Continuous production device for polyamide resin

Abstract

The utility model provides a continuous production device for polyamide resin. The system comprises a salt forming device, a concentration device, a prepolymerization device and a screw extrusion device which are connected in sequence, and the salt forming device is a salt forming reaction kettle and is used for salt forming reaction; the concentration device is used for concentrating and dewatering reactants of the salt forming reaction to obtain a concentrated polyamide salt solution; the prepolymerization device is a U-shaped tubular polymerization reactor and is used for carrying out polymerization reaction on the concentrated salt solution of polyamide; and the screw extrusion device is used for carrying out post-polycondensation reaction, melt tackifying and / or polyamide modification on the reaction materials of the polymerization reaction. According to the device, melt extrusion of the screw extruder is effectively utilized to be combined with the U-shaped tubular polymerization reactor, so that the molecular weight of a prepolymer is further improved in a secondary reaction, and meanwhile, part of micromolecular monomers, solvents and low-molecular impurities generated in the polymerization process are effectively removed.

Description

[0001] This application claims the right to file with the State Intellectual Property Office of China on July 11, 2023,

[0002] Patent application number is 202321814318.4, and the priority right is given to the prior application entitled “A continuous production device for polyamide resin”. Technical Field

[0003] The utility model relates to the field of polyamide production, in particular to a continuous production device for polyamide resin. Background Art

[0004] Polyamide material is a general term for thermoplastic resins containing repeating amide groups -[NHCO]- on the main chain of the molecule, including aliphatic PA, aliphatic-aromatic PA and aromatic PA. Due to its excellent properties such as heat resistance, chemical resistance, weathering resistance, mechanical properties, and electrical properties, it is widely used in spinning, injection molding, film making and other fields. High-temperature resistant polyamide resin has the characteristics of high strength, high modulus, and high temperature resistance. It is widely used in electronic appliances, communication equipment components, automotive components, electrical control system components and other fields, and the market demand is also increasing.

[0005] Polyamide resin can be obtained by polycondensation of diamine and diacid, or by polycondensation of lactam or ring-opening polymerization. The reaction is generally carried out in a polymerization kettle and is an intermittent polymerization, but the molecular weight of the prepolymer is unstable, and usually a viscosity-increasing treatment is required to increase the molecular weight of the polyamide. However, the increase in viscosity will lead to poor fluidity and easily cause discharge failure. In addition, the polyamide material needs to be modified to improve its functionality in a certain aspect. Generally, the prepared polyamide resin masterbatch is mixed with a certain amount of functional additives and then melt-extruded again for enhanced modification. The reheating extrusion granulation has a long process chain, and repeated heating leads to high energy consumption, and it is easy to cause the polymer to decompose at high temperature, affecting the properties and performance of the material.

[0006] However, the synthesis of high-temperature resistant polyamide resins in my country started relatively late, and the production process is mainly based on the two-step method of intermittent prepolymerization and viscosity increase. Currently, in the production of high-temperature resistant polyamide resins, there are still problems such as difficulty in controlling the viscosity of prepolymers, easy oxidation and yellowing of polymers and overheating decomposition, large molecular weight variations in batch products, low production efficiency, and unsuitability for large-scale production. Therefore, considering production costs and product stability, the continuous polymerization process is undoubtedly the best choice for the production of high-temperature resistant polyamide resins. Utility Model Content

[0007] In order to solve the deficiencies in the prior art, the utility model provides a continuous production device for polyamide resin, which comprises a salt-forming device, a concentrating device, a prepolymerization device and a screw extruder connected in sequence.

[0008] The salifying device is a salifying reaction kettle, which is used for carrying out salifying reaction;

[0009] The concentration device is used for concentrating and removing water from the reactants of the salifying reaction to obtain a concentrated polyamide salt solution;

[0010] The prepolymerization device is a U-shaped tube polymerization reactor; the U-shaped tube polymerization reactor is used for carrying out prepolymerization reaction on the salt solution after the salifying reaction.

[0011] In the present utility model, preferably, the continuous polyamide resin production device further includes a salt solution storage tank, and the salifying reaction kettle, the salt solution storage tank and the concentration device are connected in sequence.

[0012] In the present utility model, the gas outlet of the prepolymerization device is connected to a heat exchanger and a condensate collection tank in sequence; the condensate collection tank is also connected to a vacuum unit;

[0013] The heat exchanger is used for condensing the gas generated by the polymerization reaction;

[0014] The vacuum unit is used for evacuating the heat exchange liquid collection tank to obtain a vacuum environment.

[0015] In the present utility model, the continuous polyamide resin production device further includes an additive addition tank connected to the salifying reaction kettle, and the outlet of the additive addition tank is connected to the inlet of the salifying reaction kettle.

[0016] In the present utility model, preferably, the heating form of the salifying reaction kettle and / or the concentration device is one or a combination of two or more of jacket type, internal coil type and external coil type. The heating form of the salifying reaction kettle is more preferably jacket type. The heating form of the concentration device is more preferably internal coil type. The concentration device is preferably a concentration kettle.

[0017] In the present utility model, preferably, the screw extruder is more preferably a single screw extruder, a twin screw extruder, a multi-screw extruder or a plunger extruder; more preferably a twin screw extruder.

[0018] In the present utility model, for the continuous polyamide resin production device, the screw extruder is further provided with a second feed port. The first feed port is arranged at the front section of the screw extruder, and the second feed port is arranged at the middle section of the screw extruder. The second feed port is used for adding additives.

[0019] In the present utility model, the screw diameter of the screw extruder is 70 - 135 mm, more preferably 90 - 125 mm; the length-diameter ratio of the screw of the screw extruder is 28 - 70, more preferably 45 - 64.

[0020] In the present utility model, the screw rotation speed of the screw extruder is 150 - 700 rpm, the residence time is 0.1 - 30 min, more preferably 0.1 - 20 min; the extrusion output of the screw extruder is 600 - 2750 kg / h, more preferably 700 - 1100 kg / h.

[0021] In the present utility model, the number of screw vacuum exhaust ports of the screw extruder is 3 - 6, preferably 3 - 5.

[0022] In the present utility model, preferably, the continuous polyamide resin production device further comprises a pelletizing device, a drying device and a grading and screening device which are connected in sequence, and the inlet of the pelletizing device is connected to the outlet of the screw extrusion device.

[0023] In the present utility model, the pelletizing device preferably comprises an underwater pelletizer.

[0024] In the present utility model, the drying device preferably comprises a dryer, and the dryer is preferably a spray dryer, a microwave dryer or a fluidized bed dryer, and the fluidized bed dryer is more preferably a continuous fluidized bed dryer.

[0025] In the present utility model, the grading and screening device is preferably a grading and screening machine.

[0026] In the present utility model, preferably, the continuous polyamide resin production device further comprises a packaging device, and the packaging device is connected to the grading and screening device. The packaging device is preferably a packaging machine.

[0027] The continuous polyamide resin production device provided by the present utility model has the following advantages:

[0028] (1) By combining the melt extrusion of a twin-screw extruder with a U-shaped tube polymerization reactor, the prepolymer at the outlet of the U-shaped tube polymerization reactor reacts again in the twin-screw extruder, which can further increase the molecular weight of the polymer, and at the same time can effectively remove some small molecule monomers, solvents and low molecular impurities generated during the polymerization process;

[0029] (2) In the preferred scheme, a second feed inlet is arranged in the middle section of the twin-screw extruder, and other additives can be added at the second feed inlet, which can avoid catalytic polymerization side reactions of functional additives, etc., and at the same time can reduce the phenomena of agglomeration and sedimentation of the additives during the polymerization process. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic flow chart of a specific continuous polyamide resin production device of the present utility model;

[0031] Figure 2Schematic diagram of the continuous production device of polyamide resin for Embodiment 1 of the present utility model.

[0032] Among them, an auxiliary agent addition tank 1, a salt-forming reaction kettle 2, a salt solution storage tank 3, a concentration kettle 4, a U-shaped tube polymerization reactor 5, a heat exchanger 6, a condensate collection tank 7, a vacuum unit 8, a twin-screw extruder 9, a first feed inlet 10 of the twin-screw extruder, a second feed inlet 11 of the twin-screw extruder, an underwater pelletizer 12, a fluidized bed dryer 13, a grading and screening machine 14, and a packaging machine 15. Specific implementation manners

[0033] The present utility model will be further described below by way of embodiments, but the present utility model is not limited to the scope of the described embodiments. For the experimental methods without specific conditions in the following embodiments, they are carried out according to conventional methods and conditions, or selected according to the product specifications. Obviously, the described embodiments are some embodiments of the present utility model, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts belong to the scope of protection of the present utility model.

[0034] In some specific implementation manners, as Figure 1 shown, the continuous production device of polyamide resin provided by the present utility model includes a salt-forming device, a concentration device, a prepolymerization device, and a screw extrusion device connected in sequence;

[0035] The salt-forming device includes a salt-forming reaction kettle and a salt solution storage tank connected in sequence, and the outlet of the salt solution storage tank is connected to the inlet of the concentration device;

[0036] The prepolymerization device is a U-shaped tube polymerization reactor;

[0037] The screw extrusion device is a twin-screw extruder, which is provided with a first feed inlet and a second feed inlet;

[0038] The gas outlet of the prepolymerization device is connected to a heat exchanger and a condensate collection tank in sequence; the condensate collection tank is also connected to a vacuum unit.

[0039] Among them, the outlet of the salt-forming reaction kettle 2 is connected to the inlet of the salt solution storage tank 3, the material outlet pipeline of the salt solution storage tank 3 is connected to the inlet of the concentration kettle 4, the material outlet of the concentration kettle 4 is connected to the pipeline inlet of the U-shaped tube polymerization reactor 5, the material outlet of the U-shaped tube polymerization reactor 5 is connected to the first feed inlet 10 of the twin-screw extruder through a pipeline, the material outlet of the twin-screw extruder 9 is melt-pelletized by the underwater pelletizer 12 and then connected to the inlet of the fluidized bed dryer 13 through a pipeline, and the material outlet of the fluidized bed dryer 13 enters the packaging machine 15 through the grading and screening machine 14.

[0040] In some specific embodiments, the continuous production device using the polyamide resin prepares polyamide resin through the following method steps:

[0041] S1. The reaction raw materials undergo a salification reaction in a salification reactor; the reaction raw materials include water, polyamide monomers or polyamide salts;

[0042] S2. The salt solution after the salification reaction enters the concentration device through a salt storage tank to obtain a concentrated polyamide salt solution;

[0043] S3. The concentrated polyamide salt solution enters the U-shaped tube polymerization reactor for pre-polymerization reaction;

[0044] S4. The reaction gas after the pre-polymerization reaction sequentially enters a heat exchanger and a condensate collection tank from the gas outlet of the pre-polymerization device for heat exchange recovery, and a vacuum unit evacuates the condensate collection tank to obtain a vacuum environment.

[0045] S5. The reaction product of the pre-polymerization device enters the screw extrusion device for post-polycondensation reaction, melt viscosity increase and / or polyamide modification;

[0046] S6. The reaction product after the post-polycondensation reaction is pelletized by the underwater pelletizer, and finally the polyamide product is obtained through the fluidized bed dryer, grading and screening machine and packaging machine in sequence.

[0047] In the present utility model, the pressure of the salification reaction is preferably 0.001 - 0.05 Mpa. The temperature of the salification reaction is preferably 60 - 85 °C.

[0048] In the present utility model, preferably, the temperature of the concentration is preferably 120 - 140 °C.

[0049] In the present utility model, the temperature of the pre-polymerization reaction is preferably 200 - 330 °C, and the pressure is preferably 1.5 - 3.3 MPa.

[0050] In the present utility model, the temperature of the U-shaped tube polymerization reactor can be controlled at 200 - 330 °C.

[0051] In the present utility model, preferably, the reaction material formed in step S5 is fed into the first feed port of the twin-screw extruder through a melt pump, and at the same time, a certain amount of functional additives can be added to the second feed port of the twin-screw extruder according to product requirements to modify the polyamide product obtained by polymerization.

[0052] In the present utility model, preferably, the temperature of the screw extruder can be set between 225 - 350 °C according to the type of polymer.

[0053] In the present utility model, the polyamide monomer preferably includes a diamine monomer and a diacid monomer. The diamine monomer is selected from aliphatic diamines having 5 to 20 carbon atoms; preferably one or more of pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, etc.; the diacid monomer is selected from aromatic dicarboxylic acids and / or aliphatic dicarboxylic acids having 4 to 18 carbon atoms, preferably one or more of glutaric acid, adipic acid, suberic acid, sebacic acid, terephthalic acid, isophthalic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, etc. The polyamide salt is formed by the reaction of a diacid and a diamine. The polyamide salt is preferably one or more of caprolactam, 11-aminoundecanoic acid, dodecanolactam, 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, polyamide 1212 salt, etc.

[0054] Example 1: Preparation of high-temperature resistant polyamide PA12T copolymer

[0055] As Figure 2 shown, wherein, the outlet of the salt-forming reaction kettle 2 is connected to the inlet of the salt solution storage tank 3, the material outlet pipeline of the salt solution storage tank 3 is connected to the inlet of the concentration kettle 4, the material outlet of the concentration kettle 4 is connected to the pipeline inlet of the U-shaped tube polymerization reactor 5, the material outlet of the U-shaped tube polymerization reactor 5 is connected to the first feed port 10 of the twin-screw extruder, the material outlet of the twin-screw extruder 9 is melt pelletized through the underwater pelletizer 12 and then connected to the inlet of the fluidized bed dryer 13 through a pipeline, and the material outlet of the fluidized bed dryer 13 enters the packaging machine 15 through the grading and screening machine 14.

[0056] (1) 6421.86 kg of dodecamethylenediamine, 5169.96 kg of terephthalic acid, 4402 g of sodium hypophosphite and 90% of the total mass of the material of water are added to the salt-forming reaction kettle 2 and stirred evenly, evacuated and filled with inert gas to normal pressure, control the pressure in the salt-forming reaction kettle 2 within 0.01 MPa, and heat the salt-forming reaction kettle to 80 °C, and stir to form a salt solution of polyamide PA12T;

[0057] (2) The salt solution of polyamide PA12T formed in step (1) is added to the concentration kettle 4 through the salt solution storage tank 3, maintain the temperature of the concentration kettle 4 at 120 °C and keep it for 4.5 h for concentration and water removal to form a salt solution of polyamide PA12T;

[0058] (3) The salt solution of polyamide PA12T formed in step (2) enters the U-shaped tube polymerization reactor 5 through a pipeline, and the salt solution is gradually heated from 220 °C to 305 °C, with a pressure of 2.0 MPa, and the reaction is carried out for 2.5 h;

[0059] (4) Feed the reaction materials formed in step (3) into the first feed port 10 of the twin-screw extruder through a melt pump. The twin-screw extruder 9 has a screw diameter of 98 mm, a length-diameter ratio of 45, a screw rotation speed of 450 rpm, a material residence time of 3.5 min, and 3 vacuum exhaust ports. The materials from the outlet of the twin-screw extruder are underwater pelletized by the underwater pelletizer to obtain polymer pellets. Subsequently, the polymer pellets enter the inlet of the fluidized bed dryer. The outlet of the fluidized bed dryer is connected to the classification and screening machine, and the materials from the outlet of the classification and screening machine enter the packaging machine to finally obtain the polyamide PA12T copolymer.

[0060] Example 2: Preparation of heat-resistant polyamide PA610.

[0061] The device is the same as that in Example 1.

[0062] (1) Add 3935.7 kg of 1,6-hexanediamine, 6524.58 kg of sebacic acid, 1538 g of sodium hypophosphite,

[0063] 4514 g of antioxidant 1098 / 168 mixture and water accounting for 86% of the total mass of the materials into the salt-forming reactor 2

[0064] , evacuate, introduce inert gas to normal pressure, control the pressure in the salt-forming reactor 2 within 0.005 MPa, and heat the salt-forming reactor 2 to 85 °C, and stir to form a salt solution of polyamide PA610;

[0065] (2) Feed the salt solution of polyamide PA610 formed in step (1) into the concentration kettle 4 through the salt solution storage tank 3. Maintain the temperature of the concentration kettle 4 at 135 °C and keep it for 4.8 h for concentration and water removal to form a salt solution of polyamide PA610;

[0066] (3) Feed the salt solution of polyamide PA610 formed in step (2) into the U-shaped tubular polymerization reactor 5 through a pipeline. Heat the U-shaped tubular polymerization reactor 5 to 295 °C, with a pressure

[0067] of 2.2 MPa, and react for 3.2 h;

[0068] (4) Feed the reaction materials formed in step (3) into the first feed port 10 of the twin-screw extruder through a melt pump. The twin-screw extruder 9 has a screw diameter of 92 mm and a length-diameter ratio of 48. The twin-screw extruder 9 has 3 vacuum exhaust ports. The materials from the outlet of the twin-screw extruder 9 are underwater pelletized by the underwater pelletizer to obtain polymer pellets. Subsequently, the polymer pellets enter the inlet of the fluidized bed dryer. The outlet of the fluidized bed dryer is connected to the classification and screening machine, and the materials from the outlet of the classification and screening machine enter the packaging machine to finally obtain the polyamide PA610 polymer.

[0069] Effect Example 1:

[0070] (1) Detection method of relative viscosity ηr: Ubbelohde viscometer concentrated sulfuric acid method (96% concentrated sulfuric acid), Ubbelohde viscometer AVS600 was purchased from Shanghai Luwen Scientific Instruments Co., Ltd.

[0071] (2) Melting point test: Differential scanning calorimetry, differential scanning calorimeter SC Q20, was purchased from TA Instruments, USA.

[0072] (3) Yellowing index test

[0073] Testing instrument: Yellowing index meter

[0074] Testing method: The testing method refers to HG / T3862-2006.

[0075] (4) Molecular weight test: Gel permeation chromatography, tested by GPC method.

[0076] The resin materials prepared in Examples 1-2 were tested, and the test results are shown in Table 1.

[0077] Table 1. Performance test results 1

[0078] sample relative viscosity ηr melting point Tm (°C) yellow index YI molecular weight distribution PDI Example 1 2.35 315.2 1.55 2.04 Example 2 2.61 223.8 2.12 1.97

[0079] It can be seen from the data in the above table that the process of the high-temperature resistant polyamide resin production device of the present utility model is simple. By using a twin-screw extrusion device to replace the flash evaporation device, pre-polymerization reaction device and post-polymerization reaction device in the conventional polyamide production, the polyamide resin chips finally produced have stable quality, low yellowing index and narrow molecular weight distribution.

Claims

1. A continuous production device for polyamide resin, characterized in that: It includes a salt-forming device, a concentration device, a pre-polymerization device, and a screw extrusion device connected in sequence. The salt-forming device is a salt-forming reaction kettle for carrying out salt-forming reaction. The concentration device is used to concentrate and remove water from the reactants of the salt-forming reaction to obtain a concentrated polyamide salt solution. The pre-polymerization device is a U-shaped tube polymerization reactor for carrying out polymerization reaction on the concentrated polyamide salt solution. The screw extrusion device is used to carry out post-polycondensation reaction, melt viscosity increase and / or polyamide modification on the reaction materials of the polymerization reaction.

2. The continuous production device for polyamide resin according to claim 1, characterized in that: The gas outlet of the pre-polymerization device is connected to a heat exchanger and a condensate collection tank in sequence; the condensate collection tank is also connected to a vacuum unit. The heat exchanger is used to condense the gas generated by the polymerization reaction. The vacuum unit is used to evacuate the condensate collection tank to obtain a vacuum environment.

3. The continuous production device for polyamide resin according to claim 1, characterized in that: The continuous production device for polyamide resin further includes an additive addition tank connected to the salt-forming reaction kettle, and the outlet of the additive addition tank is connected to the inlet of the salt-forming reaction kettle.

4. The continuous production device for polyamide resin according to claim 1, characterized in that: The heating form of the salt-forming reaction kettle and / or the concentration device is one or a combination of two or more of jacket type, internal coil type, and external coil type.

5. The continuous production device of the polyamide resin according to claim 1, characterized in that: The continuous production device further includes a salt solution storage tank, and the salt-forming reaction kettle, the salt solution storage tank, and the concentration device are connected in sequence.

6. The continuous production device of polyamide resin according to claim 1, characterized in that: The screw extrusion device is a screw extruder; the screw extruder is one of a single-screw extruder, a twin-screw extruder, a multi-screw extruder, or a plunger extruder. The screw diameter of the screw extruder is 70 - 135 mm, the screw length-diameter ratio is 28 - 70, and the number of screw vacuum exhaust ports is 3 - 6.

7. The continuous production device for polyamide resin according to claim 6, characterized in that: The screw extruder is provided with a first feed port and a second feed port. The first feed port is arranged at the front section of the screw extruder, and the second feed port is arranged at the middle section of the screw extruder.

8. The continuous production device for polyamide resin according to claim 1, characterized in that: The continuous production device further includes a pelletizing device. The inlet of the pelletizing device is connected to the outlet of the screw extrusion device for pelletizing the product obtained from the polymerization reaction.

9. The continuous production device for polyamide resin according to claim 8, characterized in that: The continuous production device for polyamide resin further includes a drying device, and the drying device is selected from a spray dryer, a microwave dryer, or a fluidized bed dryer; the inlet of the drying device is connected to the outlet of the pelletizing device for drying the pelletized polyamide resin.

10. The continuous production device of the polyamide resin according to claim 9, characterized in that: The continuous polyamide resin production device further includes a classification and screening machine, the inlet of which is connected to the outlet of the drying device and is used for classifying and screening the dried polyamide resin.

11. The continuous production device of the polyamide resin according to claim 8, characterized in that: The pelletizing device is an underwater pelletizer.

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