CN115772262B

CN115772262B - Continuous process for preparing aliphatic dibasic acid nylon

Info

Publication number: CN115772262B
Application number: CN202111035043.XA
Authority: CN
Inventors: 李洋
Original assignee: Chengdu 401 Technology Co ltd
Current assignee: Chengdu 401 Technology Co ltd
Priority date: 2021-09-06
Filing date: 2021-09-06
Publication date: 2024-01-19
Anticipated expiration: 2041-09-06
Also published as: WO2023030428A1; CN115772262A

Abstract

The invention provides a continuous process for preparing aliphatic dibasic acid nylon. The raw materials comprise polymerized monomers and polyamide, wherein the polymerized monomers comprise dibasic acid and diamine, and the mass ratio of aliphatic dibasic acid in the dibasic acid is 80-100%; continuously feeding the dibasic acid and the polyamide raw material into a continuous mixing device with shearing, dispersing and conveying functions, wherein the system temperature is lower than the melting point of the polyamide raw material, the polyamide raw material is dispersed into molten aliphatic dibasic acid in the conveying process, the molten aliphatic dibasic acid is uniformly mixed to form a continuously flowing molten mass, diamine is continuously added, and the molten aliphatic dibasic acid are continuously fed into a subsequent polymerization device to react after being uniformly mixed until the nylon is polymerized to reach the required molecular weight. Is an energy-saving and environment-friendly process with high production efficiency.

Description

Continuous process for preparing aliphatic dibasic acid nylon

Technical Field

The invention relates to the technical field of engineering plastics, in particular to a continuous process for preparing aliphatic dibasic acid nylon.

Background

Nylon (Nylon) is a common name for polyamides, known in english as polyamide, which contains recurring amide functions in the molecular chain. The comprehensive advantages of nylon in mechanical property, weather resistance, corrosion resistance, high temperature resistance and other properties and cost make it widely used in various fields of electronics, electrics, machinery, fiber, automobiles and the like.

The raw materials for synthesizing the nylon comprise diamine and dibasic acid, wherein the dibasic acid also comprises aliphatic and aromatic monomers. The aliphatic dibasic acid has poor thermal stability, is easily decomposed at high temperature, and affects the occurrence of polymerization reaction, thereby causing quality defects of the polymer such as color change, property change and the like. The most commonly used nylon polymerization process is to prepare nylon salt from dibasic acid and diamine in a solvent at a lower temperature, so that the thermal stability of aliphatic dibasic acid in the nylon salt is obviously improved, and then gradually heating for polymerization, thereby reducing the decomposition of the aliphatic dibasic acid and improving the quality of products. This set of processes requires the preparation of nylon salt solutions in advance in solvents, during which large amounts of water or organic solvents are consumed, and the solvents in the nylon salt solutions are also evaporated in subsequent polymerizations, which in turn consumes large amounts of energy.

CN112062950B reports a continuous nylon polymerization process, which uses a molten nylon polymer as a reactive dispersion system, so that a dibasic acid and a diamine react to form a salt therein, and then a polymerization reaction occurs, and nylon as the dispersion system can become a part of a product, thereby avoiding consumption of a small molecule solvent and energy consumption of evaporating the small molecule solvent. The method is more suitable for nylon with high aromatic diacid monomer content, because nylon which is usually used as a reactive dispersion system has higher melting point, so that the temperature for starting the reaction is higher, the stability of the aliphatic diacid is not favored, and the aromatic diacid has better thermal stability.

Disclosure of Invention

Aiming at the technical problems, the invention provides a continuous process for preparing aliphatic dibasic acid nylon, which is an energy-saving and environment-friendly process with high production efficiency.

In order to achieve the above purpose, the invention adopts the following technical scheme:

the continuous process for preparing aliphatic dibasic acid nylon comprises the following raw materials of polymerized monomers and polyamide, wherein the polymerized monomers comprise dibasic acid and diamine, and the mass ratio of the aliphatic dibasic acid in the dibasic acid is 80-100%; continuously feeding the dibasic acid and the polyamide raw material into a continuous mixing device with shearing, dispersing and conveying functions, wherein the system temperature is lower than the melting point of the polyamide raw material, the polyamide raw material is dispersed into molten aliphatic dibasic acid in the conveying process, the molten aliphatic dibasic acid is uniformly mixed to form a continuously flowing molten mass, diamine is continuously added, and the molten aliphatic dibasic acid are continuously fed into a subsequent polymerization device to react after being uniformly mixed until the nylon is polymerized to reach the required molecular weight.

The diamine and the diamine are common raw materials for nylon polymerization, but if the two raw materials are only used for polymerization in a continuous melting system, the diamine and the diamine cannot bear the pressure of water vapor generated by meeting polymerization dehydration of the diamine and the diamine at high temperature in a continuous mixing device because the two raw materials have insufficient melt strength after melting, so that the leakage of the water vapor can be caused, and partial polymerized monomers can be carried out along with the diamine, so that the proportion of the acid and the amine in the system is unbalanced, and a certain amount of polyamide needs to be added into the raw materials. The polyamide is dispersed into the molten aliphatic dibasic acid under the action of temperature and shear, and can provide enough melt strength for the melt. Polyamides are polymeric products that are capable of reversible chemical reactions with dibasic acids, have outstanding compatibility, and may not affect the properties of the polymeric product.

The invention utilizes the lower melting point of the aliphatic dibasic acid, controls the mixing temperature of the dibasic acid and the polyamide to be higher than the melting point of the aliphatic dibasic acid and lower than the melting point of the polyamide raw material, and under the temperature condition, the polyamide raw material is dispersed into the molten aliphatic dibasic acid in the conveying process, and the molten material which can flow continuously is formed by uniform mixing. Because the polyamide can react with the liquid diacid reversibly, the molecular weight of the polyamide is reduced sharply, and the melting flowable temperature of the nylon Long Gua polymer with low molecular weight is also reduced, so that the flowable temperature of the whole system is reduced, the stability of the aliphatic diacid monomer is met, the aliphatic diacid monomer can be conveyed stably in a continuous mixing device, and the stability of the product is ensured.

It is known from the principle of the present invention that the amount of polyamide as the final product is equal to the amount of polyamide in the raw material plus the amount of polyamide produced by polymerization of the polymerized monomers. The difference between the amount of polyamide in the product minus the amount of polyamide raw material is therefore the actual yield of the process. For the continuous polymerization apparatus of the present invention, in the case where the effective volume thereof is constant, the polymerization time is ideally the time for the material to flow through the effective volume of the whole apparatus, and thus the total yield of the apparatus is inversely proportional to the polymerization time. In order to ensure the stability of the final product, a certain polymerization time needs to be controlled. In the case of a certain polymerization time, the total amount of the end product is also constant. In order to increase the utilization and production efficiency of the polymerization apparatus, the amount of polyamide in the raw material should be as small as possible to increase the proportion of polymer produced by the actual polymerization of the monomers in the total product.

The molten aliphatic dibasic acid has a large polarity and can dissolve the polyamide therein. Since the polymerization of the amide is a reversible reaction, the dissolved polyamide undergoes acidolysis reaction, the molecular weight is reduced, the solubility is further increased, and the melting softening temperature is also reduced. However, too high an acidolysis degree may result in too low strength after melt softening or complete liquefaction. The temperature of the melting and dispersing section can be lower than the melting point of the polyamide raw material, so that the acidolysis degree of the polyamide raw material is reduced, and the melt obtained by melt mixing the dibasic acid and the polyamide has higher melt strength under the condition that the proportion of the polyamide in the raw material is certain. The melt strength after mixing is a key factor in withstanding the vapor pressure generated by dehydration during the polymerization of diamine and diacid, and the fully liquefied mixture cannot withstand the pressure of high temperature vapor, so that the mixture barrel must have sufficient strength. Therefore, the relatively lower temperature of the melt dispersing section can better maintain the strength of the melt after mixing, so that the proportion of polyamide in the raw materials can be reduced, the proportion of the polymerized monomers can be increased, and the actual production efficiency of the device can be improved under the condition of a certain total yield.

The mass ratio of the aliphatic dibasic acid to the polyamide raw material is 0.5-50:1. the polyamide raw material is too little to play a role in enhancing the melt strength; excessive usage can result in loss of utility of the device. 0.5-50: the ratio of 1 ensures the practical production efficiency of the device and provides enough strength for the melt to withstand the pressure of the water vapor generated by the dehydration. When the required weight of polyamide raw material exceeds 50% of the total weight of the raw material to have sufficient melt strength to achieve the sealing effect, the actual yield of the process is too low, and the advantages are not obvious compared with the traditional nylon polymerization process, and the method is not recommended.

The mixing temperature of the dibasic acid and the polyamide raw material is higher than the melting point of at least one aliphatic dibasic acid raw material, so that at least one aliphatic dibasic acid raw material can form a melt in the device, and other materials are uniformly dispersed in the melt under the shearing action of the device.

The mixed melt is obtained after the binary acid and the polyamide raw materials are uniformly mixed, and at least one section of the mixed melt is filled in a device before diamine is added to form a sealing section.

The diamine and the diamine added later meet and dehydrate, and high-temperature water vapor exists in the system, so that a section of material mixing and conveying device is filled with a melt of a mixture formed by the diamine and the polyamide in the raw materials before the diamine is added, leakage of the water vapor can be avoided, and the problems of quality caused by the fact that oxygen enters into a subsequent polymerization process and leakage of diamine monomers are avoided.

Preferably, the melt temperature of the seal section is lower than the mixing temperature of the diacid and polyamide raw materials.

After the materials are uniformly dispersed, the melt strength is increased under the action of polyamide, so that the sealing effect can be achieved, and a sealing section is formed. The presence of the amide oligomer in the melt mixture of diacid and polyamide results in a further decrease in the melting point of the diacid in the melt, such that the softening temperature of the entire melt is lower than the melting point of the diacid in the feedstock. At this time, the melt can still have proper fluidity when the sealing section lowers the system temperature below the melting point of the aliphatic dibasic acid raw material. Meanwhile, the system temperature is reduced, which is beneficial to further improving the intensity of the melt. Thus, it is further preferred that the melt temperature of the seal segment is below the melting point of the at least one molten aliphatic dibasic acid.

The aliphatic dibasic acid is at least one of dibasic acids with 6-18 carbon atoms.

Preferably, the aliphatic dibasic acid in the feedstock comprises adipic acid. The highest melting point of 6-18 carbon dibasic acids is adipic acid, and the melt formed from adipic acid can maintain sufficient strength at higher temperatures at about 155 ℃ and can be operated over a wider window. In addition, adipic acid is also the most polar of these dibasic acids, and most commonly used nylons such as PA6, PA66 are the most compatible, and other monomers used to make high temperature resistant nylons are the most compatible, and its melt can better melt nylon products with relatively higher melting points, more conveniently used to make copolymerized nylons with higher temperature resistance. Meanwhile, in the dibasic acid with 6-18 carbon atoms, when the same diamine is polymerized to form nylon, the nylon formed by adipic acid polymerization has the best temperature resistance and the most wide application space.

The continuous mixing device is a screw extrusion device. All continuous compounding devices with shear dispersion conveying function can be used as appropriate, preferably screw extrusion devices. The most commonly used screw extrusion device is a double screw extrusion device, the screw combination design of the screw extrusion device is flexible, and different conveying and shearing dispersing capacities can be designed at different stages according to the requirements. The screw extrusion device has the material dispersing capability and the interface updating capability far exceeding those of a general mixing device, can enable polymer raw materials and molten dibasic acid to be mixed uniformly rapidly, and can enable heat generated during salification of diamine and dibasic acid to be dispersed rapidly, so that the problems that the material temperature is too high, the color is yellow due to local high temperature, the polymer melt strength is too low, and the like, and the production stability and quality are affected can be better avoided.

The diamine according to the invention is preferably added in liquid form to the continuous mixing device. The diamine can be melted into liquid state or dissolved in a micromolecular solvent, and is added into a material mixing device in a liquid state, so that the sealing performance of the mixing device is more easily ensured, and the loss of volatile raw materials is prevented.

Preferably, after diamine addition, at least a portion of the material flows upward.

After all the materials are mixed, the materials are preferably provided with an upward flow section, so that a melt formed by the materials forms a sealing section when flowing upward even under lower viscosity, and the upper space of the device cannot be filled with gaseous diamine to overflow greatly due to low viscosity.

The molar ratio of the dibasic acid to the diamine in the polymerized monomer is 1:0.8-1.2. In general, the molar ratio of diamine and diacid involved in polymerization is close to 1 to obtain a polymer with higher molecular weight, and the volatility of diamine is generally higher than that of diacid. The amine number and acid number imbalance of the nylon Long Gua polymer or the polymer material itself with unequal carboxyl and amino functionalities affects the final polymer molecular weight, and to balance these factors, the molar ratio of diamine to diacid of the heavy polymeric monomer of the material is 1:0.8-1.2.

The polyamide in the raw materials is selected from PA66, PA56, PA610, PA612, PA1010, PA1212 and PAMXD6, or a copolymer taking the structure of the polyamide as a main body, preferably PA66, PA56 and PAMXD6, and the diacid monomers in the three polyamides are all adipic acid, so that the whole device has a larger operation space.

The subsequent polymerization device is at least one of a screw extrusion device, a tubular reaction device and a kettle reaction device.

In order to be able to achieve sufficiently large molecular weights, a sufficient reaction time is required, so that a screw extruder with a particularly long aspect ratio is required, a multistage screw extruder is usually required to be connected in series, the fixed investment is increased, and the equipment occupation is increased. The volume of the apparatus can be reduced by connecting other polymerization devices in series. Pipe reactors, reactor-type polymerization apparatus, and screw mixing apparatus having larger diameters can be used in the present invention.

The subsequent polymerization apparatus may be a continuous flow reactor or a screw extrusion apparatus connected in sequence. The continuous flow reactor is a continuous polymerization reactor, can be in the form of a pipeline or a reaction kettle or a tower, and mainly ensures that materials enter and exit continuously, and has no reflux in ideal state, and the residence time of all materials in the reactor is equal. The continuous flow reactor can control the polymerization time of the materials, thereby obtaining polymers with different molecular weights. After the materials pass through the continuous flow reactor, the device is also preferably a polymerization device for continuously flowing and discharging the materials, and the continuous production is most beneficial.

The polymerization process is devolatilized by a screw extrusion device, and extrusion granulation is performed. In the polymerization process of polyamide, small molecules are separated out, and the complete continuous production can be realized through devolatilization of a screw extrusion device. After the polymerization of various raw materials in a subsequent polymerization device is completed, a screw extrusion device can be directly added at the back for continuous polymerization and removal of volatile small molecules, so that the materials are further homogenized.

The invention has flexible adding modes of various raw materials, can simultaneously add the raw materials into the feeding section at the machine head, can also add partial raw materials into the middle section of the equipment in a side feeding or liquid pumping mode, and even can add the same raw materials in batches at different positions, thereby further enabling the mixing to be more uniform.

The materials of the invention are fed to the discharge, and the total average residence time in the material mixing device and the subsequent polymerization device is 10-120min.

The rate of polymerization is related to the temperature, the polymerization is fast and efficient, but too high a temperature causes a series of problems such as yellowing and degradation, so that the relationship between the reaction temperature and time needs to be balanced. The average residence time of the inventive materials in the material mixing device and in the subsequent polymerization device from the feed to the discharge is preferably from 10 to 120min. It can be estimated by the time at which the volume of the mixture fills the effective volume of all mixing and polymerization devices at a certain throughput. When the materials continuously flow, the average residence time of the materials in the device is theoretically the same under the condition of fixed yield, so that the uneven molecular weight caused by different residence times of the materials in the discontinuous process due to sequential feeding and discharging can be avoided. Under the condition of fixed device, the time of polymerization reaction can be regulated by regulating the total feeding quantity, so that polymers with different molecular weights can be prepared, and the requirements of different applications can be met. Typically, the amount of time the polymerization reaction takes can be varied by varying the throughput of the apparatus, thereby controlling the molecular weight of the product; the composition of the copolymerization unit can be conveniently controlled by controlling the feeding proportion of different materials, so that products with different physical properties are obtained. The same device can realize the production of products with different performances, and the flexibility of production is improved. All adjustments can be completed on line, avoiding waste caused by stopping intermittent process switching products.

The invention has the beneficial effects that:

1. the polymerization method of the invention utilizes the low melting point of the aliphatic dibasic acid, and the polyamide raw material is dispersed into the molten aliphatic dibasic acid in the conveying process, and is uniformly mixed to form a melt body capable of continuously flowing. Because the polyamide can react with the liquid diacid reversibly, the molecular weight of the polyamide is reduced sharply, and the melting flowable temperature of the nylon Long Gua polymer with low molecular weight is also reduced, so that the flowable temperature of the whole system is reduced, the stability of the aliphatic diacid monomer is met, the aliphatic diacid monomer can be conveyed stably in a continuous mixing device, and the stability of the product is ensured. Meanwhile, polyamide is dispersed into molten aliphatic dibasic acid under the action of temperature and shearing, so that sufficient melt strength can be provided for the melt, continuous forward conveying of materials is realized, continuity of feeding, reaction and discharging is realized, and the intermittent production defect of the traditional reaction kettle process is overcome.

2. The method omits the step of preparing nylon salt in the aqueous solution, avoids the generation of waste liquid in the preparation process of the nylon salt, and is an environment-friendly nylon synthesis method. The method has the characteristics of high production efficiency, low energy consumption, energy conservation and environmental protection, and is easy to popularize and apply in large scale in actual production. The process of forming nylon salt does not need small molecular solvent, thus saving water and energy.

3. The material temperature before diamine addition is controlled below the melting point of the polyamide raw material, and the lower temperature ensures that the polyamide raw material has better stability and can improve the strength of a melt, thereby reducing the consumption of the polyamide raw material and improving the utilization rate and the production efficiency of a polymerization device.

4. After the materials are uniformly dispersed, the temperature of the system is reduced below the melting point of the molten aliphatic dibasic acid in the sealing section, so that the melt still has proper fluidity, the strength of the melt is further improved, and the tightness is ensured.

5. The continuous nylon polymerization method provided by the invention avoids the problem of unstable product quality caused by batch production, is not influenced by factors such as temperature, pH value and the like in the preparation process of nylon salt in aqueous solution, and the obtained nylon product has the characteristics of good uniformity and stable quality.

Detailed Description

The invention will be further described by the following examples for the purpose of more clearly and specifically describing the object of the invention. The following examples are only for specific illustration of the implementation method of the present invention and do not limit the protection scope of the present invention.

Example 1

A continuous process for preparing aliphatic dibasic acid nylon comprises the steps of polymerizing monomers and polyamide, wherein the polymerized monomers comprise aliphatic dibasic acid and diamine; continuously feeding aliphatic dibasic acid and polyamide raw materials into a continuous mixing device with shearing, dispersing and conveying functions, wherein the system temperature is lower than the melting point of the polyamide raw materials, dispersing the polyamide raw materials into molten aliphatic dibasic acid in the conveying process, uniformly mixing to form a continuously flowing melt, continuously adding diamine, uniformly mixing, continuously feeding into a subsequent polymerization device for reaction, and polymerizing until the nylon reaches the required molecular weight.

Example 2

A continuous process for preparing aliphatic dibasic acid nylon comprises the following raw materials of a polymerized monomer and polyamide, wherein the polymerized monomer comprises dibasic acid and diamine, and the mass ratio of the aliphatic dibasic acid in the dibasic acid is 80%; continuously feeding the dibasic acid and the polyamide raw material into a continuous mixing device with shearing, dispersing and conveying functions, wherein the system temperature is lower than the melting point of the polyamide raw material, the polyamide raw material is dispersed into molten aliphatic dibasic acid in the conveying process, the molten aliphatic dibasic acid is uniformly mixed to form a continuously flowing molten mass, diamine is continuously added, and the molten aliphatic dibasic acid are continuously fed into a subsequent polymerization device to react after being uniformly mixed until the nylon is polymerized to reach the required molecular weight.

The mass ratio of the aliphatic dibasic acid to the polyamide raw material is 50:1, about 45% effective yield.

The mixing temperature of the diacid and polyamide starting materials is above the melting point of the at least one aliphatic diacid starting material.

The mixed melt is obtained after the binary acid and the polyamide raw materials are uniformly mixed, and at least one section of the device before diamine is added is filled with the mixed melt to form a sealing section. The melt temperature of the sealing section is lower than the mixing temperature of the dibasic acid and the polyamide raw material.

The subsequent polymerization device is a screw extrusion device.

Example 3

A continuous process for preparing aliphatic dibasic acid nylon comprises the following raw materials of a polymerized monomer and polyamide, wherein the polymerized monomer comprises dibasic acid and diamine, and the mass ratio of the aliphatic dibasic acid in the dibasic acid is 90%; continuously feeding the dibasic acid and the polyamide raw material into a continuous mixing device with shearing, dispersing and conveying functions, wherein the system temperature is lower than the melting point of the polyamide raw material, the polyamide raw material is dispersed into molten aliphatic dibasic acid in the conveying process, the molten aliphatic dibasic acid is uniformly mixed to form a continuously flowing molten mass, diamine is continuously added, and the molten aliphatic dibasic acid are continuously fed into a subsequent polymerization device to react after being uniformly mixed until the nylon is polymerized to reach the required molecular weight.

The mass ratio of the aliphatic dibasic acid to the polyamide raw material is 40:1.

The diamine is added into the continuous mixing device in a liquid state.

The subsequent polymerization device is a screw extrusion device and a kettle type reaction device.

The total average residence time of the materials from the feed to the discharge in the material mixing device and in the subsequent polymerization device is from 10 to 120min.

Example 4

A continuous process for preparing aliphatic dibasic acid nylon comprises the following raw materials of polymerized monomers and polyamide, wherein the polymerized monomers comprise dibasic acid and diamine, and the mass ratio of aliphatic dibasic acid in the dibasic acid accounts for 95%; continuously feeding the dibasic acid and the polyamide raw material into a continuous mixing device with shearing, dispersing and conveying functions, wherein the system temperature is lower than the melting point of the polyamide raw material, the polyamide raw material is dispersed into molten aliphatic dibasic acid in the conveying process, the molten aliphatic dibasic acid is uniformly mixed to form a continuously flowing molten mass, diamine is continuously added, and the molten aliphatic dibasic acid are continuously fed into a subsequent polymerization device to react after being uniformly mixed until the nylon is polymerized to reach the required molecular weight.

The mass ratio of the aliphatic dibasic acid to the polyamide raw material is 30:1.

The mixed melt is obtained after the binary acid and the polyamide raw materials are uniformly mixed, and at least one section of the device before diamine is added is filled with the mixed melt to form a sealing section. The melt temperature of the sealing section is lower than the melting point of the molten aliphatic dibasic acid.

The diamine is preferably added to the continuous mixing device in liquid form.

After diamine addition, at least one section of material flows upwards.

The molar ratio of the dibasic acid to the diamine in the polymerized monomer is 1:0.8-1.2.

The polyamide in the raw material is selected from PA66, PA56, PA610, PA612, PA1010, PA1212 and PAMXD6 or a copolymer mainly comprising the structure of the polyamide.

The subsequent polymerization device is a screw extrusion device and a tubular reaction device.

Example 5

The mass ratio of the aliphatic dibasic acid to the polyamide raw material is 25:1.

The aliphatic dibasic acid is adipic acid.

The diamine is preferably added to the continuous mixing device in liquid form.

After diamine addition, at least one section of material flows upwards.

The polyamide in the raw material is selected from PA66, PA56 and PAMXD6 or copolymers mainly comprising the polyamide structures.

The subsequent polymerization device is a tubular reaction device.

Example 6

According to 4:1, adipic acid, PAMXD6 resin and 0.5% of antioxidant and 0.2% of catalyst by weight based on the total weight are mixed, and the mixture is fed from the front end through a weight loss metering device to a total length-diameter ratio of 100:1, setting the temperature of a screw feeding section to be 100-120 ℃, setting the temperature of a melt dispersing section to be 120-195 ℃, setting the temperature of a melt sealing section after material dispersion to be 145 ℃, and adding m-xylylenediamine by weight loss control, so that the molar ratio of the m-xylylenediamine to adipic acid is 1.01:1. the temperature of three cylinders into which diamine is just added is set to be 180 ℃, then the temperature is gradually increased, the three cylinders enter a continuous flow reactor with an effective volume of 150L and an active stirring device, the polymerization section temperature is 220-285 ℃, and then the length-diameter ratio is 48:1, three exhaust holes are arranged on the same-direction double-screw extruder, and the two latter exhaust holes are vacuumized. The temperature of the machine head is set to 248 ℃, continuous extrusion granulation is carried out, so as to obtain the PAMXD6 resin, the weight average residence time of the material in the device is 30 minutes, the melting point is 243 ℃, the viscosity is 2.3, the color is white, and the effective yield is about 85 percent. The device consumes approximately 197 degrees per hour.

Example 7

According to 4:1, adipic acid, PAMXD6 resin and 0.5% of antioxidant and 0.2% of catalyst by weight based on the total weight are mixed, and the mixture is fed from the front end through a weight loss metering device to a total length-diameter ratio of 100:1, setting the temperature of a screw feeding section to be 100-120 ℃, setting the temperature of a melt dispersing section to be 160-220 ℃, setting the temperature of a melt sealing section after material dispersion to be 145 ℃, and adding m-xylylenediamine by weight loss control, so that the molar ratio of the m-xylylenediamine to adipic acid is 1.01:1, setting the temperature of a three-section cylinder body into which m-xylylenediamine is just added to be 180 ℃, generating a slight air leakage phenomenon at a screw rod packing, gradually heating, then entering a continuous flow reactor with an effective volume of 150L and an active stirring device, wherein the temperature of a polymerization section is 220-285 ℃, and then entering an aspect ratio of 48:1, three exhaust holes are arranged on the same-direction double-screw extruder, and the two latter exhaust holes are vacuumized. The die temperature was set at 248 ℃, and the extrudate was continuously cooled in water to give PAMXD6 resin, which was not pelletized by drawing. The material had a weight average residence time of 30 minutes in the apparatus, a melting point of 239 ℃, a viscosity of 1.6, a yellow color, an effective yield of about 85% and an apparatus power consumption of 205 degrees per hour.

Example 8

This example was based on example 7, and the ratio of PAMXD6 in the raw material was increased to a ratio of adipic acid to PAMXD6 resin of 2:1, the temperature of a melting and dispersing section is 160-220 ℃. No air leakage phenomenon, and the effective yield of the PAMXD6 resin is about 75%. The device consumes 215 degrees of power per hour.

The materials and amounts of the materials used in example 7 and example 6 were the same, and the mixing temperature in the melt dispersion stage was higher than that in example 6, and under the same equipment conditions, slight air leakage occurred at the screw packing of the melt mixing extruder, indicating that the melt strength was lower and the sealing effect was poor due to more decrease in the molecular weight of the polymer in the materials after the temperature of the mixing process was increased. The polymerization under these conditions yields products of significantly lower quality than in example 6 and with higher energy consumption.

Example 8 the melt strength was increased after increasing the polyamide raw material ratio based on example 6, and the uniformity of mixing and the tightness of the system could be satisfied at a higher mixing temperature without air leakage, but the effective yield was reduced and the utilization of the equipment was lost. At the same time, more energy is consumed because more polymer needs to be melted initially, resulting in an increase in energy consumption of about 8%. Therefore, although the equipment is not optimized optimally, comparison under the same conditions can find that the lower mixing temperature is more beneficial to reducing the proportion of the polymer in the raw materials on the premise of meeting the mixing uniformity in the mixing process, so that the effective yield is improved, the utilization rate of the device is improved, and the production efficiency is improved.

Example 9

According to 3:1, adipic acid, PA66 resin and 0.5 percent of antioxidant and 0.2 percent of catalyst accounting for the total weight are mixed in a weight ratio, and the mixture is fed from the front end through a weight loss metering device, wherein the total length-diameter ratio is 100:1, setting the temperature of a screw feeding section to be 100-150 ℃, setting the temperature of a melt dispersing section to be 160-190 ℃, setting the temperature of a melt sealing section after material dispersion to be 130 ℃, and controlling the added hexamethylenediamine by weight loss, so that the mole ratio of the hexamethylenediamine to adipic acid is 1.01:1. the temperature of three cylinders to which hexamethylenediamine is just added is set to be 180 ℃, then the temperature is gradually increased, the mixture enters a continuous flow reactor with an effective volume of 150L and an active stirring device, the polymerization section temperature is 220-285 ℃, and the length-diameter ratio is 48:1, three exhaust holes are arranged on the same-direction double-screw extruder, and the two latter exhaust holes are vacuumized. The temperature of the machine head is set to 260 ℃, and the PA66 resin is obtained by continuous extrusion granulation, the weight average residence time of the material in the device is 30 minutes, the melting point is 268 ℃, the viscosity is 2.3, and the color is white. The effective yield is 82%, and the average power consumption of the whole device operation is about 202 DEG per hour.

Example 10

According to 3:1, adipic acid, PA66 resin and 0.5 percent of antioxidant and 0.2 percent of catalyst accounting for the total weight are mixed in a weight ratio, and the mixture is fed from the front end through a weight loss metering device, wherein the total length-diameter ratio is 100:1, setting the temperature of a screw feeding section to be 100-150 ℃, setting the temperature of a melt dispersing section to be 160-280 ℃, setting the temperature of a melt sealing section after material dispersion to be 130 ℃, and controlling the added hexamethylenediamine by weight loss, so that the mole ratio of the hexamethylenediamine to adipic acid is 1.01:1. the temperature of the three cylinders which are just added with hexamethylenediamine is set to 180 ℃, the packing of the screw extrusion device seriously leaks air, and sealing cannot be formed.

Example 11

According to 1.5:1, adipic acid, PA66 resin and 0.5 percent of antioxidant and 0.2 percent of catalyst accounting for the total weight are mixed in a weight ratio, and the mixture is fed from the front end through a weight loss metering device, wherein the total length-diameter ratio is 100:1, setting the temperature of a screw feeding section to be 100-150 ℃, setting the temperature of a melt dispersing section to be 160-280 ℃, setting the temperature of a melt sealing section after material dispersion to be 130 ℃, and controlling the added hexamethylenediamine by weight loss, so that the mole ratio of the hexamethylenediamine to adipic acid is 1.01:1. the temperature of three cylinders to which hexamethylenediamine is just added is set to be 180 ℃, then the temperature is gradually increased, the mixture enters a continuous flow reactor with an effective volume of 150L and an active stirring device, the polymerization section temperature is 220-285 ℃, and the length-diameter ratio is 48:1, three exhaust holes are arranged on the same-direction double-screw extruder, and the two latter exhaust holes are vacuumized. The temperature of the machine head is set to 268 ℃, and the PA66 resin is obtained by continuous extrusion granulation, the average residence time of the material in the device is 30 minutes, the melting point is 263 ℃, the viscosity is 2.1, and the color is yellow. The effective yield is 68%, and the average power consumption of the whole device operation is 245 DEG per hour.

Example 12

According to 3:1, adipic acid, PA66 resin and 0.5 percent of antioxidant and 0.2 percent of catalyst accounting for the total weight are mixed in a weight ratio, and the mixture is fed from the front end through a weight loss metering device, wherein the total length-diameter ratio is 100:1, setting the temperature of a screw feeding section to be 100-150 ℃, the temperature of a melting dispersion section to be 160-280 ℃, reducing the temperature of a melt sealing section to be 95 ℃ after material dispersion, and controlling the added hexamethylenediamine by weight loss, so that the molar ratio of the hexamethylenediamine to adipic acid is 1.01:1. a seal can be formed under such conditions. The added hexamethylenediamine is controlled by weight loss so that the molar ratio of hexamethylenediamine to adipic acid is 1.01:1. the temperature of three cylinders to which hexamethylenediamine is just added is set to be 180 ℃, then the temperature is gradually increased, the mixture enters a continuous flow reactor with an effective volume of 150L and an active stirring device, the polymerization section temperature is 220-285 ℃, and the length-diameter ratio is 48:1, three exhaust holes are arranged on the same-direction double-screw extruder, and the two latter exhaust holes are vacuumized. The temperature of the machine head is set to 260 ℃, and the PA66 resin is obtained by continuous extrusion and granulation, the weight average residence time of the material in the device is 30 minutes, the melting point is 261 ℃, the viscosity is 2.1, the color is yellow, the effective yield is 82%, and the power consumption of the device is 223 ℃ per hour.

Example 13

According to 3:1, adipic acid, PA66 resin and 0.5 percent of antioxidant and 0.2 percent of catalyst accounting for the total weight are mixed in a weight ratio, and the mixture is fed from the front end through a weight loss metering device, wherein the total length-diameter ratio is 100:1, setting the temperature of a screw feeding section to be 100-150 ℃, setting the temperature of a melt dispersing section to be 160-190 ℃, setting the temperature of a melt sealing section after material dispersion to be 130 ℃, and controlling the added hexamethylenediamine by weight loss, so that the mole ratio of the hexamethylenediamine to adipic acid is 1.01:1. the temperature of three cylinders to which hexamethylenediamine is just added is set to be 180 ℃, then the temperature is gradually increased, the mixture enters a continuous flow reactor with an effective volume of 150L and an active stirring device, the polymerization section temperature is 220-285 ℃, and the length-diameter ratio is 48:1, three exhaust holes are arranged on the same-direction double-screw extruder, and the two latter exhaust holes are vacuumized. The temperature of the machine head is set to 260 ℃, and the PA66 resin is obtained by continuous extrusion and granulation, the weight average residence time of the material in the device is 60 minutes, the melting point is 269 ℃, the viscosity is 2.8, and the color is yellowish. The effective yield is 82%, the average power consumption of the whole device operation is about 174 degrees per hour, and the total device yield is about 149kg/h.

In the embodiment 10, the mixing temperature of the melting and dispersing section is increased to 280 ℃ on the basis of the embodiment 9, the melting point of the PA66 resin is exceeded, the molecular weight of the PA66 resin is reduced more severely, the melt strength is obviously reduced, the seal cannot be formed, and the process cannot be continued; example 11 the weight ratio of PA66 resin to adipic acid in the feed was increased to 1 on the basis of example 9: 1.5 to increase melt strength, the actual effective yield of the plant is reduced by about 14% and the energy consumption is increased by about 20% at this feedstock level, this adjustment being not recommended.

Example 12 on the basis of example 9, the mixing temperature of the melt dispersion stage was increased to 280 ℃ too, but no seal could be formed, and on the premise of not increasing the amount of PA66 resin, example 12 was reduced to a lower temperature to 95 ℃ in the seal stage to increase the melt strength, which required a longer transmission distance to achieve cooling. Thus, example 12 adds two sections later than example 9, in fact increasing the requirements on the equipment, and the resulting product has a lower melting point, a more difficult color control and an increase in energy consumption of 10%.

Example 13 and example 9 compared, reduced overall yield, prolonged polymerization time, and higher molecular weight polymer. The method can prepare products with different molecular weights by controlling the polymerization reaction time, thereby meeting different requirements. The total yield was reduced by about half to 149kg/h from 305kg/h of example 9, the actual effective yield of the plant was unchanged, and the energy consumption was reduced by about 14% due to the doubling of the reaction time.

For this set of equipment to which the invention is practically applied, the effective volume is 150 liters, the total yield corresponding to a polymerization time of 30 minutes is about 300kg/h, and the total yield corresponding to a polymerization time of 60 minutes is about 150kg/h.

Example 14

According to 3:1, adipic acid, PA56 resin and 0.5 percent of antioxidant and 0.2 percent of catalyst accounting for the total weight are mixed in a weight ratio, and the mixture is fed from the front end through a weight loss metering device, wherein the total length-diameter ratio is 100:1, setting the temperature of a screw feeding section to be 100-150 ℃, setting the temperature of a melt dispersing section to be 160-190 ℃, setting the temperature of a melt sealing section after material dispersion to be 125 ℃, and controlling the added pentanediamine through weight loss, so that the mole ratio of the pentanediamine to the adipic acid is 1.02:1. setting the temperature of three cylinders to which the pentanediamine is just added to be 180 ℃, gradually heating the cylinders, then entering a continuous flow reactor with an effective volume of 150L and an active stirring device, wherein the temperature of a polymerization section is 220-280 ℃, and then entering an aspect ratio of 48:1, three exhaust holes are arranged on the same-direction double-screw extruder, and the two latter exhaust holes are vacuumized. The temperature of the machine head is set to 250 ℃, and the PA56 resin is obtained by continuous extrusion granulation, the weight average residence time of the material in the device is 30 minutes, the melting point is 252 ℃, the viscosity is 2.2, and the color is white.

Example 15

According to 8:1, sebacic acid, PA610 resin and 0.5 percent of antioxidant and 0.2 percent of catalyst accounting for the total weight are mixed in a weight ratio, and the total length-diameter ratio is 100 after being fed from the front end through a weight loss metering device: 1, setting the temperature of a screw feeding section to be 100-120 ℃, the temperature of a melting and dispersing section to be 120-190 ℃, maintaining the temperature of a melt sealing section at 155 ℃ at the end of dispersion after material dispersion, and controlling the added hexamethylenediamine by weight loss, so that the molar ratio of the hexamethylenediamine to the sebacic acid is 1.02:1, the packing of the screw extrusion device has slight air leakage, then gradually increases in temperature, then enters a continuous flow reactor with an effective volume of 150L and an active stirring device, the polymerization section temperature is 220-285 ℃, and then enters an aspect ratio of 48:1, three exhaust holes are arranged on the same-direction double-screw extruder, and the two latter exhaust holes are vacuumized. The temperature of the machine head is set to 220 ℃, continuous extrusion is performed, bracing granulation is not possible, and the obtained PA610 resin is collected in water. The weight average residence time of the material in the device is 30 minutes, the melting point is 218 ℃, the viscosity is 1.6, and the color is light yellow.

Example 16

According to 8:1, sebacic acid, PA610 resin and 0.5 percent of antioxidant and 0.2 percent of catalyst accounting for the total weight are mixed in a weight ratio, and the total length-diameter ratio is 100 after being fed from the front end through a weight loss metering device: 1, setting the temperature of a screw feeding section to be 100-120 ℃, the temperature of a melt dispersing section to be 120-190 ℃, setting the temperature of a melt sealing section after material dispersion to be 95 ℃, and controlling the added hexamethylenediamine by weight loss to ensure that the mole ratio of the hexamethylenediamine to the sebacic acid is 1.02:1. the temperature of three cylinders to which hexamethylenediamine is just added is set to be 180 ℃, then the temperature is gradually increased, the mixture enters a continuous flow reactor with an effective volume of 150L and an active stirring device, the polymerization section temperature is 220-285 ℃, and the length-diameter ratio is 48:1, three exhaust holes are arranged on the same-direction double-screw extruder, and the two latter exhaust holes are vacuumized. The temperature of the machine head is set to 220 ℃, and the PA610 resin is obtained by continuous extrusion and granulation, the average residence time of the material in the device is 30 minutes, the melting point is 224 ℃, the viscosity is 2.3, and the color is white.

The melt seal stage temperature of example 15 was not lowered, remained above the melting point of sebacic acid, and at this temperature, the melt strength was insufficient and there was a slight blow-by phenomenon, resulting in a serious degradation of the polymerization product quality; example 16 reduced the temperature of the melt seal zone below the melting point of sebacic acid, the melt remained fluid, and the melt strength was improved without blow-by.

Example 17

According to 9:1, dodecanedioic acid, PA612 resin and 0.5% of antioxidant, 0.2% of catalyst by weight, are mixed in a weight ratio of 100:1, setting the temperature of a screw feeding section to be 90-105 ℃, the temperature of a melt dispersing section to be 120-190 ℃, setting the temperature of a melt sealing section after material dispersion to be 85 ℃, and controlling the added hexamethylenediamine by weight loss, so that the mole ratio of the hexamethylenediamine to the dodecanedioic acid is 1.02:1. the temperature of three cylinders to which hexamethylenediamine is just added is set to be 180 ℃, then the temperature is gradually increased, the mixture enters a continuous flow reactor with an effective volume of 150L and an active stirring device, the polymerization section temperature is 220-285 ℃, and the length-diameter ratio is 48:1, three exhaust holes are arranged on the same-direction double-screw extruder, and the two latter exhaust holes are vacuumized. The temperature of the machine head is set to 220 ℃, and the PA612 resin is obtained by continuous extrusion and granulation, the weight average residence time of the material in the device is 30 minutes, the melting point is 205 ℃, the viscosity is 2.1, and the color is white.

Example 18

According to 15:1, dodecanedioic acid, PA1212 resin, 0.5 percent of antioxidant and 0.2 percent of catalyst accounting for the total weight are mixed in a weight ratio, and the mixture is fed into a reactor from the front end through a weight loss metering device, wherein the total length-diameter ratio is 100:1, setting the temperature of a screw feeding section to be 90-95 ℃, the temperature of a melting and dispersing section to be 120-160 ℃, setting the temperature of a melt sealing section after material dispersion to be 75 ℃, and controlling the added dodecanediamine by weight loss, so that the molar ratio of the dodecanediamine to the dodecanedioic acid is 1.01:1. the temperature of three cylinders into which diamine is just added is set to be 180 ℃, then the temperature is gradually increased, the three cylinders enter a continuous flow reactor with an effective volume of 150L and an active stirring device, the polymerization section temperature is 220-285 ℃, and then the length-diameter ratio is 48:1, three exhaust holes are arranged on the same-direction double-screw extruder, and the two latter exhaust holes are vacuumized. The temperature of the machine head is set to 180 ℃, continuous extrusion granulation is carried out, PA1212 resin is obtained, the average residence time of the material in the device is 30 minutes, the melting point is 178 ℃, the viscosity is 2.1, the color is white, and the effective yield is 97%.

Example 19

According to 9:1, mixing sebacic acid, PA1010 resin and an antioxidant accounting for 0.5 percent of the total weight, and feeding a catalyst accounting for 0.2 percent of the total weight from the front end through a weight loss metering device, wherein the total length-diameter ratio is 100:1, setting the temperature of a screw feeding section to be 100-120 ℃, the temperature of a melt dispersing section to be 120-170 ℃, setting the temperature of a melt sealing section after material dispersion to be 95 ℃, and controlling the added hexamethylenediamine by weight loss to ensure that the mole ratio of the hexamethylenediamine to the sebacic acid is 1.01:1. the temperature of three cylinders into which diamine is just added is set to be 180 ℃, then the temperature is gradually increased, the three cylinders enter a continuous flow reactor with an effective volume of 150L and an active stirring device, the polymerization section temperature is 220-285 ℃, and then the length-diameter ratio is 48:1, three exhaust holes are arranged on the same-direction double-screw extruder, and the two latter exhaust holes are vacuumized. The temperature of a machine head is set to 220 ℃, and the PA1010 resin is obtained through continuous extrusion and granulation, the weight average residence time of the material in the device is 30 minutes, the melting point is 192 ℃, the viscosity is 2.1, the color is white, the effective yield is 95%, and the power consumption per hour is 194 ℃ when the device runs.

Example 20

According to 9:1, mixing sebacic acid, PA1010 resin and an antioxidant accounting for 0.5 percent of the total weight, and feeding a catalyst accounting for 0.2 percent of the total weight from the front end through a weight loss metering device, wherein the total length-diameter ratio is 100:1, setting the temperature of a screw feeding section to be 100-120 ℃, the temperature of a melt dispersing section to be 120-230 ℃, setting the temperature of a melt sealing section after material dispersion to be 95 ℃, and controlling the added hexamethylenediamine by weight loss to ensure that the mole ratio of the hexamethylenediamine to the sebacic acid is 1.01:1. the temperature of the three cylinders which are just added with the decamethylene diamine is set to 180 ℃, and at the moment, the screw rod packing part of the mixing device starts to leak air.

Increasing the proportion of PA1010 in the feed, so that the ratio of sebacic acid to PA1010 is 3:1, the air leakage stops. Then gradually heating, then entering a continuous flow reactor with an effective volume of 150L and an active stirring device, wherein the polymerization section temperature is 220-285 ℃, and then entering an aspect ratio of 48:1, three exhaust holes are arranged on the same-direction double-screw extruder, and the two latter exhaust holes are vacuumized. The temperature of the machine head is set to 220 ℃, and the continuous extrusion granulation is carried out, so that the PA1010 resin is obtained, the weight average residence time of the material in the device is 30 minutes, the melting point is 193 ℃, the viscosity is 2.2, the color is white, the effective yield is 75%, and the power consumption of the device is 213 ℃ in an average per hour.

Example 20 was identical to example 19 in both raw materials and amounts, and the mixing temperature in the melt dispersion stage was higher than that in example 19, exceeding the PA1010 resin melting point, causing a more decrease in polymer molecular weight, resulting in a decrease in melt strength, requiring more polymer to achieve material sealing, thus increasing the PA1010 ratio to 3:1, the energy consumption and the total yield are kept unchanged, the actual production efficiency is reduced, the effective yield is reduced from 95% to 75%, and the energy consumption of the whole set of device is increased by 10% due to the increase of the amount of the polymer to be remelted.

Example 21

According to 4:1 weight percent of mixed dibasic acid, PA66 resin and antioxidant accounting for 0.5 percent of the total weight, and catalyst accounting for 0.2 percent. Wherein the composition of the dibasic acid in the raw materials is 5:1 adipic acid and terephthalic acid. Fed from the front end through a weight loss metering device to a total aspect ratio of 100:1, setting the temperature of a screw feeding section to be 100-150 ℃, setting the temperature of a melt dispersing section to be 160-200 ℃, setting the temperature of a melt sealing section after material dispersion to be 110 ℃, and controlling the added hexamethylenediamine by weight loss, so that the mole ratio of the hexamethylenediamine to adipic acid is 1.01:1. the temperature of three cylinders into which diamine is just added is set to be 180 ℃, then the temperature is gradually increased, the three cylinders enter a continuous flow reactor with an effective volume of 150L and an active stirring device, the polymerization section temperature is 220-285 ℃, and then the length-diameter ratio is 48:1, three exhaust holes are arranged on the same-direction double-screw extruder, and the two latter exhaust holes are vacuumized. The temperature of the machine head is set to 260 ℃, and the PA66/6T copolymer resin is obtained by continuous extrusion granulation, the weight average residence time of the material in the device is 30 minutes, the melting point is 272 ℃, the viscosity is 2.2, and the color is white.

Example 22

According to 4:1 weight percent of mixed dibasic acid, PA66 resin and antioxidant accounting for 0.5 percent of the total weight, and catalyst accounting for 0.2 percent. Wherein the composition of the dibasic acid in the raw materials is 5:1, sebacic acid and terephthalic acid. Fed from the front end through a weight loss metering device to a total aspect ratio of 100:1, setting the temperature of a screw feeding section to be 100-150 ℃ and the temperature of a melting dispersion section to be 160-245 ℃, wherein materials cannot be well dispersed, continuously heating to 275 ℃ to achieve good dispersion, and seriously leaking gas by a packing of a screw extrusion device, so that sealing cannot be formed.

Example 23

According to 4:1 weight percent of mixed dibasic acid, PA66 resin and antioxidant accounting for 0.5 percent of the total weight, and catalyst accounting for 0.2 percent. Wherein the composition of the dibasic acid in the raw materials is 5:1 and terephthalic acid. Fed from the front end through a weight loss metering device to a total aspect ratio of 100:1, setting the temperature of a screw feeding section to be 100-150 ℃ and the temperature of a melting dispersion section to be 160-245 ℃, wherein materials cannot be well dispersed, continuously heating to 275 ℃ to achieve good dispersion, and seriously leaking gas by a packing of a screw extrusion device, so that sealing cannot be formed.

The method of the invention can also be used for synthesizing the copolymerized nylon with the aromatic diacid monomer, but because the aromatic diacid has higher melting point, the proportion of the aromatic diacid is not more than 20 percent, so that the diacid and the polyamide can be uniformly mixed below the melting point of the base polymer.

The mixed diacid of example 21 adopts adipic acid and terephthalic acid, and can obtain evenly dispersed melt at the mixing temperature of 160-200 ℃, and the polyamide product can be successfully obtained by continuous polymerization. Examples 22 and 23 each use sebacic acid and dodecanedioic acid instead of adipic acid of example 21, and a uniformly dispersed melt was obtained at a mixing temperature of 275 ℃ at the same polymer usage, and since the mixing temperature exceeded the melting point of the PA66 resin, the PA66 resin was also melted and the melt strength was significantly reduced with a more drastic reduction in polymer molecular weight, and sealing was not completed, and the process was not continued, and the melt strength was improved only by increasing the polymer usage, which in turn resulted in a reduction in effective productivity and an increase in energy consumption. The adipic acid is the most polar of 6-18 carbon aliphatic dibasic acid, and the most common nylon product PA6 and PA66 have the best compatibility, and the common monomer has better compatibility, so that a melt which is uniformly mixed is easier to obtain, and the preparation of the copolymerized nylon is more flexible.

The nylon finished product prepared by the continuous process has good uniformity, can be discharged by using a conventional melt conveying and die, is smooth and uniform, is not broken, is fully and uniformly mixed after being cut into particles, and has stable performance and high product qualification rate.

The preparation method of the invention can add certain or a plurality of auxiliary agents such as conventional antioxidants, catalysts, toughening agents, molecular weight regulators, lubricants and the like for polyamide synthesis according to the requirements, and can also directly complete the polymerization reaction without adding the auxiliary agents. The preparation method is suitable for synthesizing the polyamide resin with the diacid monomer mainly containing aliphatic diacid, is not limited to the types listed in the examples, and has wide application range.

The foregoing examples merely illustrate specific embodiments of the invention, which are described in greater detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention.

Claims

1. A continuous process for preparing aliphatic dibasic acid nylon is characterized in that: the raw materials comprise polymerized monomers and polyamide, wherein the polymerized monomers comprise dibasic acid and diamine, and the mass ratio of aliphatic dibasic acid in the dibasic acid is 80-100%; continuously feeding the dibasic acid and the polyamide raw material into a continuous mixing device with shearing, dispersing and conveying functions, wherein the system temperature is lower than the melting point of the polyamide raw material, the polyamide raw material is dispersed into molten aliphatic dibasic acid in the conveying process, the molten aliphatic dibasic acid is uniformly mixed to form a continuously flowing molten mass, diamine is continuously added, and the molten aliphatic dibasic acid are continuously fed into a subsequent polymerization device to react after being uniformly mixed until the nylon is polymerized to reach the required molecular weight;

The aliphatic dibasic acid in the raw material is at least one of dibasic acids with 6-18 carbon atoms;

the aliphatic dibasic acid in the raw materials contains adipic acid;

the mass ratio of the aliphatic dibasic acid to the polyamide raw material is 0.5-50:1, a step of;

the mixing temperature of the diacid and polyamide raw materials is higher than the melting point of at least one aliphatic diacid raw material;

the method comprises the steps of uniformly mixing the raw materials of the dibasic acid and the polyamide to obtain a mixed melt, and filling at least one section of the mixed melt in a device before diamine is added to form a sealing section;

the melt temperature of the seal segment is below the melting point of at least one molten aliphatic dibasic acid.

2. The continuous process for preparing aliphatic dibasic acid nylon according to claim 1, wherein: the melt temperature of the sealing section is lower than the mixing temperature of the dibasic acid and the polyamide raw material.

3. The continuous process for preparing aliphatic dibasic acid nylon according to claim 1, wherein: the continuous mixing device is a screw extrusion device.

4. The continuous process for preparing aliphatic dibasic acid nylon according to claim 1, wherein: the diamine is added into the continuous mixing device in a liquid state.

5. The continuous process for preparing aliphatic dibasic acid nylon according to claim 1, wherein: after diamine addition, at least one section of material flows upwards.

6. The continuous process for preparing aliphatic dibasic acid nylon according to claim 1, wherein: the molar ratio of the dibasic acid to the diamine in the polymerized monomer is 1:0.8-1.2.

7. The continuous process for preparing aliphatic dibasic acid nylon according to claim 1, wherein: the polyamide in the raw material is selected from PA66, PA56, PA610, PA612, PA1010, PA1212 and PAMXD6.

8. The continuous process for preparing aliphatic dibasic acid nylon according to claim 7, wherein: the polyamide in the raw material is selected from PA66, PA56 and PAMXD6.

9. The continuous process for preparing aliphatic dibasic acid nylon according to claim 1, wherein: the subsequent polymerization device is at least one of a screw extrusion device, a tubular reaction device and a kettle reaction device.

10. The continuous process for preparing aliphatic dibasic acid nylon according to claim 1, wherein: the total average residence time of the materials from the feed to the discharge in the material mixing device and in the subsequent polymerization device is from 10 to 120min.