CN112979941A - Continuous solid phase polycondensation method for producing high temperature resistant nylon - Google Patents
Continuous solid phase polycondensation method for producing high temperature resistant nylon Download PDFInfo
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Abstract
The invention belongs to the field of preparation of nylon, and particularly relates to a continuous solid phase polycondensation method for producing high temperature resistant nylon. The continuous solid phase polycondensation method comprises the following steps: continuously feeding starting materials, combining the starting materials by a reactor, and continuously discharging to obtain a powdery nylon product; the starting materials comprise wet powdery nylon salt, a catalyst and an antioxidant; the solvent content of the wet powdery nylon salt is 5-20%, and the starting materials are subjected to continuous solid-phase polymerization in the reactor assembly. The method greatly shortens the polymerization period, improves the polymerization efficiency, simultaneously improves the automation degree and reduces the labor intensity; solid phase polycondensation is adopted, the problem of wall sticking does not exist, the reaction temperature is reduced, side reactions are reduced, and the obtained product has excellent physical and mechanical properties and stable quality; meanwhile, different combinations of three sections of polymerization reactors are adopted, so that the process adjustment space is large, and the requirements of different varieties of nylon or different molecular weights of the same nylon can be met.
Description
Technical Field
The invention belongs to the field of preparation of nylon, and particularly relates to a continuous solid phase polycondensation method for producing high temperature resistant nylon.
Background
The high-temperature resistant nylon prepared by polycondensation is in various types, and mainly comprises PA46, PA9T, PA10T, PA12T, PA6T/66, PA6T/6I, PA12T/6T, PA10C, PA12C, PA10N, PA12N and the like. The nylon has good heat resistance, high strength and low water absorption, and also has good toughness and good molding processability, so that the nylon is widely applied to the automobile and electronic and electrical industries, the market demand is continuously increased, and the application field is gradually expanded.
The industrial production of high temperature resistant nylon mostly adopts the intermittent two-step polycondensation: namely, a high-pressure polymerization kettle is firstly utilized to prepare a prepolymer with lower viscosity and better fluidity through melt prepolymerization, and then solid-phase post polymerization is carried out. The patents of US4603166, US4163101, US5153250, US5500473, CN103923313A, CN110845721A, CN101759853A and the like all adopt the method to prepare nylons with different viscosities. However, this polymerization method has many disadvantages, such as: in the prepolymerization process, a certain amount of prepolymer is inevitably left in a kettle, so that each batch of material is mixed with the previous batch of material, and the product quality is influenced; the solid-phase post-polymerization reaction temperature is up to above 260 ℃, the reaction time is from dozens of hours to dozens of hours, the energy consumption of the production is high, the efficiency is low, the product is easy to form gel and yellow, even black spots are generated, and the product performance and the appearance are influenced. CN103539934A reports a method for continuous copolymerization to prepare semi-aromatic nylon: firstly, diamine, dibasic acid and a chain extender are used for salifying, then the salt is melted and prepolymerized in a high-pressure polymerization kettle, then the obtained product is granulated by an extruder, and finally solid-phase post-polymerization is carried out in a drum reactor, but the solid-phase post-polymerization is still semi-continuous polymerization substantially, the reaction temperature of the solid-phase post-polymerization is up to 280-300 ℃, the time is 72-144h, the production efficiency is seriously influenced by overhigh temperature and overlong time, and the product quality is poor.
In order to solve the problem of preparing high temperature resistant nylon by polycondensation in a two-step method, in recent years, more and more reports about preparing nylon by solid-phase batch polymerization are researched: related patents such as CN104327265A, CN101768266A, CN105339415A, CN104817693A and CN110467724A describe the preparation of high temperature resistant nylon by batch solid phase polycondensation: adding a certain amount of nylon salt into a rotary drum reactor, and preparing nylon through high pressure, normal pressure and vacuum pumping; the method has short reaction period, solves the problems of easy gel formation, yellowing and even black spot generation of products in the traditional method (melt prepolymerization and solid phase postpolymerization), obtains white powdery nylon with excellent performance, can obtain products with high viscosity without a chain extender, but has the defects of low automation degree, high manual dependence, high labor intensity and low production efficiency in actual production.
Disclosure of Invention
The invention aims to provide a continuous solid phase polycondensation method for producing high temperature resistant nylon, which greatly shortens the polymerization period, improves the polymerization efficiency, improves the automation degree and reduces the labor intensity; solid phase polycondensation is adopted, the problem of wall sticking does not exist, the reaction temperature is reduced, side reactions are reduced, and the obtained product has excellent physical and mechanical properties and stable quality; meanwhile, different combinations of three sections of polymerization reactors are adopted, so that the process adjustment space is large, and the requirements of different varieties of nylon or different molecular weights of the same nylon can be met.
In order to achieve the aim, the technical scheme of the continuous solid phase polycondensation method for producing the high temperature resistant nylon comprises the following steps:
a continuous solid phase polycondensation method for producing high temperature resistant nylon, comprising the steps of: continuously feeding starting materials, combining the starting materials by a reactor, and continuously discharging to obtain a powdery nylon product;
the starting materials comprise wet powdery nylon salt, a catalyst and an antioxidant; the solvent content of the wet powdery nylon salt is 5-20%; carrying out continuous solid-phase polymerization on the starting materials in the reactor combination;
the reactor combination comprises a first reactor and a second reactor, or a first reactor and a third reactor, or a first reactor, a second reactor and a third reactor which are sequentially arranged along the material conveying direction;
the heating temperature of the first reactor is 20-210 ℃, and the heating temperature is gradually increased along the material conveying direction; pre-polymerizing the powdery material in a first reactor and releasing steam to ensure that the first reactor is in a positive pressure environment and the relative pressure is 0.70-2.00 MPa; the retention time of the materials in the first reactor is 2-5 h;
the heating temperature of the second reactor is 180-230 ℃, and the heating temperature is gradually increased along the material conveying direction; further polymerizing the powdery material in a second reactor, wherein the second reactor maintains the environment from normal pressure to micro positive pressure, and the relative pressure is 0-0.50 MPa; the retention time of the materials in the second reactor is 0.5-3 h;
the heating temperature of the third reactor is 240-260 ℃; further polymerizing the powdery material in a third reactor, wherein a negative pressure environment is maintained in the third reactor, and the absolute pressure is 10-200 Pa; the residence time of the material in the third reactor is 2-10 h.
The continuous solid phase polycondensation method for producing high temperature resistant nylon of the invention mainly makes the raw materials continuously solid phase polymerized in a non-dissolved and non-molten state. The continuous polycondensation method reaction means that the reaction process from the addition of the nylon salt to the outflow of the nylon is a continuous reaction process, the method simplifies the process operation, shortens the reaction time, 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 solid phase polycondensation ensures that the product exists in a solid form in the whole polymerization process, reduces the reaction temperature, solves the problem that the product is easy to stick to the wall in the production process of the nylon industry, discharges the product in a powdery form, avoids the influence of the residual material of the previous batch on the material of the next batch, and is favorable for the quality stability and the quality control of the product.
In the first reactor, the solvent carried by the wet powdery nylon salt itself and the water generated in the prepolymerization process are converted into steam, and the steam pressure of the solvent is formed above the normal pressure. The existence of steam further accelerates the reaction rate, shortens the reaction time, and improves the reaction efficiency, and the principle of improving the reaction efficiency is as follows:
i) hydrogen bond action among molecular chains of the nylon salt is destroyed, and the activity of the end group is greatly improved; the large increase of the proportion of the active end groups leads the effective collision times to be obviously increased, thereby effectively improving the reaction efficiency of the solid-phase prepolymerization.
II) the existence of the steam can inhibit the decomposition of the nylon salt, keep the mole ratio balance of the diamine and the diacid, avoid the excessively low molecular weight of the nylon caused by the unbalanced mole ratio of the diamine and the diacid, and ensure that the nylon meeting the molecular weight requirement is prepared.
The continuous polycondensation method, the solid phase polycondensation and the steam are mutually dependent and promoted, and the existence of the steam reduces the reaction temperature, so that the solid phase polycondensation becomes possible; the solid phase polycondensation solves the problem of wall sticking in the whole process and ensures the smooth operation of the continuous polycondensation method; the continuous polycondensation method improves the reaction efficiency. The three components act together to finally obtain the high-quality and high-quality nylon product.
Further experimental detection shows that the basic physical indexes of the product are good, and the overall quality is excellent.
In the whole solid-phase polymerization process, the system is in an oxygen-free state and can pass through inert gas N2、CO2Or Ar or the like.
The preparation of wet powdery nylon salt is prior art, and reference can be made to prior art or earlier research results of this project group, such as the content described in patent CN103724209B, etc., which is obtained by salt-forming reaction of dibasic acid and diamine in solvent. The solvent may be selected from methanol, ethanol, water, etc., and generates methanol vapor, ethanol vapor, water vapor, etc. in the first reactor.
The reason for controlling the temperature in the first polymerization reactor to gradually increase is that the molecular weight of the prepolymer at the initial stage is lower, which results in a lower melting point of the product, so that a lower reaction temperature is required, and the melting point of the product is further increased with the increase of the reaction degree, and at this time, the prepolymer can enter a higher temperature zone on the premise of ensuring that the prepolymer is not melted, so as to accelerate the reaction rate and improve the reaction efficiency. The temperature range of the reaction can be increased or decreased according to specific needs by aiming at different nylon types. In this stage, the residence time, reaction temperature and pressure act synergistically to control the optimum end point of the reaction according to the product performance requirements.
The temperature in the second reactor is generally not lower than that of the first reactor, and the pressure control is lower than that of the first reactor, so that the forward progress of the polymerization reaction can be promoted, and the nylon product meeting the requirements can be obtained.
The temperature in the third reactor is generally not lower than that of the first reactor and the second reactor, and the polymerization degree is further improved by controlling the negative pressure, so that a nylon product with larger molecular weight is obtained. Residence times in the third reactor include, but are not limited to, 2h, 5h, 8h, 10 h. Within the reaction time range, the intrinsic viscosity and the universality of the product are good, and the application requirements under most conditions can be met.
Preferably, the step-by-step increase of the heating temperature along the material conveying direction is that at least 2 heating sections are arranged in the reactor along the material conveying direction, and the heating temperatures of different heating sections are arranged from low to high along the material conveying direction. The heating sections can be generally arranged in 2-10, and the more the heating sections are, the more the temperature control of the polymerization reaction is fine, which is beneficial to improving the polymerization quality. More preferably, the number of heating sections is set to 3 to 7.
Further preferably, the first reactor comprises an initial heating section and a final heating section, the temperature of the initial heating section is 20-180 ℃, and the temperature of the final heating section is 150-210 ℃. The second reactor comprises an initial heating section and a final heating section, wherein the temperature of the initial heating section is 180-220 ℃, and the temperature of the final heating section is 200-230 ℃.
Preferably, the heating temperature of the first reactor is 140-210 ℃; the nylon salt is nylon 12T salt, nylon 6T/66 salt and nylon 12T/6T salt.
Preferably, the powdery nylon product is high-temperature-resistant nylon, the wet powdery nylon salt used as the starting material is prepared by salifying diamine and dibasic acid in a solvent, the dibasic acid at least comprises high-temperature-resistant dibasic acid, and the high-temperature-resistant dibasic acid contains an aliphatic ring and/or an aromatic ring structure. More preferably, the high temperature resistant dibasic acid is selected from one or more of terephthalic acid, 2, 6-naphthalene dicarboxylic acid and 1, 4-cyclohexane dicarboxylic acid. The diamine is selected from one or more of butanediamine, pentanediamine, hexanediamine, heptanediamine, octanediamine, nonanediamine, decanediamine, undecanediamine, dodecanediamine, tridecanediamine and tetradecanediamine.
Preferably, the catalyst is one or the combination of more than two of phosphorous acid, sodium hypophosphite, triphenyl phosphate and H10, and the dosage of the catalyst is 0.1-0.6% of the dry mass of the nylon salt. The catalyst can accelerate the reaction rate of the nylon salt and improve the polymerization efficiency.
Preferably, the antioxidant is one or a combination of more than two of sodium hypophosphite, antioxidant 1010, antioxidant s9228, antioxidant SH120 and antioxidant B215, and the dosage of the antioxidant is 0.1-0.5% of the dry mass of the nylon salt. The addition of the antioxidant can prevent the nylon material from being oxidized in the polymerization process to influence the appearance and the performance of the product.
The method is suitable for preparing high-temperature-resistant nylon by polycondensation, and the obtained product has stable comprehensive performance and excellent quality, can be widely applied to the industries of electronics, electrics, automobiles and the like, and is a new material with good application prospect.
Drawings
FIG. 1 is a process flow diagram of preparing high temperature resistant nylon by continuous solid phase polycondensation;
FIG. 2 is a FT-IR plot of PA12T obtained in example 1;
FIG. 3 shows PA12T from example 11H-NMR chart.
Detailed Description
The following examples are provided to further illustrate the practice of the invention.
In the following examples, a system for producing nylon by continuous solid phase polycondensation comprises a starting material storage tank, a reactor combination, a buffer tank combination and a product collector combination, and the corresponding process flow chart is shown in fig. 1.
The starting material storage tank is filled with raw materials for producing nylon, and the raw materials comprise a powdery mixture consisting of nylon salt, a catalyst and an antioxidant. Two starting material storage tanks can be arranged so as to facilitate the preparation of the starting materials and enable the continuous feeding to be unaffected.
The reactor combination comprises a first polymerization reactor, a second polymerization reactor and a third polymerization reactor which are sequentially arranged along the material conveying direction, wherein the first polymerization reactor is connected with a starting material storage tank, receives the starting material stored in the starting material storage tank, and conveys the material forwards in a spiral conveying mode. The first polymerization reactor is connected with the second polymerization reactor through a first buffer pipeline and a second buffer pipeline which are parallel, the second polymerization reactor is connected with the third polymerization reactor through a third buffer pipeline and a fourth buffer pipeline which are parallel, a first buffer tank, a second buffer tank, a third buffer tank and a fourth buffer tank are respectively arranged on the first buffer pipeline, the second buffer pipeline, the third buffer pipeline and the fourth buffer pipeline, and valves for controlling the connection and disconnection of the first buffer pipeline and the second buffer pipeline and the polymerization reactor are correspondingly arranged on the buffer pipelines.
The first buffer tank, the second buffer tank, the third buffer tank and the fourth buffer tank form a buffer tank combination.
The outlet of the third polymerization reactor is connected with a first product collector and a second product collector, and the first product collector and the second product collector form a product collector combination.
In other embodiments, if only the first polymerization reactor, the second polymerization reactor (or the third polymerization reactor) is used for production, the product collector assembly is connected to the outlet of the second polymerization reactor (or the third polymerization reactor).
The production system meets the requirements of different solid-phase polymerization stages on different pressure environments mainly through switching of parallel pipelines among polymerization reactors, and further realizes continuous production. The following is a detailed description of specific embodiments.
First, the specific embodiment of the continuous solid phase polycondensation method for producing high temperature resistant nylon of the present invention
Example 1
The continuous solid phase polycondensation method for producing high temperature resistant nylon of the embodiment is described by taking the synthesis example of the high temperature resistant nylon PA12T, and comprises the following steps:
1) solid phase prepolymerization stage: adding 10kg nylon 12T salt (water content is 10%), 30g catalyst sodium hypophosphite and 20g antioxidant s9228 into the first and second initial material storage tanks, stirring uniformly, sealing, and adding N2The whole polymerization system was subjected to gas substitution three times and charged to a pressure of 0.05 MPa. The heating system of the polymerization reactor, the surge tank and the product accumulator was started, allowed to rise to the predetermined temperature and stabilized for 1 h.
And switching the system connection to a first starting material storage tank, a first polymerization reactor and a first buffer tank, and closing the system connections of the rest starting material storage tanks, the polymerization reactors, the buffer tanks and the product collector. Starting a material conveying system, conveying the nylon 12T salt mixture in the first starting material storage tank to a first polymerization reactor at a constant speed for solid-phase prepolymerization: the nylon 12T salt sequentially passes through four temperature zones of 180 ℃, 190 ℃, 200 ℃ and 210 ℃, the residence time of each temperature zone is 0.5h, and in the process, the relative pressure in the system is kept at 1.70 MPa. The powdery PA12T prepolymer obtained was introduced into a first buffer vessel having an internal temperature of 210 ℃.
2) Solid phase low pressure polymerization stage: and (2) switching the system connection of the solid-phase prepolymerization stage to a second starting material storage tank, a first polymerization reactor and a second buffer tank, simultaneously switching the system connection of the solid-phase low-pressure polymerization stage to the first buffer tank, the second polymerization reactor and a third buffer tank, and conveying the powdery PA12T prepolymer in the first buffer tank to the second polymerization reactor at a constant speed for depressurization reaction: the prepolymer was passed through three temperature zones of 220 deg.C, 225 deg.C and 230 deg.C in this order, and the residence time in each temperature zone was 0.5h, during which the pressure inside the system was kept at normal pressure. The resulting higher molecular weight PA12T was fed to a third buffer tank with an internal temperature of 230 ℃.
3) Solid phase negative pressureA polymerization stage: and (2) switching the system connection of the solid-phase low-pressure polymerization stage to a second buffer tank, a second polymerization reactor and a fourth buffer tank, simultaneously switching the system connection of the solid-phase negative-pressure polymerization stage to a third buffer tank, a third polymerization reactor and a first product collector, and conveying the PA12T with higher molecular weight in the third buffer tank to the third polymerization reactor at a constant speed for solid-phase post-polymerization: the reaction temperature was 240 ℃ and the residence time was 2 hours, during which the absolute pressure inside the system was 20 Pa. The resulting high molecular weight PA12T entered the first product collector. After the reaction is finished, the third polymerization reactor is switched to be connected with the second product collector, the system connection of the first product collector is cut off, the internal temperature of the first product collector is reduced to room temperature, and N is charged2And discharging to normal pressure to obtain a powdery PA12T product.
Example 2
The continuous solid phase polycondensation method for producing the high temperature resistant nylon of the embodiment synthesizes the high temperature resistant nylon PA6T/66, and comprises the following steps:
1) solid phase prepolymerization stage: adding 10kg nylon 6T/66 salt (water content is 8%; molar ratio of nylon 6T salt to nylon 66 salt is 55:45), 30g catalyst sodium hypophosphite and 20g antioxidant s9228 into the first and second starting material storage tanks, stirring, sealing, and adding CO2The whole polymerization system was subjected to gas substitution three times and charged to a pressure of 0.05 MPa. The heating system of the polymerization reactor, the surge tank and the product accumulator was started, allowed to rise to the predetermined temperature and stabilized for 1 h.
And switching the system connection to a first starting material storage tank, a first polymerization reactor and a first buffer tank, and closing the system connections of the rest starting material storage tanks, the polymerization reactors, the buffer tanks and the product collector. Starting a material conveying system, conveying the nylon 6T/66 salt mixture in a first starting material storage tank to a first polymerization reactor at a constant speed for solid-phase prepolymerization: the nylon 6T/66 salt sequentially passes through six temperature sections of 140 ℃, 150 ℃, 160 ℃, 190 ℃, 200 ℃ and 210 ℃, the retention time of each temperature section is 0.5h, and the relative pressure in the system is kept to be 1.70MPa in the process. The powdery PA6T/66 prepolymer obtained was introduced into a first buffer vessel having an internal temperature of 210 ℃.
2) Solid phase low pressure polymerization stage: and (2) switching the system connection of the solid-phase prepolymerization stage to a second starting material storage tank, a first polymerization reactor and a second buffer tank, simultaneously switching the system connection of the solid-phase low-pressure polymerization stage to the first buffer tank, the second polymerization reactor and a third buffer tank, and conveying the powdery PA6T/66 prepolymer in the first buffer tank to the second polymerization reactor at a constant speed for depressurization reaction: the prepolymer was passed through three temperature zones of 220 deg.C, 225 deg.C and 230 deg.C in this order, and the residence time in each temperature zone was 0.5h, during which the inside of the system was kept at normal pressure. The resulting higher molecular weight PA6T/66 was taken to a third buffer tank with an internal temperature of 230 ℃.
3) Solid phase negative pressure polymerization stage: and (2) switching the system connection of the solid-phase low-pressure polymerization stage to a second buffer tank, a second polymerization reactor and a fourth buffer tank, simultaneously switching the system connection of the solid-phase negative-pressure polymerization stage to a third buffer tank, a third polymerization reactor and a first product collector, and conveying the PA6T/66 with higher molecular weight in the third buffer tank to the third polymerization reactor at a constant speed for solid-phase post-polymerization: the reaction temperature was 240 ℃ and the residence time was 2 hours, during which the absolute pressure inside the system was 20 Pa. The resulting high molecular weight PA6T/66 entered the first product collector. Switching the third polymerization reactor to be connected with the second product collector, cutting off the system connection of the first product collector, reducing the internal temperature of the first product collector to room temperature, and charging N2And discharging to normal pressure to obtain powdered PA6T/66 product.
Example 3
The continuous solid phase polycondensation method for producing the high temperature resistant nylon of the embodiment synthesizes the high temperature resistant nylon PA12T/6T, and comprises the following steps:
1) solid phase prepolymerization stage: adding 10kg nylon 12T/6T salt (water content is 12%; molar ratio of nylon 12T salt to nylon 6T salt is 6:4), 30g catalyst sodium hypophosphite and 20g antioxidant s9228 into the first and second starting material storage tanks, stirring, sealing, and adding CO2The whole polymerization system is subjected to three gas replacements, anInflating to the pressure of 0.05 MPa. The heating system of the polymerization reactor, the surge tank and the product accumulator was started, allowed to rise to the predetermined temperature and stabilized for 1 h.
And switching the system connection to a first starting material storage tank, a first polymerization reactor and a first buffer tank, and closing the system connections of the rest starting material storage tanks, the polymerization reactors, the buffer tanks and the product collector. Starting a material conveying system, conveying the nylon 12T/6T salt mixture in a first starting material storage tank to a first polymerization reactor at a constant speed for solid-phase prepolymerization: the nylon 12T/6T salt sequentially passes through four temperature sections of 190 ℃, 195 ℃, 200 ℃ and 210 ℃, the residence time of each temperature section is 0.5h, and the relative pressure in the system is kept to be 1.70MPa in the process. The powdery PA12T/6T prepolymer obtained was introduced into a first buffer vessel having an internal temperature of 210 ℃.
2) Solid phase low pressure polymerization stage: and (2) switching the system connection of the solid-phase prepolymerization stage to a second starting material storage tank, a first polymerization reactor and a second buffer tank, simultaneously switching the system connection of the solid-phase low-pressure polymerization stage to the first buffer tank, the second polymerization reactor and a third buffer tank, and conveying the powdery PA12T/6T prepolymer in the first product collector to the second polymerization reactor at a constant speed for depressurization reaction: the prepolymer was passed through three temperature zones of 220 deg.C, 225 deg.C and 230 deg.C in this order, and the residence time in each temperature zone was 0.5h, during which the inside of the system was kept at normal pressure. The resulting higher molecular weight PA12T/6T was taken to a third surge tank with an internal temperature of 230 ℃.
3) Solid phase negative pressure polymerization stage: the system connection of the solid-phase low-pressure polymerization stage is switched to a second buffer tank, a second polymerization reactor and a fourth buffer tank, meanwhile, the system connection of the solid-phase negative-pressure polymerization stage is switched to a third buffer tank, a third polymerization reactor and a first product collector, and PA12T/6T with higher molecular weight in the third buffer tank is conveyed to the third polymerization reactor at a constant speed for solid-phase post-polymerization reaction: the reaction temperature was 240 ℃ and the residence time was 2 hours, during which the absolute pressure inside the system was 20 Pa. The resulting high molecular weight PA12T/6T entered the first product collector. After the reaction is finished, the third stepSwitching the polymerization reactor to connect with the second product collector, cutting off the system connection of the first product collector, reducing the internal temperature of the first product collector to room temperature, charging N2And discharging to normal pressure to obtain powdery PA12T/6T product.
Example 4
The continuous solid phase polycondensation method for producing high temperature resistant nylon of this example is different from example 1 only in the amount of the catalyst added in the solid phase prepolymerization stage, and other process parameters are the same as example 1, and the amount of the catalyst sodium hypophosphite added in the prepolymerization stage is 10 g.
Example 5
The continuous solid phase polycondensation method for producing high temperature resistant nylon of this example is different from example 1 only in the amount of the catalyst added in the solid phase prepolymerization stage, and other process parameters are the same as example 1, and the amount of the catalyst sodium hypophosphite added in the prepolymerization stage is 50 g.
Example 6
The continuous solid phase polycondensation method for producing high temperature resistant nylon of this example is different from example 1 only in that the pressure in the solid phase prepolymerization stage system is different, and other process parameters are the same as example 1, and the relative pressure in the prepolymerization stage in this example is 1.50 MPa.
Example 7
The continuous solid phase polycondensation method for producing high temperature resistant nylon of this example is different from example 1 only in that the pressure in the solid phase prepolymerization stage system is different, and other process parameters are the same as example 1, and the relative pressure in the prepolymerization stage in this example is 1.30 MPa.
Example 8
The continuous solid phase polycondensation method for producing the high temperature resistant nylon of the embodiment is different from the embodiment 1 only in that a solid phase negative pressure polymerization stage is not provided, and other process parameters are the same as those of the embodiment 1.
Example 9
The continuous solid phase polycondensation method for producing high temperature resistant nylon of the present example is different from example 1 only in that there is no solid phase low pressure polymerization stage, and other process parameters are the same as example 1.
Example 10
The continuous solid phase polycondensation method for producing high temperature resistant nylon of this example is different from example 1 only in that the reaction temperature of the solid phase negative pressure polymerization stage is different, and other process parameters are the same as example 1, and the reaction temperature of the solid phase negative pressure polymerization stage in this example is 250 ℃.
Example 11
The continuous solid phase polycondensation method for producing high temperature resistant nylon of this example is different from example 1 only in that the reaction temperature of the solid phase negative pressure polymerization stage is different, and other process parameters are the same as example 1, and the reaction temperature of the solid phase negative pressure polymerization stage in this example is 260 ℃.
Example 12
The continuous solid phase polycondensation method for producing high temperature resistant nylon of the present example is different from example 1 only in that the residence time of the solid phase negative pressure polymerization stage is different, the other process parameters are the same as example 1, and the residence time of the solid phase negative pressure polymerization stage in the present example is 5 h.
Example 13
The continuous solid phase polycondensation method for producing the high temperature resistant nylon of the embodiment is different from the embodiment 1 only in that the residence time of the solid phase negative pressure polymerization stage is different, the other process parameters are the same as the embodiment 1, and the residence time of the solid phase negative pressure polymerization stage in the embodiment is 8 h.
In other embodiments of the method for synthesizing high temperature resistant nylon of the present invention, the difference from the embodiment 1 is that, depending on the difference of the raw material variety and the product performance requirements, the solvent content of the nylon salt in the solid phase prepolymerization stage can be different from 5%, 7%, 15%, 18% and 20%, the residence time can be different from 4h and 5h, the relative pressure can be different from 0.7, 1.0, 1.8 and 2.0MPa, and different temperature zones can be flexibly set within the range of 20 to 210 ℃ on the premise of confirming the occurrence of the solid phase polymerization; in the solid phase low-pressure polymerization stage, the pressure can be in micro-positive pressure environments of 0.1, 0.3, 0.5MPa and the like, the residence time can be different from 0.5h to 1h to 3h, and different temperature zones can be flexibly arranged within the range of 230 ℃ of 180-; in the solid phase negative pressure polymerization stage, the absolute pressure is kept to be different from 10 Pa, 20Pa, 50 Pa, 100 Pa, 150 Pa and 200Pa, and high temperature resistant nylon products with corresponding performance requirements can be obtained.
In other embodiments of the method for synthesizing the high temperature resistant nylon of the present invention, the difference from the embodiment 1 is that other high temperature resistant diacid varieties, such as nylon salt formed by 2, 6-naphthalenedicarboxylic acid and 1, 4-cyclohexanedicarboxylic acid, are selected, other diamine varieties, such as butanediamine, pentanediamine, heptanediamine, octanediamine, nonanediamine, decanediamine, undecanediamine, tridecanediamine, tetradecanediamine, etc., are selected, and the varieties and the usage amounts of the catalyst and the antioxidant are selected within the range defined by the present invention, so that the corresponding high temperature resistant nylon salt products can be obtained.
Second, description of comparative example
Comparative example 1
The synthesis method of the high temperature resistant PA12T of the comparative example is different from that of example 1 only in that the pressure in the solid phase prepolymerization stage system is different, and other process parameters are the same as those of example 1, in the comparative example, the pressure in the solid phase prepolymerization stage system is normal pressure.
Comparative example 2
The synthesis method of the high temperature resistant PA12T of the comparative example is different from that of the example 1 only in that the polymerization process does not pass through a solid phase low pressure polymerization stage and a solid phase negative pressure polymerization stage, and other process parameters are the same as those of the example 1.
Third, Experimental example
Experimental example 1
FT-IR and FT-IR were carried out on the high temperature resistant PA12T obtained in example 11The results of H-NMR measurement are shown in FIGS. 2 and 3.
In FIG. 2, 3321cm-1Is the stretching vibration peak of N-H, 2928cm-1And 2855cm-1Are each CH21628cm of antisymmetric stretching vibration peak and symmetric stretching vibration peak-1Is the stretching vibration peak (amide I band) of C ═ O, 1543cm-1Is the N-H in-plane bending vibration peak (amide II band), 3069cm-1Combined with N-H and C-N oscillation peaksFrequency doubling peak, 1285cm-1Is the C-N stretching vibration peak (amide III band), 862cm-1Is the peak of C-H in-plane bending vibration on the benzene ring.
Fig. 3 shows the chemical shift of each H.
From the results of fig. 2 and 3, it is understood that the powder product obtained in example 1 is high temperature resistant PA 12T.
Experimental example 2
In the examples of the present invention, the physical properties of the obtained products were characterized, and the test reactors and test standards used for the respective characterization are shown below.
TABLE 1 test items, reactors and standards
Examples 1 to 3 reflect the results of the physical property test of the high temperature resistant nylon prepared by the continuous solid phase polycondensation method, as shown in table 2.
TABLE 2 physical Properties of the high temperature resistant nylons obtained in examples 1 to 3
| Item | Example 1 | Example 2 | Example 3 |
| Melting Point (. degree.C.) | 312 | 311 | 313 |
| Intrinsic viscosity (dL/g) | 1.14 | 1.24 | 1.29 |
| Tensile Strength (MPa) | 75.9 | 96.1 | 93.5 |
| Elongation at Break (%) | 40.5 | 48.3 | 17.1 |
| Flexural Strength (MPa) | 92.6 | 125 | 118 |
| Flexural modulus (GPa) | 2.03 | 2.53 | 2.82 |
| Notched impact strength (kJ/m)2) | 13 | 8.4 | 2.7 |
As can be seen from the data in Table 2, all of the 3 nylons have better melting points and mechanical properties, which indicates that the process for preparing the high-temperature-resistant nylon by adopting the continuous solid-phase polycondensation method can be applied to various nylons and the obtained nylons have excellent properties.
The influence of the amount of the catalyst used on the physical properties of PA12T is reflected in examples 1 and 4 to 5, and the specific results are shown in table 3.
TABLE 3 physical Properties of PA12T obtained in example 1 and examples 4 to 5
| Item | Example 1 | Example 4 | Example 5 |
| Melting Point (. degree.C.) | 312 | 311 | 312 |
| Intrinsic viscosity (dL/g) | 1.14 | 0.65 | 1.29 |
| Tensile Strength (MPa) | 75.9 | 48.1 | 74.8 |
| Elongation at Break (%) | 40.5 | 7.3 | 42.2 |
| Flexural Strength (MPa) | 92.6 | 91.3 | 91.7 |
| Flexural modulus (GPa) | 2.03 | 2.07 | 2.06 |
| Notched impact strength (kJ/m)2) | 13 | 3.2 | 14 |
As can be seen from table 3, when the polymerization process conditions were the same, decreasing the amount of catalyst used reduced the physical properties of PA12T, but increasing the amount of catalyst used increased the intrinsic viscosity of PA12T, but the other physical properties were almost unchanged.
Examples 1 and 6 to 7 reflect the influence of the pressure change in the solid phase prepolymerization stage on the physical properties of PA12T, and the specific results are shown in Table 4.
TABLE 4 physical Properties of PA12T obtained in example 1 and examples 6 to 7
| Item | Example 1 | Example 6 | Example 7 |
| Melting Point (. degree.C.) | 312 | 313 | 311 |
| Intrinsic viscosity (dL/g) | 1.14 | 0.97 | 0.85 |
| Tensile Strength (MPa) | 75.9 | 74.6 | 68.3 |
| Elongation at Break (%) | 40.5 | 43.1 | 10.5 |
| Flexural Strength (MPa) | 92.6 | 92.3 | 92.7 |
| Flexural modulus (GPa) | 2.03 | 2.04 | 2.06 |
| Notched impact strength (kJ/m)2) | 13 | 11 | 5.6 |
As is clear from Table 4, the physical properties of PA12T were controlled by adjusting the vapor pressure during the solid phase prepolymerization, and the lower the pressure, the lower the intrinsic viscosity of PA12T, and the more or less the other properties were changed.
Examples 1 and 8 reflect the influence of whether solid-phase negative pressure polymerization was performed or not on the physical properties of PA12T, and the specific results are shown in table 5.
TABLE 5 physical Properties of PA12T obtained in example 1 and example 8
| Item | Example 1 | Example 8 |
| Melting Point (. degree.C.) | 312 | 311 |
| Intrinsic viscosity (dL/g) | 1.14 | 0.78 |
| Tensile Strength (MPa) | 75.9 | 68.4 |
| Elongation at Break (%) | 40.5 | 11.3 |
| Flexural Strength (MPa) | 92.6 | 91.5 |
| Flexural modulus (GPa) | 2.03 | 2.04 |
| Notched impact strength (kJ/m)2) | 13 | 5.2 |
As can be seen from table 5, the PA12T obtained without solid phase negative pressure polymerization had slightly inferior performance, but could completely satisfy the performance requirements for blend processing such as reinforcement and flame retardancy of nylon.
Examples 1 and 9 reflect the influence of whether or not the solid-phase low-pressure polymerization stage was performed on the physical properties of PA12T, and specific results are shown in table 6.
TABLE 6 physical Properties of PA12T obtained in example 1 and example 9
| Item | Example 1 | Example 9 |
| Melting Point (. degree.C.) | 312 | 311 |
| Intrinsic viscosity (dL/g) | 1.14 | 1.08 |
| Tensile Strength (MPa) | 75.9 | 74.4 |
| Elongation at Break (%) | 40.5 | 42.3 |
| Flexural Strength (MPa) | 92.6 | 91.8 |
| Flexural modulus (GPa) | 2.03 | 2.04 |
| Notched impact strength (kJ/m)2) | 13 | 12.6 |
As is clear from Table 6, the reaction in the solid phase low pressure polymerization stage has little influence on the properties of PA12T, and the obtained product has excellent properties.
The results of examples 1 and 10 to 11, which reflect the influence of the change in the reaction temperature in the solid-phase negative pressure polymerization stage on the physical properties of PA12T, are shown in Table 7.
TABLE 7 physical Properties of PA12T obtained in example 1 and examples 10 to 11
As is clear from Table 7, PA12T having different viscosities was obtained by adjusting the reaction temperature in the solid phase negative pressure polymerization stage, and the higher the reaction temperature, the higher the viscosity of the obtained product.
The effect of the change in the residence time in the solid phase negative pressure polymerization stage on the physical properties of PA12T is reflected in examples 1 and 12 to 13, and the specific results are shown in table 8.
TABLE 8 physical Properties of PA12T obtained in example 1 and examples 12 to 13
| Item | Example 1 | Example 12 | Example 13 |
| Melting Point (. degree.C.) | 312 | 311 | 311 |
| Intrinsic viscosity (dL/g) | 1.14 | 1.44 | 1.75 |
| Tensile Strength (MPa) | 75.9 | 75.4 | 75.8 |
| Elongation at Break (%) | 40.5 | 41.5 | 40.6 |
| Flexural Strength (MPa) | 92.6 | 93.6 | 92.2 |
| Flexural modulus (GPa) | 2.03 | 2.07 | 2.04 |
| Notched impact strength (kJ/m)2) | 13.0 | 12.4 | 13.1 |
As can be seen from Table 8, by adjusting the residence time in the solid phase negative pressure polymerization stage, PA12T with different viscosities was obtained, and the longer the residence time, the greater the viscosity of the product obtained.
The physical properties of the PA12T obtained in comparative example 1 to comparative example 2 were characterized, and the results are shown in Table 9.
TABLE 9 physical Properties of PA12T obtained in example 1, comparative example 1 and comparative example 2
In comparative example 1, the inside of the solid phase prepolymerization stage system is normal pressure, the melting point of the product is only 289 ℃, and the intrinsic viscosity is 0.32 dL/g; in comparative example 2, which had only a solid phase prepolymerization stage, the product had a melting point of only 284 ℃ and an intrinsic viscosity of 0.24 dL/g. The intrinsic viscosity of the products of the two comparative examples is much lower than that of example 1 and cannot be processed for use.
Claims (10)
1. The continuous solid phase polycondensation method for producing the high temperature resistant nylon is characterized by comprising the following steps: continuously feeding starting materials, combining the starting materials by a reactor, and continuously discharging to obtain a powdery nylon product;
the starting materials comprise wet powdery nylon salt, a catalyst and an antioxidant; the solvent content of the wet powdery nylon salt is 5-20%; carrying out continuous solid-phase polymerization on the starting materials in the reactor combination;
the reactor combination comprises a first reactor and a second reactor, or a first reactor and a third reactor, or a first reactor, a second reactor and a third reactor which are sequentially arranged along the material conveying direction;
the heating temperature of the first reactor is 20-210 ℃, and the heating temperature is gradually increased along the material conveying direction; pre-polymerizing the powdery material in a first reactor and releasing steam to ensure that the first reactor is in a positive pressure environment and the relative pressure is 0.70-2.00 MPa; the retention time of the materials in the first reactor is 2-5 h;
the heating temperature of the second reactor is 180-230 ℃, and the heating temperature is gradually increased along the material conveying direction; further polymerizing the powdery material in a second reactor, wherein the second reactor maintains the environment from normal pressure to micro positive pressure, and the relative pressure is 0-0.50 MPa; the retention time of the materials in the second reactor is 0.5-3 h;
the heating temperature of the third reactor is 240-260 ℃; further polymerizing the powdery material in a third reactor, wherein a negative pressure environment is maintained in the third reactor, and the absolute pressure is 10-200 Pa; the residence time of the material in the third reactor is 2-10 h.
2. The continuous solid-phase polycondensation method for producing high-temperature-resistant nylon according to claim 1, wherein the step-by-step increase in the heating temperature in the material-conveying direction is achieved by arranging at least 2 heating zones in the reactor in the material-conveying direction, and the heating temperatures of the different heating zones are arranged from low to high in the material-conveying direction.
3. The continuous solid phase polycondensation method for producing high temperature resistant nylon according to claim 2, wherein the first reactor comprises an initial heating section and a final heating section, the temperature of the initial heating section is 20 to 180 ℃, and the temperature of the final heating section is 150 ℃ to 210 ℃.
4. The continuous solid-phase polycondensation method for producing high-temperature-resistant nylon according to claim 2, wherein the second reactor comprises an initial heating section and a final heating section, the temperature of the initial heating section is 180-.
5. The continuous solid phase polycondensation method for producing high temperature resistant nylon according to any one of claims 1 to 4, wherein the heating temperature of the first reactor is 140 ℃ and 210 ℃; the nylon salt is nylon 12T salt, nylon 6T/66 salt and nylon 12T/6T salt.
6. The continuous solid phase polycondensation method for producing a high temperature resistant nylon according to any one of claims 1 to 4, wherein the powdered nylon product is a high temperature resistant nylon, the wet powdered nylon salt used as a starting material is prepared by salifying a diamine and a dibasic acid in a solvent, the dibasic acid comprises at least a high temperature resistant dibasic acid containing an aliphatic ring and/or an aromatic ring structure.
7. The continuous solid phase polycondensation method for producing high temperature resistant nylon according to claim 6, wherein the high temperature resistant dibasic acid is one or a combination of two or more selected from terephthalic acid, 2, 6-naphthalenedicarboxylic acid, and 1, 4-cyclohexanedicarboxylic acid.
8. The continuous solid-phase polycondensation method for producing high-temperature-resistant nylon according to claim 6, wherein the diamine is selected from the group consisting of butanediamine, pentanediamine, hexanediamine, heptanediamine, octanediamine, nonanediamine, decanediamine, undecanediamine, dodecanediamine, tridecanediamine, and tetradecanediamine.
9. The continuous solid phase polycondensation method for producing high temperature resistant nylon according to any one of claims 1 to 4, wherein the catalyst is one or a combination of two or more of phosphorous acid, sodium hypophosphite, triphenyl phosphate and H10, and the amount of the catalyst is 0.1 to 0.6 percent of the dry mass of the nylon salt.
10. The continuous solid-phase polycondensation method for producing high-temperature-resistant nylon according to any one of claims 1 to 4, wherein the antioxidant is one or a combination of more than two of sodium hypophosphite, antioxidant 1010, antioxidant s9228, antioxidant SH120 and antioxidant B215, and the amount of the antioxidant is 0.1-0.5% of the dry mass of the nylon salt.
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| CN102477219A (en) * | 2010-11-29 | 2012-05-30 | 上海杰事杰新材料(集团)股份有限公司 | High-temperature resistant semi-aromatic nylon and its preparation method |
| CN110885442A (en) * | 2019-12-17 | 2020-03-17 | 郑州大学 | Synthetic method of copolymerized semi-aromatic nylon |
| CN112321820A (en) * | 2020-11-10 | 2021-02-05 | 郑州大学 | Synthesis method of long-carbon-chain semi-aromatic nylon |
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| JP2009114429A (en) * | 2007-10-19 | 2009-05-28 | Toray Ind Inc | Continuous production method of polyamide |
| CN102477219A (en) * | 2010-11-29 | 2012-05-30 | 上海杰事杰新材料(集团)股份有限公司 | High-temperature resistant semi-aromatic nylon and its preparation method |
| CN110885442A (en) * | 2019-12-17 | 2020-03-17 | 郑州大学 | Synthetic method of copolymerized semi-aromatic nylon |
| CN112321820A (en) * | 2020-11-10 | 2021-02-05 | 郑州大学 | Synthesis method of long-carbon-chain semi-aromatic nylon |
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| CN115197416A (en) * | 2022-08-19 | 2022-10-18 | 鞍山七彩化学股份有限公司 | Continuous solid phase polycondensation method for producing high temperature resistant nylon |
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