting device, the molar ratio of long-chain nylon salt to water is 1:4;

[0167] The operating pressure of the melting device is 0.8 MPaG;

[0168] The temperature of the melting device is 175°C;

[0169] Once the device is running stably, the mass ratio of the solid material conveyed from the powder conveying device to the melting device to the molten material contained in the melting device is 1:18.

[0170] b) The molten material in the melting device is sent to the first polymerization device for a primary polymerization reaction; the temperature of the primary polymerization reaction is 230°C; the pressure of the primary polymerization reaction is 2.7 MPaG; and the time of the primary polymerization reaction is 3 hours.

[0171] c) The material after reaction in the first polymerization unit is sent to the second polymerization unit for secondary polymerization to obtain a long-chain nylon intermediate; the temperature of the secondary polymerization reaction is 255℃; the pressure of the secondary polymerization reaction is 0.005MPaG; and the time of the secondary polymerization reaction is 3h.

[0172]

Example 8

[0173] The system for continuous preparation of long-chain nylon intermediates as described in Example 1, specifically the method for continuous preparation of long-chain nylon intermediates, includes the following steps:

[0174] a) Under a protective atmosphere, long-chain nylon salt, antioxidant, catalyst, and molecular weight regulator in a mass ratio of 1:0.005:0.001:0.005 are fed into a powder conveying device and thoroughly mixed before being fed into a melting device. Water is also fed into the melting device. The protective gas in the protective atmosphere is selected from carbon dioxide. The oxygen content in the protective atmosphere is ≤10ppm.

[0175] The long-chain nylon salt is a solid powder, preferably a long-chain nylon salt formed by the reaction of a diacid and a diamine, wherein the molar ratio of diacid structural units to diamine structural units in the long-chain nylon salt molecule is 0.996, and the pH value of the long-chain nylon salt solution formed by the reaction of the diacid and the diamine is 7.14; the diacid is selected from C12 diacids; the diamine is selected from C12 diamines;

[0176] In the melting device, the molar ratio of long-chain nylon salt to water is 1:1;

[0177] The operating pressure of the melting device is 0.2 MPaG;

[0178] The temperature of the melting device is 120°C;

[0179] Once the device is running stably, the mass ratio of the solid material conveyed from the powder conveying device to the melting device to the molten material contained in the melting device is 1:4.

[0180] b) The molten material in the melting device is sent to the first polymerization device for a primary polymerization reaction; the temperature of the primary polymerization reaction is 195°C; the pressure of the primary polymerization reaction is 1.3 MPaG; and the time of the primary polymerization reaction is 5 h.

[0181] c) The material after reaction in the first polymerization unit is sent to the second polymerization unit for secondary polymerization to obtain a long-chain nylon intermediate; the temperature of the secondary polymerization reaction is 220℃; the pressure of the secondary polymerization reaction is -0.02MPaG; and the time of the secondary polymerization reaction is 5h.

[0182] Comparative Example 1

[0183] Its adoption and Figure 1 A similar production system, the difference being that the material in the powder conveying device does not enter the melting device, but directly enters the first polymerization device for reaction, and then enters the second polymerization device for reaction. The specific technical solution includes the following steps:

[0184] a) Under a protective atmosphere, long-chain nylon salt, antioxidant, catalyst and molecular weight regulator in a mass ratio of 1:0.005:0.001:0.005 are fed into a powder conveying device and thoroughly mixed before being fed into the first polymerization reactor. The protective gas in the protective atmosphere is selected from argon. The oxygen content in the protective atmosphere is ≤10ppm.

[0185] The long-chain nylon salt is a solid powder, preferably a long-chain nylon salt formed by the reaction of a diacid and a diamine, wherein the molar ratio of diacid structural units to diamine structural units in the long-chain nylon salt molecule is 0.999, and the pH value of the long-chain nylon salt solution formed by the reaction of the diacid and the diamine is 7.01; the diacid is selected from C12 diacids; the diamine is selected from C12 diamines;

[0186] b) The material undergoes a single polymerization reaction in the first polymerization unit; the temperature of the single polymerization reaction is 215°C; the pressure of the single polymerization reaction is 2.0 MPaG; and the time of the single polymerization reaction is 4 hours.

[0187] c) The material after reaction in the first polymerization unit is sent to the second polymerization unit for secondary polymerization to obtain a long-chain nylon intermediate; the temperature of the secondary polymerization reaction is 250℃; the pressure of the secondary polymerization reaction is 0.0MPaG; and the time of the secondary polymerization reaction is 4h.

[0188] The powder conveying device cannot continuously and stably transport materials to the first polymerization unit; the conveyor outlet is prone to blockage or gas backflow into the feeding hopper. The volume utilization rate of the first polymerization unit is only 25%.

[0189] Comparative Example 2

[0190] Its adoption and Figure 1 Similar production systems, but with the difference that the material in the powder conveying device does not enter the melting device; it all reacts in the first polymerization device. The specific technical solution is as follows:

[0191] A method for preparing a long-chain nylon intermediate includes the following steps:

[0192] a) Under a protective atmosphere and at room temperature, long-chain nylon salt, antioxidant, catalyst, and molecular weight regulator in a mass ratio of 1:0.005:0.001:0.005 are fed into a powder conveying device and thoroughly mixed before being fed into the polymerization reactor. The powder conveying device is then shut off. The protective gas in the protective atmosphere is selected from argon, and the oxygen content in the protective atmosphere is ≤10ppm.

[0193] The long-chain nylon salt is a solid powder, preferably a long-chain nylon salt formed by the reaction of a diacid and a diamine, wherein the molar ratio of diacid structural units to diamine structural units in the long-chain nylon salt molecule is 0.999, and the pH value of the long-chain nylon salt solution formed by the reaction of the diacid and the diamine is 7.01; the diacid is selected from C12 diacids; the diamine is selected from C12 diamines;

[0194] b) The material undergoes a polymerization reaction in the polymerization unit; the polymerization temperature is gradually increased to 215°C; the polymerization pressure is 2.0 MPaG, and the polymerization time is 4 hours. The polymerization pressure is then gradually reduced to 0.0 MPaG, the polymerization temperature is 250°C, and the polymerization time is 4 hours. Because the powder directly enters the polymerization unit, the volume utilization rate of the unit is only 25%. Furthermore, in Comparative Example 2 (similar to existing conventional technology), the melting vessel, primary polymerization reaction, and secondary polymerization reaction all occur in a single reactor. This has the disadvantage of different pressures at each stage of the reaction, requiring pressure relief, making continuous operation impossible and reducing production efficiency.

[0195] Comparative Example 3

[0196] Its adoption and Figure 1 Similar production systems, the difference being that the material in the powder conveying device enters the melting device, but all reactions occur in the first polymerization unit. The specific technical solution is as follows:

[0197] A method for the continuous preparation of long-chain nylon intermediates includes the following steps:

[0198] a) Under a protective atmosphere, long-chain nylon salt, antioxidant, catalyst, and molecular weight regulator in a mass ratio of 1:0.005:0.001:0.005 are fed into a powder conveying device and thoroughly mixed before being fed into a melting device. Water is also fed into the melting device. The protective gas in the protective atmosphere is selected from argon. The oxygen content in the protective atmosphere is ≤10ppm.

[0199] The long-chain nylon salt is a solid powder, preferably a long-chain nylon salt formed by the reaction of a diacid and a diamine, wherein the molar ratio of diacid structural units to diamine structural units in the long-chain nylon salt molecule is 0.999, and the pH value of the long-chain nylon salt solution formed by the reaction of the diacid and the diamine is 7.01; the diacid is selected from C12 diacids; the diamine is selected from C12 diamines;

[0200] In the melting device, the molar ratio of long-chain nylon salt to water is 1:2;

[0201] The operating pressure of the melting device is 0.32 MPaG;

[0202] The temperature of the melting device is 145°C;

[0203] Once the device is running stably, the mass ratio of the solid material conveyed from the powder conveying device to the melting device to the molten material contained in the melting device is 1:10.

[0204] b) The molten material in the melting device is sent to the polymerization device for polymerization reaction; the polymerization reaction temperature is 215℃; the polymerization reaction pressure is 2.0 MPaG; and the polymerization reaction time is 4h. Gradually reduce the pressure of the polymerization reactor to 0.0 MPaG; the polymerization reaction temperature is 250℃; and the polymerization time is 4h.

[0205] The long-chain nylon intermediates prepared in the above examples and comparative examples were tested, and the specific results are shown in Table 1.

[0206] Test methods: The molecular weight of the long-chain nylon prepared in the examples and comparative examples was evaluated in this application. The number-average molecular weight Mn and the molecular weight distribution index PDI of the long-chain nylon products were determined by gel permeation chromatography (GPC).

[0207] Table 1

[0208] Example Mn PDI Mode of operation Example 2 14918.2 2.12 Continuous Example 3 14602.6 2.13 Continuous Example 4 14687.6 2.13 Continuous Example 5 13724.1 2.28 Continuous Example 6 14098.7 2.25 Continuous Example 7 14152.2 2.30 Continuous Example 8 13915.7 2.29 Continuous Comparative Example 1 10236.2 2.43 Continuous Comparative Example 2 13736.5 2.38 Batch Comparative Example 3 13682.8 2.39 Batch

[0209] As can be seen from the comparison of the results in Table 1, the method of the present invention not only realizes the continuous production of long carbon chain nylon intermediates, but also has simple operation and can produce long carbon chain nylon intermediates with narrow molecular weight distribution, which is beneficial to the subsequent production of long carbon chain nylon products with narrow molecular weight distribution and improves product quality.

[0210] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

[0211] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0212] When this specification uses the prefixes “known to those skilled in the art,” “prior art,” or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those commonly used in the art at the time of this application’s filing, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0213] In the context of this specification, except where expressly stated, any matters or issues not mentioned shall apply directly to those known in the art without any modification.

Claims

1. A method for the continuous preparation of a long-chain nylon intermediate, comprising the following steps: Under a protective atmosphere, the raw materials for preparing long-chain nylon intermediates are fed into a melting device for melting. The molten material is then continuously fed into a first polymerization device for a first polymerization reaction, and then into a second polymerization device for a second polymerization reaction to obtain the long-chain nylon intermediate.

2. The method for continuous preparation of long-chain nylon intermediates according to claim 1, characterized in that, Includes the following steps: a) Under a protective atmosphere, long-chain nylon salt, antioxidant, catalyst and molecular weight regulator are fed into a powder conveying device and mixed thoroughly before being fed together into a melting device. Solvent is also fed into the melting device. b) The molten material in the melting device is sent to the first polymerization device for a primary polymerization reaction; c) The reacted material from the first polymerization unit is sent to the second polymerization unit for a secondary polymerization reaction to obtain a long-chain nylon intermediate.

3. The method for continuous preparation of long-chain nylon intermediates according to claim 2, characterized in that: In step a), Under a protective atmosphere, long-chain nylon salt is first fed into a powder conveying device; then antioxidants, catalysts, and molecular weight regulators are fed into the powder conveying device. After the above materials are fully mixed in the powder conveying device, they are sent together to the melting device, while the solvent is sent directly to the melting device.

4. The method for continuous preparation of long-chain nylon intermediates according to claim 3, characterized in that: Step a) includes the following steps: a1) Under a protective atmosphere, long-chain nylon salt is fed into the powder silo; a2) The long-chain nylon salt in the powder silo is first fed into the powder conveying device through the hopper of the powder conveying device; a3) Then, the antioxidant, catalyst and molecular weight regulator are fed into the mixing section of the powder conveying device. After the above materials are fully mixed in the powder conveying device, they are sent to the melting device together. The solvent is sent directly to the melting device. According to the material conveying direction of the powder conveying device, the hopper of the powder conveying device is in front and the mixing section of the powder conveying device is in the back. Preferably, The long-chain nylon salt is fed intermittently and / or continuously into the powder silo, preferably continuously; and / or, Long-chain nylon salts from the powder silo are intermittently and / or continuously fed into the hopper of the powder conveying device, preferably continuously; and / or, Antioxidants, catalysts, and molecular weight regulators are introduced separately into the mixing section of the powder conveying device and / or mixed before entering the mixing section of the powder conveying device, preferably mixed before entering the mixing section of the powder conveying device; and / or, The solvent is water.

5. The method for continuous preparation of long-chain nylon intermediates according to claim 1 or 2, characterized in that: The protective gas in the protective atmosphere is selected from at least one of nitrogen, carbon dioxide, or argon, preferably carbon dioxide; and / or, The oxygen content in the protective atmosphere does not exceed 10 ppm; preferably 2–8 ppm; and / or, The long-chain nylon salt is a solid powder. Preferably, the long-chain nylon salt is a long-chain nylon salt generated by the reaction of a diacid and a diamine, wherein the molar ratio of diacid structural units to diamine structural units in the long-chain nylon salt is 0.995 to 1.005; more preferably, the pH value of the long-chain nylon salt solution generated by the reaction of a diacid and a diamine is 6.8 to 7.

2. More preferably, The dicarboxylic acid is selected from C10 to C20 dicarboxylic acids; and / or, The diamine is selected from C10 to C20 diamines.

6. The method for continuous preparation of long-chain nylon intermediates according to claim 2, characterized in that: In the raw materials for preparing long-chain nylon intermediates, the mass ratio of long-chain nylon salt: antioxidant: catalyst: molecular weight regulator is 1:0.0001~0.01:0.0001~0.01:0.0001~0.01, preferably 1:0.0005~0.005:0.0005~0.005:0.0005~0.005; and / or, In the melting apparatus, the molar ratio of long-chain nylon salt to water is 1:0.5–5, preferably 1:1–3; and / or, The operating pressure of the melting device is 0.1–0.9 MPaG, preferably 0.2–0.5 MPaG; and / or, The temperature of the melting device is 120–180°C, preferably 130–160°C; The melting device may or may not emit gas, preferably it does not emit gas. More preferably, after the continuous preparation process of the long carbon chain nylon intermediate is stabilized, the mass ratio of the solid material conveyed from the powder conveying device to the melting device to the molten material contained in the melting device is 1:3 to 20, preferably 1:5 to 15.

7. The method for continuous preparation of long-chain nylon intermediates according to claim 1, characterized in that: The temperature for the primary polymerization reaction is 190–235°C, preferably 200–227°C; and / or, The pressure of a single polymerization reaction is 1.2–3.0 MPaG, preferably 1.5–2.5 MPaG; and / or, The time for one polymerization reaction is 0.5 to 5 hours, preferably 1 to 4 hours.

8. The method for continuous preparation of long-chain nylon intermediates according to claim 1, characterized in that: The temperature for the secondary polymerization reaction is 210–260°C, preferably 220–250°C; and / or, The pressure for the secondary polymerization reaction is -0.09 to 0.15 MPaG, preferably -0.05 to 0.05 MPaG; and / or, The secondary polymerization reaction takes 0.5 to 5 hours, preferably 1 to 3 hours.

9. A system for the continuous preparation of long-chain nylon intermediates, comprising: The assembly consists of a powder conveying device, a melting device, a molten material conveying device, a first polymerization device, a first polymerization device discharge conveying device, a second polymerization device, and optionally a second polymerization device discharge conveying device, all connected in sequence. The melting device is also equipped with a solvent inlet. The powder conveying device is equipped with a feed pipeline for the raw materials used to prepare long-chain nylon intermediates. Preferably, the method described in any one of claims 1-8 is prepared using the system described above.

10. The system for continuous preparation of long-chain nylon intermediates according to claim 9, characterized in that: The system also includes a powder silo and an additive mixing device. The powder silo is equipped with an inert gas pipeline and a long-chain nylon salt feed pipeline. The outlet of the powder silo is connected to the hopper of the powder conveying device. The additive mixing device is equipped with separate and / or mixed feed pipelines for antioxidants, catalysts, and molecular weight regulators. The outlet of the additive mixing device is connected to the inlet of the mixing section of the powder conveying device. According to the material conveying direction of the powder conveying device, the hopper of the powder conveying device is located in front, and the mixing section of the powder conveying device is located behind. Preferably, a rotary discharge valve is also provided between the powder silo and the hopper of the powder conveying device; More preferably, the rotary discharge valve is connected to the hopper of the powder conveying device by a flexible hose.

11. The system for continuous preparation of long-chain nylon intermediates according to claim 9, characterized in that: The connecting pipeline between the powder conveying device and the discharge conveying device of the second polymerization unit is a jacketed pipe and / or a heat tracing pipe, preferably a jacketed pipe; and / or, The powder conveying device is selected from a screw conveyor; preferably, the powder hopper of the screw conveyor is equipped with a weighing scale; and / or, the screw conveyor is a single screw or a twin screw, preferably a twin screw; and / or The melting device is selected from a melting kettle; and / or, The first polymerization apparatus is selected from the first polymerization reactor; and / or, The second polymerization apparatus is selected from the second polymerization reactor; Preferably, the melting vessel, the first polymerization vessel, and the second polymerization vessel are each independently provided with at least one of a stirring paddle and a jacket; more preferably, the stirring paddle is selected from at least one of an anchor type, a frame type, or a ribbon type stirring paddle.

12. The system for continuous preparation of long-chain nylon intermediates according to claim 9, characterized in that: The molten material conveying device is a molten material discharge conveying pump; and / or, The first polymerization unit discharge conveying device is a first polymerization reactor discharge conveying pump; and / or, The discharge conveying device of the second polymerization unit is the discharge conveying pump of the second polymerization reactor; Preferably, the molten material discharge conveying device, the first polymerization device discharge conveying device, and the second polymerization device discharge conveying device are each independently selected from gear pumps; More preferably, the gear pump is equipped with a heat tracing jacket and / or a heating module.

13. The system for continuous preparation of long-chain nylon intermediates according to claim 9, characterized in that: The melting apparatus is also equipped with gas pipelines for the introduction of inert gas and / or the discharge of non-condensable gas; and / or, The melting device is also equipped with a sight glass; and / or The melting device is also equipped with a level gauge; and / or, Preferably, The gas pipeline of the melting device is equipped with a pressure gauge and a pressure regulating valve; and / or, The level gauge is preferably a radar level gauge.

14. The use of a long-chain nylon intermediate prepared by the method of any one of claims 1 to 8 or the system of any one of claims 9 to 13 in the preparation of long-chain nylon.

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