Production apparatus of polyamide resin and preparation method thereof

Abstract

The application discloses a polyamide resin production device and a preparation method thereof. The polyamide resin production device comprises a screw cylinder and a screw rod unit; the screw rod unit is arranged in a containing cavity of the screw cylinder; the screw rod unit comprises a mandrel and a screw rod assembly arranged on the mandrel; the screw rod assembly comprises a first screw rod assembly, a second screw rod assembly and a third screw rod assembly arranged in sequence along a material conveying direction; the first screw rod assembly is used for material conveying; the second screw rod assembly is used for melting polymerization and devolatilization of the material; the second screw rod assembly is arranged repeatedly n times, and n is greater than or equal to 2; and the third screw rod assembly is used for extrusion to obtain the polyamide resin. The polyamide resin production device is designed and combined particularly, heat degradation is effectively reduced, the polyamide resin obtained has a higher melting point and relative viscosity, a lower resin chip yellow index, a narrower molecular weight distribution, a higher production efficiency, and the product quality is better as a whole.

Description

Technical Field

[0001] This invention relates to the field of polymer technology, specifically to a production equipment for polyamide resin and its preparation method. Background Technology

[0002] In industrial applications, high-temperature nylon is typically produced by reacting diamines with diacids to form salts, which are then introduced into subsequent reactors for pressure holding, prepolymerization, post-polymerization, and finally granulation to obtain the product. However, regardless of whether batch or continuous polymerization is used, the entire polymerization process usually lasts for several or even tens of hours. During this process, intermediate products from each stage need to be transferred back and forth to different polymerizers, involving long pipelines and large storage and reaction equipment. Furthermore, due to the lengthy polymerization process, timely feedback is often difficult to obtain when adjusting the process, and it usually takes a long time to obtain a stable product again when polymerization is unstable or problems occur. In summary, existing high-temperature nylon preparation processes are inefficient, time-consuming, and relatively inflexible in terms of process adjustments.

[0003] Screw extruders are widely used in polymer modification, allowing for rapid process adjustments, and are extensively applied in polymer plasticizing, reinforcing, and compounding. In recent years, numerous patents have been published regarding polymerization using screw extruders. However, there are few patents and literature reports on the direct preparation of high-temperature nylon using screw extruders. Furthermore, due to the high melting point of high-temperature nylon, screw extrusion faces challenges such as thermal degradation caused by excessively high temperatures. Moreover, the type and combination of screw components in the screw extruder significantly impacts mixing, polymerization, and devolatilization, directly affecting the molecular weight and viscosity of the product. Therefore, the preparation of high-temperature nylon places high demands on the screw component configuration and combination, devolatilization, and temperature control systems, requiring specialized design. Overall, the direct preparation of high-temperature nylon using screw extruders presents significant technological barriers.

[0004] In view of this, there is an urgent need to provide a screw-type equipment and preparation method that, compared with existing technologies, not only ensures that the high-temperature nylon products produced have better performance, but also greatly improves the efficiency of high-temperature nylon preparation. At the same time, it enables timely and rapid adjustment of the polymerization process to better adapt to the production of high-temperature nylon. Summary of the Invention

[0005] This invention addresses the shortcomings of existing technologies in the preparation of high-temperature nylon (i.e., high-temperature resistant polyamide resin), such as long polymerization time, low efficiency, and inflexible processes, by providing a production equipment and preparation method for polyamide resin.

[0006] The present invention solves the above-mentioned technical problems through the following technical solutions.

[0007] One of the technical solutions of the present invention is: a production equipment for polyamide resin, comprising a screw barrel and a screw unit; the screw unit is disposed within the receiving cavity of the screw barrel;

[0008] The screw unit includes a spindle and a screw assembly sleeved on the spindle;

[0009] The screw assembly includes a first screw assembly, a second screw assembly, and a third screw assembly arranged sequentially along the material conveying direction;

[0010] The first screw assembly is used for material conveying;

[0011] The second screw assembly is used to melt polymerize and devolatilize the material; the second screw assembly is repeated n times, where n≥2;

[0012] The second screw assembly includes a first group of elements and a second group of elements arranged sequentially along the material conveying direction;

[0013] The first set of components includes a forward threaded element, a meshing block, and a reverse threaded element arranged in sequence, used to enable the material to undergo a polymerization reaction;

[0014] The second set of elements includes threaded elements for removing volatiles from the polymer;

[0015] The third screw assembly is used for extrusion to obtain polyamide resin.

[0016] In this invention, the screw barrel can be conventional in the art, generally composed of several barrel sections connected in series; preferably, it includes 6 to 30 barrel sections; more preferably, it includes 6 to 16 barrel sections; for example, 10 barrel sections. According to conventional art, each barrel section can be equipped with an independent temperature control and heating system.

[0017] In this invention, preferably, the polyamide resin production equipment includes at least two screw units rotating in the same direction. More preferably, the mandrels of any two screw units and the screw assemblies sleeved on the mandrels are identical.

[0018] In this invention, the length-to-diameter ratio of the mandrel can be (20-68):1; preferably (40-60):1; more preferably (45-55):1; and even more preferably 48:1.

[0019] The diameter of the mandrel can be 20-95 mm, preferably 35-50 mm.

[0020] In this invention, according to conventional art, the mandrel can be fixedly connected to a screw assembly sleeved on the mandrel, so that there is no relative movement between the screw mandrel and the screw assembly.

[0021] In this invention, the first screw assembly may include a forward thread element and a reverse thread element arranged sequentially along the material conveying direction.

[0022] The number of the forward threaded elements can be conventional in the art, for example, 1 to 10, preferably 2 to 8, and more preferably 3 to 6. The number of the reverse threaded elements can be conventional in the art, for example, 1 to 10, preferably 2 to 8, and more preferably 3 to 6.

[0023] Preferably, the first screw assembly consists of one or more forward threaded elements and one or more reverse threaded elements. For example, the first screw assembly consists of four forward threaded elements and four reverse threaded elements.

[0024] The positive thread element can be a large-lead positive thread element. The lead of the positive thread element can be 1D to 2.5D. The lead of the negative thread element can be 1D to 2D.

[0025] In this invention, the first screw assembly and its corresponding several cylindrical sections can be understood as a feeding and conveying system, which is preferably used for rapid melting and conveying of raw materials.

[0026] The first screw assembly can generally correspond to two or more cylinder sections.

[0027] Preferably, the upper end of the first cylinder of the feeding and conveying system is provided with a main feeding port, and is connected to the main feeding system through the main feeding port.

[0028] Preferably, the upper end of the second cylinder of the feeding and conveying system is provided with an auxiliary feeding port, and is connected to the auxiliary feeding system through the auxiliary feeding port.

[0029] When the feeding and conveying system includes three or more cylinders, optionally, the upper end of the third cylinder of the feeding and conveying system is provided with an additive feeding port, and is connected to the additive feeding system through the additive feeding port.

[0030] In this invention, in the first group of components of the second screw assembly, the number of both the forward threaded element and the reverse threaded element can be independently 1 to 5, preferably 2 to 4. The number of engagement blocks is preferably 2 or more.

[0031] Preferably, the first set of components of the second screw assembly includes two forward threaded elements, two meshing blocks, and two reverse threaded elements arranged sequentially along the material conveying direction.

[0032] In the first group of components of the second screw assembly, the forward thread element can be a small-lead thread element. The lead of the forward thread element can be 0.1D to 0.5D, for example, 8 mm. The length of the forward thread element can be 4 to 60 mm, preferably 8 mm.

[0033] In the first group of elements of the second screw assembly, the lead of the reverse thread element can be 0.5D to 2D, preferably 0.57D to 1D, for example, 20mm. The length of the reverse thread element can be 10 to 120mm, preferably 20mm.

[0034] In the first group of elements of the second screw assembly, the engagement block can be conventional in the art, such as a forward engagement block or a reverse engagement block. When the number of engagement blocks is two, it is preferable to include one forward engagement block and one reverse engagement block.

[0035] The length of the meshing block can be 20-120 mm, preferably 56 mm.

[0036] The staggered angle between the contact end faces of adjacent meshing blocks can be conventional in the art, generally referring to the included angle by which the contact end faces of adjacent meshing blocks are rotated and staggered about the axis of the meshing disc element, preferably 45°, 60° or 90°. The meshing disc element is a composite element composed of at least two separate meshing blocks.

[0037] In this invention, the first set of elements of the second screw assembly and its corresponding barrel can be understood as a polymerization system, preferably used to fully polymerize the raw materials.

[0038] Preferably, the cylinder corresponding to the first set of elements of the second screw assembly is a closed cylinder used to maintain pressure.

[0039] In this invention, the second set of components of the second screw assembly may include a forward thread element. The forward thread element may be a conventional slotted thread element used in the art to increase the material distribution area and facilitate devolatilization. Generally, the slotted thread element may have grooves of different shapes, such as rectangles, formed on its threads.

[0040] The number of the positive threaded elements can be 1 to 6, preferably 2 to 4.

[0041] The lead of the positive thread element can be 1.5D to 2.5D.

[0042] In this invention, the second set of elements of the second screw assembly and its corresponding cylinder can be understood as a devolatilization system.

[0043] Preferably, a volatilization port is provided at the upper end of the cylinder corresponding to the second set of elements of the second screw assembly; this is used to discharge small molecule by-products, increase molecular weight, and increase polymer viscosity.

[0044] The devolatilization port can be directly connected to the atmosphere for natural devolatilization. Preferably, the devolatilization port can be equipped with a vacuum device for vacuum devolatilization.

[0045] In this invention, n is preferably 3 to 20, more preferably 3 to 8, and even more preferably 3 to 5, for example 3; used to obtain polyamide resins with suitable molecular weight and relative viscosity.

[0046] In this invention, the third screw assembly may include a reverse thread element to establish head pressure and extrude the material smoothly.

[0047] The number of the reverse threaded elements can be 5 to 15, preferably 6 to 12.

[0048] The reverse thread element can be a small lead thread element. The lead of the reverse thread element can be 0.1D to 0.5D.

[0049] In this invention, the third screw assembly and its corresponding several cylindrical sections can be understood as an extrusion system.

[0050] In this invention, the forward threaded element can be a conventional element that rotates in the direction of rotation of the conveying screw, and its thread groove can be rectangular; it is used for material conveying. It is generally selected from any one of forward single-start threaded elements, forward double-start threaded elements, forward threaded elements that transition from single-start to double-start, forward threaded elements that transition from double-start to single-start, and forward triple-start threaded elements, preferably a forward double-start threaded element.

[0051] In this invention, the reverse threaded element can be a conventional element that rotates in the opposite direction to the rotation direction of the conveying screw. Its shape is similar to that of the forward threaded element, but the helical direction of the thread groove is opposite to that of the forward threaded element. It is generally selected from any one of the following: reverse single-start threaded element, reverse double-start threaded element, reverse threaded element transitioning from single-start to double-start, reverse threaded element transitioning from double-start to single-start, and reverse triple-start threaded element, preferably a reverse double-start threaded element.

[0052] In this invention, those skilled in the art will understand that D is the conventional major diameter (outer diameter) of a thread.

[0053] Wherein, D can be 5 to 60 mm independently, preferably 10 to 40 mm.

[0054] In this invention, the production equipment for the polyamide resin can generally be understood as a screw extruder, such as a twin-screw extruder. According to conventional art, the production equipment for the polyamide resin may also include a drive motor, a coupling, and a gearbox sequentially connected at the front end of the screw extruder, and an extrusion pelletizing system located at the rear end of the screw extruder.

[0055] In this invention, preferably, the temperature settings of the polyamide resin production equipment are as follows: 120-300°C for the feeding and conveying system, 240-330°C for the polymerization system, 250-330°C for the devolatilization system, and 260-320°C for the extrusion system; this is to prevent side reactions such as material failure to melt and be conveyed due to excessively low temperature and thermal degradation of material during the extrusion process due to excessively high temperature.

[0056] In this invention, the screw speed of the polyamide resin production equipment can be 30-500 rpm, preferably 60-500 rpm, and more preferably 60-200 rpm. The residence time of the material in the polyamide resin production equipment can be 10s-30min, preferably 10s-15min, and more preferably 1min-15min.

[0057] Preferably, the screw speed of the polyamide resin production equipment is 60-500 rpm, and the residence time of the material in the polyamide resin production equipment is 10s-15min; this can effectively avoid the problem of low output when the screw speed is too slow; and the problem that the material may undergo thermal degradation at high temperature due to the excessively slow speed causing the material to stay in the screw equipment for too long.

[0058] More preferably, the screw speed of the polyamide resin production equipment is 60-200 rpm, and the residence time of the material in the polyamide resin production equipment is 1 min-15 min; in order to avoid the problem that although increasing the speed can increase the output per unit time, the residence time of the material in the screw equipment is also greatly shortened, resulting in a lower viscosity of the final product.

[0059] The second technical solution of the present invention is: a method for preparing polyamide resin, which uses the polyamide resin production equipment as described above.

[0060] In this invention, the preparation method of the polyamide resin may include the following steps: adding a diamine and a diacid, or a nylon salt obtained from a diamine and a diacid, into the production equipment of the polyamide resin, and after conveying, polymerization and devolatilization, extruding to obtain the polyamide resin; wherein the number of polymerization and devolatilization is ≥2.

[0061] The diamine may be selected from diamines having 2 to 18 carbon atoms.

[0062] The dicarboxylic acid may include dicarboxylic acid A1 and dicarboxylic acid A2; the dicarboxylic acid A1 is selected from aromatic dicarboxylic acids and their derivatives, and the dicarboxylic acid A2 is selected from aliphatic dicarboxylic acids having 2 to 18 carbon atoms.

[0063] In this invention, the diamine includes one or more of 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, 1,13-tridecanediamine, and 1,14-tetradecanediamine; preferably 1,5-pentanediamine, or 1,5-pentanediamine and 1,10-decanediamine, or 1,5-pentanediamine and 1,12-diaminododecane.

[0064] In this invention, the dicarboxylic acid A1 includes terephthalic acid and its derivatives and / or isophthalic acid and its derivatives. Preferably, the terephthalic acid and its derivatives include terephthalic acid.

[0065] In this invention, the dicarboxylic acid A2 includes one or more of adipic acid, 1,8-octanoic acid, 1,10-decanoic acid, 1,11-undecanoic acid, 1,12-dodecanoic acid, 1,13-tridecanoic acid, 1,14-tetradecanoic acid, and 1,16-hexadecanoic acid; preferably, it includes adipic acid. The preferred adipic acid is 1,6-adipic acid.

[0066] In this invention, preferably, the dicarboxylic acid includes terephthalic acid and / or 1,6-adipic acid, more preferably terephthalic acid and 1,6-adipic acid.

[0067] In this invention, the molar ratio of the diacid to the diamine can be 1:(0.85-1.2), preferably 1:(0.95-1.15). Those skilled in the art will understand that the diacid in the "molar ratio of the diacid to the diamine" refers to diacid A1 and diacid A2.

[0068] In this invention, the nylon salt may include nylon salt B1 and nylon salt B2.

[0069] The nylon salt B1 is generally prepared from the diamine and the diacid A1. For example, PA5T salt prepared from 1,5-pentanediamine and terephthalic acid or its derivatives, or PA10T salt prepared from 1,10-pentanediamine and terephthalic acid or its derivatives, or PA12T salt prepared from 1,12-dodecanediamine and terephthalic acid or its derivatives.

[0070] The nylon salt B2 is generally prepared from a diamine and a diacid A2. For example, PA56 salt is prepared from 1,5-pentanediamine and 1,6-adipic acid.

[0071] Preferably, the molar ratio of nylon salt B1 to nylon salt B2 is (30-90):(70-10).

[0072] In this invention, the nylon salt preferably includes one or more of 5T salt, 56 salt, 10T salt and 12T salt; more preferably it is 5T salt and 56 salt, or 10T salt and 56 salt, or 12T salt and 56 salt.

[0073] When the nylon salt is 5T salt and 56 salt, the molar ratio of the 5T salt to the 56 salt can be (30-70):(70-30), preferably (40-70):(60-30), for example 51:49 or 56:44.

[0074] When the nylon salt is 10T salt and 56 salt, the molar ratio of the 10T salt and 56 salt can be (90-50):(10-50), preferably (90-70):(10-30), and more preferably 86:14.

[0075] When the nylon salt is 12T salt and 56 salt, the molar ratio of the 12T salt and 56 salt can be (90-60):(10-40), preferably (90-70):(10-30), and more preferably 82:18.

[0076] In this invention, preferably, the catalyst and / or antioxidant are added together with "diamine and diacid" or "nylon salt prepared from diamine and diacid" into the production equipment of the polyamide resin.

[0077] The catalyst may be conventional in the art, such as phosphoric acid compounds or metal salts of phosphoric acid, preferably one or more of phosphoric acid, phosphorous acid, hypophosphite, phenyl hypophosphite, phosphoric anhydride, tetrapolyphosphite, pyrophosphite, trimetaphosphite, phosphorus pentachloride, triphenyl phosphite, ammonium hypophosphite, sodium hypophosphite, calcium hypophosphite, sodium hypophosphite, calcium hypophosphite, and H10, preferably one or more of phosphoric anhydride, pyrophosphite, triphenyl phosphite, ammonium hypophosphite, sodium hypophosphite, calcium hypophosphite, sodium hypophosphite, calcium hypophosphite, and H10.

[0078] The antioxidant may be conventional in the art, such as one or more of N,N′-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine, tris[2,4-di-tert-butylphenyl]phosphite, tris[2,4-di-tert-butylphenyl]phosphite, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

[0079] The amount of catalyst and / or antioxidant added can be conventional in the art, for example, 10 to 10,000 ppm, preferably 50 to 6,000 ppm. The amount of catalyst and / or antioxidant added can be understood as the percentage by mass of the catalyst and / or antioxidant relative to the sum of the masses of all diamines and diacids or the sum of the masses of all nylon salts. According to conventional art, ppm can be used to express a mass percentage, and 100 ppm = 0.01%.

[0080] In this invention, the screw speed of the screw extruder can be 30-500 rpm, preferably 60-500 rpm, more preferably 120-200 rpm, and even more preferably 140-160 rpm, for example 150 rpm.

[0081] Preferably, the residence time of the diamine and diacid, or the nylon salt prepared from the diamine and diacid, in the screw is 10s to 30min, more preferably 1min to 15min, and even more preferably 3min to 5min, for example 3min10s, 3min25s, 3min40s, or 4min30s.

[0082] When the catalyst and / or the antioxidant are added to the screw extruder together with "diamine and diacid" or "nylon salt made from diamine and diacid", the residence time in the screw is as described above.

[0083] In this invention, the material melts during the conveying process; the melting temperature can be 120-350°C, preferably 200-330°C, more preferably 250-325°C, for example 260°C.

[0084] In this invention, the polymerization temperature can be 200-350°C, preferably 240-330°C, more preferably 295-320°C, and even more preferably 300-310°C.

[0085] In this invention, the devolatilization temperature can be 220–350°C, preferably 250–330°C, more preferably 295–325°C, and even more preferably 298–320°C, for example 305–310°C.

[0086] In this invention, the devolatilization can generally be vacuum devolatilization. The vacuum degree of the vacuum devolatilization can be -0.095 to 0 MPa, preferably -0.09 to 0 MPa, for example -0.09 MPa.

[0087] In this invention, the extrusion temperature can be 220-350°C, preferably 240-320°C, more preferably 290-310°C, and even more preferably 300-305°C.

[0088] In this invention, after extrusion, a pelletizing step is generally included.

[0089] In this invention, polyamide resin can be obtained by using the preparation method of polyamide resin as described above.

[0090] The melting point of the polyamide resin can be 260-330℃, preferably 280-320℃.

[0091] The relative viscosity of the polyamide resin can be 1.5 to 3.5, preferably 1.8 to 2.8.

[0092] The yellowness index (YI) of the polyamide resin can be 1 to 20, preferably 1 to 10, more preferably 1 to 5, and even more preferably 1 to 2.5.

[0093] The molecular weight distribution (PDI) of the polyamide resin can be 1 to 3.2, preferably 1.5 to 2.6, and more preferably 1.5 to 2.

[0094] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0095] The reagents and raw materials used in this invention are all commercially available.

[0096] The positive and progressive effects of this invention are as follows:

[0097] (1) The polyamide resin production equipment provided by the present invention effectively reduces the occurrence of thermal degradation through special design and combination of screw elements. The resulting polyamide resin has a higher melting point and relative viscosity, a lower yellow index of resin chips, a narrower molecular weight distribution, higher production efficiency, and better overall product quality.

[0098] (2) The reaction process of the polyamide resin production method provided by the present invention can be better controlled, the reaction efficiency is higher, the yield is significantly increased, and the mechanical properties of the final polyamide resin are better than those of polyamide resin products prepared by conventional processes. Attached Figure Description

[0099] Figure 1 The diagram shows the structure of the production equipment for polyamide resin in Examples 1-9.

[0100] Figure label:

[0101] First cylinder 1

[0102] Main feed port 11

[0103] Second cylinder 2

[0104] Auxiliary feeding port 21

[0105] Third cylinder 3

[0106] Additive feeding port 31

[0107] First forward thread element 121

[0108] First reverse thread element 122

[0109] Fourth cylinder 4

[0110] Second forward thread element 41

[0111] First forward engagement block 42

[0112] First reverse meshing block 43

[0113] Second reverse thread element 44

[0114] Fifth cylinder 5

[0115] Third forward thread element 51

[0116] First exhaust port 52

[0117] Sixth cylinder 6

[0118] Fourth forward threaded element 61

[0119] Second forward engagement block 62

[0120] Second reverse engagement block 63

[0121] Third reverse thread element 64

[0122] Seventh cylinder 7

[0123] Fifth forward threaded element 71

[0124] Second evaporator 72

[0125] Eighth cylinder 8

[0126] Sixth forward thread element 81

[0127] Third forward engagement block 82

[0128] Third reverse engagement block 83

[0129] Fourth reverse thread element 84

[0130] Ninth cylinder 9

[0131] Seventh forward thread element 91

[0132] Third evaporation port 92

[0133] Tenth cylinder 10

[0134] Fifth reverse thread element 101 Detailed Implementation

[0135] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0136] The diamines, diacids, and additives (catalysts and antioxidants) used in the following examples are all general-purpose products that can be purchased from the market.

[0137] In the following embodiments, the preparation method of nylon salt specifically includes the following steps: adding diamine, diacid and deionized water into a 10L reaction vessel, setting the vessel temperature, reacting for 3 hours under nitrogen protection, followed by centrifugation, filtration, and drying.

[0138] Nylon salt preparation method:

[0139] Preparation method of PA5T salt: 1287g of 1,5-pentanediamine, 2076g of terephthalic acid and 3400g of deionized water are put into a 10L reactor. The reactor temperature is set to 80℃ and the reaction is carried out for 3 hours under nitrogen protection. Then, the mixture is centrifuged, filtered and dried to obtain the final product.

[0140] Preparation method of PA56 salt: 1450g of 1,5-pentanediamine, 2045g of 1,6-adipic acid and 3500g of deionized water are put into a 10L reactor. The reactor temperature is set to 60℃ and the reaction is carried out for 3 hours under nitrogen protection. Then, the mixture is centrifuged, filtered and dried to obtain the final product.

[0141] Preparation method of PA10T salt: 1757g of 1,10-decanediamine, 1694g of terephthalic acid and 4500g of deionized water are put into a 10L reactor. The reactor temperature is set to 90℃ and the reaction is carried out for 3 hours under nitrogen protection. Then, the mixture is centrifuged, filtered and dried to obtain the final product.

[0142] Preparation method of PA12T salt: 1903g of 1,12-dodecanediamine, 1578g of terephthalic acid and 4700g of deionized water are put into a 10L reactor. The reactor temperature is set to 90℃ and the reaction is carried out for 3 hours under nitrogen protection. Then, the mixture is centrifuged, filtered and dried to obtain the final product.

[0143] Examples 1-9 employ the following methods: Figure 1 The polyamide resin production equipment shown is a twin-screw extruder, which includes: a screw barrel composed of 10 sections and two screw units rotating in the same direction; both screw units rotating in the same direction are located in the receiving cavity of the screw barrel.

[0144] Each of the two screw units that rotate in the same direction independently includes a mandrel, and a first screw assembly, a second screw assembly, and a third screw assembly arranged sequentially along the material conveying direction and sleeved on the mandrel;

[0145] The mandrel has a diameter of 35mm and a length-to-diameter ratio of 48:1, which can increase the residence time of the material in the screw, thereby increasing the vacuum time of the material in the screw and ultimately achieving a better overall thickening effect.

[0146] In this screw extruder, the feeding and conveying system includes: a first screw assembly and its corresponding first barrel 1, second barrel 2 and third barrel 3;

[0147] The first cylinder 1 has a main feeding port 11 at its upper end, which is connected to the main feeding system; the second cylinder 2 has an auxiliary feeding port 21 at its upper end, which is connected to the auxiliary feeding system; and the third cylinder 3 has an additive feeding port 31 at its upper end, which is connected to the additive feeding system.

[0148] The first screw assembly is composed of a first forward thread element 121 and a first reverse thread element 122 in sequence, and is used for rapid melting and conveying of raw materials;

[0149] The first positive thread element 121 includes four positive thread elements (positive double-ended thread elements); the lead of any one positive thread element is 70 mm (2D) and the length is 70 mm. The first negative thread element 122 includes four negative thread elements (negative double-ended thread elements); the lead of any one negative thread element is 50 mm (1.42D) and the length is 50 mm.

[0150] In this screw extruder, the first polymerization system includes: a first set of elements of the second screw assembly and its corresponding fourth barrel 4;

[0151] The first set of components of the second screw assembly includes: a second forward thread element 41, a first forward engagement block 42, a first reverse engagement block 43, and a second reverse thread element 44 arranged in sequence, which can enable the raw materials to fully polymerize.

[0152] The second positive thread element 41 includes two positive thread elements (positive double-ended thread elements); the lead of any one positive thread element is 8 mm (0.23D), and the length is 8 mm; the stagger angle between adjacent meshing blocks is 60°, and the length is 56 mm; the second negative thread element 44 includes two negative thread elements (negative double-ended thread elements); the lead of any one negative thread element is 20 mm (0.57D), and the length is 20 mm;

[0153] The fourth cylinder 4 is a closed cylinder to maintain pressure.

[0154] In this screw extruder, the first devouring system includes: a second set of elements of the second screw assembly and its corresponding fifth barrel 5;

[0155] The second set of components of the second screw assembly includes: a third positive thread element 51;

[0156] The third positive thread element 51 consists of two positive thread elements (slotted thread elements), which can be used to increase the material distribution area and facilitate devolatilization; the lead of any positive thread element is 85mm (2.43D), and the length is 85mm.

[0157] The fifth cylinder 5 is provided with a first devolatilization port 52, and the first devolatilization port 52 is provided with a vacuum device for vacuum devolatilization and discharge of small molecule by-products.

[0158] In this screw extruder, the second polymerization system includes: a third set of elements of the second screw assembly and its corresponding sixth barrel 6;

[0159] The third set of components of the second screw assembly includes: a fourth forward thread element 61, a second forward engagement block 62, a second reverse engagement block 63 and a third reverse thread element 64 arranged in sequence, which can enable the raw materials to fully polymerize.

[0160] The fourth positive thread element 61 includes two positive thread elements (positive double-ended thread elements); the lead of any one positive thread element is 8 mm (0.23D), and the length is 8 mm; the stagger angle between adjacent meshing blocks is 60°, and the length is 56 mm; the third negative thread element 64 includes two negative thread elements (negative double-ended thread elements); the lead of any one negative thread element is 20 mm (0.57D), and the length is 20 mm;

[0161] The sixth cylinder 6 is a closed cylinder to maintain pressure.

[0162] In this screw extruder, the second devouring system includes: the fourth set of elements of the second screw assembly and its corresponding seventh barrel 7;

[0163] The fourth group of elements in the second screw assembly includes: a fifth forward thread element 71;

[0164] The fifth positive thread element 71 consists of two positive thread elements (slotted thread elements), which can be used to increase the material distribution area and facilitate devolatilization; the lead of any positive thread element is 85mm (2.43D), and the length is 85mm.

[0165] The seventh cylinder 7 is provided with a second devolatilization port 72, and the second devolatilization port 72 is equipped with a vacuum device for vacuum devolatilization and discharge of small molecule by-products.

[0166] In this screw extruder, the third polymerization system includes: the fifth set of elements of the second screw assembly and its corresponding eighth barrel 8;

[0167] The fifth set of components of the second screw assembly includes: a sixth forward thread element 81, a third forward engagement block 82, a third reverse engagement block 83 and a fourth reverse thread element 84 arranged in sequence, which can enable the raw materials to fully polymerize.

[0168] The sixth positive thread element 81 includes two positive thread elements (positive double-ended thread elements); the lead of any one positive thread element is 8 mm (0.23D), and the length is 8 mm; the stagger angle between adjacent meshing blocks is 60°, and the length is 56 mm; the fourth negative thread element 84 includes two negative thread elements (negative double-ended thread elements); the lead of any one negative thread element is 20 mm (0.57D), and the length is 20 mm;

[0169] The eighth cylinder 8 is a closed cylinder to maintain pressure.

[0170] In this screw extruder, the third devouring system includes: the sixth set of elements of the second screw assembly and its corresponding ninth barrel 9;

[0171] The sixth group of elements in the second screw assembly includes: a seventh positive thread element 91;

[0172] The seventh positive thread element 91 consists of two positive thread elements (slotted thread elements), which can be used to increase the material distribution area and facilitate devolatilization; the lead of any positive thread element is 85mm (2.43D), and the length is 85mm.

[0173] The ninth cylinder 9 is provided with a third devolatilization port 92, and the third devolatilization port 92 is equipped with a vacuum device for vacuum devolatilization and discharge of small molecule by-products.

[0174] In this screw extruder, the extrusion system includes: a third screw assembly and its corresponding tenth barrel 10;

[0175] The third screw assembly includes a fifth reverse thread element 101, which consists of 10 reverse thread elements (reverse double-ended thread elements) and can be used to establish die head pressure to extrude the material smoothly. The lead of any one of the reverse thread elements is 14 mm (0.4D) and the length is 14 mm.

[0176] Example 1

[0177] 2624g of 5T salt, 2526g of 56 salt (5T / 56 molar ratio 51 / 49), 1.5g of sodium hypophosphite, and 5g of tris[2,4-di-tert-butylphenyl]phosphite were added to a twin-screw extruder. The feeding and conveying section temperature was set to 250℃, the polymerization section to 310℃, the devolatilization section to 310℃, and the extrusion section to 305℃. The extruder speed was set to 140rpm, the vacuum degree of the devolatilization section was set to -0.09MPa, and the residence time was 3min40s. The extrudate was extruded through the die, drawn, cooled, and pelletized to obtain the corresponding product.

[0178] Example 2

[0179] The same twin-screw extruder, feed ratio, and process as in Example 1 were used. The difference was that a combination of dicarboxylic acid and diamine was used for preparation. The feed ratio was as follows: 1,5-pentanediamine 1972g, terephthalic acid 1624g, 1,6-adipic acid 1369g, wherein the molar ratio of dicarboxylic acid to diamine was 1:1.009.

[0180] Example 3

[0181] The same twin-screw extruder as in Example 1 was used, with the same vacuum level in the devolatilization section and the same granulation method. The difference was that the 5T / 56 molar ratio was 56:44, and the feeding conditions were as follows: 2871g of 5T salt, 2079g of 56 salt, 1.5g of sodium hypophosphite, and 7.5g of tris[2,4-di-tert-butylphenyl] phosphite. The extruder feeding and conveying section temperature was 250℃, the polymerization section temperature was 320℃, the devolatilization section temperature was 320℃, the extrusion section temperature was 310℃, the rotation speed was 160rpm, and the residence time was 3min10s.

[0182] Example 4

[0183] The same twin-screw extruder, feed ratio, and process as in Example 3 were used. The difference was that a combination of dicarboxylic acid and diamine was used for preparation. The feed ratio was as follows: 1,5-pentanediamine 1960g, terephthalic acid 1777g, adipic acid 1223g, wherein the molar ratio of dicarboxylic acid to diamine was 1:1.007.

[0184] Example 5

[0185] The same twin-screw extruder as in Example 1 was used, except that the 10T / 56 molar ratio was 86:14. The feed conditions were as follows: 4455g of 10T salt, 495g of 56 salt, 3g of sodium hypophosphite, and 7.5g of N,N′-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine. The extruder feeding and conveying section temperature was 260℃, the polymerization section temperature was 300℃, the devolatilization section temperature was 305℃, the extrusion section temperature was 305℃, the rotation speed was 150rpm, and the residence time was 3min25s.

[0186] Example 6

[0187] The same twin-screw extruder, feed ratio, and process as in Example 5 were used, except that a combination of a dicarboxylic acid and a diamine was added to prepare the product. The feed ratio was as follows: 214g of 1,5-pentanediamine, 2278g of 1,10-decanediamine, 2187g of terephthalic acid, and 291g of 1,6-adipic acid. The molar ratio of the dicarboxylic acid to the diamine was 1:1.01.

[0188] Example 7

[0189] The same twin-screw extruder as in Example 1 was used, except that the 12T / 56 molar ratio was 82:18. The feed conditions were as follows: 4356g of 12T salt, 594g of 56 salt, 2.75g of sodium hypophosphite, and 9g of (3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine. The extruder feeding and conveying section temperature was 250℃, the polymerization section temperature was 295℃, the devolatilization section temperature was 298℃, the extrusion section temperature was 290℃, the rotation speed was 120rpm, and the residence time was 4min30s.

[0190] Example 8

[0191] The same twin-screw extruder, feed ratio, and process as in Example 7 were used, except that a combination of a dicarboxylic acid and a diamine was added to prepare the product. The feed ratio was as follows: 252g of 1,5-pentanediamine, 2531g of 1,12-diaminododecane, 1825g of terephthalic acid, and 278g of 1,6-adipic acid, wherein the molar ratio of the dicarboxylic acid to the diamine was 1:1.17.

[0192] Example 9

[0193] The same twin-screw extruder as in Example 1 was used, with different additive feed rates, rotation speeds, and residence times. The differences lay in the feed ratio and temperature settings. Specifically, the 5T / 56 molar ratio was 7.5 / 92.5, and the feed details were as follows: 396g of 5T salt and 4554g of 56 salt. The extruder feeding and conveying section temperature was 250℃, the polymerization section temperature was 270℃, the devolatilization section temperature was 265℃, and the extrusion section temperature was 265℃.

[0194] Comparative Example 1

[0195] (1) Add the raw materials (same as in Example 1) into a twin-screw extruder;

[0196] Compared with the screw extruder in Example 1, the first, third, and fifth groups of elements in the second screw assembly of this screw extruder are all composed of three meshing blocks, excluding forward and reverse thread elements. The three meshing blocks are, in order, a forward meshing block, a reverse meshing block, and a forward meshing block. The staggered angle between adjacent meshing blocks is 90° and the length is 60 mm. Everything else is the same as in Example 1.

[0197] (2) Same as Example 1;

[0198] (3) Same as Example 1.

[0199] Comparative Example 2

[0200] (1) Add the raw materials (same as in Example 1) into a twin-screw extruder;

[0201] Compared to the screw extruder in Example 1, this screw extruder has the following components arranged in sequence: a first screw assembly and its corresponding barrels 1-3 (i.e., feeding and conveying system); a first set of elements of the second screw assembly and its corresponding barrel 4 (i.e., first polymerization system); a second set of elements of the second screw assembly and its corresponding barrel 5 (i.e., first devolatilization system); a first screw assembly and its corresponding barrels 6-9 (i.e., feeding and conveying system); and a third screw assembly and its corresponding barrel 10 (extrusion system); all other aspects are the same as in Example 1.

[0202] (2) Same as Example 1;

[0203] (3) Same as Example 1.

[0204] Comparative Example 3

[0205] (1) 2624g of 5T salt, 2526g of 56 salt and 4950g of deionized water were put into a 20L polymerization reactor, wherein the molar ratio of 5T salt and 56 salt was 51:49.

[0206] (2) After holding at 2MPa for 50 minutes, depressurizing to atmospheric pressure for 60 minutes, and then vacuuming (-0.09MPa) for 30 minutes, the material is discharged to obtain polyamide resin.

[0207] The polymerization time of the above production process is at least 140 minutes, which is much longer than the time of directly preparing polyamide resin by twin-screw extruder in Examples 1-9 (about 3-5 minutes), resulting in lower efficiency.

[0208] Example 1

[0209] The polyamide resins obtained in Examples 1-9 and Comparative Examples 1-3 were tested as follows:

[0210] (1) Relative viscosity ηr

[0211] Testing instrument: Ubbelohde viscometer AVS600, purchased from Shanghai Luwen Scientific Instruments Co., Ltd.

[0212] Test method: Ubbelohde viscometer concentrated sulfuric acid method. Accurately weigh 0.5±0.0002g of dried polyamide resin material sample, add 50mL of concentrated sulfuric acid (96%) to dissolve it, and measure and record the flow time t0 of concentrated sulfuric acid and the flow time t of polyamide resin material solution in a 25℃ constant temperature water bath. Relative viscosity calculation formula: Relative viscosity ηr=t / t0; where: t: solution flow time; t0: solvent flow time.

[0213] (2) Melting point

[0214] Test instrument: Differential scanning calorimeter DSC Q20, purchased from TA Instruments, USA.

[0215] Test method: Weigh 5-8 mg of sample into an aluminum crucible, with an empty crucible as a control. Under nitrogen protection (gas flow rate of 50 mL / min), heat to 300 °C at 20 °C / min, hold for 3 min to eliminate thermal history, then cool to 30 °C at 20 °C / min, and then heat to 300 °C at 20 °C / min. Record the enthalpy change during the temperature scan.

[0216] (3) Yellowness Index

[0217] Testing instrument: Yellowness index meter

[0218] Test method: The test method refers to HG / T3862-2006.

[0219] (4) Molecular weight

[0220] Testing instrument: Gel permeation chromatography

[0221] Test method: The test was performed by gel permeation chromatography (GPC). The standard substance was PMMA, and the solvent was trifluoroethanol + 0.05% potassium trifluoroacetate. After complete dissolution, the solution was filtered through a PTFE membrane and injected at 40°C for analysis to obtain the molecular weight and distribution relative to PMMA.

[0222] (5) Yield:

[0223] Yield = Polyamide resin output / Total input

[0224] The total amount of feed is the sum of the masses of diamine and diacid, or the sum of the masses of different types of nylon salts.

[0225] The results are shown in Table 1.

[0226] Table 1

[0227] Example 1 90 297.7 2.33 1.68 1.89 Example 2 88 296.3 2.45 1.73 1.81 Example 3 92 303.5 2.39 1.58 1.94 Example 4 86 304.1 2.40 1.66 1.71 Example 5 89 291.7 2.38 1.99 2.04 Example 6 87 292.2 2.31 1.87 1.90 Example 7 90 284.7 2.49 2.28 1.78 Example 8 88 284.2 2.36 2.20 1.86 Example 9 85 252.7 2.33 2.03 1.98 Comparative Example 1 87 278.2 1.71 11.8 3.25 Comparative Example 2 85 283.5 1.75 5.89 4.56 Comparative Example 3 72 296.6 2.44 36.4 2.78

[0228] As can be seen from Table 1, the production equipment for polyamide resin in this invention, after special design of the screw element, has a significantly higher yield than conventional production equipment; and the polyamide resin produced under the same production conditions has the excellent effects of high melting point and high relative viscosity, with lower yellow index, narrower molecular weight distribution, and higher chemical reaction efficiency in the resin chips.

[0229] Those skilled in the art will know that PDI (Polymer Dispersity Index) is a polymer dispersion index used to describe the molecular weight distribution of polymers. Its value is also equal to M(w) / M(n), and the value is greater than 1. The larger the PDI, the wider the molecular weight distribution; the smaller the PDI, the more uniform the molecular weight distribution.

[0230] Example 2

[0231] Resin mechanical property testing

[0232] Testing instruments: UTM4304 electronic universal testing machine and PTM1000 impact strength tester, both purchased from Shenzhen Sansi Zongheng Technology Co., Ltd.

[0233] Test methods: Polyamide resin chips were dried to a moisture content below 1000 ppm and then injection molded using an injection molding machine (any conventional equipment in this field is acceptable). The tensile strength (MPa) and elongation at break (%) of the resin were determined according to GB / T14344-2008 (tensile test specimen specifications: 170*20*4mm, dumbbell shape); the flexural strength (MPa) of the resin was determined according to ISO527-2 (flexural test specimen specifications: 80*10*4mm); and the notched impact strength of the resin cantilever beam (kJ·m) was measured. -2 The test method refers to ISO 197 / leA (impact test specimen specifications: 80*10*4mm, with a notch on one side).

[0234] The performance of the resin materials prepared in Examples 1-9 and Comparative Examples 1-3 was tested, and the results are shown in Table 2 below.

[0235] Table 2

[0236]

[0237] As can be seen from Table 2, the polyamide resin production equipment in Examples 1-9, by selecting specific extruders for conveying, polymerization, devolatilization and extrusion, produces resin materials with better mechanical properties, while the resin produced using conventional equipment has significantly inferior properties compared to Examples 1-9.

Claims

1. A production equipment for polyamide resin, characterized in that, It includes a screw barrel and a screw unit; the screw unit is disposed within the receiving cavity of the screw barrel; The screw unit includes a spindle and a screw assembly sleeved on the spindle; The screw assembly includes a first screw assembly, a second screw assembly, and a third screw assembly arranged sequentially along the material conveying direction; The first screw assembly is used for material conveying; The second screw assembly is used to melt polymerize and devolatilize the material; the second screw assembly is repeated n times, where n≥2; The second screw assembly includes a first group of elements and a second group of elements arranged sequentially along the material conveying direction; The first set of elements consists of a forward threaded element, a meshing block, and a reverse threaded element arranged in sequence, used to enable the material to undergo a polymerization reaction; The second set of elements includes threaded elements for removing volatiles from the polymer; The third screw assembly is used for extrusion to obtain polyamide resin.

2. The polyamide resin production equipment as described in claim 1, characterized in that, The polyamide resin production equipment meets one or more of the following conditions I to IV: I. The screw barrel comprises 6 to 30 sections; II. The production equipment for the polyamide resin includes at least two screw units rotating in the same direction. III. The length-to-diameter ratio of the mandrel is (20-68):1; IV. The diameter of the mandrel is 20-95 mm.

3. The polyamide resin production equipment as described in claim 2, characterized in that, The polyamide resin production equipment simultaneously meets the above conditions I to IV; and / or, The screw barrel comprises 6 to 16 sections; and / or, The mandrels of any two screw units, and the screw assemblies fitted onto the mandrels, are identical; and / or, The length-to-diameter ratio of the mandrel is (40-60):

1.

4. The polyamide resin production equipment as described in claim 2, characterized in that, The length-to-diameter ratio of the mandrel is (45–55):1; and / or, The diameter of the mandrel is 35-50 mm.

5. The polyamide resin production equipment as described in claim 1, characterized in that, The polyamide resin production equipment meets the following conditions i and / or ii: i. The first screw assembly includes a forward threaded element and a reverse threaded element arranged sequentially along the material conveying direction; ii. The first screw assembly corresponds to two or more sections of the cylinder; The first cylinder has a main feeding port at its upper end, which is connected to the main feeding system; the second cylinder has an auxiliary feeding port at its upper end, which is connected to the auxiliary feeding system. When the first screw assembly corresponds to three or more sections of the cylinder, the upper end of the third cylinder is provided with an additive feeding port, and is connected to the additive feeding system through the additive feeding port.

6. The polyamide resin production equipment as described in claim 5, characterized in that, The number of positive thread elements in the first screw assembly is 1 to 10; and / or, The number of reverse thread elements in the first screw assembly is 1 to 10.

7. The polyamide resin production equipment as described in claim 5, characterized in that, The number of forward threaded elements in the first screw assembly is 2 to 8; and / or, The number of reverse thread elements in the first screw assembly is 2 to 8.

8. The polyamide resin production equipment as described in claim 5, characterized in that, The number of positive thread elements in the first screw assembly is 3 to 6; and / or, The number of reverse threaded elements in the first screw assembly is 3 to 6; and / or, The lead of the forward thread element of the first screw assembly is 1D to 2.5D, and the lead of the reverse thread element of the first screw assembly is 1D to 2D; where D is the major diameter of the thread.

9. The polyamide resin production equipment as described in claim 5, characterized in that, The first screw assembly consists of one or more forward threaded elements and one or more reverse threaded elements.

10. The polyamide resin production equipment as described in claim 1, characterized in that, The polyamide resin production equipment meets one or more of the following conditions a to h: a. In the first group of components of the second screw assembly, the number of both the forward threaded element and the reverse threaded element is independently 1 to 5; b. In the first group of elements of the second screw assembly, the lead of the positive thread element is 0.1D to 0.5D, where D is the major diameter of the thread; c. In the first group of components of the second screw assembly, the length of the positive thread element is 4 to 60 mm; d. In the first group of elements of the second screw assembly, the lead of the reverse thread element is 0.5D to 2D, where D is the major diameter of the thread; e. In the first group of components of the second screw assembly, the length of the reverse thread element is 10-120 mm; f. In the first group of elements of the second screw assembly, the meshing block is a forward meshing block or a reverse meshing block; g. In the first group of components of the second screw assembly, the length of the meshing block is 20-120 mm; h. In the first group of elements of the second screw assembly, the staggered angle between the contact end faces of adjacent meshing blocks is 45°, 60° or 90°.

11. The polyamide resin production equipment as described in claim 10, characterized in that, The polyamide resin production equipment simultaneously meets the above conditions a to h; and / or In the first group of elements of the second screw assembly, the number of both the forward threaded element and the reverse threaded element is independently 2 to 4; and / or, In the first group of elements of the second screw assembly, the number of meshing blocks is two or more; and / or, In the first group of elements of the second screw assembly, the lead of the reverse thread element is 0.57D to 1D.

12. The polyamide resin production equipment as described in claim 1, characterized in that, The polyamide resin production equipment meets one or more of the following conditions ① to ③: ① The second set of elements of the second screw assembly includes a positive thread element; ② The upper end of the cylinder corresponding to the second set of elements of the second screw assembly is provided with a blowout port; ③ n is 3 to 20.

13. The polyamide resin production equipment as described in claim 12, characterized in that, The polyamide resin production equipment simultaneously meets the above conditions ①~③; and / or, In the second group of elements of the second screw assembly, the number of the positive threaded elements is 1 to 6; and / or, In the second group of elements of the second screw assembly, the lead of the positive thread element is 1.5D to 2.5D, where D is the major diameter of the thread; and / or, n is between 3 and 8.

14. The polyamide resin production equipment as described in claim 12, characterized in that, The number of the positive threaded elements is 2 to 4; and / or, The devolatilization port is equipped with a vacuum device; and / or, n is 3 to 5.

15. The production equipment for polyamide resin as described in any one of claims 1 to 14, characterized in that, The polyamide resin production equipment meets the following condition ④: ④ The third screw assembly includes a reverse thread element.

16. The polyamide resin production equipment as described in claim 15, characterized in that, The number of reverse thread elements in the third screw assembly is 5 to 15; and / or, The reverse thread element of the third screw assembly is a small lead thread element, and the lead of the reverse thread element is 0.1D to 0.5D, where D is the major diameter of the thread.

17. The polyamide resin production equipment as described in claim 15, characterized in that, The number of reverse thread elements in the third screw assembly is 6 to 12.

18. A method for preparing a polyamide resin, characterized in that, It uses the production equipment for polyamide resin as described in any one of claims 1 to 17.

19. The method for preparing the polyamide resin according to claim 18, characterized in that, The polyamide resin production equipment meets one or more of the following conditions ⑥ to ⑧: ⑥ The temperature settings of the polyamide resin production equipment are as follows: feeding and conveying system 120-300℃, polymerization system 240-330℃, devolatilization system 250-330℃, extrusion system 260-320℃; ⑦ The screw speed of the polyamide resin production equipment is 30-500 rpm; ⑧ The residence time of the material in the polyamide resin production equipment is 10s to 30min.

20. The method for preparing the polyamide resin according to claim 19, characterized in that, The polyamide resin production equipment simultaneously meets the above conditions ⑥ to ⑧; and / or The screw speed of the polyamide resin production equipment is 60–500 rpm; and / or, The residence time of the material in the polyamide resin production equipment is 10s to 15min.

21. The method for preparing the polyamide resin according to claim 19, characterized in that, The screw speed of the polyamide resin production equipment is 60–200 rpm; and / or, The residence time of the material in the polyamide resin production equipment is 1 min to 15 min.

22. The method for preparing polyamide resin according to claim 18, characterized in that, The preparation method of the polyamide resin includes the following steps: adding a diamine and a diacid, or a nylon salt obtained from a diamine and a diacid, into the production equipment of the polyamide resin, and after conveying, polymerization and devolatilization, extruding to obtain the polyamide resin; the number of polymerization and devolatilization is ≥2.

23. The method for preparing polyamide resin according to claim 22, characterized in that, The method for preparing the polyamide resin satisfies one or more of the following conditions A to E: A. During the conveying process, the material melts; the melting temperature is 120–350°C. B. The polymerization temperature is 200–350°C; C. The devolatilization temperature is 220–350°C; D. The devolatilization described is vacuum devolatilization; E. The extrusion temperature is 220–350°C.

24. The method for preparing polyamide resin according to claim 23, characterized in that, The method for preparing the polyamide resin simultaneously satisfies conditions A to E above; and / or, The melting temperature is 200–330°C; and / or, The polymerization temperature is 240–330°C; and / or, The devolatilization temperature is 250–330°C.

25. The method for preparing polyamide resin according to claim 23, characterized in that, The melting temperature is 250–325°C; and / or, The polymerization temperature is 295–320°C; and / or, The devolatilization temperature is 295–325°C; and / or, The extrusion temperature is 240–320°C.

26. The method for preparing polyamide resin according to claim 23, characterized in that, The polymerization temperature is 300–310°C; and / or, The devolatilization temperature is 298–320°C; and / or, The vacuum degree of the vacuum devouring is -0.095 to 0 MPa; and / or, The extrusion temperature is 290–310°C.

27. The method for preparing polyamide resin according to claim 23, characterized in that, The devolatilization temperature is 305–310°C; and / or, The vacuum degree of the vacuum devouring is -0.09 to 0 MPa; and / or, The extrusion temperature is 300–305°C.

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