CN219482638U - Polyamide resin serialization apparatus for producing - Google Patents

Abstract

The utility model discloses a continuous production device for polyamide resin. The continuous production device for the polyamide resin comprises a salifying reaction device, a prepolymerization reaction device, a flash evaporation device, a pre-polymerization reaction device and a post-polymerization reaction device which are connected in sequence; the prepolymerization reaction device, the pre-polymerization reaction device and the post-polymerization reaction device are one-section straight pipe type reactors or more than two sections of straight pipe type reactors which are connected by U-shaped pipes and are sequentially connected in series; static mixing internals are arranged in the pre-polymerization reaction device and the post-polymerization reaction device. The continuous production device of the polyamide resin can strengthen mass and heat transfer, enable the reaction to be more sufficient, reduce the reaction residence time and realize narrower molecular weight distribution in the process of forming the high polymer of the polyamide resin.

Description

Polyamide resin serialization apparatus for producing

Technical Field

The utility model particularly relates to a continuous production device for polyamide resin.

Background

Polyamide materials are a generic term for thermoplastic resins containing a repeating amide group- [ NHCO ] -in the molecular main chain, and include aliphatic polyamides, aliphatic-aromatic polyamides and aromatic polyamides, which are widely used in spinning, injection molding, film forming and other products because of their excellent heat resistance, chemical resistance, weather resistance, mechanical properties, electrical properties and the like. The high-temperature resistant polyamide resin has the characteristics of high strength, high modulus, high temperature resistance and the like, and is widely applied to the fields of electronic appliances, communication equipment parts, automobile parts, electric control system parts and the like, and the market demand is also increasing.

One of the preparation modes of the polyamide resin is obtained by polycondensation of diamine and diacid, and the other is obtained by polycondensation or ring-opening polymerization of lactam. The reaction is generally carried out by batch polymerization in a polymerization kettle, but the molecular weight of the prepolymer is unstable, tackifying treatment is usually needed to improve the molecular weight of polyamide, but the viscosity is increased to cause poor flowability and easy discharge failure, and in addition, the polyamide material is needed to be modified to improve the functionality of the polyamide material in a certain aspect, generally, the prepared polyamide resin master batch is mixed with a certain amount of functional additive and then subjected to melt extrusion again for reinforcement modification, and then the mixture is subjected to re-heating extrusion granulation, so that the process chain is longer, the repeated heating causes higher energy consumption, and the polymer is easy to decompose at high temperature, thereby influencing the properties and performances of the material.

The high temperature resistant polyamide resin in China is relatively late in synthesis start, and the production process route is mainly based on a gap prepolymerization and tackifying two-step method. The problems of high difficulty in prepolymer viscosity control, easy oxidation yellowing and overheat decomposition of polymers, large molecular weight change of batch products, low production efficiency, inapplicability to large-scale production and the like exist in the production of high-temperature-resistant polyamide resin at present.

Disclosure of Invention

The utility model provides a continuous production device for polyamide resin, which aims to overcome the technical defects of poor mass and heat transfer effect, insufficient reaction, long reaction time, high cost and the like in the technical process of producing polyamide resin in the prior art. The utility model strengthens mass and heat transfer by arranging the static mixing inner member in the polymerization reaction device, ensures more complete reaction, reduces reaction residence time and realizes narrower molecular weight distribution in the process of forming the high polymer of the polyamide resin. In addition, the utility model further promotes the reaction to be sufficient by selecting specific tubular reactor types as a prepolymerization device, a prepolymerization device and a post-polymerization device.

The utility model provides a continuous production device for polyamide resin, which comprises a salifying reaction device, a prepolymerization reaction device, a flash evaporation device, a pre-polymerization reaction device and a post-polymerization reaction device which are connected in sequence;

the prepolymerization reaction device is a straight pipe type reactor with one section or more than two sections connected by U-shaped pipes and connected in series in sequence.

The pre-polymerization reaction device is a straight pipe type reactor with one section or more than two sections connected by U-shaped pipes and connected in series in sequence.

The post-polymerization reaction device is a straight pipe type reactor or a straight pipe type reactor with more than two sections connected by U-shaped pipes and connected in series in sequence;

static mixing internal components are arranged in the pre-polymerization reaction device and the post-polymerization reaction device;

the salifying reaction device is used for carrying out salifying reaction on polyamide;

the prepolymerization reaction device is used for carrying out prepolymerization reaction on the salt solution after the salification reaction;

the flash evaporation device is used for carrying out flash evaporation on the reaction product of the prepolymerization reaction;

the pre-polymerization reaction device is used for carrying out gas-liquid separation and polymerization reaction on the reaction product after flash evaporation;

the post-polymerization device is used for further polymerizing the products of the polymerization reaction in the pre-polymerization device.

In the present utility model, preferably, the prepolymerization reaction device is a straight pipe reactor with two sections connected in series in turn, wherein the two sections are connected by a U-shaped pipe.

In the present utility model, preferably, the pre-polymerization reaction apparatus is a one-stage straight tube type reactor. The post-polymerization reaction device is preferably a straight pipe reactor with two sections connected in series in sequence, wherein the two sections are connected by a U-shaped pipe.

In the utility model, more than two sections of U-shaped pipes are connected in series in turn, and the U-shaped pipes are connecting pipes for connecting the two sections of straight pipe reactors. For example, two sections of straight pipe type reactors are connected through a section of U-shaped pipe, namely, two ends of the U-shaped pipe are respectively connected with the tail part of the first section of straight pipe type reactor and the head part of the second section of straight pipe type reactor; the three-section straight tube type reactor is connected into an S shape through two sections of U-shaped tubes in a tail-end way, and the like. According to the utility model, more than two sections of straight pipe reactors which are sequentially connected in series are connected through the U-shaped pipe, so that the physical space of the device can be saved on the basis of ensuring sufficient reaction. The number of the straight pipe reactors in the two or more sections of the straight pipe reactors connected in series in sequence in the U-shaped pipe is an integer of more than 2, for example, the straight pipe reactors can be two sections, three sections or four sections, and the straight pipe reactors can be specifically set according to actual reaction requirements.

In the present utility model, the static mixing internals may be one or more of an SV type static mixer, an SK type static mixer, an SL type static mixer, an SX type static mixer and an SH type static mixer.

In the utility model, the static mixing internal component is connected with the pre-polymerization reaction device or the post-polymerization reaction device through a flange.

In the present utility model, the ratio of the inlet distance of the static mixing internals to the pre-polymerization apparatus to the length of the tube of the pre-polymerization apparatus is preferably (1:3) to (1:2).

In the present utility model, the post-polymerization reaction apparatus is preferably provided with two of the static mixing internals, and the ratio of the inlet distance of the first static mixing internals to the post-polymerization reaction apparatus to the length of the pipe body of the post-polymerization reaction apparatus is preferably (1:4) - (1:2); the ratio of the outlet distance of the second static mixing internals from the post-polymerization apparatus to the length of the tube of the post-polymerization apparatus is preferably (1:4) - (1:2).

Wherein the inlet distance of the first static mixing internals from the post-polymerization reaction apparatus may be 900-1500mm, for example 900mm, 1250mm, 1350mm or 1500mm. The outlet distance of the second static mixing internals from the post-polymerization reaction apparatus may be 1100-2000mm,1200mm, 1500mm, 1100mm or 2000mm.

In the present utility model, the length of the static mixing internals is preferably 500mm to 2000mm. The nominal size of the static mixing internals is preferably DN65-DN600.

Those skilled in the art know that the unit structure of the SV-type static mixer is assembled from corrugated sheets, which enable different fluids to flow in a zigzag manner in three dimensions.

The skilled person knows that the unit structure of the SK type static mixer is formed by 180 degrees of left and right torsion and 90 degrees of cross welding.

Those skilled in the art know that the unit structure of the SL type static mixer is formed by welding unit pieces which are mutually intersected by 60 degrees, and two adjacent units are mutually intersected by 90 degrees.

Those skilled in the art know that the unit structure of the SX type static mixer is formed by welding unit pieces which are mutually crossed by 90 degrees, and two adjacent units are crossed by 90 degrees in combination.

The skilled person knows that the unit structure of the SH type static mixer consists of double-pore canal units, a distribution chamber is arranged between the units, and spiral sheets which are twisted by 180 degrees left and right are arranged in the double pore canal.

In the present utility model, the length of the tube body of the one-stage straight tube reactor is preferably 5-20m, and the ratio of the length of the tube body of the one-stage straight tube reactor to the inner diameter of the tube body is preferably 60-650. The number of the exhaust ports of the straight pipe type reactor is preferably 5-50, and the distance between two adjacent exhaust ports is preferably 10-100 cm.

In the utility model, the length of the tube body of the straight tube type reactor in the above two sections of the U-shaped tube connected in series is preferably 5-20m, and the ratio of the length of the tube body to the inner diameter of the tube body is preferably 60-650. The number of the exhaust ports of the straight pipe type reactor is preferably 5-50, and the distance between two adjacent exhaust ports is preferably 10-100 cm.

In some embodiments, the size of the U-shaped tube in the two or more sections of straight tube reactors connected in series in turn is not particularly limited, and the two sections of straight tube reactors may be connected end to end by a U-shaped tube, preferably, the diameter of the U-shaped tube is the same as the diameter of the straight tube reactor connected with the U-shaped tube.

In some specific embodiments, each of the two or more sections of the sequentially connected straight-tube reactors connected by the U-shaped tube has the same specification, for example, the length of the tube, the ratio of the length of the tube to the inner diameter of the tube, and the number of the exhaust ports of the two sections of straight-tube reactors are the same.

In the present utility model, preferably, the continuous production apparatus for polyamide resin further comprises a raw material storage tank, and an outlet of the raw material storage tank is connected with an inlet of the salifying reaction apparatus.

In the present utility model, the salt forming reaction device is preferably a salt forming reaction kettle, and the heating mode of the salt forming reaction kettle can be one or a combination of more than two of a jacket type, an inner coil type and an outer coil type, and is preferably a jacket type.

In the present utility model, the flash device may be a flash device conventional in the art, preferably a flash vessel.

In the present utility model, preferably, the continuous production apparatus for polyamide resin further comprises a condensing unit, wherein any one or more of the gas outlet of the prepolymerization unit, and the gas outlet of the post-polymerization unit is connected to the inlet of the condensing unit.

Wherein the condensing device preferably comprises a condenser, a condensate collection tank and a spray tower which are connected in sequence, wherein a liquid outlet of the condenser is connected with an inlet of the condensate collection tank, and a gas outlet of the condensate collection tank is connected with an inlet of the spray tower; any one or more than two gas outlets of the prepolymerization reaction device, the pre-polymerization reaction device and the post-polymerization reaction device are connected with an inlet of a condenser, and the condenser is used for condensing reaction steam of the prepolymerization reaction device, the pre-polymerization reaction device and/or the post-polymerization reaction device.

In the present utility model, preferably, the continuous production device for polyamide resin further comprises a granulating device, a drying device and a classifying and screening device which are connected in sequence, wherein the inlet of the granulating device is connected with the outlet of the post-polymerization reaction device.

Wherein the pelletizer preferably includes an underwater pelletizer.

Wherein the drying means preferably comprises a spray dryer, a microwave dryer or a fluid bed dryer, more preferably a continuous fluid bed dryer.

Wherein the hierarchical screening device preferably comprises a hierarchical screening machine.

In the present utility model, preferably, the continuous production apparatus for polyamide resin further comprises a packing apparatus, and the packing apparatus is connected to the classifying screen apparatus. The packaging device is preferably a packaging machine.

In the present utility model, preferably, the outlet of the flash evaporation device and the inlet of the pre-polymerization reaction device are connected by a feed pump.

In the present utility model, preferably, the outlet of the pre-polymerization reaction apparatus and the inlet of the post-polymerization reaction apparatus are connected by a melt pump.

The utility model provides a preparation method of polyamide resin, which adopts the continuous production device of polyamide resin, and comprises the following steps:

S1, carrying out salt forming reaction on reaction raw materials in the salt forming reaction device; the reaction raw materials comprise water, polyamide monomers or polyamide salts.

S2, enabling the salt solution after the salification reaction to enter the prepolymerization reaction device for prepolymerization reaction;

s3, enabling the reaction product of the prepolymerization reaction to enter a flash evaporation device for flash evaporation;

s4, enabling the reaction product subjected to flash evaporation to enter the pre-polymerization reaction device for polymerization reaction;

s5, enabling reaction products in the pre-polymerization reaction device to enter the post-polymerization reaction device for further polymerization reaction.

In the step S1, the pressure of the salification reaction is preferably 0.01 to 0.5MPa. The temperature of the salification reaction is preferably 95 to 135 ℃. The salifying reaction device is preferably a paddle stirring salifying reaction kettle, and the stirring speed is preferably 10-100 r/min; the stirring time is preferably 0.5 to 6 hours. The concentration of polyamide in the salt solution after the salt formation reaction is preferably 40 to 80wt%, more preferably 55 to 75wt%.

In step S1, the reaction atmosphere of the salification reaction may be conventional in the art, and is generally an inert atmosphere or a carbon dioxide atmosphere or a nitrogen atmosphere. The inert atmosphere may be under conditions conventional in the art, for example, by evacuating for 3 to 10 minutes, introducing inert gas to normal pressure, and circulating for 5 to 10 times. The reaction atmosphere is preferably nitrogen or argon.

In step S1, the polyamide monomer preferably includes a diamine monomer and a diacid monomer, and the diamine monomer may be selected from aliphatic diamine having 5 to 20 carbon atoms; preferably one or more of pentyenediamine, hexamethylenediamine, heptenediamine, octylenediamine, nonylenediamine, decylenediamine, undecylenediamine and dodecylenediamine; the diacid monomer can be selected from aromatic diacid and/or aliphatic diacid with 4-18 carbon atoms, preferably one or more of glutaric acid, adipic acid, suberic acid, sebacic acid, terephthalic acid, isophthalic acid, undecanediacid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid and hexadecanedioic acid. The polyamide salts are generally formed from the reaction of diacids with diamines. The polyamide salt is preferably one or more of caprolactam, 11-aminoundecanoic acid, laurolactam, polyamide 56 salt, polyamide 5T salt, polyamide 66 salt, polyamide 6T salt, polyamide 10T salt, polyamide 12T salt, polyamide 610 salt, polyamide 612 salt, polyamide 1010 salt, polyamide 1012 salt, and polyamide 1212 salt.

In step S2, the temperature of the prepolymerization is preferably 185 to 300 ℃. The pressure of the prepolymerization is preferably 1.0 to 3.3MPa. The residence time of the reaction mass in the prepolymerization is preferably 1.5 to 4.5 hours.

In the step S3, the reaction product of the prepolymerization is decompressed in the flash evaporation device, and in the decompression process, the moisture in the material is gasified rapidly, and finally the gas-liquid mixed foam polymer is obtained.

In step S4, the reaction product after flash evaporation is preferably conveyed to the pre-polymerization reactor by a melt pump to perform gas-liquid separation and further polycondensation reaction, and the gas generated in the polycondensation process and the reaction steam clamped in the flash evaporation device are discharged from a gas outlet of the pre-polymerization reaction device.

In step S4, the reaction temperature in the pre-polymerization reactor is preferably 255 to 295 ℃. The reaction mass residence time is preferably from 0.2 to 0.8h.

In step S5, the reaction product in the pre-polymerization reaction unit is preferably fed into the post-polymerization reactor via a melt pump. The reaction pressure of the post-polymerization reactor is preferably-0.06 MPa or less. The reaction temperature of the postpolymerization reactor is preferably 280-335 ℃. The reaction product after the polycondensation reaction of the pre-polymerization reaction device is further subjected to the polycondensation reaction in the post-polymerization reaction device to form a polymerization product with the number average molecular weight of 22000-38000.

Preferably, after step S5, the reaction product of the post-polymerization reaction device is pelletized underwater by the underwater pelletizer to obtain polymer particles, and the method further includes sequentially passing the reaction product of the post-polymerization reaction device through the pelletizing device, the drying device and the classifying and screening device;

the granulating device is used for granulating the reaction product of the post-polymerization reaction device to obtain polymer particles;

the drying device is used for drying the polymer particles,

the classifying and screening device is used for screening the dried polymer particles to obtain polyamide particles.

In step S1, the reaction raw materials preferably further comprise additives for performing the salt formation reaction, as known to those skilled in the art. The additive may be conventional in the art, and may be generally any one or a combination of several of a capping agent, a catalyst, an antioxidant, a heat stabilizer, a weather-resistant agent, a pigment, a gloss enhancer, a dye, a crystallization accelerator, a matting agent, a plasticizer, an antistatic agent, a flame retardant, an inorganic filler, a metal, and a metal salt. The content of the additive is 0.01-3% of the total amount of polyamide monomers or the mass of polyamide salt.

Wherein the heat stabilizer further comprises one or more of phosphoric acid, phosphorous acid, trimethyl phosphite, triphenyl phosphite, trimethyl phosphate, triphenyl phosphate, sodium hypophosphite, zinc hypophosphite, calcium hypophosphite and potassium hypophosphite.

Wherein the crystallization promoter further comprises a long carbon chain carboxylic acid metal salt, the number of carbon atoms of the long carbon chain carboxylic acid is preferably 10-30, and the metal preferably comprises one or more of calcium, magnesium and zinc.

Wherein the inorganic filler further comprises one or more of glass fiber, glass beads, carbon fiber, carbon black and graphite.

Wherein the weathering agent may be of any type known in the art including, but not limited to, resorcinol, salicylates, benzotriazoles, benzophenones, hindered amines, and the like.

Wherein the pigment may be of any type known in the art including, but not limited to, cadmium sulfide, phthalocyanines, carbon black, and the like.

Wherein the gloss enhancer may be of any type known in the art including, but not limited to, titanium oxide, calcium carbonate, and the like.

Wherein the plasticizer may be of any type known in the art including, but not limited to, octyl paraoxybenzoate, N-butylbenzenesulfonamide, and the like.

The antistatic agent may be any type known in the art, including but not limited to alkyl sulfate type anionic antioxidants, quaternary ammonium salt type cationic antistatic agents, nonionic antistatic agents (such as polyoxyethylene sorbitan monostearate), amphoteric antistatic agents based on betaine, and the like.

The flame retardant may be any type known in the art including, but not limited to, melamine cyanurate, hydroxides (such as magnesium hydroxide or aluminum hydroxide), ammonium polyphosphate, brominated polystyrene, brominated polyphenylene oxide, brominated polycarbonate, brominated epoxy resin, a combination of any bromine-based flame retardant and antimony trioxide, and the like.

Those skilled in the art know that d is known as daltons (Da 1 ton), and d is an index used to represent the degree of dispersion of the molecular weight distribution.

On the basis of the common general knowledge in the field, the above preferred conditions can be arbitrarily combined to obtain the preferred examples of the utility model.

The reagents and materials used in the present utility model are commercially available.

The utility model has the positive progress effects that:

the continuous production device for polyamide resin provided by the utility model has the following advantages: according to the utility model, the static mixing internal component is arranged in the reactor, so that the reaction device is simpler and more efficient, and is convenient to assemble, disassemble and clean; on the other hand, the fluid entering the tubular reactor can meet the condition of plug flow on the whole, and can realize the full mixing of local units in the flowing process of the fluid, strengthen mass and heat transfer, and make the reaction more sufficient, thereby reducing the residence time of the fluid in the reactor, and the molecular weight distribution in the process of forming the high polymer of the polyamide resin is narrower, and the molecular weight distribution index can be smaller than 2.5. In addition, by selecting a specific tubular reactor as a prepolymerization reactor, a prepolymerization reactor and a postpolymerization reactor, the reactor replaces a conventional horizontal prepolymerization reactor and a postpolymerization reactor, effectively reduces the back mixing degree of the fluid, avoids the defect of insufficient surface area of the reaction fluid in unit volume, and has no dead angle in the reactor.

Drawings

FIG. 1 is a schematic view of an apparatus for continuously producing a polyamide resin of example 1.

Fig. 2 is a process flow diagram of example 1.

FIG. 3 is a schematic view of an SK-type internals.

Fig. 4 is a schematic view of an SX type internals.

Reference numerals illustrate:

auxiliary agent adding groove 1

Paddle type stirring salification reaction kettle 2

Two sections of first U-shaped pipe connected in series straight pipe type reactor 3

Flash evaporator 4

Straight pipe reactor 5

Two sections of the second U-shaped pipe are connected in series with each other in sequence to form a straight pipe type reactor 6

Condenser 7

Condensate collector 8

Spray tower 9

Underwater granulator 10

Fluidized bed dryer 11

Hierarchical screening machine 12

Packaging machine 13

Detailed Description

The utility model is further illustrated by means of examples which follow, without thereby restricting the scope of the utility model thereto. The experimental methods, in which specific conditions are not noted in the following examples, were selected according to conventional methods and conditions, or according to the commercial specifications. It will be apparent that the described embodiments are some, but not all, embodiments of the utility model. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

The present example 1 provides a continuous production apparatus for polyamide resin, as shown in fig. 1, comprising a salifying reaction apparatus, a prepolymerization reaction apparatus, a flash evaporation apparatus, a pre-polymerization reaction apparatus and a post-polymerization reaction apparatus, which are connected in sequence;

the prepolymerization reaction device is a straight pipe type reactor 3 with two sections connected in series in sequence, wherein the two sections are connected with a first U-shaped pipe; the front polymerization reaction device is a straight pipe type reactor 5; the post-polymerization reaction device is a straight pipe type reactor 6 with two sections connected in series in sequence, wherein the two sections are connected by a second U-shaped pipe;

and static mixing internal components are arranged in the front polymerization reaction device and the rear polymerization reaction device;

the salifying reaction device is a paddle stirring salifying reaction kettle 2 and is used for carrying out salifying reaction on polyamide monomers or polyamide salt and water;

the prepolymerization reaction device is used for carrying out prepolymerization reaction on the salt solution after the salification reaction;

the flash evaporation device is used for carrying out flash evaporation on the reaction product of the prepolymerization reaction;

the pre-polymerization reaction device is used for carrying out gas-liquid separation and polymerization reaction on the reaction product subjected to flash evaporation;

the post-polymerization device is used for further polymerizing the products of the polymerization reaction in the pre-polymerization device.

The continuous production device for the polyamide resin can also comprise a raw material storage tank, an amine liquid preparation kettle and/or an acid liquid preparation kettle, wherein after monomer raw materials form solution or slurry in the amine liquid/acid liquid preparation kettle, the raw materials are connected with an inlet of a paddle stirring salification reaction kettle 2 through a preparation kettle outlet.

Wherein, the heating mode of the paddle stirring salification reaction kettle 2 is a jacket type.

Wherein the flash evaporation device is a flash evaporator 4.

The continuous production device of the polyamide resin further comprises a condensing device, wherein the condensing device comprises a condenser 7, a condensate collecting tank 8 and a spray tower 9 which are sequentially connected, a liquid outlet of the condenser 7 is connected with an inlet of the condensate collecting tank 8, and a gas outlet of the condensate collecting tank 8 is connected with an inlet of the spray tower 9; the inlet of the condenser 7 is connected with the gas outlet of the straight pipe reactor 3, the straight pipe reactor 5 and the second U-shaped pipe connected with the two sections of the straight pipe reactor 6 which are sequentially connected in series, and the condenser 7 is used for condensing the reaction steam of the prepolymerization device, the prepolymerization device and the post polymerization device.

The continuous production device for the polyamide resin further comprises a granulating device, a drying device and a classifying and screening device which are sequentially connected, wherein an inlet of the granulating device is connected with an outlet of the second U-shaped tube connected two sections of the straight tube type reactor 6 which are sequentially connected in series.

Wherein the pelletizer includes an underwater pelletizer 10.

Wherein the drying means comprise a fluid bed dryer 11.

Wherein the hierarchical screening device comprises a hierarchical screening machine 12.

Wherein, the continuous production device of the polyamide resin also comprises a packaging machine 13, the packaging machine 13 and a classifying screen 12.

Wherein the outlet of the flash evaporator 4 and the inlet of the straight tube reactor 5 are connected by a feed pump.

Wherein the outlet of the straight pipe type reactor 5 is connected with the inlet of the two sections of the straight pipe type reactor 6 which are connected in series in sequence and connected with the second U-shaped pipe through a melt pump.

Example 1:

the continuous production apparatus of polyamide resin of example 1 is shown in FIG. 1. The length of the tube body of the straight tube type reactor 5 is 5.5m, the outer diameter is 114mm, the number of the exhaust ports is 12, and the distance between two adjacent exhaust ports is 20cm; the inside of the straight pipe part of the straight pipe reactor 5 is connected with an SK type static mixer through a flange, the length of the static mixing internal component is 1000mm, the nominal size DN100, and the ratio of the inlet distance of the SK type static mixer to the straight pipe reactor 5 to the length of the pipe body of the straight pipe reactor 5 is 1:3.

Two sections of straight pipe reactors 6 connected in series in sequence are connected with each other through a second U-shaped pipe, and an SK-type static mixer (shown in figure 3) and an SX-type static mixer (shown in figure 4) are respectively connected inside the two sections of straight pipe reactors through flanges. Wherein, two sections of straight tube body lengths of the two sections of straight tube reactor 6 that the second U type union coupling connects gradually are 6.5m, external diameter 165mm, and the gas vent quantity is 18, and two adjacent gas vent interval is 30cm, external diameter 165mm of U type pipe.

The SX-type static mixer is connected to the front section of the two sections of the straight pipe type reactors 6 connected in series in sequence, the distance between the SX-type static mixer and the inlet of the two sections of the straight pipe type reactors 6 connected in series in sequence, which are connected in sequence, of the second U-type pipe is 900mm, the length of the SX-type static mixer is 1000mm, and the nominal size DN150.

The SK type static mixer is connected to the rear section of the two sections of the straight pipe type reactors 6 connected in series in sequence, which are connected in series through a flange, the outlet distance between the SK type static mixer and the two sections of the straight pipe type reactors 6 connected in series in sequence is 1200mm, the length of the SK type static mixer is 1000mm, and the nominal size DN150.

Fig. 2 is a process flow diagram of example 1. The preparation method of the polyamide resin of example 1 is as follows:

(1) 3382.09kg (33.1 kmol) of pentanediamine, 3663.8kg (31.53 kmol) of adipic acid, 4402g of sodium hypophosphite and water accounting for 62 percent of the total mass of the materials are added into a paddle stirring salifying reaction kettle 2, stirring is carried out for 60min, vacuum pumping is carried out for 3min, inert gas is introduced to normal pressure, circulation is carried out for 10 times, after replacement is completed, the temperature of the paddle stirring salifying reaction kettle 2 is increased to 80 ℃, the stirring speed is 70r/min and the stirring speed is kept for 3.5h, so that a salt solution with 61.7 percent of polyamide PA56 is formed;

(2) Introducing the polyamide PA56 salt solution formed in the step (1) into a first U-shaped pipe connected two-section sequentially connected straight pipe type reactor 3 through a pipeline, controlling the temperature and the pressure of each section of the first U-shaped pipe connected two-section sequentially connected straight pipe type reactor 3 through multi-section heating and controlling the opening of an exhaust port valve, gradually heating the first U-shaped pipe connected two-section sequentially connected straight pipe type reactor 3 from 185 ℃ to 255 ℃, controlling the pressure in the reactor to 1.7MPa, controlling the residence time of the reaction materials to 2.5h, and then introducing the reaction materials into a flash evaporator 4 through a flash evaporator 4 supply pump;

(3) The reaction materials are decompressed through a flash evaporator 4, in the decompression process, moisture in the materials is gasified rapidly, a gas-liquid mixed foam polymer is finally obtained, then the reaction materials are conveyed to a straight pipe type reactor 5 through a melt pump to carry out gas-liquid separation and further polycondensation, and meanwhile, the temperature of the straight pipe type reactor 5 is controlled to be 275 ℃, and the residence time of the reaction materials is controlled to be 0.4h;

(4) The materials from the outlet in the straight tube reactor 5 enter a straight tube reactor 6 connected with a second U-shaped tube through a melt pump, the pressure in the reactor is kept below-0.08 MPa, the temperature in the reactor is 280 ℃, and the prepolymer with the molecular weight of 14000 is further subjected to polycondensation reaction in the two sections of the straight tube reactor 6 connected with the second U-shaped tube in series; after a residence time of 0.4h, the reaction product is subjected to underwater pelletization by an underwater pelletizer 10 to obtain polymer particles, then the polymer particles enter an inlet of a fluidized bed dryer 11 through a pipeline, an outlet of the fluidized bed dryer 11 is connected with a classifying screen 12, and an outlet material of the classifying screen 12 enters a packaging machine 13, so that polyamide PA56 polyamide particles with the relative viscosity of 2.67 are finally obtained.

Example 2:

The continuous production apparatus of polyamide resin of example 2 is shown in FIG. 1. The length of the tube body of the straight tube type reactor 5 is 9.2m, the outer diameter is 140mm, the number of the exhaust ports is 14, and the distance between two adjacent exhaust ports is 22cm; the straight pipe part of the straight pipe reactor 5 is connected with an SX type static mixer through a flange, the length of a static mixing internal component is 1500mm, the nominal size DN125, and the ratio of the distance between the static mixing internal component and the inlet of the straight pipe reactor 5 to the length of the pipe body of the straight pipe reactor 5 is 1:3.

Two sections of straight pipe reactors 6 connected in series in sequence are connected with each other through a second U-shaped pipe, and an SV type static mixer and an SX type static mixer are respectively connected inside the two sections of straight pipe reactors through flanges. The length of the tube body of the straight tube type reactor 6 connected with the second U-shaped tube in series in sequence is 10.6m, the outer diameter is 114mm, the number of the exhaust ports is 12, the distance between two adjacent exhaust ports is 30cm, and the outer diameter of the U-shaped tube is 114mm;

wherein, the SV type static mixer is connected with the front section of a second U-shaped pipe connected two sections of straight pipe type reactors 6 which are connected in series in sequence, the distance from the inlet of the reactor is 1250mm, the length of the SV type static mixer is 1500mm, and the nominal size DN100.

The SX-type static mixer is connected with the rear section of the second U-shaped tube connected two sections of straight tube type reactors 6 which are sequentially connected in series through a flange, the distance from the rear section to the outlet of the reactor is 1500mm, the length of the SX-type static mixer is 1000mm, and the nominal size DN100 is achieved.

The preparation method of the polyamide resin of example 2 is as follows:

(1) 3841.07kg (37.59 kmol) of pentanediamine, 1689.12kg (10.17 kmol) of terephthalic acid, 3746.13kg (25.63 kmol) of adipic acid, 2730g of sodium hypophosphite and 58% of water by total mass of the materials are added into a paddle stirring salifying reaction kettle 2, vacuumizing is carried out for 3min, inert gas is introduced to normal pressure, circulation is carried out for 10 times, after replacement is completed, the paddle stirring salifying reaction kettle 2 is heated to 135 ℃, the stirring speed is 78r/min and kept for 4.5h, and a salt solution of polyamide PA5T/56 with the concentration of 63.3% is formed;

(2) Introducing the polyamide PA5T/56 salt solution formed in the step (1) into two sections of straight pipe reactors 3 which are sequentially connected in series and are connected with a first U-shaped pipe through a pipeline, controlling the temperature and the pressure of each section of the two sections of straight pipe reactors 3 which are sequentially connected in series and are connected with the first U-shaped pipe through a plurality of sections of heating and controlling the opening degree of an exhaust port valve, gradually heating the two sections of straight pipe reactors 3 which are sequentially connected in series and are connected with the first U-shaped pipe from 185 ℃ to 271.5 ℃, controlling the pressure in the reactors to 2.1MPa, keeping the reaction materials for about 2.3 hours, and then introducing the reaction materials into a flash evaporator 4 through a flash evaporator 4 supply pump;

(3) The reaction material is decompressed through a flash evaporator 64, and then the reaction material is conveyed to a straight pipe type reactor 5 through a melt pump for gas-liquid separation and further polycondensation, and meanwhile, the temperature of the straight pipe type reactor 5 is controlled to be 285 ℃, and the residence time of the reaction material is controlled to be 0.7h;

(4) The outlet materials in the straight pipe type reactor 7 enter the two sections of the straight pipe type reactors 6 connected in series in sequence through a melt pump, and the straight pipe parts in the two sections of the straight pipe type reactors 6 connected in series in sequence through the second U-shaped pipe are respectively connected with an SV type static mixer and an SX type static mixer through flanges. The pressure of the two sections of the straight pipe type reactors 6 which are connected in series in sequence, which are connected in the second U-shaped pipe, is kept below-0.07 MPa, the temperature in the reactors is 295 ℃, and the prepolymer with the molecular weight of about 15000 is further subjected to polycondensation reaction in the two sections of the straight pipe type reactors 6 which are connected in series in sequence, which are connected in the second U-shaped pipe; after the residence time of 0.6h, the reaction product is subjected to underwater pelletization by an underwater pelletizer 10 to obtain polymer particles, then the polymer particles enter an inlet of a fluidized bed dryer 11 through a pipeline, an outlet of the fluidized bed dryer 11 is connected with a classifying screen 12, and the material at the outlet of the classifying screen 12 enters a packaging machine 13, so that polyamide PA5T/56 polyamide particles with the relative viscosity of 2.71 are finally obtained.

Example 3:

the apparatus for continuous production of polyamide resin of example 3 is shown in FIG. 1. Wherein, the length of the tube body of the straight tube type reactor 5 is 7.5m, the outer diameter is 219mm, the number of the exhaust ports is 12, and the distance between two adjacent exhaust ports is 16cm; the straight pipe part is connected with an SX-type static mixer through a flange, the length of a static mixing inner member is 600mm, the nominal size DN200, and the static mixing inner member is positioned at a half section of the front polymerization reactor from the inlet.

Two sections of straight pipe reactors 6 connected in series in sequence are connected with each other through a second U-shaped pipe, and an SK-type static mixer and an SX-type static mixer are respectively connected inside the two sections of straight pipe reactors through flanges. The length of the tube body of the straight tube type reactor 8 connected with the second U-shaped tube in sequence is 16.5m, the outer diameter is 140mm, the number of exhaust ports is 24, the distance between two adjacent exhaust ports is 30cm, and the outer diameter of the U-shaped tube is 140mm.

The SX-type static mixer is connected to the front section of the two sections of straight pipe type reactors 6 connected in series in sequence, the distance between the SX-type static mixer and the front section of the two sections of straight pipe type reactors 6 connected in series in sequence is 1350mm, the length of the SX-type static mixer is 1500mm, and the nominal size DN125 is obtained;

The SK type static mixer is connected to the rear section of the two sections of the straight pipe type reactors 6 connected in series in sequence, which are connected in series through a flange, the outlet distance between the SK type static mixer and the two sections of the straight pipe type reactors 6 connected in series in sequence is 1100mm, the length of the SK type static mixer is 2000mm, and the nominal size DN125 is achieved.

The preparation method of the polyamide resin of example 3 is as follows:

(1) 2874.07kg (17.30 kmol) of terephthalic acid, 2925.25kg (16.78 kmol) of 1, 10-decanediamine, 105.17kg (0.52 kmol) of 1, 10-decanedioic acid, 63.50kg (0.52 kmol) of benzoic acid, 2984g of sodium hypophosphite and water accounting for 60% of the total mass of the materials are added into a paddle stirring salification reaction kettle 2, vacuumizing is carried out for 5min, inert gas is introduced to normal pressure, circulation is carried out for 10 times, after replacement is completed, the pressure in the paddle stirring salification reaction kettle 2 is controlled to be within 0.5Mpa, the temperature of the paddle stirring salification reaction kettle 2 is raised to 120 ℃, the stirring speed is 71r/min and maintained for 3.6h, and a salt solution of polyamide PA10T/1010 with the concentration of 62.5% is formed;

(2) Introducing the polyamide PA10T/1010 salt solution formed in the step (1) into two sections of straight pipe reactors 3 which are sequentially connected in series and are connected with a first U-shaped pipe through a pipeline, controlling the temperature and the pressure of each section of the two sections of straight pipe reactors 3 which are sequentially connected in series and are connected with the first U-shaped pipe through multistage heating and controlling the opening degree of an exhaust port valve, gradually heating the temperature 170 ℃ of the two sections of straight pipe reactors 3 which are sequentially connected in series and are connected with the first U-shaped pipe to 275.5 ℃, controlling the pressure in the reactors to 2.5MPa, keeping the reaction materials for about 2.6 hours, and then supplying the reaction materials into a flash evaporator 4 through a flash evaporator 4 supply pump;

(3) The reaction mass is decompressed through a flash evaporator 4, and then the reaction mass is conveyed to a straight pipe type reactor 75 through a melt pump for gas-liquid separation and further polycondensation, and meanwhile, the temperature of the straight pipe type reactor 5 is controlled to be 297.5 ℃, and the residence time of the reaction mass is controlled to be 0.8h;

(4) The material from the outlet in the straight tube reactor 5 enters a straight tube reactor 6 connected with a second U-shaped tube through a melt pump, the pressure in the reactor is kept below minus 0.08MPa, the temperature in the reactor is 315 ℃, and prepolymer with molecular weight of about 17500 is further subjected to polycondensation reaction in the two sections of the straight tube reactor 6 connected with the second U-shaped tube in series; after the residence time of 0.72h, the reaction product is subjected to underwater pelletization by an underwater pelletizer 10 to obtain polymer particles, then the polymer particles enter an inlet of a fluidized bed dryer 11 through a pipeline, an outlet of the fluidized bed dryer 11 is connected with a classifying screen 12, and the material at the outlet of the classifying screen 12 enters a packaging machine 13, so that polyamide PA10T/1010 polyamide particles with the relative viscosity of 2.21 are finally obtained.

Example 4:

the apparatus for continuous production of polyamide resin of example 4 is shown in FIG. 1. Wherein, the length of the tube body of the straight tube type reactor 5 is 8.2m, the outer diameter is 140mm, the number of the exhaust ports is 12, and the distance between two adjacent exhaust ports is 18cm; the straight pipe part is connected with an SK type static mixer through a flange, the length of the SK type static mixer is 800mm, the nominal size DN125, the inlet distance between the static mixing internal component and the straight pipe type reactor 5, and the ratio of the length of the pipe body of the straight pipe type reactor 5 is 1:3.

Two sections of straight pipe reactors 6 connected in series in sequence are connected with each other through a second U-shaped pipe, and an SH type static mixer and an SX type static mixer are respectively connected inside the two sections of straight pipe reactors through flanges. Wherein, two sections of the second U-shaped tube connected in series in turn are 14.8m in tube length, 140mm in outer diameter, 18 in number of exhaust ports, 24cm in interval between two adjacent exhaust ports and 140mm in outer diameter of the U-shaped tube.

The SH type static mixer is connected to the front section of the two sections of straight pipe type reactors 6 connected in series in sequence, the distance between the SH type static mixer and the inlet of the two sections of straight pipe type reactors 6 connected in series in sequence, which are connected in sequence, of the second U type pipe is 1350mm, the length of the SH type static mixer is 1500mm, and the nominal size DN125;

the SX-type static mixer is connected to the rear section of the two sections of the straight pipe type reactors 6 connected in series in sequence, which are connected in series through a flange, the distance between the SX-type static mixer and the outlet of the two sections of the straight pipe type reactors 6 connected in series in sequence, which are connected in series, is 2000mm, the length of the static mixing internal component is 2000mm, and the nominal size DN125 is achieved.

The preparation method of the polyamide resin of example 4 is as follows:

(1) 4761.03kg (40.97 kmol) of hexamethylenediamine, 2278.45kg (15.59 kmol) of adipic acid, 3159.49kg (19.02 kmol) of terephthalic acid, 3059g of sodium hypophosphite, 4588g of antioxidant H10 and 55% of water by mass of the total mass of the materials are added into a paddle stirring salification reaction kettle 2, vacuumizing is carried out for 5min, inert gas is introduced to normal pressure, the circulation is carried out for 10 times, after replacement is completed, the paddle stirring salification reaction kettle 2 is heated to 125 ℃, the stirring speed is 66r/min and kept for 4.1H, and a salt solution of polyamide PA6T/66 with the concentration of 64.5% is formed;

(2) Introducing the polyamide PA6T/66 salt solution formed in the step (1) into two sections of straight pipe type reactors 3 which are sequentially connected in series and are connected with a first U-shaped pipe through a pipeline, controlling the temperature and the pressure of each section of the two sections of straight pipe type reactors 3 which are sequentially connected in series and are connected with the first U-shaped pipe through a plurality of sections of heating and controlling the opening degree of an exhaust port valve, gradually heating the temperature of the two sections of straight pipe type reactors 3 which are sequentially connected in series and are connected with the first U-shaped pipe from 160 ℃ to 280.5 ℃, controlling the pressure in the reactors to 2.0MPa, keeping the reaction materials for about 1.8 hours, and then introducing the reaction materials into a flash evaporator 4 through a flash evaporator 4 feed pump;

(3) The pressure of the reaction material is reduced through a flash evaporator 4, then the reaction material is conveyed to a straight pipe type reactor 5 through a melt pump for gas-liquid separation, and meanwhile, the temperature of the straight pipe type reactor 5 is controlled to be 295 ℃, and the residence time of the reaction material is 0.8h;

(4) The material from the outlet in the straight tube reactor 5 enters a straight tube reactor 6 connected with a second U-shaped tube through a melt pump, the pressure in the reactor is kept below minus 0.08MPa, the temperature in the reactor is 315 ℃, and the prepolymer with the molecular weight of 16000 is further subjected to polycondensation reaction in the two sections of the straight tube reactor 6 connected with the second U-shaped tube in series; after a residence time of 1.0h, the reaction product is subjected to underwater pelletization by an underwater pelletizer 10 to obtain polymer particles, then the polymer particles enter an inlet of a fluidized bed dryer 11 through a pipeline, an outlet of the fluidized bed dryer 11 is connected with a classifying screen 12, and an outlet material of the classifying screen 12 enters a packaging machine 13, so that polyamide PA6T/66 polyamide particles with the relative viscosity of 2.28 are finally obtained.

Comparative example 1

In this example, the steps (1) to (4) were the same as in example 1, except that the pre-polymerization reaction apparatus and the post-polymerization reaction apparatus were not provided with static mixing internals.

Comparative example 2

In this example, the steps (1) to (4) were the same as in example 2, except that the pre-polymerization reaction apparatus and the post-polymerization reaction apparatus were not provided with static mixing internals.

Comparative example 3

In this example, the steps (1) to (4) were the same as in example 3, except that the pre-polymerization reaction apparatus and the post-polymerization reaction apparatus were not provided with static mixing internals.

Effect example 1

(1) Method for detecting relative viscosity eta r

Test instrument: ubbelohde viscometer AVS600, available from Shanghai Lu scientific instruments Inc.

The testing method comprises the following steps: the concentrated sulfuric acid method of the Ubbelohde viscometer accurately weighs 0.5+/-0.0002 g of the dried polyamide resin material sample, 50mL of concentrated sulfuric acid (96%) is added for dissolution, and the flow-through time t0 of the concentrated sulfuric acid and the flow-through time t of the polyamide resin material solution are measured and recorded in a constant temperature water bath at 25 ℃. The relative viscosity number calculation formula: relative viscosity ηr=t/t 0; wherein: t: the time of the solution flow; t0: solvent flow-through time.

(2) Melting Point test

Test instrument: differential scanning calorimeter DSC Q20, available from TA Instruments, USA.

The testing method comprises the following steps: weighing 5-8mg of sample, placing into an aluminum crucible, comparing with an empty crucible, heating to 300 ℃ at 20 ℃/min under the protection of nitrogen (the air flow rate is 50 mL/min), staying for 3min to eliminate heat history, cooling to 30 ℃ at 20 ℃/min, heating to 300 ℃ at 20 ℃/min, and recording the change of thermal break in the temperature scanning process.

(3) Yellowness index test

Test instrument: yellowness index instrument

The testing method comprises the following steps: test methods refer to HG/T3862-2006.

(4) Molecular weight test

Test instrument: gel permeation chromatograph

The testing method comprises the following steps: the molecular weight and distribution relative to PMMA are obtained by testing by a Gel Permeation Chromatography (GPC) method, wherein the standard substance is PMMA, the solvent is trifluoroethanol+0.05% potassium trifluoroacetate, filtering by a PTFE membrane after complete dissolution, and analyzing by sample injection at 40 ℃.

The resin materials prepared in examples 1 to 4 and comparative examples 1 to 3 were tested, and the test results are shown in Table 1.

TABLE 1 Performance test results 1

As can be seen from the data in Table 1, the polyamide resin production device of the utility model has a simpler flow than the conventional production device, and after the static mixing internal component unit assembly is added, the obtained polymer has high relative viscosity under the same production conditions, the melting point is closer to that of a small-scale formula and process, the yellow index of the resin slice is lower, the molecular weight distribution is narrower, and the chemical reaction efficiency is higher.

It is known to those skilled in the art that PDI, (Polymer dispersity index) is a polymer dispersibility index, which is used to describe the molecular weight distribution of a polymer, and its value is also =m (w)/M (n), the larger the value is greater than 1. The wider the molecular weight distribution, the smaller the PDI, and the more uniform the molecular weight distribution.

Effect example 2

Mechanical property test of resin

Test instrument: the electronic universal tester UTM4304 and impact strength tester PTM1000 are all purchased from Shenzhen Sansi aspect technology Co., ltd

The testing method comprises the following steps: drying the polyamide resin slice until the moisture content is below 1000ppm, and performing injection molding by using an injection molding machine (the injection molding machine is conventional equipment in the field), wherein the determination method of the tensile strength (MPa) and the elastic modulus (MPa) of the resin is detected by referring to the method of GB/T14344-2008 (the specification of a tensile test spline is 170 x 20 x 4mm and the polyamide resin slice is dumbbell-shaped); method for determining flexural strength (MPa) of resin with reference to ISO527-2 method (flexural test bar specification: 80 x 10 x 4 mm); the determination of the notched impact strength (J/cm 2) of the resin cantilever beam was carried out with reference to ISO 197/leA (impact test bars: 80X 10X 4mm, notched on one side).

The resin materials prepared in examples 1 to 4 and comparative examples 1 to 3 were tested, and the test results are shown in Table 2.

TABLE 2 Performance test results 2

As can be seen from Table 2, the continuous production apparatus for polyamide resin in examples 1 to 4 produced a resin material having better mechanical properties than the resin produced by the equipment without adding the static mixing member, which is generally inferior, by selecting a specific tubular reactor as the prepolymerization apparatus, the prepolymerization apparatus and the postpolymerization apparatus, and by providing the static mixing internals in combination.

Claims (10)

1. The continuous production device for the polyamide resin is characterized by comprising a salifying reaction device, a prepolymerization reaction device, a flash evaporation device, a pre-polymerization reaction device and a post-polymerization reaction device which are connected in sequence;

the prepolymerization reaction device is a straight pipe type reactor with one section or more than two sections connected by U-shaped pipes and connected in series in sequence;

the pre-polymerization reaction device is a straight pipe type reactor with one section or more than two sections connected by U-shaped pipes and connected in series in sequence;

the post-polymerization reaction device is a straight pipe type reactor or a straight pipe type reactor with more than two sections connected by U-shaped pipes and connected in series in sequence;

static mixing internal components are arranged in the pre-polymerization reaction device and the post-polymerization reaction device;

The salifying reaction device is used for carrying out salifying reaction on polyamide;

the prepolymerization reaction device is used for carrying out prepolymerization reaction on the salt solution after the salification reaction;

the flash evaporation device is used for carrying out flash evaporation on the reaction product of the prepolymerization reaction;

the pre-polymerization reaction device is used for carrying out gas-liquid separation and polymerization reaction on the reaction product after flash evaporation;

the post-polymerization device is used for further polymerizing the products of the polymerization reaction in the pre-polymerization device.

2. The continuous production apparatus for polyamide resin as claimed in claim 1, wherein the continuous production apparatus for polyamide resin satisfies one or more of the following conditions:

(1) the prepolymerization reaction device is a straight pipe type reactor with two sections connected in series in sequence, wherein the two sections are connected through a U-shaped pipe;

(2) the pre-polymerization reaction device is a section of straight pipe type reactor;

(3) the post-polymerization reaction device is a straight pipe type reactor with two sections connected in series in sequence, wherein the two sections are connected through a U-shaped pipe.

3. The continuous production apparatus for polyamide resin as claimed in claim 1, wherein the continuous production apparatus for polyamide resin satisfies one or more of the following conditions:

(1) The static mixing internal component is selected from one or more of an SV type static mixer, an SK type static mixer, an SL type static mixer, an SX type static mixer and an SH type static mixer;

(2) the ratio of the inlet distance between the static mixing internal component and the pre-polymerization reaction device to the length of the pipe body of the pre-polymerization reaction device is (1:3) - (1:2);

(3) the post-polymerization reaction device is provided with two static mixing internal components, and the ratio of the inlet distance between the first static mixing internal component and the post-polymerization reaction device to the length of the pipe body of the post-polymerization reaction device is (1:4) - (1:2); the ratio of the outlet distance of the second static mixing internal component to the post-polymerization reaction device to the length of the pipe body of the post-polymerization reaction device is (1:4) - (1:2);

(4) the length of the static mixing inner member is 500mm-2000mm.

4. The continuous production apparatus for polyamide resin as claimed in claim 3, wherein the continuous production apparatus for polyamide resin satisfies one or more of the following conditions:

(1) the inlet distance between the first static mixing inner member and the post-polymerization reaction device is 900mm-1500mm;

(2) The outlet distance between the second static mixing inner member and the post-polymerization reaction device is 1100mm-2000mm.

5. The continuous production apparatus for polyamide resin as claimed in claim 1, wherein the continuous production apparatus for polyamide resin satisfies one or more of the following conditions:

(1) the length of the tube body of the first-section straight tube type reactor is 5-20m, and the ratio of the length of the tube body of the first-section straight tube type reactor to the inner diameter of the tube body is 60-650;

(2) the length of the tube body of the straight tube type reactor which is connected with more than two sections of U-shaped tubes in series in sequence is 5-20m, and the ratio of the length of the tube body to the inner diameter of the tube body is 60-650.

6. The continuous production apparatus for polyamide resin as claimed in claim 1, wherein the continuous production apparatus for polyamide resin satisfies one or more of the following conditions:

(1) the continuous production device of the polyamide resin also comprises a raw material storage tank, wherein the outlet of the raw material storage tank is connected with the inlet of the salifying reaction device;

(2) the flash evaporation device is a flash evaporator.

7. The continuous production apparatus for a polyamide resin as claimed in claim 1, further comprising a condensing means, wherein any one or more of the gas outlet of the prepolymerization means, the gas outlet of the prepolymerization means and the gas outlet of the postpolymerization means is connected to the inlet of the condensing means.

8. The continuous production apparatus for polyamide resin as claimed in claim 7, wherein the condensing means comprises a condenser, a condensate collecting tank and a spray tower which are connected in this order, a liquid outlet of the condenser is connected to an inlet of the condensate collecting tank, and a gas outlet of the condensate collecting tank is connected to an inlet of the spray tower; any one or more than two gas outlets of the prepolymerization reaction device, the pre-polymerization reaction device and the post-polymerization reaction device are connected with an inlet of a condenser, and the condenser is used for condensing reaction steam of the prepolymerization reaction device, the pre-polymerization reaction device and/or the post-polymerization reaction device.

9. The continuous production apparatus for polyamide resin as claimed in claim 1, further comprising a pelletizing apparatus, a drying apparatus and a classifying screen apparatus connected in this order, wherein an inlet of the pelletizing apparatus is connected to an outlet of the post-polymerization reaction apparatus.

10. The continuous production apparatus for polyamide resin as claimed in claim 9, wherein the continuous production apparatus for polyamide resin satisfies one or more of the following conditions:

(1) The granulating device comprises an underwater granulator;

(2) the drying device comprises a spray dryer, a microwave dryer or a fluidized bed dryer;

(3) the grading screening device comprises a grading screening machine;

(4) the continuous production device for the polyamide resin further comprises a packaging device, and the packaging device is connected with the classifying and screening device.