A method and device for continuously producing a long carbon chain nylon brine solution

Abstract

The present invention relates to a method and device for continuously producing a long-chain nylon salt aqueous solution, and belongs to the field of preparation and production of nylon salt. A long-chain diacid is melted, mixed with a long-chain diamine and water, and subjected to a secondary salt-forming reaction. After the pH value of the aqueous solution is adjusted, a nylon salt aqueous solution for polycondensation reaction is obtained. The device includes a continuous melting unit of the long-chain diacid and a corresponding control system, a salt-forming reaction unit and a corresponding control system and a salt storage unit. The method uses water as a solvent, avoids the use of organic solvents such as alcohol, simplifies the production process, and ensures the quality of the produced long-chain nylon salt by flexibly controlling parameters such as temperature and pH during the production process, thereby reducing production costs and facilitating large-scale production.

Description

Technical Field

[0001] The invention belongs to the technical field of nylon salt preparation and production, and particularly relates to a method for continuously producing a long-carbon-chain nylon salt aqueous solution and a corresponding production device. Background Art

[0002] Long carbon chain nylon is a nylon with more than 10 methylene groups between adjacent amide groups. The long methylene chain and polar amide group make it have the dual characteristics of polyolefin and polyamide. The flexible methylene chain limited by the long carbon chain makes it have unique advantages such as good toughness, low water absorption, good dimensional stability, low temperature impact resistance and dielectric properties. It has important applications in the fields of automobiles, electronics, aerospace, oil and alcohol transportation.

[0003] In the industrial preparation of nylon salt, ethanol or water is usually used as a solvent. Invention CN 107573502 A discloses a preparation process of long carbon chain nylon 1211 salt: undecane dicarboxylic acid is added to alcohol at room temperature, heated to 40-60°C, dodecacarbon diamine is added to react until the pH value reaches 7.0-8.0, and the reaction is continued at a constant temperature for 1-1.5 hours to obtain a nylon salt solution. Invention CN 102010506 B discloses a preparation process of long carbon chain nylon 1212 salt: add petroleum fermentation dodecane dicarboxylic acid, ethanol, and activated carbon into a batching tank, mix evenly, and filter through an ultrafiltration membrane filter to obtain a refined petroleum fermentation dodecane dicarboxylic acid ethanol solution; mix dodecane diamine with 2-3 times ethanol to prepare an ethanol solution, slowly add it to the dodecane dicarboxylic acid ethanol solution, react while stirring, and control the reaction temperature at 70-78°C until the pH value of the neutralization solution in the kettle is 7.0-7.2, and separate to obtain nylon 1212 salt. The above method for preparing long carbon chain nylon salt is similar to that for preparing short carbon chain nylon salt, but ethanol is flammable and explosive and is not suitable for large-scale industrial production.

[0004] Water is also a commonly used solvent for preparing nylon salts. The temperature for preparing short-chain nylon salt aqueous solution is generally 60-90°C and the pressure is normal pressure. However, the solubility of long-chain nylon salt in water is very low. Under normal temperature and pressure, long-chain nylon salt is very easy to precipitate and cannot be mixed with water. Invention CN 109180931 A discloses a preparation process of long carbon chain nylon 1313 salt: 1,13-tridecanediamine is added to 3-8 times the mass of water, heated to 60-80°C, then 1,13-tridecanediamine is added in a measured amount according to the molar ratio of 1,13-tridecanediamine to 1,13-tridecanediamine of 1:0.98-1.2, heated to 120-180°C in an inert gas atmosphere, the pressure in the kettle is maintained at 0.4-2.2MPa, the pH value of the system is measured, and an appropriate amount of 1,13-tridecanediamine or 1,13-tridecanediamine is added according to the measured pH value, the pH value of the system is adjusted to between 7.0-7.4, and the reaction is continued for 20-30min to obtain PA1313 salt. The preparation of long carbon chain nylon salt requires higher temperature and pressure, and the intermittent production method is usually adopted. Summary of the invention

[0005] The object of the present invention is to provide a method and device for continuously producing a long carbon chain nylon salt solution.

[0006] According to the technical solution provided by the present invention,

[0007] A method for continuously producing long carbon chain nylon salt, wherein a powdered or granular long carbon chain diacid is melted at a melting temperature of 140-180°C, preferably 140-170°C, and more preferably 140-150°C. The molten long carbon chain diacid, long carbon chain diamine and deionized water are mixed in a first stage reaction unit. The molar ratio of the long carbon chain diacid to the long carbon chain diamine is controlled at 1.01-1.1, preferably 1.01-1.05, and more preferably 1.01-1.03. The first stage reaction temperature is controlled at 120-150°C, preferably 120-140°C, and more preferably 120-130°C. The salt concentration is controlled at 40-60%, preferably 45-55% of the salt solution, and more preferably 50-55%. The pH of the salt solution is controlled at 6.0-9.0, preferably, the pH of the salt solution is controlled at 6.8-8.0, and more preferably, the pH of the salt solution is controlled at 7.0-8.5. The salt solution after the reaction is filtered and enters the second-stage reaction unit. The temperature of the second-stage reaction unit is controlled at 120-150°C, preferably, the reaction temperature is controlled at 120-140°C, and more preferably, the reaction temperature is controlled at 120-130°C. The pH of the salt solution is controlled at 7.0-8.5, preferably, the pH of the salt solution is controlled at 7.0-8.0, and more preferably, the pH of the salt solution is controlled at 7.0-7.8. The salt solution after pH adjustment in the second-stage reaction unit is filtered and enters the salt storage tank unit for standby.

[0008] A device for continuously producing a long-chain nylon salt solution comprises a continuous melting unit of a long-chain diacid and a corresponding control system, a salt-forming reaction unit and a corresponding control system and a salt storage unit; the continuous melting unit of the long-chain diacid comprises more than two diacid storage tanks, a feeding system feeds powdered or granular long-chain diacid into a melting tank, and the melting tank is connected to the salt-forming reaction unit; the salt-forming reaction unit is provided with a discharge pipe and a plurality of feed pipes, and the discharge pipe is connected to the salt storage system.

[0009] There is a valve or screw feeder at the bottom of the diacid storage tank to continuously feed the melting tank; the feeding amount can be controlled by the opening of the valve or the speed of the screw feeder.

[0010] Preferably, the diacid storage tank is protected by an inert gas, and the inert gas is preferably nitrogen.

[0011] The melting tank is a vertical tank with stirring, with a jacket outside the tank, a coil inside the tank, and a heating medium passing through it. There is a feed pipe at the top and a discharge pipe at the bottom.

[0012] Preferably, the melting tank is protected by an inert gas, and the inert gas is preferably nitrogen.

[0013] The control system of the melting unit includes a diacid storage tank level control system for controlling the feed switching of the diacid storage tank; the control system of the melting unit also includes a melting tank temperature control system, the melting tank temperature control system includes a temperature transmitter A in the melting tank, and the temperature transmitter A is connected to a temperature regulating valve A for controlling the flow of the heating medium.

[0014] There is a gear pump at the bottom of the melting tank, which is used to continuously send liquid long-chain diacid into the salt-forming reaction unit.

[0015] The salt-forming reaction unit includes a secondary reaction unit; the first-stage reaction unit includes a vertical first-stage reactor with stirring, the first-stage reactor is provided with a jacket outside, a coil inside the tank, and a heating medium passes through the first-stage reactor during operation; a plurality of feed pipes are provided on the top of the first-stage reactor, and a discharge pipe is provided at the bottom; the discharge pipe is connected to the second-stage reaction unit.

[0016] The first-stage reaction unit control includes a temperature control system, which includes a temperature transmitter B in the first-stage reaction kettle, and the temperature transmitter B is connected to a temperature regulating valve B for controlling the flow of the heating medium.

[0017] The first-stage reaction system unit includes a pH control system, wherein the feed pipeline includes a diamine feed pipeline A, and the pH control system includes an online pH meter A arranged on the discharge pipeline or the first-stage reactor and a diamine regulating valve A arranged on the diamine feed pipeline A, and the online pH meter A is connected to the diamine regulating valve A so that the opening of the diamine regulating valve A is controlled by the pH result detected by the online pH meter A.

[0018] Preferably, a filter is provided on the discharge pipe.

[0019] The second-stage reaction unit includes a vertical secondary reactor with stirring, a jacket outside the secondary reactor, a coil inside the secondary reactor, and a heating medium passing through the reactor during operation; a feed pipe is provided on the top of the secondary reactor and a discharge pipe is provided on the bottom; the discharge pipe is connected to the salt storage tank.

[0020] The second-stage reaction unit control includes a temperature control system, which includes a temperature transmitter C in the secondary reactor, and the temperature transmitter C is connected to a temperature regulating valve C for controlling the flow of the heating medium.

[0021] The second-stage reaction unit control includes a pH control system, the feed pipeline includes a diamine feed pipeline B, the pH control system includes an online pH meter B arranged on the external circulation pipeline or the secondary reactor and a diamine regulating valve B arranged on the diamine feed pipeline B, and the online pH meter B is connected to the diamine regulating valve B to control the opening of the diamine regulating valve B according to the pH result detected by the online pH meter B.

[0022] Preferably, the second stage reaction system has an external circulation pipeline.

[0023] Preferably, a filter is provided on the external circulation pipeline.

[0024] The salt storage system is a vertical storage tank with a jacket outside the tank and a coil inside the tank, through which a heating medium flows when the tank is in operation.

[0025] Preferably, the salt storage system has an external circulation pipeline.

[0026] Preferably, the salt storage system is protected by an inert gas, and the inert gas is preferably nitrogen.

[0027] The invention provides a continuous production method and device for a long carbon chain nylon salt, which uses water as a solvent, avoids the use of organic solvents such as alcohol, simplifies the production process, ensures the quality of the produced long carbon chain nylon salt by flexibly controlling parameters such as temperature and pH in the production process, reduces the production cost, and facilitates the subsequent polycondensation reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a system diagram of the present invention.

[0029] In the figure: nitrogen pipe 1, deionized water pipe 2, salt steam pipe 3, diamine pipe 4.

[0030] Storage tank A 101, storage tank B 102, rotary valve A 103 and rotary valve B 104, melting tank 105, gear pump A 106, temperature regulating valve A 107, level control system 1001, temperature transmitter A 1002, diacid flow meter 1003.

[0031] Primary reactor 201, deionized water regulating valve 202, temperature regulating valve B 203, diamine regulating valve C 204, gear pump B205, online filter A206, diamine regulating valve B 207, diamine regulating valve A208, temperature regulating valve C 209, gear pump C210, online filter B211, secondary reactor 212, deionized water flow meter 2001, temperature transmitter B 2002, online pH meter A2003, diamine flow meter 2004, temperature transmitter C 2005, online pH meter B2006.

[0032] Salt storage tank 301, gear pump D302, temperature regulating valve D303, temperature transmitter D3001. DETAILED DESCRIPTION

[0033] In order to make the technical purpose, technical solution and beneficial effects of the present invention more clear, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0034] Example 1

[0035] like Figure 1 As shown, a continuous production system of long carbon chain nylon salt is composed of storage tank A 101, storage tank B 102, melting tank 105, primary reactor 201, secondary reactor 212 and salt storage tank 301. A nitrogen pipe 1 is provided on the top of storage tank A 101 to provide nitrogen protection. A rotary valve A 103 is provided at the bottom of storage tank A 101 and a rotary valve B 104 is provided at the bottom of storage tank B 102 to feed into melting tank 105 respectively. A level control system 1001 controls the feeding of long carbon chain diacid. When storage tank B 102 reaches a low level, rotary valve B 104 is stopped, rotary valve A 103 is started, and feeding into melting tank 105 continues. While storage tank A 101 is feeding into melting tank 105, storage tank B 102 is reloaded with long carbon chain diacid.

[0036] The temperature transmitter A 1002 monitors the temperature of the melting tank 105 and controls the temperature by controlling the opening of the steam regulating valve A 107 on the steam pipe 3. The bottom gear pump A 106 pumps the long carbon chain diacid liquid in the melting tank 105 into the primary reactor 201. There is also a nitrogen pipe 1 on the top of the melting tank 105 to provide nitrogen protection.

[0037] Deionized water pipeline 2 and diamine pipeline 4 add deionized water and long carbon chain diamine to the primary reactor 201 respectively. In order to maintain the stability of the molar ratio of long carbon chain diacid and long carbon chain diamine, diacid flowmeter 1003 and diamine flowmeter 2004 monitor the mass flow of long carbon chain diacid and long carbon chain diamine respectively, and control the flow and ratio of the two by controlling gear pump A 106 and diamine regulating valve C 204. Deionized water flowmeter 2001 monitors the deionized water flow and controls it by controlling deionized water regulating valve 202 to keep the salt concentration stable. Temperature transmitter B 2002 monitors the temperature of the primary reactor 201 and controls the temperature by controlling the opening of temperature regulating valve B 203 on steam pipeline 3. Gear pump B 205 at the bottom of the primary reactor 201 pumps the salt solution into the secondary reactor 212. Online pH meter A2003 monitors the pH value of the salt solution and controls the pH value of the salt solution by controlling the opening of diamine regulating valve A208.

[0038] An online filter A206 is installed on the discharge pipe of the primary reactor to protect the online pH meter A2003.

[0039] The temperature transmitter C 2005 monitors the temperature of the secondary reactor 212 and regulates the temperature by controlling the opening of the temperature regulating valve C 209 on the steam pipe 3. The online pH meter B2006 located on the inner circulation pipe detects the pH value of the salt solution and controls it by adjusting the opening of the diamine regulating valve B 207. The online filter B211 is used to protect the online pH meter B2006. The gear pump C 210 delivers the regulated salt solution to the salt storage tank 301.

[0040] The temperature transmitter D3001 monitors the temperature of the salt storage tank 301 and regulates the temperature by controlling the opening of the temperature regulating valve D303 on the steam pipe 3. The gear pump D302 performs internal circulation to keep the salt solution in the salt storage tank 301 uniform and at the same time transports the salt solution to the depolymerization unit.

Claims

1. A method for continuously producing a long carbon chain nylon salt solution, wherein a powder or granular long carbon chain diacid is melted at a melting temperature of 140-180°C; Mixing molten long-chain diacid, long-chain diamine and deionized water in a first-stage reaction unit; the molar ratio of the long-chain diacid to the long-chain diamine is controlled to be 1.01-1.1; The first stage reaction temperature is controlled at 120-150°C; The salt concentration is controlled at 45-55%; The pH of the salt solution is controlled at 6.8-8.0; The salt solution after the reaction is filtered and enters the second-stage reaction unit, and the temperature of the second-stage reaction unit is controlled at 120-150°C; The pH of the salt solution is controlled at 7.0-8.0; The salt solution after pH adjustment in the second-stage reaction unit is filtered and enters the salt storage tank unit for standby use. in, The long carbon chain nylon is a nylon in which the number of methylene groups between adjacent amide groups is greater than 10.

2. A device for continuously producing a long-chain nylon salt solution, comprising a continuous melting unit of a long-chain diacid and a corresponding control system, a salt-forming reaction unit and a corresponding control system and a salt storage unit; the continuous melting unit of the long-chain diacid comprises two or more diacid storage tanks, a feeding system feeds powdered or granular long-chain diacid into a melting tank, and the melting tank is connected to the salt-forming reaction unit; the salt-forming reaction unit is provided with a discharge pipe and a plurality of feed pipes, and the discharge pipe is connected to the salt storage system, in, The long carbon chain nylon is a nylon in which the number of methylene groups between adjacent amide groups is greater than 10.

3. The device for continuously producing a long carbon chain nylon salt solution according to claim 2, Its characteristics are: There is a valve or screw feeder at the bottom of the diacid storage tank; the feeding amount is controlled by the opening of the valve or the speed of the screw feeder.

4. The device for continuously producing a long carbon chain nylon salt solution according to claim 2, Its characteristics are: The melting tank is a vertical tank with stirring, with a jacket outside the tank, a coil inside the tank, and a heating medium passing through it; there is a feed pipe on the top and a discharge pipe at the bottom.

5. The device for continuously producing a long carbon chain nylon salt solution according to claim 2, Its characteristics are: The control system of the melting unit includes a tank level control system for controlling the feed switching of the tank; the control system of the melting unit also includes a melting tank temperature control system, the melting tank temperature control system includes a temperature transmitter A in the melting tank, and the temperature transmitter A is connected to a temperature regulating valve A for controlling the flow of the heating medium.

6. The device for continuously producing a long carbon chain nylon salt solution according to claim 2, Its characteristics are: The salt-forming reaction unit includes a secondary reaction unit; the first-stage reaction unit includes a vertical first-stage reactor with stirring, a jacket outside the first-stage reactor, and a coil inside the tank; the first-stage reactor has a plurality of feed pipes on the top and a discharge pipe on the bottom; the discharge pipe is connected to the second-stage reaction unit.

7. The device for continuously producing a long-chain nylon brine solution according to claim 6 is characterized in that the first-stage reaction unit control includes a temperature control system, the temperature control system includes a temperature transmitter B in the first-stage reactor, and the temperature transmitter B is connected to a temperature regulating valve B that controls the flow rate of the heating medium.

8. The device for continuously producing a long-chain nylon salt solution according to claim 6 is characterized in that the first-stage reaction system unit includes a pH control system, the feed pipeline includes a diamine feed pipeline A, the pH control system includes an online pH meter A arranged on the discharge pipeline or the first-stage reactor and a diamine regulating valve A arranged on the diamine feed pipeline A, and the online pH meter A is connected to the diamine regulating valve A so that the pH result detected by the online pH meter A controls the opening of the diamine regulating valve A.

9. The device for continuously producing a long carbon chain nylon salt solution according to claim 6, Its characteristics are: The second-stage reaction unit comprises a vertical secondary reactor with stirring, a jacket outside the secondary reactor and a coil inside the secondary reactor; a feed pipe is provided at the top of the secondary reactor and a discharge pipe is provided at the bottom; the discharge pipe is connected to the salt storage tank.

10. The device for continuously producing a long carbon chain nylon salt solution according to claim 6, Its characteristics are: The second-stage reaction unit control includes a temperature control system, which includes a temperature transmitter C in the secondary reactor, and the temperature transmitter C is connected to a temperature regulating valve C for controlling the flow of the heating medium.

11. The device for continuously producing a long carbon chain nylon salt solution according to claim 6, Its characteristics are: The second-stage reaction unit control includes a pH control system, the feed pipeline includes a diamine feed pipeline B, the pH control system includes an online pH meter B arranged on the external circulation pipeline or the secondary reactor and a diamine regulating valve B arranged on the diamine feed pipeline B, and the online pH meter B is connected to the diamine regulating valve B to control the opening of the diamine regulating valve B according to the pH result detected by the online pH meter B.

12. The device for continuously producing a long carbon chain nylon salt solution according to claim 2, Its characteristics are: The salt storage system is a vertical storage tank with a jacket outside the tank and a coil inside the tank through which a heating medium passes.

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