CN113698288B - Novel method for continuously preparing powdery nylon salt and matched device - Google Patents
Novel method for continuously preparing powdery nylon salt and matched device Download PDFInfo
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- C07C51/41—Preparation of salts of carboxylic acids
- C07C51/412—Preparation of salts of carboxylic acids by conversion of the acids, their salts, esters or anhydrides with the same carboxylic acid part
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- B01D—SEPARATION
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Abstract
The invention discloses a new method for continuously preparing powdery nylon salt and a matched device, belonging to the technical field of synthesis of nylon. The method comprises the following steps: 1) Replacing air of the system with inert gas, heating the neutralization reactor, the salt solution temporary storage tank, the solution delivery pump and the solution delivery pipeline, and simultaneously starting a heating switch of the spray drying equipment to heat the high-temperature air delivery pipeline; 2) Continuously adding diamine, dibasic acid, a catalyst and a solvent into a neutralization reactor according to a certain proportion, wherein the retention time is 10-20min, and feeding the obtained nylon salt solution into a salt solution temporary storage tank and adjusting the pH; 3) And (3) sending the adjusted nylon salt solution into a drying tower of spray drying equipment through a solution delivery pump, and after the action of high-temperature air, enabling the solvent to be changed into steam to escape to obtain powdery nylon salt. The invention can continuously prepare the nylon salt solution into white powdery nylon salt which can directly enter a solid phase polymerization reactor to participate in continuous solid phase polymerization.
Description
Technical Field
The invention belongs to the field of synthesis of nylon, and particularly relates to a novel method and a matched device for continuously preparing powdery nylon salt.
Background
Nylon, known as polyamide, is a generic name for thermoplastic resins containing recurring amide groups-NHCO-in the molecular main chain, and is usually prepared by polycondensation of a diamine and a dibasic acid. Nylon is one of five engineering plastics, and has the advantages of good wear resistance, corrosion resistance and oil/chemical resistance, and also has the excellent characteristics of good self-lubricating property, low friction coefficient and easy processing. The method can be widely applied to the fields of automobiles, electronics, electrics, aerospace and the like, the market demand is continuously increased, and the application field is gradually expanded.
A new method for preparing nylon, namely a continuous solid phase polycondensation method, is proposed in patent CN 112979941A applied in the laboratory. Compared with the traditional two-step method (melting prepolymerization and solid phase post polymerization), the polymerization method reduces the reaction temperature, shortens the reaction time, and also solves the problems that the product is easy to form gel, yellow and even generates black spots in the traditional polymerization method; compared with an intermittent solid-phase polymerization method, the polymerization method simplifies the process operation, improves the automation degree of production, reduces the labor intensity of workers, greatly improves the adaptability and the economy of industrial production, improves the production efficiency, and simultaneously has stable preparation process, excellent physical and mechanical properties of products and stable quality. The polymerization method can be used for the polymerization of pure nylon and the polymerization of copolymerized nylon, and has the advantages that the polymerization method can occupy important positions in future nylon production, particularly in the production of high-temperature nylon.
However, this polymerization method requires that the starting material be a solid, powdery nylon salt. For this reason, we consult the conventional method for preparing powdered nylon salt, and patents such as CN 105622930A, CN 109180931A, CN 107573502A, CN 1289788A, CN 1255507A, CN 105924358A, etc. describe the relevant salt forming conditions and centrifugation processes in detail: adding diamine and dibasic acid into a solvent, heating to a preset temperature, preparing a nylon salt solution through a neutralization reaction, cooling, and performing centrifugal separation to obtain powdery nylon salt. For pure nylon continuous solid phase polymerization, the method can be used. However, when the continuous solid phase polymerization of the copolymerized nylon is carried out, because the solubility of two or more nylon salts in a solvent is different, the centrifugal separation is directly carried out, the proportion of the nylon salts is distorted, and the polymerized product can not meet the preset requirement; if centrifugal separation is performed before mixing, the mixing of nylon salt is not uniform, and the quality of the polymerized product is not stable.
Therefore, there is a need for a new method for preparing powdered nylon salt, which can not only solve the above-mentioned disadvantages of the preparation process of nylon salt, but also continuously provide the required nylon salt for continuous solid-phase polymerization.
Disclosure of Invention
The invention aims to provide a novel method for continuously preparing powdery nylon salt and a matched device, which is a practical industrial amplification production scheme and is used for better matching continuous solid-phase polymerization.
In order to realize the purpose, the technical scheme of the invention is as follows:
a novel method for continuously preparing powdery nylon salt comprises the following steps:
1) Replacing air in the system with inert gas, heating the temperature of the neutralization reactor, the salt solution temporary storage tank, the solution delivery pump and the solution delivery pipeline to 80-140 ℃, simultaneously starting a heating switch of spray drying equipment, heating the high-temperature air delivery pipeline to 100-160 ℃, and keeping the temperature for 0.5-1h;
2) Continuously adding diamine, dibasic acid, solvent and catalyst into a neutralization reactor according to a certain proportion for reaction, wherein the retention time is 10-20min, and the obtained nylon salt solution enters a salt solution temporary storage tank and the pH value is adjusted to 7.0-7.2;
3) And (3) conveying the prepared nylon salt solution into a drying tower of spray drying equipment through a solution conveying pump, and performing high-temperature air action to obtain white powdery nylon salt.
In the step 3), the escaped solvent steam is further separated by a cyclone separator to obtain nylon salt, and the obtained gas can be recycled and enter a system for continuous recycling.
The diamine is one or the mixture of more than two of aliphatic diamine with 4-14 carbon atoms, p-xylylenediamine, m-xylylenediamine, 1,4-cyclohexanediamine and 1,4-cyclohexanediamine; preferably, the diamines are hexamethylene diamine, decamethylene diamine, and dodecamethylene diamine, which are in greater market presence.
The dibasic acid is one or more than two of fatty dibasic acid with 4-14 carbon atoms, terephthalic acid, isophthalic acid, 1,4-cyclohexanedicarboxylic acid, 2,6-naphthalenedicarboxylic acid and 2,5-furandicarboxylic acid; preferably, the dibasic acid is adipic acid, sebacic acid, dodecanedioic acid, terephthalic acid, and the use amount of these dibasic acids is larger.
Particularly, the nylon prepared by the diamine and the diacid is more common, has excellent performance and larger using amount.
Preferably, the solvent is one or more than two of pure water, ethanol and methanol; preferably, the solvent is pure water, which is low in price and does not have the danger of flammability and explosiveness.
Preferably, the mass ratio of the total mass of diamine and diacid to the mass of solvent is 1:1-10, preferably 1:1-5, and the amount of solvent is too much, which not only wastes energy and solvent and increases the production cost, but also increases the cost of removing and recycling solvent.
The catalyst is one or more than two of phosphorous acid, sodium hypophosphite, triphenyl phosphate and H10, and the dosage of the catalyst is 0.1 to 0.5 percent of the total mass of the diamine and the dibasic acid
Preferably, the temperature of the high-temperature air is 100-160 ℃, the temperature is too low, the solvent removing effect is poor, a large amount of solvent is mixed into the nylon salt, and the drying effect is poor; if the temperature is too high, the nylon salt may melt and stick to the wall, a large amount of energy is consumed, resources are wasted, and the cost of the product is increased.
The method is suitable for continuously preparing powdery nylon salt, the obtained nylon salt is white powdery, the yield of the product is high, the performance is stable, the quality is excellent, and the use requirement of continuous solid-phase polymerization reaction can be completely met.
The invention also provides a matching device for continuously preparing powdery nylon salt, which comprises a neutralization reactor, a salt solution temporary storage tank and spray drying equipment which are sequentially connected by pipelines, wherein a solution delivery pump is arranged on a connecting pipeline between the salt solution temporary storage tank and the spray drying equipment, and heating devices are arranged on the neutralization reactor, the salt solution temporary storage tank and the pipelines connecting the neutralization reactor, the salt solution temporary storage tank and the spray drying equipment.
The spray drying equipment comprises a drying tower, a compressed air inlet, a liquid inlet and a high-temperature air inlet are arranged at the top of the drying tower, and a discharge port and an air outlet are arranged at the bottom of the drying tower.
The spray drying equipment further comprises a cyclone separator, wherein the top of the cyclone separator is provided with an air inlet and an air outlet, the bottom of the cyclone separator is provided with a discharge hole, a first solvent steam escape pipeline is arranged between the air inlet of the cyclone separator and the air outlet of the drying tower, and a second solvent steam escape pipeline is arranged at the air outlet of the cyclone separator.
The neutralization reactor comprises a reactor body, an upper end enclosure and a stirring device, wherein the upper end enclosure is respectively provided with a dibasic acid inlet, a diamine inlet, a solvent inlet, a catalyst inlet, an inert gas inlet and an inert gas outlet.
The top of the salt solution temporary storage tank is provided with a diamine outlet and a liquid inlet connected with a discharge port at the bottom of the neutralization reactor, and the bottom of the salt solution temporary storage tank is provided with a discharge port connected with a dryer.
The key points of the invention are as follows:
(1) Temperature of solution delivery pump and solution delivery pipe: the temperature in the solution delivery pump and the solution delivery pipeline is kept consistent with the temperature in the neutralization reactor, so that the phenomenon that solid salt is separated out due to temperature reduction in the delivery process of the nylon salt solution to block the pipeline can be prevented, and the energy waste caused by overhigh temperature can be prevented.
(2) Controlling the temperature of the high-temperature air conveying pipeline: the temperature is too low, the solvent in the nylon salt solution can not be completely changed into steam, and a considerable part of the solvent exists in a free state, so that the yield and the efficiency are influenced; the temperature is too high, which not only wastes energy and increases cost, but also seriously causes diamine generated by decomposition of nylon salt to escape in the form of steam, so that the molar ratio of amine to acid is unbalanced, and the molecular weight of the product in the polymerization process is influenced.
(3) The dosage of the solvent is as follows: the amount of the solvent is too small, the nylon salt cannot be completely dissolved in the solvent, and the phenomenon of blockage caused by the precipitation of part of nylon is not beneficial to the transportation of salt liquid; more solvent will affect the efficiency of drying.
Compared with the prior art, the invention has the technical effects that:
(1) The invention develops a new method for preparing nylon salt, and the method can be used for quickly and efficiently preparing powdery nylon salt: when only one nylon salt exists in the solution, the method has higher efficiency; when more than two kinds of nylon salts exist in the solution, the method solves the problem of nylon salt proportion distortion caused by different solubilities when the mixed nylon salt is prepared by direct centrifugal separation, and the obtained product has excellent mixing effect and is superior to the nylon salt prepared separately and then mixed.
(2) The nylon salt prepared by the method can generate solvent steam which can be recycled as a heating medium, thereby saving energy and avoiding the problems of waste liquid and solid waste; in the conventional salt formation, after the nylon salt solution is separated, the recycling of the mother solution easily causes the phenomena of yellowing of the product and performance reduction.
(3) The diameter of the nylon salt particles prepared by the method is far smaller than that of nylon salt prepared by a conventional method, the specific surface area of the particles is increased, the full contact between the nylon salt and solvent steam in the solid-phase polymerization process is facilitated, the reaction rate is accelerated, and the reaction efficiency is improved.
(4) The method and the device can continuously obtain the white powdery nylon salt, the product has high yield, stable performance and excellent quality, and can completely meet the use requirement of continuous solid-phase polymerization reaction.
Drawings
FIG. 1 is a schematic structural diagram of an apparatus for continuously preparing powdered nylon salt according to an embodiment of the present invention.
Detailed Description
The following examples are provided to further illustrate the practice of the invention.
The device matched with the method for continuously preparing powdery nylon salt in the embodiment of the invention comprises a neutralization reactor 1, a salt solution temporary storage tank 2 and a spray drying device 4 which are sequentially connected by pipelines, wherein a solution delivery pump 3 is arranged on a connecting pipeline between the salt solution temporary storage tank 2 and the spray drying device 4, heating devices are arranged on the neutralization reactor 1, the salt solution temporary storage tank 2 and pipelines connecting the neutralization reactor 1, the salt solution temporary storage tank 2 and the spray drying device 4, the adopted heating devices can be in any form in the prior art, such as heat conduction oil, resistance wires and other heating modes, the requirement for heating the pipelines of the neutralization reactor 1, the salt solution temporary storage tank 2 and the spray drying device 4 is met, the specific arrangement mode of the heating devices is not limited, and the reactor body 6, the salt solution temporary storage tank 2, the spray drying device and the pipelines thereof are all provided with double-layer interlayers, and the heat conduction oil is arranged in the interlayers or the resistance wires are not shown in the attached drawings.
The spray drying equipment 4 comprises a drying tower 16, a compressed air inlet, a liquid inlet and a high-temperature air inlet are arranged at the top of the drying tower 16, and a discharge hole and an air outlet are arranged at the bottom of the drying tower. The compressed air inlet is connected with a compressed air conveying pipeline 19, the high-temperature air inlet is connected with a high-temperature air conveying pipeline 20, and the liquid inlet is connected with the solution conveying pipeline 5.
The spray drying equipment 4 further comprises a cyclone separator 17, wherein the top of the cyclone separator 17 is provided with an air inlet and an air outlet, the bottom of the cyclone separator 17 is provided with a discharge hole 22, a first solvent steam escape pipeline 18 is arranged between the air inlet of the cyclone separator and the air outlet of the drying tower, and a second solvent steam escape pipeline 18-1 is arranged at the air outlet of the cyclone separator.
The neutralization reactor 1 comprises a reactor body 6, an upper end enclosure 7 and a stirring device 8, wherein a dibasic acid inlet, a diamine inlet, a solvent inlet, a catalyst inlet, an inert gas inlet and an inert gas outlet are respectively arranged on the upper end enclosure and are respectively connected with a dibasic acid conveying pipeline 9, a diamine conveying pipeline 10, a solvent conveying pipeline 11, a catalyst conveying pipeline 12, an inert gas inlet pipeline 13 and an inert gas outlet pipeline 14.
The top of the salt solution temporary storage tank 2 is provided with a diamine outlet connected with a diamine conveying pipeline 15, and is also provided with a liquid inlet connected with a discharge port at the bottom of the neutralization reactor 1, and the bottom of the salt solution temporary storage tank is provided with a discharge port connected with the spray drying equipment 4.
The working process comprises the following steps: inert gas (nitrogen in the embodiment of the invention) is introduced through the gas inlet pipeline 13, and nitrogen is discharged through the gas outlet pipeline 14 for gas replacement, so that the gas replacement of the neutralization reactor 1 and pipelines arranged above and below the neutralization reactor 1 is completed; setting the service temperatures of a neutralization reactor 1, a salt solution temporary storage tank 2, a solution delivery pump 3, a spray drying device 4, a solution delivery pipeline 5 and a high-temperature air delivery pipeline 20, starting a heating switch, and preserving heat for 1h when the temperatures are raised to set values; starting an air compressor of a stirring and compressed air conveying pipeline 19 of the neutralization reactor 1, adding raw materials into the neutralization reactor 1 according to a predetermined proportion through a dibasic acid conveying pipeline 9, a diamine conveying pipeline 10, a solvent conveying pipeline 11 and an additive conveying pipeline 12 respectively, keeping the raw materials in the raw materials for 10-20min, feeding the obtained nylon salt solution into a salt solution temporary storage tank 2, and adjusting the pH value of the nylon salt solution to 7.0-7.2; then the nylon salt enters the spray drying equipment 4 through the solution conveying pipeline 5 and the solution conveying pump 3, meanwhile, the hot air flow from the high-temperature air conveying pipeline 20 can instantly evaporate the solvent in the nylon salt solution to dryness, the dried powdery nylon salt flows out through a discharge port 21 below the drying tower 16, the solvent steam is discharged through a first solvent steam escape pipeline 18 under the action of compressed air in a compressed air conveying pipeline 19, at the moment, a small amount of nylon salt powder exists in the steam, the powdery nylon salt descends again and flows out through a discharge port 22 under the action of a cyclone separator 17, the solvent steam is discharged and recycled through a second steam escape pipeline 18-1, and the nylon salt flowing out from the discharge ports 21 and 22 can be directly subjected to polymerization reaction. The device can continuously prepare the nylon salt solution into powdery nylon salt and send the powdery nylon salt into the continuous solid-phase polymerization reactor, thereby realizing perfect matching of salt formation and solid-phase polymerization, simplifying process operation, improving the automation degree of production, reducing the labor intensity, greatly improving the adaptability and the economy of industrial production, improving the production efficiency, and simultaneously, the preparation process is stable, and the product has excellent physical properties and stable quality.
Example 1
The new method for continuously preparing powdered nylon salt of this example comprises the following steps:
1) With N 2 Replacing air in the system, heating the temperature of the neutralization reactor, the salt solution temporary storage tank, the solution delivery pump and the solution delivery pipeline to 120 ℃, simultaneously starting a heating switch of the spray drying equipment, heating the temperature of the high-temperature air delivery pipeline to 150 ℃, and keeping the temperature for 0.5h;
2) Continuously feeding decamethylenediamine (1.74kg, 10.1mol), terephthalic acid (1.66kg, 10mol), pure water (10.2kg, 300 wt%) and sodium hypophosphite (10.2g, 0.3 wt%) into a neutralization reactor for a retention time of 15min, feeding the resulting nylon 10T salt solution into a salt solution holding tank and adjusting the pH value to 7.2;
3) And (3) sending the adjusted nylon salt solution into a drying tower of spray drying equipment through a solution delivery pump, and after the nylon salt solution is acted by high-temperature air at 150 ℃, water is changed into steam to escape to obtain powdery nylon 10T salt, wherein the steam can be recycled as a heating medium for continuous use.
Example 2
The new method for continuously preparing powdered nylon salt of this example comprises the following steps:
1) With CO 2 Replacing air in the system, heating the temperature of the neutralization reactor, the salt solution temporary storage tank, the solution delivery pump and the solution delivery pipeline to 140 ℃, simultaneously starting a heating switch of the spray drying equipment, heating the temperature of the high-temperature air delivery pipeline to 160 ℃, and keeping the temperature for 0.5h;
2) Continuously feeding dodecanediamine (2.02kg, 10.1mol), terephthalic acid (1.66kg, 10mol), pure water (11kg, 300% by weight) and phosphorous acid (11.0g, 0.3% by weight) into a neutralization reactor for a residence time of 20min, feeding the obtained nylon 12T salt solution into a salt solution temporary storage tank and adjusting the pH value to 7.1;
3) And (3) sending the adjusted nylon salt solution into a drying tower of spray drying equipment through a solution delivery pump, and after the nylon salt solution is acted by high-temperature air at 160 ℃, changing water into steam to escape to obtain powdery nylon 12T salt, wherein the steam can be recycled as a heating medium for continuous use.
Example 3
The new method for continuously preparing powdered nylon salt of this example comprises the following steps:
1) Replacing air in the system with Ar, heating the temperature of the neutralization reactor, the salt solution temporary storage tank, the solution conveying pump and the solution conveying pipeline to 80 ℃, simultaneously starting a heating switch of spray drying equipment, heating the temperature of the high-temperature air conveying pipeline to 100 ℃, and keeping the temperature for 0.5h;
2) Hexamethylenediamine (1.17kg, 10.1mol), adipic acid (1.46kg, 10mol), pure water (3.95kg, 150% by weight) and triphenyl phosphate (7.89g, 0.3% by weight) were continuously added to the neutralization reactor for a residence time of 10min, and the resulting nylon 66 salt solution was introduced into a salt solution holding tank and adjusted to a pH of 7.2;
3) And (3) sending the adjusted nylon salt solution into a drying tower of spray drying equipment through a solution delivery pump, and after the nylon salt solution is acted by high-temperature air at 100 ℃, converting water into steam to escape to obtain powdery nylon 66 salt, wherein the steam can be recycled as a heating medium for continuous use.
Example 4
The new method for continuously preparing powdered nylon salt of this example comprises the following steps:
1) With N 2 Replacing air in the system, heating the temperature of the neutralization reactor, the salt solution temporary storage tank, the solution delivery pump and the solution delivery pipeline to 140 ℃, simultaneously, starting a heating switch of the spray drying equipment, heating the temperature of the high-temperature air delivery pipeline to 140 ℃, and keeping the temperature for 0.5h;
2) Continuously adding dodecanedioic acid (2.02kg, 10.1mol), dodecanedioic acid (2.30kg, 10 mol), pure water (13.0kg, 300% by weight) and catalyst H10 (13.0g, 0.3% by weight) into a neutralization reactor for a residence time of 20min, and feeding the obtained nylon 1212 salt solution into a salt solution temporary storage tank and adjusting the pH value to 7.2;
3) And (3) sending the adjusted nylon salt solution into a drying tower of spray drying equipment through a solution delivery pump, and after the nylon salt solution is acted by high-temperature air at 140 ℃, dissolving water into steam to escape to obtain powdery nylon 1212 salt, wherein the steam can be recycled as a heating medium for continuous use.
Example 5
The novel method for continuously preparing powdered nylon salt of this example comprises the following steps:
1) With N 2 Replacing air in the system, heating the temperature of the neutralization reactor, the salt solution temporary storage tank, the solution delivery pump and the solution delivery pipeline to 80 ℃, simultaneously starting a heating switch of the spray drying equipment, heating the temperature of the high-temperature air delivery pipeline to 110 ℃, and keeping the temperature for 0.5h;
2) Decamethylenediamine (1.74kg, 10.1mol), 1,4-cyclohexanedicarboxylic acid (1.72kg, 10mol), pure water (3.46kg, 100% wt) and sodium hypophosphite (10.4 g,0.3% wt) were continuously added to the neutralization reactor for a residence time of 10min, and the resulting nylon 10C salt solution was fed into the salt solution temporary storage tank and adjusted to a pH of 7.2;
3) And (3) sending the adjusted nylon salt solution into a drying tower of spray drying equipment through a solution delivery pump, and after the nylon salt solution is acted by high-temperature air at 110 ℃, changing water into steam to escape to obtain powdery nylon 10C salt, wherein the steam can be recycled as a heating medium for continuous use.
Example 6
The novel method for continuously preparing powdered nylon salt of this example comprises the following steps:
1) With N 2 Replacing air in the system, heating the temperature of the neutralization reactor, the salt solution temporary storage tank, the solution delivery pump and the solution delivery pipeline to 120 ℃, simultaneously starting a heating switch of the spray drying equipment, heating the temperature of the high-temperature air delivery pipeline to 150 ℃, and keeping the temperature for 0.5h;
2) Decamethylenediamine (1.74kg, 10.1 mol), 2,6-naphthalenedicarboxylic acid (2.16kg, 10mol), ethanol (11.7kg, 300% wt) and sodium hypophosphite (11.7g, 0.3% wt) were continuously added to the neutralization reactor for a residence time of 20min, and the resulting nylon 10N salt solution was charged into a salt solution storage tank and adjusted to a pH of 7.1;
3) And (3) conveying the adjusted nylon salt solution into a drying tower of spray drying equipment through a solution conveying pump, and converting ethanol into steam to escape under the action of high-temperature air at 150 ℃ to obtain powdery nylon 10N salt, wherein the ethanol steam can be recycled for continuous use.
Example 7
The new method for continuously preparing powdered nylon salt of this example comprises the following steps:
1) With N 2 Replacing air in the system, heating the temperature of the neutralization reactor, the salt solution temporary storage tank, the solution delivery pump and the solution delivery pipeline to 100 ℃, simultaneously starting a heating switch of the spray drying equipment, heating the temperature of the high-temperature air delivery pipeline to 130 ℃, and keeping the temperature for 0.5h;
2) Continuously adding hexamethylenediamine (1.15kg, 9.9mol), terephthalic acid (0.83kg, 5mol), adipic acid (0.73kg, 5mol), pure water (5.42kg, 200% wt) and sodium hypophosphite (8.13g, 0.3% wt) to the neutralization reactor for a residence time of 10min, the resulting nylon 6T/66 salt solution was fed to the salt solution temporary storage tank and the pH was adjusted to 7.0;
3) The adjusted nylon salt solution is sent into a drying tower of spray drying equipment through a solution delivery pump, and water is changed into steam to escape after the action of high-temperature air at 130 ℃ to obtain powdery nylon 6T/66 salt; the water vapor can be recycled as the heating medium for continuous use.
Example 8
The novel method for continuously preparing powdered nylon salt of this example comprises the following steps:
1) With N 2 Replacing air in the system, heating the temperature of the neutralization reactor, the salt solution temporary storage tank, the solution delivery pump and the solution delivery pipeline to 100 ℃, simultaneously starting a heating switch of the spray drying equipment, heating the temperature of the high-temperature air delivery pipeline to 120 ℃, and keeping the temperature for 0.5h;
2) Continuously adding pentanediamine (1.04kg, 10.2 mol), terephthalic acid (0.83kg, 5 mol), adipic acid (0.73kg, 5 mol), pure water (5.20kg, 200% by weight) and sodium hypophosphite (7.80g, 0.3% by weight) into a neutralization reactor for a residence time of 10min, and feeding the resultant nylon 5T/56 salt solution into a salt solution temporary storage tank and adjusting the pH to 7.2;
3) And (3) conveying the adjusted nylon salt solution into a drying tower of spray drying equipment through a solution conveying pump, and after the nylon salt solution is acted by high-temperature air at 120 ℃, changing water into steam to escape to obtain powdery nylon 5T/56 salt, wherein the steam can be recycled as a heating medium for continuous use.
Example 9
The new method for continuously preparing powdered nylon salt of this example comprises the following steps:
1) With N 2 Replacing air in the system, heating the temperature of the neutralization reactor, the salt solution temporary storage tank, the solution delivery pump and the solution delivery pipeline to 120 ℃, simultaneously starting a heating switch of the spray drying equipment, heating the temperature of the high-temperature air delivery pipeline to 150 ℃, and keeping the temperature for 0.5h;
2) Continuously adding hexamethylene diamine (0.58kg, 5.00mol), decamethylene diamine (0.86kg, 5.00mol), terephthalic acid (1.66kg, 10mol), pure water (15.5kg, 500 percent by weight) and sodium hypophosphite (3.1g, 0.1 percent by weight) into a neutralization reactor, wherein the residence time is 20min, and feeding the obtained nylon 6T/10T salt solution into a salt solution temporary storage tank and adjusting the pH value to be 7.1;
3) And (3) sending the adjusted nylon salt solution into a drying tower of spray drying equipment through a solution delivery pump, and after the nylon salt solution is acted by high-temperature air at 150 ℃, water is changed into steam to escape to obtain powdery nylon 6T/10T salt, wherein the steam can be recycled as a heating medium for continuous use.
Example 10
The new method for continuously preparing powdered nylon salt of this example comprises the following steps:
1) With N 2 Replacing air in the system, heating the temperature of the neutralization reactor, the salt solution temporary storage tank, the solution delivery pump and the solution delivery pipeline to 140 ℃, simultaneously starting a heating switch of the spray drying equipment, heating the temperature of the high-temperature air delivery pipeline to 155 ℃, and keeping the temperature for 0.5h;
2) Decamethylenediamine (0.86kg, 5.00mol), dodecanediamine (1.00kg, 5.00mol), terephthalic acid (1.66kg, 10mol), pure water (14.1kg, 400% wt) and sodium hypophosphite (17.6 g,0.5% wt) were continuously added into a neutralization reactor for a residence time of 20min, and the resulting nylon 10T/12T salt solution was fed into a salt solution temporary storage tank and adjusted to a pH of 7.2;
3) And (3) conveying the adjusted nylon salt solution into a drying tower of spray drying equipment through a solution conveying pump, and after the nylon salt solution is acted by high-temperature air at 155 ℃, changing water into steam to escape to obtain powdery nylon 10T/12T salt, wherein the steam can be recycled as a heating medium for continuous use.
2. Description of the comparative examples
Comparative example 1
The novel method for continuously preparing powdered nylon salt of the comparative example comprises the following steps:
1) Replacing air of the system with Ar, heating the temperature of the neutralization reactor, the salt solution temporary storage tank, the solution conveying pump and the solution conveying pipeline to 80 ℃, simultaneously starting a heating switch of the spray drying equipment, heating the temperature of the high-temperature air conveying pipeline to 90 ℃, and keeping the temperature for 0.5h;
2) Hexamethylenediamine (1.17kg, 10.1mol), adipic acid (1.46kg, 10mol), pure water (3.95kg, 150% by weight) and triphenyl phosphate (7.89g, 0.3% by weight) were continuously added to the neutralization reactor for a residence time of 10min, and the resulting nylon 66 salt solution was introduced into a salt solution holding tank and adjusted to a pH of 7.2;
3) And (3) sending the adjusted nylon salt solution into a drying tower of spray drying equipment through a solution delivery pump, and after the nylon salt solution is acted by high-temperature air at 90 ℃, changing water into steam to escape to obtain powdery nylon 66 salt, wherein the steam can be recycled as a heating medium for continuous use.
The yield of comparative example 1 was low compared to example 3, mainly because the temperature of the high temperature air delivery pipe of the spray drying equipment was too low to completely remove water from the nylon salt solution, resulting in a part of liquid water remaining in the nylon salt temporary storage tank, which part of water dissolved the nylon salt, resulting in a decrease in the yield of powdered nylon salt.
Comparative example 2
The novel method for continuously preparing powdered nylon salt of the comparative example comprises the following steps:
1) With N 2 Replacing air in the system, heating the temperature of the neutralization reactor, the salt solution temporary storage tank, the solution delivery pump and the solution delivery pipeline to 80 ℃, simultaneously starting a heating switch of the spray drying equipment, heating the temperature of the high-temperature air delivery pipeline to 180 ℃, and keeping the temperature for 0.5h;
2) Continuously adding hexamethylenediamine (1.17kg, 10.1mol), adipic acid (1.46kg, 10mol), pure water (3.95kg, 150% wt) and triphenyl phosphate (7.89g, 0.3% wt) to a neutralization reactor for a residence time of 10min, feeding the resulting nylon 66 salt solution into a brine holding tank and adjusting the pH to 7.2;
3) And (3) conveying the adjusted nylon salt solution into a drying tower of spray drying equipment through a solution conveying pump, and reacting with air at a high temperature of 180 ℃ to enable water to be changed into steam to escape so as to obtain powdery nylon 66 salt.
Compared with example 3, the yield of comparative example 2 is slightly reduced, and the molar ratio of the hexamethylene diamine to the adipic acid is changed from 1.01.
TABLE 1 test items, instruments and standards
| Test item | Test instrument | Test standard |
| Melting Point | DSC(NETZSCH DSC 214) | 10℃/min |
| Molar ratio of amine to acid | Bruker DPX-400 | / |
| Yield of the product | Analytical balance (Aohaus CP 214) | / |
Wherein the content of the first and second substances,
m 0 -the total mass of the starting diamine and diacid;
m 1 and spray drying and thoroughly drying to obtain the quality of the nylon salt.
TABLE 2 physical Properties of the Nylon salts obtained in examples and comparative examples
Claims (8)
1. A method for continuously preparing powdery nylon salt is characterized by comprising the following steps:
1) Replacing air in the system with inert gas, heating the temperature of the neutralization reactor, the salt solution temporary storage tank, the solution delivery pump and the solution delivery pipeline to 80-140 ℃, simultaneously starting a heating switch of spray drying equipment, and heating the high-temperature air delivery pipeline to 100-160 ℃ and keeping the temperature for 0.5-1h;
2) Continuously adding diamine, dibasic acid, solvent and catalyst into a neutralization reactor according to a certain proportion for reaction, wherein the retention time is 10-20min, and the obtained nylon salt solution enters a salt solution temporary storage tank and the pH value is adjusted to 7.0-7.2;
3) The prepared nylon salt solution is sent into a drying tower of spray drying equipment through a solution delivery pump, and white powdery nylon salt is obtained after the action of high-temperature air;
the device matched with the method comprises a neutralization reactor, a salt solution temporary storage tank and spray drying equipment which are sequentially connected through pipelines, wherein a solution delivery pump is arranged on a connecting pipeline between the salt solution temporary storage tank and the spray drying equipment, and heating devices are arranged on the neutralization reactor, the salt solution temporary storage tank and the pipelines connecting the neutralization reactor, the salt solution temporary storage tank and the spray drying equipment; the spray drying equipment comprises a drying tower, a compressed air inlet, a liquid inlet and a high-temperature air inlet are arranged at the top of the drying tower, and a discharge port and an air outlet are arranged at the bottom of the drying tower.
2. The novel process for continuously preparing nylon salt powder of claim 1, wherein in step 3), the escaped solvent vapor is further separated by a cyclone separator to obtain nylon salt, and the obtained gas can be recycled into the system for further recycling.
3. The novel process for continuously preparing powdery nylon salt according to claim 1, wherein the diamine is one or a mixture of two or more of aliphatic diamine having 4 to 14 carbon atoms, p-xylylenediamine, m-xylylenediamine, 1,4-cyclohexanediamine, and 1,4-cyclohexanedimethylamine, and the dibasic acid is one or two or more of aliphatic dibasic acid having 4 to 14 carbon atoms, terephthalic acid, isophthalic acid, 1,4-cyclohexanedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 2,5-furandicarboxylic acid.
4. The novel process for continuously preparing powdery nylon salt according to claim 1, wherein the molar ratio of diamine to dibasic acid is 0.99 to 1.02.
5. The novel process for continuously preparing powdery nylon salt according to claim 1, wherein the solvent is one or more of pure water, ethanol and methanol, and the mass ratio of the total mass of the diamine and the dibasic acid to the solvent is 1:1-10; the catalyst is one or more than two of phosphorous acid, sodium hypophosphite, triphenyl phosphate and H10, and the dosage of the catalyst is 0.1-0.5% of the total mass of diamine and dibasic acid.
6. The matched device which is adapted to the method for continuously preparing powdery nylon salt according to claim 1, comprises a neutralization reactor, a salt solution temporary storage tank and a spray drying device which are sequentially connected by pipelines, wherein a solution delivery pump is arranged on a connecting pipeline between the salt solution temporary storage tank and the spray drying device, and heating devices are arranged on the neutralization reactor, the salt solution temporary storage tank and the pipelines which are connected with the neutralization reactor, the salt solution temporary storage tank and the spray drying device; the spray drying equipment comprises a drying tower, wherein the top of the drying tower is provided with a compressed air inlet, a liquid inlet and a high-temperature air inlet, and the bottom of the drying tower is provided with a discharge hole and an air outlet; the spray drying equipment further comprises a cyclone separator, wherein the top of the cyclone separator is provided with an air inlet and an air outlet, the bottom of the cyclone separator is provided with a discharge hole, a first solvent steam escape pipeline is arranged between the air inlet of the cyclone separator and the air outlet of the drying tower, and a second solvent steam escape pipeline is arranged at the air outlet of the cyclone separator.
7. The apparatus as claimed in claim 6, wherein the neutralization reactor comprises a reactor body, an upper head and a stirring device, and the upper head is provided with a diacid inlet, a diamine inlet, a solvent inlet, a catalyst inlet, an inert gas inlet and an inert gas outlet.
8. The apparatus as claimed in claim 7, wherein the salt solution temporary storage tank is provided with a diamine outlet at the top and a liquid inlet connected to the outlet at the bottom of the neutralization reactor, and the bottom is provided with a discharge outlet connected to the dryer.
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