CN117467132A - Continuous preparation method and device for polyamide - Google Patents

Continuous preparation method and device for polyamide Download PDF

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Publication number
CN117467132A
CN117467132A CN202311419646.9A CN202311419646A CN117467132A CN 117467132 A CN117467132 A CN 117467132A CN 202311419646 A CN202311419646 A CN 202311419646A CN 117467132 A CN117467132 A CN 117467132A
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China
Prior art keywords
polyamide
prepolymer
screw extruder
extruder
acid
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CN202311419646.9A
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程圣利
李雪婷
谭丁系印
孙学德
牛家浩
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Shandong Guangyin New Materials Co ltd
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Shandong Guangyin New Materials Co ltd
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Priority to CN202311419646.9A priority Critical patent/CN117467132A/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/06—Flash distillation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J19/18—Stationary reactors having moving elements inside
    • B01J19/1856—Stationary reactors having moving elements inside placed in parallel
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G69/00—Macromolecular compounds obtained by reactions forming a carboxylic amide link in the main chain of the macromolecule
    • C08G69/02—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids
    • C08G69/26—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids derived from polyamines and polycarboxylic acids
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G69/00—Macromolecular compounds obtained by reactions forming a carboxylic amide link in the main chain of the macromolecule
    • C08G69/02—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids
    • C08G69/26—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids derived from polyamines and polycarboxylic acids
    • C08G69/28—Preparatory processes

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Organic Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Polyamides (AREA)

Abstract

The invention discloses a continuous preparation method and device of polyamide, and belongs to the technical field of polyamide. The technical proposal is as follows: the method comprises the following steps: 1) Salt forming stage: adding dicarboxylic acid monomer, diamine monomer, end capping agent and water into a salifying reaction kettle, and performing salifying reaction; 2) A pre-polymerization stage: transferring to a pre-polycondensation reaction stage, and concentrating and pre-polymerizing to obtain prepolymer; 3) Flashing of the prepolymer: conveying the prepolymer into an extruder through a control valve and a metering device, and carrying out flash evaporation on the prepolymer in the extruder; 4) Extrusion tackifying: conveying the flash-evaporated prepolymer into a double-screw extruder to complete extrusion tackifying reaction; and (3) granulating, drying and packaging the extruded and tackified material to obtain the polyamide. The invention has the advantages of easy replacement of polyamide continuous production equipment and difficult blockage of a flash evaporation device, and realizes continuous production of polyamide products of various varieties and masses.

Description

Continuous preparation method and device for polyamide
Technical Field
The invention belongs to the technical field of polyamide, and particularly relates to a continuous preparation method and device of polyamide.
Background
Polyamides refer to a class of polymers whose backbone contains amide linkages (-CONH-). The polyamide resin has good mechanical properties, wear resistance, chemical resistance and the like, and is generally applied to various fields such as automobiles, electronic appliances, building materials, illumination, aerospace fields and the like in the forms of pipes, sectional materials, products, films or fibers.
Compared with the common batch polymerization production process, the continuous polymerization has the advantages of high yield, stable product performance and high automation degree. However, compared with batch polymerization production, the continuous polymerization production line is difficult to replace and is complex to operate, and the whole production line is stopped and thoroughly cleaned for each replacement.
As described in US3789584, US3113843, US3357955, US3846681, US4299498, US4831108 and chinese patent CN111363142A, CN113694551a, in a continuous polymerization process of polyamide, a polyamide nylon salt is concentrated and prepolymerized, and then needs to be converted from a high pressure state to a low pressure state and then fed into a post polycondensation reaction vessel or reaction apparatus. The operation is generally realized by adopting a tubular flash evaporation device, the operation of materials from high-pressure and high-moisture materials to low-pressure and low-moisture materials is completed, the separation of water vapor and the materials is realized in the tubular flash evaporation device through a short-time rapid pressure release process, the heating of the materials is completed through a heat transfer medium, the temperature reduction of the materials caused by flash evaporation is prevented, and the melting state of the materials is ensured. After passing through the flash evaporation device, the prepolymer enters a post-polycondensation reaction kettle or corresponding equipment to complete the further polymerization reaction of the prepolymer.
The tubular flash evaporation device has the advantages of simplicity and high efficiency, but because the tubular flash evaporation device is of a coil pipe or straight pipe structure, the pipeline of the device is slender, and degradation and aging of accumulated materials and residues are easy to cause after long-time working, the tubular flash evaporation device is blocked. In addition, for continuous polymerization production units, the entire production line, especially the flash distillation unit and the finishing reaction unit, needs to be thoroughly cleaned during the production change. The reason is that the prepolycondensation and nylon salt concentration device in the former stage has low prepolymer polymerization degree, low prepolymer viscosity and good solubility, so that the salifying, concentrating and prepolymerization device before the flash evaporation device has low cleaning difficulty. For the above reasons, continuous polymerization equipment of polyamide is generally not easy to change, production operation is not flexible, and the continuous polymerization equipment is only suitable for producing polyamide products with large yield and single product like nylon 66, but is not suitable for producing products with more variety and less single product like special polyamide.
Therefore, there is a need to develop a continuous process for the preparation of polyamides to achieve continuous production of multi-variety, popular polyamide products.
Disclosure of Invention
The invention provides a continuous preparation method and a continuous preparation device for polyamide, which replace the traditional flash evaporation equipment by adopting a single screw extruder or a double screw extruder, so that the flash evaporation equipment has a certain self-cleaning function, has the advantages of easy replacement of polyamide continuous production equipment and replacement and difficult blockage of the flash evaporation equipment, and realizes continuous production of polyamide products of various varieties and masses.
The technical scheme of the invention is as follows:
in a first aspect, there is provided a continuous process for the preparation of a polyamide comprising the steps of:
1) Salt forming stage: adding dicarboxylic acid monomer, diamine monomer, end-capping agent and water into a salifying reaction kettle, and carrying out salifying reaction at 30-110 ℃ under stirring to obtain nylon salt solution;
2) A pre-polymerization stage: transferring the nylon salt solution to a pre-polycondensation reaction stage, and concentrating and pre-polymerizing at 150-300 ℃ and 0.8-15MPa to obtain a prepolymer;
3) Flashing of the prepolymer: conveying the prepolymer into an extruder through a metering device, carrying out flash evaporation on the prepolymer in the extruder, reducing the pressure of a prepolymer system from 0.8-15MPa to 0.01-0.5MPa, and simultaneously heating through a charging barrel of the extruder or converting mechanical energy of a screw rod to ensure that the temperature of the prepolymer system is higher than the precipitation temperature of materials;
4) Extrusion tackifying: conveying the flash-evaporated prepolymer into a double-screw extruder to complete extrusion tackifying reaction, and carrying out multistage exhaust through the double-screw extruder, wherein the working temperature of the double-screw extruder is 180-360 ℃;
and (3) granulating, drying and packaging the extruded and tackified material to obtain the polyamide.
The continuous preparation method of the polyamide is suitable for preparing nylon 66, nylon 6, nylon 610, nylon 612, nylon 1010, nylon 1012 and special nylon or the nylon copolymerization products. The special nylon comprises transparent nylon, nylon elastomer, high-temperature nylon and long carbon chain nylon.
Preferably, the extruder in step 3) is a twin screw extruder or a single screw extruder.
Preferably, the extruder barrel is set to a temperature in the range of 180-400 ℃.
Preferably, the dicarboxylic acid monomer is a dicarboxylic acid monomer containing 4 to 36 carbon atoms, including aliphatic dicarboxylic acid monomers and/or aromatic dicarboxylic acid monomers; the dicarboxylic acid monomer is dicarboxylic acid monomer containing 4-36 carbon atoms, including aliphatic dicarboxylic acid monomer, alicyclic dicarboxylic acid monomer and/or aromatic dicarboxylic acid monomer. Such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, tridecanedicarboxylic acid, tetradecanedicarboxylic acid, pentadecanedicarboxylic acid, hexadecanedicarboxylic acid, heptadecanedicarboxylic acid, octadecanedicarboxylic acid, nonadecanedicarboxylic acid, eicosanedicarboxylic acid, 2-methyladipic acid, 2-dimethylglutaric acid, 3-diethylsuccinic acid, maleic acid, fumaric acid, itaconic acid, dimer acid, cis-and/or trans-cyclohexane-1, 2-dicarboxylic acid, cis-and/or trans-cyclohexane-1, 3-dicarboxylic acid, cis-and/or trans-cyclohexane-1, 4-dicarboxylic acid, cis-and/or trans-cyclopentane-1, 2-dicarboxylic acid, cis-and/or trans-cyclopentane-1, 3-dicarboxylic acid, 2-methylpentanedioic acid; aromatic dicarboxylic acid monomers such as terephthalic acid, isophthalic acid, phthalic acid, 2, 6-naphthalenedicarboxylic acid, 2, 7-naphthalenedicarboxylic acid, 1, 4-phenylenedioxydiacetic acid, 1, 3-phenylenedioxydiacetic acid, 2' -biphenyl dicarboxylic acid, 4' -oxybis (benzoic acid), diphenylmethane-4, 4' -dicarboxylic acid, diphenylsulfone-4, 4' -dicarboxylic acid, 4' -biphenyldicarboxylic acid, furandicarboxylic acid, and combinations thereof.
The diamine monomer is diamine monomer containing 2-36 carbon atoms, and comprises aliphatic diamine monomer and/or aromatic diamine monomer; the diamine monomer is diamine monomer containing 2-36 carbon atoms, including aliphatic diamine monomer, alicyclic diamine monomer and/or aromatic diamine monomer. Such as ethylenediamine, 1, 4-butanediamine, 1, 5-pentanediamine, 1, 6-hexanediamine, 1, 7-heptanediamine, 1, 8-octanediamine, 1, 9-nonanediamine, 1, 10-decanediamine, 1, 11-undecanediamine, 1, 12-dodecanediamine, 1, 13-tridecanediamine, 1, 14-tetradecanediamine, 1, 15-pentadecanediamine, 1, 16-hexadecanediamine, 1, 17-heptadecanediamine, 1, 18-octadecanediamine, 1, 19-nonadecanediamine, 1, 20-eicosanediamine, 2-methyl-1, 5-pentanediamine, 3-methyl-1, 5-pentanediamine, 2-butyl-2-ethyl-1, 5-pentanediamine, 2, 4-dimethyl-1, 6-hexanediamine, 2, 4-trimethyl-1, 6-hexanediamine, 2-methyl-1, 8-octanediamine, 5-methyl-1, 9-nonanediamine, 2, 4-dimethyl-1, 4-octanediamine, 3 '-dicyclohexyl-1, 5-pentanediamine, 3-methyl-1, 4-cyclohexanediamine, 4-dicyclohexyl-1, 4-diaminocyclohexane, 3-methyl-1, 4' -diaminocyclohexane; aromatic diamine monomers such as one or more of m-xylylenediamine, p-phenylenediamine, m-phenylenediamine, bis (4-aminophenyl) methane, 3-methylbenzidine, 2-bis (4-aminophenyl) propane, 1-bis (4-aminophenyl) cyclohexane, 1, 4-diaminonaphthalene, 1, 5-diaminonaphthalene, 2, 6-diaminonaphthalene, 1, 3-diaminotoluene, N '-dimethyl-4, 4' -biphenyldiamine, bis (4-methylaminophenyl) methane, 2-bis (4-methylaminophenyl) propane.
The molar ratio of dicarboxylic acid monomer to diamine monomer is 0.85-1.2:1, preferably 0.95-1.1:1.
preferably, the capping agent is one or more of an aliphatic monocarboxylic acid compound, an alicyclic monocarboxylic acid compound, an aromatic monocarboxylic acid compound, an aliphatic monoamine compound, an alicyclic monoamine compound, and an aromatic monoamine compound, including acetic acid, propionic acid, n-butyric acid, isobutyric acid, t-butyric acid, valeric acid, pivalic acid, dimethyl acetic acid, caproic acid, heptanoic acid, caprylic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, cyclopropanecarboxylic acid, cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, benzoic acid, p-methylbenzoic acid, o-methylbenzoic acid, m-methylbenzoic acid, p-t-butylbenzoic acid, salicylic acid, p-methoxybenzoic acid, α -naphthoic acid, methylnaphthalene carboxylic acid, phenylacetic acid, oleic acid, lactic acid, ricinoleic acid, linoleic acid, linolenic acid, erucic acid, and various fatty acids from plants, acrylic acid, methacrylic acid, and mixtures thereof; the monoamine compounds include methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, heptylamine, octylamine, decylamine, octadecylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, cyclohexylamine, dicyclohexylamine, aniline, toluidine, diphenylamine, naphthylamine, and mixtures thereof; particularly preferred capping agents are at least one of acetic acid, propionic acid, benzoic acid; the amount of end-capping agent is 0.01 to 10wt%, preferably 0.1 to 5wt%, most preferably 0.2 to 0.8wt% based on the total weight of the polymerized monomers.
Preferably, the salt forming stage in step 1) is carried out under an inert atmosphere, wherein the inert atmosphere is nitrogen or water vapor, and a catalyst and a defoaming agent can be added in the salt forming stage.
Preferably, the catalyst is an inorganic and/or organic phosphorus, tin or lead compound and mixtures thereof; as suitable phosphorus-containing compounds there are phosphoric acid, phosphorous acid, hypophosphorous acid, phenylphosphoric acid, phenylphosphinic acid and/or salts thereof with monovalent or trivalent cations, and/or esters thereof, for example triphenyl phosphate, triphenyl phosphite or tris (nonylphenyl) phosphite; tin oxide, tin hydroxide, tin salts of monocarboxylic or polycarboxylic acids are suitable tin catalysts. Such as tin dibenzoate, tin di (2-ethylhexanoate), tin oxalate, dibutyltin oxide, butylstannoic acid, tin dilaurate, and the like; suitable lead compounds include lead oxide, lead hydroxide, lead acetate, basic lead acetate, lead carbonate, etc.; particularly preferred catalysts are hypophosphorous acid and its salts, such as sodium or potassium hypophosphite; the catalyst is used in an amount of 0.0001 to 5wt%, preferably 0.001 to 0.1wt%, most preferably 0.01 to 0.05wt% based on the total weight of the polymerized monomers.
The defoamer comprises polyether type, organosilicon type and polyether modified organosilicon type defoamers, and the addition of the defoamer accounts for 0-5wt% of the total mass of diamine monomers and diacid monomers.
Preferably, the pre-polycondensation reaction stage of the step 2) is realized by connecting a concentration reaction kettle with a tubular homogenizing reactor or by intermittently and alternately working two pre-polymerization kettles, and the semi-aromatic polyamide prepolymer with certain molecular weight is obtained by continuously releasing water vapor in a reaction vessel and pushing the reaction to the polymerization reaction direction under the pressure of 0.8-15MPa at the temperature of 150-300 ℃.
In a second aspect, a device adopted by the continuous preparation method of polyamide is disclosed, which comprises a diamine storage tank and a diacid storage tank, wherein the diamine storage tank and the diacid storage tank are connected with a salifying reaction kettle, the salifying reaction kettle is connected with a saline solution storage tank, the saline solution storage tank is connected with a pre-polycondensation reaction mechanism, the pre-polycondensation reaction mechanism is connected with a plunger pump, the plunger pump is connected with a tubular homogenizing reactor, the tubular homogenizing reactor is connected with a gear pump, the gear pump is connected with a single-screw extruder, the single-screw extruder is connected with a double-screw extruder, an upstream vacuum exhaust port and a downstream vacuum exhaust port are arranged on the double-screw extruder, and a pressure release valve is arranged on the upstream vacuum exhaust port.
Preferably, the pre-polycondensation reaction mechanism comprises a circulating pump connected with a salt solution storage tank, the circulating pump is connected with a concentration reaction kettle, a heat exchanger is arranged on a bypass between the circulating pump and the concentration reaction kettle, and the concentration reaction kettle is in circulating connection with the rectifying tower; a discharge hole of the concentration reaction kettle is connected with a plunger pump;
or comprises a first prepolymerization reactor connected with a salt solution storage tank, wherein the first prepolymerization reactor is connected with a second prepolymerization reactor in parallel, and the first prepolymerization reactor and the second prepolymerization reactor are connected with a plunger pump.
In the step 3), the metering device is a device capable of quantitatively conveying materials and comprises a gear pump, a plunger pump, a diaphragm pump and a screw pump.
In the step 3), the pressure of the prepolymer melt in the thread groove of the single-screw or double-screw extruder is reduced, so that the gradual separation of the prepolymer and water vapor is realized, and meanwhile, a heating plate on a charging barrel of the extruder provides heat for the material in the flash evaporation process, so that the material is prevented from being separated and solidified due to the temperature reduction of the material caused by flash evaporation. The prepolymer flows rapidly along the screw grooves of the extruder under the action of vapor pressure, and the separation of materials and water vapor is gradually realized under the action of centrifugal force. In the normal continuous production process, the single screw extruder or the double screw extruder can run at a low speed, the rotation of the screws has the functions of updating the liquid level and accelerating stirring, and the rotation speed of the screws of the extruder is in the range of 0-500r/min. Under extreme conditions, the screws of a single screw extruder or a twin screw extruder may not be rotated, at which time the material is moved helically along the screw grooves by the air flow, the material pressure is gradually reduced, and the lowest pressure is reached as the material exits the extruder. The material is left in step 3) in the single-screw extruder or twin-screw extruder for a residence time of 1 to 600s, preferably 10 to 120s.
The invention is different from the traditional spiral pipe or straight pipe flash evaporation reactor, adopts a single screw or double screw extruder, easily realizes the setting of the temperature in different temperature areas, and has wider process condition range. The traditional spiral tube or straight tube flash evaporation reactor is difficult to set different temperature ranges of the flash evaporation tube due to the fact that an external heating medium is adopted for heating.
In the production process, the upstream salifying reaction kettle and the prepolymerization kettle drain out materials, at the moment, the screw rotation speed of a single screw or a double screw is increased, and the materials in the extruder serving as a flash evaporation reactor are drained out through the rotation of the screws. The twin-screw tackifying extruder as the downstream of the flash reactor extruder has self-cleaning function, and thorough discharge of materials is easily realized by increasing the rotation speed of the extruder. Therefore, the continuous polyamide polymerization device can easily realize the production change and cleaning, and only part of the head washing machine materials are discarded in each production change process, so that the easy production change can be realized without detaching and cleaning the flash evaporation reactor.
In the step 4), the materials coming out of the single screw extruder or the double screw extruder directly enter the other double screw extruder, the upstream of the feeding port of the double screw extruder is provided with an exhaust port, and the pressure of the discharged steam can be controlled through a pressure release valve at the upstream of the exhaust port, so that the stability of the process conditions is maintained. The downstream of the extruder feed inlet is provided with a plurality of exhaust ports, which can be a pressure exhaust port, a normal pressure exhaust port and a vacuum exhaust port, and the number of the exhaust ports is 2-20, and 3-8 are preferable. The twin-screw extruder is preferably a homodromous twin-screw extruder with a self-cleaning function, and the working temperature of the extruder charging barrel is 180-360 ℃, and the specific working temperature is determined according to the melting point of the produced polyamide resin. The residence time of the material in the extruder is 1 to 600s, preferably 20 to 300s.
And 4) granulating the extruded material in the step 4) under water or granulating by a brace to obtain polyamide resin particles after polymerization. The resin particles can be used after being continuously thickened to the required viscosity by a solid-phase tackifying device, and can also be directly used.
Compared with the prior art, the invention has the following beneficial effects:
(1) According to the continuous preparation method of polyamide, in the actual production process, the production is easy to change, the disassembly of cleaning equipment is not needed, and the cleaning of materials can be realized through the extrusion action of a single screw or a double screw.
(2) According to the continuous preparation method of polyamide, in the long-term operation process, the phenomenon of blockage of a flash evaporation pipeline of a traditional flash evaporation reactor can not occur through the rotation and stirring action of the screw rod, and the equipment can work for a long time without stopping.
(3) According to the continuous preparation method of polyamide, disclosed by the invention, the single-screw extruder or the double-screw extruder serving as a flash evaporation reactor can be used for realizing full mixing of materials in a flash evaporation process due to the stirring effect of screws, so that the uniformity of the materials is ensured, and the product quality is improved.
(4) The continuous preparation method of polyamide of the invention, because of being different from the traditional flash evaporation reactor which heats through the heating medium, the single screw extruder or the double screw extruder is provided with a plurality of temperature areas for heating, thus being capable of easily realizing different temperature settings of different temperature areas, having larger process operation space, wider coverage of equipment production products and being suitable for continuous production operation of various polyamides.
Drawings
FIG. 1 is a schematic view of a continuous production apparatus of a polyamide according to the present invention.
Fig. 2 is a schematic diagram of an alternative configuration to the a configuration of fig. 1.
In fig. 1:1. a diamine storage tank; 2. a diacid storage tank; 3. a salifying reaction kettle; 4. diamine feed control valve; 5. a diacid feed control valve; 6. a salt solution storage tank; 7. a heat conducting oil outlet a; 8. a heat conducting oil inlet a; 9. a heat exchanger; 10. a heat conducting oil outlet b; 11. a heat conducting oil inlet b; 12. a circulation pump; 13. concentrating the reaction kettle; 14. a rectifying tower; 15. a plunger pump; 16. a tubular homogenizing reactor; 17. a heat conducting oil outlet c; 18. a heat conducting oil inlet c; 19. a gear pump; 20. a single screw extruder; 21. an upstream vacuum exhaust port; 22. a downstream vacuum exhaust; 23. a pressure release valve; 24. a twin screw extruder.
In fig. 2: 25. a first prepolymerization reactor; 26. and (3) a second prepolymerization reactor.
Detailed Description
As shown in fig. 1, the continuous preparation method of polyamide adopts a device, a diamine storage tank 1 and a diacid storage tank 2 are connected with a salifying reaction kettle 3, the salifying reaction kettle 3 is connected with a saline solution storage tank 6, the saline solution storage tank 6 is connected with a pre-polycondensation reaction mechanism, the pre-polycondensation reaction mechanism comprises a circulating pump 12 connected with the saline solution storage tank 6, the circulating pump 12 is connected with a concentration reaction kettle 13, a heat exchanger 9 is arranged on a bypass between the circulating pump 12 and the concentration reaction kettle 13, and the concentration reaction kettle 13 is in circulating connection with a rectifying tower 14; the discharge gate of concentrated reation kettle 13 is connected with plunger pump 15, and plunger pump 15 is connected with tubular homogenization reactor 16, and tubular homogenization reactor 16 is connected with gear pump 19, and gear pump 19 is connected with single screw extruder 20, and single screw extruder 20 is connected with twin screw extruder 24, is provided with upstream vacuum vent 21 and downstream vacuum vent 22 on the twin screw extruder 24, is provided with relief valve 23 on the upstream vacuum vent 21. And a 2000L stirring reaction kettle with a jacket for heating is arranged in the salifying reaction kettle 3. The tubular homogenizing reactor 16 is provided with a heat transfer oil outlet c17 and a heat transfer oil inlet c18.
A diamine feeding control valve 4 is arranged between the diamine storage tank 1 and the salifying reaction kettle 3, a diacid feeding control valve 5 is arranged between the diacid storage tank 2 and the salifying reaction kettle 3, and a heat conducting oil outlet a7 and a heat conducting oil inlet a8 are arranged on an outer interlayer of the salifying reaction kettle 3. The heat exchanger 9 is provided with a heat transfer oil outlet b10 and a heat transfer oil inlet b11.
As shown in fig. 2, the pre-polycondensation reaction mechanism may be a first pre-polymerizer 25 connected to the salt solution tank 6, the first pre-polymerizer 25 is connected in parallel to a second pre-polymerizer 26, and the first pre-polymerizer 25 and the second pre-polymerizer 26 are connected to the plunger pump 15.
The continuous preparation method of polyamide by using the device in fig. 1 comprises the following steps:
(1) Salt forming stage: diamine monomer and diacid monomer are added into a salifying reaction kettle 3 from a diamine storage tank 1 and a diacid storage tank 2 through a diamine feeding control valve 4 and a diacid feeding control valve 5 on a pipeline, the salifying reaction kettle continuously operates, a heat conducting oil outlet a7 and a heat conducting oil inlet a8 are arranged on an outer interlayer of the salifying reaction kettle 3, heating is carried out for salifying reaction, after salifying is finished, a salt solution is conveyed into a 5000L salt solution storage tank 6, and a heat preservation device is arranged outside the storage tank 6. The salt solution stored in the salt solution storage tank is continuously conveyed into a concentration reaction kettle 13, the effective volume of the concentration reaction kettle 13 is 1500L, the concentration reaction kettle is provided with a heat exchanger 9 for external circulation heating and a rectifying tower 14 provided with 7 layers of tower plates, and the rich amine solution concentrated by the rectifying tower 14 flows back to the concentration reaction kettle 13. The average residence time of the nylon salt in the concentration reaction kettle 13 is 2 hours, and the water content of the concentrated nylon salt is controlled within 8 weight percent, so as to obtain a nylon salt solution.
(2) A pre-polymerization stage: the concentrated nylon salt solution enters a tubular homogenizing reactor 16 through a plunger pump 15, the pre-polymerization reaction is further fully carried out in the tubular homogenizing reactor 16, the tubular homogenizing reactor 16 is heated to 220-300 ℃ through a heat conducting oil outlet c17 and a heat conducting oil inlet c18, the average residence time is controlled to be 15min, the pressure in the tubular homogenizing reactor 16 is controlled to be 8MPa through the plunger pump 15 and a gear pump 19, and the prepolymer is ensured not to be gasified heterogeneous, so that the prepolymer is obtained;
(3) Flashing of the prepolymer: the polyamide prepolymer exiting the tubular homogenizing reactor 16 is fed quantitatively via a gear pump 19 to a single-screw extruder 20, and the flash-off operation is completed. The single screw extruder 20 had a screw diameter of 35mm and an aspect ratio of 46. The outlet pressure of the single screw extruder 20 was controlled at 0.05MPa by controlling the pressure relief valve 23 upstream of the feed port in the twin screw extruder 24. The prepolymer material is subjected to a flash operation in a single screw extruder 20 to effect separation of water vapor from the prepolymer. The heating temperature zone of the single screw extruder 20 is set to 250 to 350 ℃, and the temperature of the single screw extruder 20 is set depending on the type of polyamide to be polymerized, and the higher the melting point of the polyamide, the higher the set temperature. When the single screw extruder was operated, the rotational speed of the continuous polymerization process was set at 10r/min. When the continuous polymerization production line is changed, the rotating speed of the single-screw extruder 20 is set to be 200r/min until the discharging is finished, and after the new materials are stably produced again, the rotating speed of the single-screw extruder 20 is regulated to be 10r/min.
(4) Extrusion tackifying: the process is carried out on a double-screw extruder with the screw diameter of 65mm, the length-diameter ratio of the double-screw extruder 24 is 56, and the downstream of the feeding port comprises 6 vacuum exhaust ports, four normal pressure exhaust ports and two vacuum exhaust ports. The temperature setting of the twin-screw extruder is dependent on the type of polyamide produced, different temperatures being set depending on the melting point of the polyamide. The rotation speed of the extruder screw is regulated between 100 r/min and 250r/min, and the rotation speed is regulated according to the viscosity requirement of the required polyamide product.
The material extruded from the twin-screw extruder 24 is extruded through an extruder die, cooled in a water tank, and pelletized by an air knife and a pelletizer to obtain the polyamide resin.
The test methods used in the examples are as follows:
(1) Intrinsic viscosity:
the logarithmic intrinsic viscosity eta of polyamides having concentrations of 0.5, 0.1, 0.3 and 1g/dl is measured in concentrated sulfuric acid at 25 DEG C inh 。
η inh ＝[ln(t 1 /t 0 )]/C
Wherein,η inh represents logarithmic specific viscosity (dl/g), t 0 Indicating the flow time (sec) of the solvent, t 1 The flow-through time (sec) of the sample solution is represented, and C represents the concentration (g/dl) of the sample solution.
Will eta inh Extrapolated to a concentration of 0 to obtain the intrinsic viscosity [ eta ] of the sample]。
Example 1
The continuous preparation process of polyamide PA610 using the apparatus described above was identical to the process described above, and the raw materials used, the parameters of the apparatus operation, and the results of the test on the intrinsic viscosity of the polyamide resin are shown in table 1.
TABLE 1
Example 1 was run for 1000 hours stably and no blockage of the flash section extruder was observed.
Example 2
After the experiment of example 1 was completed, the materials in the salifying reactor 3, the saline solution storage tank 6, the concentrating reactor 13 and the tubular homogenizing reactor 16 were discharged, and the experiment of example 2 was performed according to the operation process conditions of table 2. In the process of switching the continuous production line from the embodiment 1 to the embodiment 2, only the head material flow of the cleaning pipeline just switched to the embodiment 2 is discarded, and after the process condition of the embodiment 2 is stable, the production changing operation of different materials can be realized, and the whole process does not need to disassemble and clean the flash evaporation section extruder and the extrusion tackifying double-screw extruder. The continuous preparation process of polyamide PA612 using the apparatus described above was the same as that described above, as shown in table 2.
TABLE 2
Example 3
The process of example 3 was continued as described in example 2, and the continuous preparation of polyamide PA66 using the apparatus described above was identical to the process described above, as shown in table 3.
TABLE 3 Table 3
Example 4
The process of example 4 was continued as described in example 2, and the continuous preparation of polyamide PA1010 using the apparatus described above was identical to the process described above, as shown in table 4.
TABLE 4 Table 4
Example 5
The process of example 5 was continued as described in example 2, and the continuous preparation of polyamide PA1012 using the apparatus described above was identical to the process described above, as shown in table 5.
TABLE 5
Example 6
The process of example 6 was continued as described in example 2, and the continuous preparation of polyamide pamcm 12 using the apparatus described above was identical to the process described above, as shown in table 6.
Table 6 parameters and results
Example 7
The process of example 7 was continued as described in example 2, and the continuous preparation of polyamide PAPACM12 using the apparatus described above was identical to the process described above, as shown in table 7.
TABLE 7
Example 8
The process of example 8 was continued as described in example 2, and the continuous preparation of polyamide PA6T/66 using the apparatus described above was identical to the process described above, as shown in table 8.
TABLE 8
Example 9
The process of example 9 was continued as described in example 2, and the continuous preparation of polyamide PA6T/6I using the apparatus described above was identical to the process described above, as shown in table 9.
TABLE 9
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Example 10
The process of example 10 was continued as described in example 2, and the continuous preparation of polyamide PA6T/6I/66 using the apparatus described above was identical to the process described above, as shown in table 10.
Table 10
Example 11
The process of example 11 was continued as described in example 2, and the continuous preparation of polyamide PA10T using the apparatus described above was identical to the process described above, as shown in table 11.
TABLE 11
Example 12
The process of example 12 was continued as described in example 2, and the continuous preparation of polyamide PA12T using the apparatus described above was identical to the process described above, as shown in table 12.
Table 12
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Example 13
The single screw extruder as the flash reactor was replaced with a twin screw extruder having a diameter of 32mm and an aspect ratio of 46, the temperature zone of which was set at 335℃and the other reaction conditions were the same as in example 8. The (PA 6T/66) parameters and results are shown in Table 13.
TABLE 13
Comparative example 1
The flash reactor single screw extruder of comparative example 1 was replaced with a tubular evaporation reactor having a length of 6.5m and a pipe diameter of 5mm, and the other reaction conditions were the same as in example 1. The parameters and results are shown in table 14.
TABLE 14
After five start-up and shut-down operations of comparative example 1, the tube flash steam was blocked with residue.
The continuous preparation method of the polyamide is suitable for preparing nylon 66, nylon 6, nylon 610, nylon 612, nylon 1010, nylon 1012 and special nylon or the nylon copolymerization products. The special nylon comprises transparent nylon, nylon elastomer, high-temperature nylon and long carbon chain nylon, can stably run, and does not have the phenomenon of residual material blockage of the flash evaporation section extruder.
Although the present invention has been described in detail by way of preferred embodiments with reference to the accompanying drawings, the present invention is not limited thereto. Various equivalent modifications and substitutions for embodiments of the invention may be made by those skilled in the art without departing from the spirit and scope of the invention, and these modifications and substitutions are intended to be within the scope of the invention. Therefore, the protection scope of the invention is subject to the protection scope of the claims.

Claims (10)

1. A continuous process for the preparation of polyamides, characterized in that it comprises the following steps:
1) Salt forming stage: adding dicarboxylic acid monomer, diamine monomer, end-capping agent and water into a salifying reaction kettle, and carrying out salifying reaction at 30-110 ℃ under stirring to obtain nylon salt solution;
2) A pre-polymerization stage: transferring the nylon salt solution to a pre-polycondensation reaction stage, and concentrating and pre-polymerizing at 150-300 ℃ and 0.8-15MPa to obtain a prepolymer;
3) Flashing of the prepolymer: conveying the prepolymer into an extruder through a metering device, carrying out flash evaporation on the prepolymer in the extruder, reducing the pressure of a prepolymer system from 0.8-15MPa to 0.01-0.5MPa, and simultaneously heating through a charging barrel of the extruder or converting mechanical energy of a screw rod to ensure that the temperature of the prepolymer system is higher than the precipitation temperature of materials;
4) Extrusion tackifying: conveying the flash-evaporated prepolymer into a double-screw extruder to finish extrusion tackifying reaction, and exhausting air through the double-screw extruder, wherein the working temperature of the double-screw extruder is 180-360 ℃;
and (3) granulating, drying and packaging the extruded and tackified material to obtain the polyamide.
2. The continuous production process of a polyamide as claimed in claim 1, wherein in step 3), the extruder is a twin-screw extruder or a single-screw extruder.
3. The continuous production process of a polyamide according to claim 1, wherein in step 3), the extruder barrel is set to a temperature in the range of 180 to 400 ℃.
4. The continuous production process of polyamide according to claim 1, wherein the dicarboxylic acid monomer is a dicarboxylic acid monomer having 4 to 36 carbon atoms, including an aliphatic dicarboxylic acid monomer and/or an aromatic dicarboxylic acid monomer;
the diamine monomer is diamine monomer containing 2-36 carbon atoms, and comprises aliphatic diamine monomer and/or aromatic diamine monomer;
the molar ratio of dicarboxylic acid monomer to diamine monomer is 0.85-1.2:1.
5. the continuous production method of polyamide as claimed in claim 1, wherein the end-capping agent is one or more of aliphatic monocarboxylic acid compound, alicyclic monocarboxylic acid compound, aromatic monocarboxylic acid compound, aliphatic monoamine compound, alicyclic monoamine compound and aromatic monoamine compound, and the amount of the end-capping agent is 0.01 to 10% by weight based on the total weight of the polymerized monomers.
6. The continuous process for the preparation of polyamides according to claim 1 wherein the salt forming stage in step 1) is carried out under an inert atmosphere of nitrogen or steam, optionally with the addition of catalysts and defoamers.
7. The continuous process for preparing polyamides according to claim 4 wherein the catalyst is an inorganic and/or organic phosphorus, tin or lead compound or mixtures thereof; the catalyst is used in an amount of 0.0001 to 5wt% based on the total weight of the polymerized monomers; the defoamer comprises polyether type, organosilicon type and polyether modified organosilicon type defoamers, and the addition of the defoamer accounts for 0-5wt% of the total mass of diamine monomers and diacid monomers.
8. The continuous process for the preparation of polyamides according to claim 1 wherein the pre-polycondensation stage of step 2) is carried out using a concentrating reactor in combination with a tubular homogenizing reactor or using two pre-polymerization reactors working intermittently and alternately.
9. The apparatus used in the continuous production process of a polyamide as claimed in any one of claims 1 to 8, characterized by comprising a diamine tank (1) and a diacid tank (2) connected to a salifying reaction vessel (3), the salifying reaction vessel (3) connected to a salt solution tank (6), the salt solution tank (6) connected to a pre-polycondensation reaction mechanism connected to a plunger pump (15), the plunger pump (15) connected to a tubular homogenizing reactor (16), the tubular homogenizing reactor (16) connected to a gear pump (19), the gear pump (19) connected to a single screw extruder (20), the single screw extruder (20) connected to a twin screw extruder (24), an upstream vacuum vent (21) and a downstream vacuum vent (22) provided on the twin screw extruder (24), and a pressure release valve (23) provided on the upstream vacuum vent (21).
10. The apparatus for continuous production of polyamide according to claim 9, characterized in that:
the pre-polycondensation reaction mechanism comprises a circulating pump (12) connected with a salt solution storage tank (6), the circulating pump (12) is connected with a concentration reaction kettle (13), a heat exchanger (9) is arranged on a bypass between the circulating pump (12) and the concentration reaction kettle (13), and the concentration reaction kettle (13) is in circulating connection with a rectifying tower (14); a discharge hole of the concentration reaction kettle (13) is connected with a plunger pump (15);
or comprises a first prepolymerization kettle (25) connected with a salt solution storage tank (6), the first prepolymerization kettle (25) is connected with a second prepolymerization kettle (26) in parallel, and the first prepolymerization kettle (25) and the second prepolymerization kettle (26) are connected with a plunger pump (15).
CN202311419646.9A 2023-10-30 2023-10-30 Continuous preparation method and device for polyamide Pending CN117467132A (en)

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