阅读说明：本技术 一种聚酰胺的连续反应工艺 (Continuous reaction process of polyamide ) 是由 赵风轩 余爱平 梁法锋 朱昊臣 于 2020-06-30 设计创作，主要内容包括：一种聚酰胺的连续反应工艺,利用反应装置连续反应的步骤为：1)加热系统的壳程中通入加热介质；2)聚合原料穿过预热系统、脱轻系统,排入加热系统的管程,升温至200-250℃,至聚合原料中水分降至≤20％,进行预聚合反应；3)预聚合得到的物料排入反应系统,进行预聚合后反应,产生工艺蒸汽；4)工艺蒸汽进入脱轻系统,将经过脱轻系统的聚合原料升温至180-240℃,进入预热系统的壳程,对穿过预热系统的聚合原料升温至180-230℃；5)预热系统壳程内的工艺蒸汽冷凝,作为回流液；6)至粘度150-300cp时,连续排料,得到聚酰胺预聚合产品。本发明工艺简单、合成成本低,可有效保证聚酰胺的品质稳定,是生产高端聚酰胺的保证。(A continuous reaction process of polyamide comprises the following steps of utilizing a reaction device to carry out continuous reaction: 1) heating medium is introduced into the shell pass of the heating system; 2) the polymerization raw materials pass through a preheating system and a light component removal system and are discharged into a tube pass of a heating system, the temperature is increased to 200 ℃ and 250 ℃, and the water content in the polymerization raw materials is reduced to be less than or equal to 20 percent, and a prepolymerization reaction is carried out; 3) discharging the material obtained by prepolymerization into a reaction system, and carrying out prepolymerization reaction to generate process steam; 4) the process steam enters a light component removal system, the temperature of the polymerization raw material passing through the light component removal system is raised to 180-fold 240 ℃, the polymerization raw material enters a shell pass of a preheating system, and the temperature of the polymerization raw material passing through the preheating system is raised to 180-fold 230 ℃; 5) condensing process steam in a preheating system shell pass to be used as reflux; 6) when the viscosity reaches 150-300cp, the continuous discharging is carried out to obtain the polyamide prepolymerization product. The invention has simple process and low synthesis cost, can effectively ensure the stable quality of the polyamide and is the guarantee for producing high-end polyamide.)

1. A continuous reaction process of polyamide is characterized in that the following reaction device is adopted for carrying out continuous reaction,

the reaction device comprises a preheating system (1), a light component removal system (2), a heating system (3) and a reaction system (4),

the light component removal system (2) is positioned below the preheating system (1) and above the heating system (3) and the reaction system (4),

the tube side inlet of the preheating system (1) is a polymerization raw material inlet (11), the tube side outlet of the preheating system (1) is a polymerization raw material outlet (12) and is connected with the feed inlet of the lightness removing system (2), the shell side inlet of the preheating system (1) is a heating medium inlet (13) and is connected with the light component outlet of the lightness removing system (2), the shell side of the preheating system (1) is connected with the reflux port of the lightness removing system (2) through a reflux pipeline (14),

the shell side of the heating system (3) is a heating medium channel, a tube side inlet (31) of the heating system (3) is connected with a discharge hole of the lightness removing system (2), a tube side outlet (32) of the heating system (3) is connected with a feed inlet of the reaction system (4),

a process steam outlet (41) of the reaction system (4) is connected with a heating medium inlet of the lightness removing system (2),

the continuous reaction comprises the following steps:

1) heating medium is introduced into the shell pass of the heating system;

2) the polymerization raw materials pass through a preheating system and a light component removal system and are discharged into a tube pass of a heating system, the temperature is increased to 200 ℃ and 250 ℃, part of water is evaporated till the water content in the polymerization raw materials is reduced to be less than or equal to 20 percent, and a prepolymerization reaction is carried out;

3) discharging the material obtained by the prepolymerization reaction into a reaction system, dehydrating, and carrying out prepolymerization reaction to generate process steam;

4) the process steam generated in the reaction system enters a light component removal system, the polymerization raw material passing through the light component removal system is heated to 180-fold-240 ℃, and part of water and part of light components are carried out, and then the polymerization raw material enters the shell side of a preheating system, and the polymerization raw material passing through the preheating system is heated to 180-fold-230 ℃;

5) condensing process steam in a shell pass of the preheating system, feeding the process steam into a reflux port of the lightness removing system along a reflux pipeline under the action of gravity to serve as reflux liquid, and enabling organic diamine in the polymerization raw materials passing through the lightness removing system to completely enter a tube pass of the heating system;

6) when the viscosity reaches 150-300cp, the discharge port of the reaction system is opened, and continuous discharge is carried out to obtain the polyamide prepolymerization product.

2. The continuous polyamide reaction process according to claim 1, wherein the discharge port of the reaction system is connected to the tube side of the heating system (3) through a circulating tube (5), and the materials in the reaction system circulate along the circulating tube, the tube side of the heating system and the reaction system under the effect of the density difference.

3. The continuous polyamide reaction process according to claim 1, wherein the tube side of the heating system is connected to a steam source through a steam pipe (6), and the density of the material in the tube side of the heating system is reduced by supplying steam to the tube side of the heating system.

4. The continuous polyamide reaction process according to claim 1, wherein the lightness-removing system (2) is a plate tower, N layers of tower plates are arranged in the plate tower, and N is more than or equal to 1.

5. The continuous reaction process of polyamide according to claim 1, characterized in that the heating medium of step 1) is biphenyl-diphenyl ether or 3.8MPa steam.

6. The continuous reaction process of polyamide as claimed in claim 1, wherein the polymerization raw material in step 2) is a salt solution obtained by mixing dicarboxylic acid and organic diamine, and the solid content is 50-80 wt%.

7. Continuous process for the reaction of polyamides according to claim 6, characterized in that the dicarboxylic acid is C₄～C₆Any one or a mixture of several of dicarboxylic acids of (1), the organic diamine is C₄～C₆Any one or a mixture of several of the diamines (c).

8. The continuous reaction process of polyamide according to claim 7, wherein the dicarboxylic acid is succinic acid, glutaric acid, adipic acid, and the organic diamine is butanediamine, pentanediamine, hexanediamine.

9. The continuous reaction process of polyamide according to claim 6, characterized in that the molar ratio of dicarboxylic acid and organic diamine is 1: 1 to 1.02.

Technical Field

The invention relates to the field of chemical industry, in particular to a continuous reaction process of polyamide.

Background

Polyamides, commonly known as Nylon (Nylon), and the english name Polyamide, are a generic name for polymers containing amide groups in the repeating units of the macromolecular main chain. The polyamide can be prepared by ring-opening polymerization of lactam, or polycondensation of diamine and diacid. The Polyamide (PA) is a polymer having a polar amide group (-CO-NH-) in the main chain. Originally used as a raw material for manufacturing fibers, the PA is later used as an engineering plastic widely applied in the industry at present due to toughness, wear resistance, self-lubrication and wide use temperature range. The PA can be widely used for replacing copper and nonferrous metals to manufacture mechanical, chemical and electrical parts, such as a fuel pump gear of a diesel engine, a water pump, a high-pressure sealing ring, an oil delivery pipe and the like. The DuPont company in the United states originally developed resins for fibers and was commercialized in 1939. In the 50 th of the 20 th century, injection molded products are developed and produced to replace metals to meet the requirements of light weight and cost reduction of downstream industrial products. The PA has good comprehensive properties including mechanical property, heat resistance, abrasion resistance, chemical resistance and self-lubricity, has low friction coefficient and certain flame retardance, is easy to process, is suitable for being filled with glass fiber and other fillers for reinforcing modification, improves the performance and expands the application range.

At present, in the process of obtaining polyamide by using the polymerization of dibasic acid and diamine, salt solution is generally prepared by using the dibasic acid and diamine and then is conveyed to a reactor for polymerization, and byproduct steam generated by the reactor cannot be utilized, so that the polymerization energy consumption of polyamide is high, and in addition, the quality of products of different batches is unstable.

Disclosure of Invention

The invention aims to provide a continuous reaction process of polyamide, which is simple in process and low in synthesis cost, can effectively ensure the stable quality of the polyamide and is a guarantee for producing high-end polyamide.

The technical scheme of the invention is as follows: a continuous reaction process of polyamide adopts the following reaction device to carry out continuous reaction, the reaction device comprises a preheating system, a lightness removing system, a heating system and a reaction system, the lightness removing system is positioned below the preheating system and above the heating system and the reaction system, a tube side inlet of the preheating system is a polymerization raw material inlet, a tube side outlet of the preheating system is a polymerization raw material outlet and is connected with a feed inlet of the lightness removing system, a shell side inlet of the preheating system is a heating medium inlet and is connected with a light component outlet of the lightness removing system, a shell side of the preheating system is connected with a return port of the lightness removing system through a return pipeline, a shell side of the heating system is a heating medium channel, a tube side inlet of the heating system is connected with a discharge port of the lightness removing system, a tube side outlet of the heating system is connected with a feed inlet of the reaction system, a process steam outlet of the reaction system is connected with a heating medium inlet of the lightness removing system,

the continuous reaction comprises the following steps:

1) heating medium is introduced into the shell pass of the heating system;

2) the polymerization raw materials pass through a preheating system and a light component removal system and are discharged into a tube pass of a heating system, the temperature is increased to 200 ℃ and 250 ℃, part of water is evaporated till the water content in the polymerization raw materials is reduced to be less than or equal to 20 percent, and a prepolymerization reaction is carried out;

3) discharging the material obtained by the prepolymerization reaction into a reaction system, dehydrating, and carrying out prepolymerization reaction to generate process steam;

4) the process steam generated in the reaction system enters a light component removal system, the polymerization raw material passing through the light component removal system is heated to 180-fold-240 ℃, and part of water and part of light components are carried out, and then the polymerization raw material enters the shell side of a preheating system, and the polymerization raw material passing through the preheating system is heated to 180-fold-230 ℃;

5) condensing process steam in a shell pass of the preheating system, feeding the process steam into a reflux port of the lightness removing system along a reflux pipeline under the action of gravity to serve as reflux liquid, and enabling organic diamine in the polymerization raw materials passing through the lightness removing system to completely enter a tube pass of the heating system;

6) when the viscosity reaches 150-300cp, the discharge port of the reaction system is opened, and continuous discharge is carried out to obtain the polyamide prepolymerization product.

The discharge port of the reaction system is connected with the tube side of the heating system through a circulating tube, and materials in the reaction system form circulation along the circulating tube, the tube side of the heating system and the reaction system under the action of density difference.

The tube pass of the heating system is connected with a steam source through a steam tube, and the density of materials in the tube pass of the heating system is reduced by providing steam into the tube pass of the heating system.

The light component removal system is a plate tower, N layers of tower plates are arranged in the plate tower, and N is more than or equal to 1.

The heating medium in the step 1) is biphenyl-diphenyl ether or 3.8MPa steam.

And 2) the polymerization raw material is salt solution formed by mixing dicarboxylic acid and organic diamine, and the solid content is 50-80 wt%.

The dicarboxylic acid is C₄～C₆Any one or a mixture of several of dicarboxylic acids of (1), the organic diamine is C₄～C₆Any one or a mixture of several of the diamines (c).

The dicarboxylic acid is succinic acid, glutaric acid and adipic acid, and the organic diamine is butanediamine, pentanediamine and hexanediamine.

The molar ratio of the dicarboxylic acid to the organic diamine is 1: 1-1.02.

Adopt above-mentioned technical scheme to have following beneficial effect:

1. the reaction device used in the continuous reaction process of the polyamide comprises a preheating system, a light component removal system, a heating system and a reaction system, wherein the preheating system is used for preheating and heating a polymerization raw material (refined salt), the light component removal system is used for removing part of water and light components in the polymerization raw material (refined salt) and intercepting macromolecular diamine in the polymerization raw material to ensure that low-boiling-point component organic diamine in the polymerization raw material completely enters the reaction system for reaction, the heating system is used for heating the polymerization raw material (refined salt) to 200 ℃ and 250 ℃ and carrying out prepolymerization reaction, the reaction system is used for carrying out prepolymerization post-reaction to obtain a target product and generating process steam, the gas supply is carried out on the light component removal system and the preheating system, the heat energy is effectively utilized, and the reaction energy consumption of the polyamide is reduced.

2. The invention uses condensate condensed in the shell pass of the preheating system to flow back to the lightness removing system under the action of gravity, intercepts the low-boiling-point macromolecular organic diamine in the polymerization raw materials, and evaporates out water and small molecules, so that the prepolymerization reaction is carried out under the condition of excessive organic diamine, thereby effectively ensuring the stable product quality of the polyamide and ensuring the production of high-end polyamide. In addition, the macromolecular organic diamine is intercepted, the light components discharged by the light component removal system are mainly water vapor and micromolecules, the water vapor enters the shell pass of the preheating system to preheat the polymerization raw materials entering the tube pass of the preheating system, and on the premise of improving the utilization rate of process vapor and reducing the energy consumption of polyamide synthesis, the macromolecular organic diamine with high viscosity is effectively prevented from entering the preheating system, and the long-period normal operation of the preheating system is guaranteed.

3. The lightness-removing system is a plate tower, wherein the plate tower is provided with a tower plate and is used for retaining metal ions in polymerization raw materials, reducing the content of the metal ions entering a reaction system and improving the synthesis quality of polyamide.

4. The invention controls the molar ratio of dicarboxylic acid to organic diamine in the polymerization raw materials to be 1: 1-1.02. If the content of the dicarboxylic acid is too high, the polycondensation reaction can be terminated early, so that the molecular weight of a polymerization product is not high, and the molecular weight of a synthesized product is low; if the content of the organic diamine is too high, the imidization reaction is easily caused. By controlling the solid content in the salt solution to be 50-80 wt%, if the solid content is lower than 50 wt%, the temperature in the heating system cannot reach 200-250 ℃, and if the solid content is higher than 80 wt%, the situation that the viscosity in the heating system is too high, the circulation is poor, and even the heating system is blocked can occur. The invention controls the discharge temperature of the light component removal reaction to be 180-240 ℃, if the discharge temperature is lower than 180 ℃, the temperature of a preheating system is too low, which is not beneficial to heat utilization, and if the discharge temperature is higher than 240 ℃, the molecular weight of a prepolymer formed by the reaction system is too large, which causes difficulty in material conveying.

5. The polymerization raw materials in the tube pass of the heating system are heated to 200-250 ℃ by passing the heating medium through the shell pass of the heating system, and the water content is ensured to be less than or equal to 20 percent.

6. The circulating pipe is arranged between the discharge port of the reaction system and the pipe pass of the heating system, so that materials in the reaction system are continuously circulated along the circulating pipe and the pipe pass of the heating system by utilizing density difference, the temperature of the reaction system in the reaction system is kept, and an additional power device is not needed.

7. The steam pipe is arranged for supplying steam to the pipe pass of the heating system, and the steam is supplied to the pipe pass of the heating system, so that the density of materials in the pipe pass of the heating system is reduced, the fluidity is improved, the circulating power of the materials is improved, the retention time of reactants on the inner wall of the pipe pass of the heating system is reduced, the heat exchange is facilitated, the time of the materials at high temperature is reduced, and the molecular weight of the products after the reaction is close to the consistency.

The following further description is made with reference to the accompanying drawings and detailed description.

Drawings

FIG. 1 is a schematic view of the connection of a reaction apparatus of the present invention.

In the figure, 1 is a preheating system, 11 is a polymerization raw material inlet, 12 is a polymerization raw material outlet, 13 is a heating medium inlet, 14 is a reflux pipeline, 2 is a light component removal system, 3 is a heating system, 31 is a tube pass inlet, 32 is a tube pass outlet, 4 is a reaction system, 41 is a process steam outlet, 5 is a circulating tube, and 6 is a steam tube.

Detailed Description

In the invention, the structures or devices which are not marked are all the structures or devices which are conventional in the chemical field, and the connection modes or installation modes which are not marked are all the structures or devices which are conventional in the chemical field, or the structures or devices which are not marked are connected or installed according to the suggestions of manufacturers.