Production process of methyl isobutyl ketone diimide for one-component polyurethane

Abstract

This invention relates to a production process for methyl isobutyl ketone diimide for single-component polyurethane, belonging to the field of chemical technology. The process includes the following steps: adding methyl isobutyl ketone, m-phenylenediamine, water, and methyl isobutyl ketone diimide to the bottom I of a reactive distillation column, initiating total reflux; continuously feeding methyl isobutyl ketone and m-phenylenediamine, collecting methyl isobutyl ketone diimide from the bottom I, and collecting a mixture of methyl isobutyl ketone and water from the top of the reactive distillation column; the mixture of methyl isobutyl ketone and water collected from the top of the reactive distillation column is subjected to heat exchange with the liquid in the bottom II of the column via a heat exchanger, allowing for preliminary separation of the water and methyl isobutyl ketone before entering a recovery column for further separation and purification; the top of the recovery column contains an azeotrope of methyl isobutyl ketone and water, while the methyl isobutyl ketone collected from the bottom of the recovery column is returned to the methyl isobutyl ketone feed tank for recycling. This invention reduces energy consumption by 30% and achieves a product purity greater than 99.5% wt.

Description

Technical Field

[0001] This invention relates to a production process for methyl isobutyl ketone diimide for one-component polyurethane, belonging to the field of chemical technology. Background Technology

[0002] Single-component polyurethane has become a mainstream product due to its advantages such as convenient construction, low construction cost, and low labor load, and is widely used in industries such as sealants, coatings, and flooring.

[0003] To improve the curing speed, single-component polyurethanes require the addition of organotin and tertiary amine compounds as catalysts. However, the isocyanate groups in polyurethane are sensitive to moisture under the action of catalysts, leading to a significant increase in viscosity and even gelation during storage. The trade-off between storage stability and curing speed in single-component moisture-curing polyurethane sealants has always been a challenge. The emergence of latent curing agents has successfully solved this problem. Methyl isobutyl ketone diimide is an excellent latent curing agent, but its production process mainly uses traditional batch production methods, with reaction equipment in reactors, severely limiting its production capacity. The main shortcomings are as follows:

[0004] 1. Insufficient heat exchange area prevents timely removal of reaction heat, resulting in high heat consumption; the process is prone to localized excessively high material concentration and temperature, which can easily lead to side reactions and unstable product quality.

[0005] 2. Intermittent production is difficult to automate, requiring time and manual intervention to adjust temperature and pressure, feed materials, and prepare for the next batch of materials.

[0006] 3. Methyl isobutyl ketone diimide requires a high reaction temperature (usually around 160℃), and the production process requires a large amount of heat energy, which cannot be recovered and reused, resulting in serious waste.

[0007] 4. Methyl isobutyl ketone azeotropically reacts with water, making it difficult to separate using conventional distillation processes.

[0008] Therefore, there is an urgent need for a production process for methyl isobutyl ketone diimide for single-component polyurethane that can solve the above-mentioned technical problems. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a production process for methyl isobutyl ketone diimide for single-component polyurethane. This process uses reactive distillation, coupling the reaction and distillation processes into one device, allowing the reaction and separation to occur simultaneously. The heat released by the reaction can be used in the distillation process, and products are continuously collected during the reaction, which can shift the reaction towards the forward reaction direction. The reaction conversion rate can reach over 80%. By employing double-effect distillation, the heat from the top of the reactive distillation column is used to heat the bottom of the recovery column, making full use of heat and reducing energy consumption by 30%. This process is simple, has good separation effect, high product purity (greater than 99.5% wt), and low production cost, making it suitable for industrial and continuous production.

[0010] The production process of methyl isobutyl ketone diimide for one-component polyurethane of the present invention is characterized by including the following steps:

[0011] Step 1: Add 40-60% by weight of methyl isobutyl ketone, 20-40% by weight of m-phenylenediamine, 10-20% by weight of water, and 10-25% by weight of methyl isobutyl ketone diimide to the bottom I2 of the reactive distillation column 1. When the liquid level in the bottom I2 reaches 80%, stop feeding and preheat the reactive distillation column 1 to start total reflux.

[0012] Preferably, the reactive distillation column 1 comprises, from bottom to top: a reboiler I2, a stripping section I3, a reaction section I4, and a rectification section I5; the stripping section I3 and the rectification section I5 are filled with θ-ring packing, and the reaction section I4 is filled with θ-ring packing or a solid catalyst; the pressure of the reactive distillation column 1 is 0.2-2 MPa.

[0013] Step 2: Methyl isobutyl ketone and m-phenylenediamine are continuously fed from the bottom and top of reaction section I4, respectively. At the same time, the top of reactive distillation column 1 and the bottom of column I2 are collected. Methyl isobutyl ketone diimide is collected from the bottom of column I2, and a mixture of methyl isobutyl ketone and water is collected from the top of reactive distillation column 1.

[0014] Preferably, step 2 specifically involves: after total reflux for 30 minutes in step 1, methyl isobutyl ketone and m-phenylenediamine are fed again at a mass ratio of (3-12):1 (by increasing the feed ratio of methyl isobutyl ketone, the reaction conversion rate is improved), and at the same time, the top of the reactive distillation column 1 and the bottom of column I2 begin to be drawn out, maintaining the liquid level of bottom I2 at 50% and the liquid level of reflux tank I6 at 50%, controlling the reflux ratio of reactive distillation column 1 to be 2-8, and the bottom I2 is equipped with a heater with a heating power of 4000-6000W;

[0015] Step 3: The mixture of methyl isobutyl ketone and water collected from the top of the reactive distillation column 1 is exchanged with the liquid in the bottom of column II 12 through heat exchanger 8. Part of the mixture is refluxed back to the top of the reactive distillation column 1, and the other part is added to the liquid-liquid phase separator 17 to initially separate the water and methyl isobutyl ketone before entering the recovery column 11 for further separation and purification.

[0016] Preferably, the other part is cooled to 10-30°C by condenser I7 and then enters liquid-liquid phase separator I7;

[0017] Preferably, the liquid-liquid phase separator 17 includes an aqueous phase inlet, an aqueous phase outlet, and an oil phase outlet. The purpose of the aqueous phase inlet is to improve the separation degree of the aqueous and oil phases. The oil phase outlet is connected to the inlet of the recovery tower 11, and the aqueous phase outlet is sent to wastewater treatment.

[0018] Step 4: The azeotrope of methyl isobutyl ketone and water is collected from the top of recovery tower 11 and returned to liquid-liquid phase separator 17 to further separate excess water. The methyl isobutyl ketone collected from the bottom of recovery tower 11 is returned to methyl isobutyl ketone feed tank 10 for recycling.

[0019] Preferably, heating begins after the bottom liquid level of the recovery tower 11 reaches 50%, the pressure of the recovery tower is 0.03-0.1 MPa, the reflux ratio at the top of the tower is 1-3, and the liquid level in the reflux tank II 16 is maintained at 50%.

[0020] Preferably, the recovery tower 11 includes, from bottom to top: a tower bottom II 12, a stripping section II 13, and a rectification section II 14. The vapor outlet at the top of the recovery tower 11 is sequentially connected to a condenser II 15 and a reflux tank II 16. One end of the outlet of the reflux tank II 16 is connected to the liquid inlet at the top of the recovery tower 11, and the other end is connected to the inlet of the condenser I 7. The high-purity methyl isobutyl ketone collected from the tower bottom II 12 is connected to the methyl isobutyl ketone feed tank 10 for recycling.

[0021] Preferably, the rectification section II 14 and the stripping section II 13 of the recovery tower 11 are both filled with θ-ring packing.

[0022] Preferably, the bottom of the tower II 12 is heated by the heat exchanger 8 during normal operation. In the initial preparation stage, a heater is used for heating, and an electric heating jacket is adopted. The heating power of the bottom of the recovery tower 11 is 1000-2000W.

[0023] Preferably, the reactive distillation column 1 and the recovery column 11 are externally insulated with electric heating wires.

[0024] The production process of methyl isobutyl ketone diimide for single-component polyurethane of the present invention has the following beneficial effects:

[0025] (1) The distillation process allows the product to be continuously extracted from the system, thereby shifting the reaction towards the positive reaction direction and reducing the occurrence of side reactions. The product quality is stable, and the single-pass conversion rate in this process can reach more than 80%. The reaction process and the distillation process are carried out simultaneously. The reaction is an exothermic reaction, and the heat of reaction can be used in the distillation process, which can reduce energy consumption by 10%.

[0026] (2) Intermittent production requires time and manpower to adjust temperature and pressure, feed materials, prepare for the next batch of feeding materials, etc., and the process is complex and the equipment investment is large. This invention can realize the reaction and distillation process in one piece of equipment, reducing equipment investment by 20%, and can realize automated production, reducing labor costs by 50%.

[0027] (3) Double-effect distillation is adopted, and the top steam of the reactive distillation column 1 is used as the heat source of the reboiler of the recovery column 11. By adjusting the pressure and reflux ratio of the reactive distillation column 1 and the recovery column 11, the two heats are coupled. The heat removed from the top of the reactive distillation column 1 is exactly equal to the heat required for heating the recovery column 11, thereby reducing the energy consumption of the distillation process by 20%.

[0028] (4) Taking advantage of the azeotropic properties of methyl isobutyl ketone with water and its slight solubility in water, the liquid-liquid phase separator 17 is combined with the distillation column 1 to improve the separation effect and reduce energy consumption by 20%. Furthermore, methyl isobutyl ketone can be recycled, reducing production costs by 30%, which is suitable for industrial production. Attached Figure Description

[0029] Figure 1 This is a diagram of the apparatus for producing methyl isobutyl ketone diimide for single-component polyurethane according to the present invention. Detailed Implementation

[0030] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0031] Example 1

[0032] The production process of methyl isobutyl ketone diimide for one-component polyurethane in this embodiment includes the following steps:

[0033] Add 40% methyl isobutyl ketone, 30% m-phenylenediamine, 15% water, and 15% methyl isobutyl ketone diimide by mass fraction to the bottom I2 of the reactive distillation column 1 until the liquid level in the bottom I2 reaches 80%. Add a certain amount of zeolite to prevent bumping. Heat the bottom I2, control the heating power of the bottom I2 to 4500W, and turn on the column body insulation switch to control the pressure inside the reactive distillation column 1 to 1.8MPa.

[0034] Feeding begins when the temperature of column I2 reaches 200℃. The feed rate of methyl isobutyl ketone is controlled at 6 kg / h, and the feed rate of m-phenylenediamine is controlled at 1.5 kg / h. Both are fed at room temperature until the reactive distillation column I starts to reflux. Feeding is then stopped. After about 30 minutes of total reflux, methyl isobutyl ketone and m-phenylenediamine are fed again, and the reflux ratio at the top of the column is controlled at 3.

[0035] Start feeding by turning on the liquid-liquid phase separator 17. After the liquid-liquid phase separator 17 stabilizes, turn on the regulating valve of the recovery tower to start feeding. Once the liquid level in column bottom II reaches 50%, start heating and turn on the column insulation switch. Control the reflux ratio at the top of the column to be 1.2, and the pressure of the recovery tower to be 0.05 MPa. The product composition of the reactive distillation column bottom, the aqueous phase of the liquid-liquid phase separator, and the product composition of the recovery tower bottom after the system reaches a stable state is shown in Table 1-3 below.

[0036] Table 1 Composition of the product in the bottom product of the reactive distillation column

[0037] ;

[0038] Table 2 Composition of Aqueous Phase Products in Liquid-Liquid Separator

[0039] ;

[0040] Table 3 Composition of Recycled Tower Boiler Products

[0041] ;

[0042] Example 2

[0043] The production process of methyl isobutyl ketone diimide for one-component polyurethane in this embodiment includes the following steps:

[0044] Add 50% methyl isobutyl ketone (MBE), 30% m-phenylenediamine (m-PPE), 10% water, and 10% MBE diimide (MPI) to the bottom I of the reactive distillation column, bringing the liquid level to 80%. Add a certain amount of zeolite to prevent bumping. Heat the bottom I of the column, controlling the heating power at 4800W, and turn on the column insulation switch, controlling the pressure inside the column at 1.2 MPa. When the bottom temperature reaches 200℃, start feeding, controlling the feed rate of MBE at 8 kg / h and the feed rate of m-PPE at 1.5 kg / h, both at room temperature. Stop feeding when the reactive distillation column starts refluxing. After about 30 minutes of total reflux, start feeding MBE and m-PPE again, controlling the reflux ratio at the top of the column at 4. Start feeding by turning on the liquid-liquid phase separator switch. After the liquid-liquid phase separator stabilizes, turn on the regulating valve of the recovery tower to start feeding. Once the liquid level in column II reaches 60%, start heating and turn on the tower insulation switch. Control the reflux ratio at the top of the tower to be 1.2, and the pressure in the recovery tower to be 0.06 MPa. The product composition of the reactive distillation column bottom, the aqueous phase of the liquid-liquid phase separator, and the product composition of the recovery tower bottom after the system reaches a steady state is shown in Table 1-3 below.

[0045] Table 1 Composition of the product in the bottom product of the reactive distillation column

[0046] ;

[0047] Table 2 Composition of Aqueous Phase Products in Liquid-Liquid Separator

[0048] ;

[0049] Table 3 Composition of Recycled Tower Boiler Products

[0050] ;

[0051] Example 3

[0052] The production process of methyl isobutyl ketone diimide for one-component polyurethane in this embodiment includes the following steps:

[0053] Add 60% methyl isobutyl ketone, 20% m-phenylenediamine, 10% water, and 10% methyl isobutyl ketone diimide (by mass) to the bottom I of the reactive distillation column, bringing the liquid level to 80%. Add a certain amount of zeolite to prevent bumping. Heat the bottom I of the column, controlling the heating power at 4500W, and turn on the column insulation switch, controlling the pressure inside the column at 0.6 MPa. When the bottom temperature reaches 200℃, start feeding, controlling the feed rate of methyl isobutyl ketone at 10 kg / h and the feed rate of m-phenylenediamine at 1 kg / h, both at room temperature. Stop feeding when the reactive distillation column starts refluxing. After about 30 minutes of total reflux, start feeding methyl isobutyl ketone and m-phenylenediamine again, controlling the reflux ratio at the top of the reactive distillation column at 6. Start feeding by turning on the liquid-liquid phase separator switch. After the liquid-liquid phase separator stabilizes, turn on the regulating valve of the recovery tower to start feeding. Once the liquid level in column II reaches 70%, start heating and turn on the tower body insulation switch. Control the reflux ratio at the top of the recovery tower to 2, and maintain the recovery tower at atmospheric pressure. The output rate is as follows: After the system reaches a steady state, the product composition of the reactive distillation column bottom, the aqueous phase of the liquid-liquid phase separator, and the product composition of the recovery tower bottom are shown in Table 1-3 below.

[0054] Table 1 Composition of the product in the bottom product of the reactive distillation column

[0055] ;

[0056] Table 2 Composition of Aqueous Phase Products in Liquid-Liquid Separator

[0057] ;

[0058] Table 3 Composition of Recycled Tower Boiler Products

[0059] ;

[0060] This invention couples the reaction and distillation processes into a single device using reactive distillation, allowing the reaction and separation to occur simultaneously. The heat released by the reaction can be used in the distillation process, and products are continuously collected during the reaction, which can shift the reaction towards the forward reaction direction. The reaction conversion rate can reach over 80%. By employing double-effect distillation, the heat from the top product of the reactive distillation column is used to heat the bottom of the recovery column, making full use of heat and reducing energy consumption by 30%. This process is simple, has good separation effect, high product purity (greater than 99.5% wt), and low production cost, making it suitable for industrial and continuous production.

[0061] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. Process for the production of methyl isobutyl ketone diimine for one-component polyurethanes, characterized in that The method comprises the following steps: Step 1: adding 40-60% of methyl isobutyl ketone, 20-40% of m-xylylenediamine, 10-20% of water and 10-25% of methyl isobutyl ketone diimine into the bottom of the reaction rectifying tower, stopping feeding when the liquid level of the bottom reaches 80%, preheating the reaction rectifying tower and starting full reflux of the reaction rectifying tower; Step 2: continuously feeding methyl isobutyl ketone and m-xylylenediamine from the bottom and the top of the reaction section I respectively, meanwhile, starting to collect the products from the top of the reaction rectifying tower and the bottom of the reaction rectifying tower, collecting methyl isobutyl ketone diimine from the bottom of the reaction rectifying tower and collecting the mixture of methyl isobutyl ketone and water from the top of the reaction rectifying tower; Step 3: the mixture of methyl isobutyl ketone and water collected from the top of the reaction rectifying tower is exchanged with the liquid in the bottom of the tower II through a heat exchanger, part of which is returned to the top of the reaction rectifying tower, and the other part is added into a liquid-liquid separator, and then the water and methyl isobutyl ketone are preliminarily separated and then further separated and purified in a recovery tower; Step 4: the azeotrope of methyl isobutyl ketone and water collected from the top of the recovery tower is returned to the liquid-liquid separator to separate the excess water, and the methyl isobutyl ketone collected from the bottom of the recovery tower is returned to the methyl isobutyl ketone feeding tank for recycling.

2. The process for the production of methyl isobutyl ketone diimine for one-component polyurethanes according to claim 1, characterized in that The reaction rectifying tower comprises, from bottom to top, the bottom of the reaction rectifying tower, the distillation section I, the reaction section I and the rectifying section I, the distillation section I and the rectifying section I are filled with θ ring type fillers, the reaction section I is filled with θ ring type fillers or solid catalysts, and the pressure of the reaction rectifying tower is 0.2-2 MPa.

3. The process for the production of methyl isobutyl ketone diimine for one-component polyurethane according to claim 2, characterized in that In step 2, after full reflux for 30 minutes in step 1, methyl isobutyl ketone and m-xylylenediamine are continuously fed again at a mass ratio of 3-12:1, meanwhile, the products are collected from the top of the reaction rectifying tower and the bottom of the reaction rectifying tower, the liquid level of the bottom of the reaction rectifying tower is kept at 50%, the liquid level of the reflux tank I is kept at 50%, the reflux ratio of the reaction rectifying tower is controlled to be 2-8, the bottom of the reaction rectifying tower is provided with a heater, and the heating power is 4000-6000 W.

4. The process for the production of methyl isobutyl ketone diimine for one-component polyurethane according to claim 1, characterized in that In step 3, the other part is cooled to 10-30 DEG C through a condenser I and then enters the liquid-liquid separator.

5. The process for the production of methyl isobutyl ketone diimine for one-component polyurethane according to claim 4, characterized in that The liquid-liquid separator comprises a water phase feeding port, a water phase outlet and an oil phase outlet, the water phase feeding port is used to improve the separation degree of the water phase and the oil phase, the oil phase outlet is connected with the feeding port of the recovery tower, and the water phase outlet is discharged to a sewage treatment plant.

6. The process for the production of methyl isobutyl ketone diimine for one-component polyurethane according to claim 1, characterized in that After the liquid level of the bottom of the recovery tower reaches 50%, the bottom of the recovery tower is heated, the pressure of the recovery tower is 0.03-0.1 MPa, the reflux ratio of the top of the recovery tower is 1-3, and the liquid level of the reflux tank II is kept at 50%.

7. The process for the production of methyl isobutyl ketone diimine for one-component polyurethane according to claim 1, characterized in that The recovery tower comprises, from bottom to top, the bottom of the recovery tower, the distillation section II and the rectifying section II, the gas phase outlet of the top of the recovery tower is connected with a condenser II and a reflux tank II in sequence, one end of the outlet of the reflux tank II is connected with the liquid phase feeding port of the top of the recovery tower, and the other end is connected with the feeding port of the condenser I, the bottom of the recovery tower is connected with the methyl isobutyl ketone feeding tank to recycle the methyl isobutyl ketone collected from the bottom of the recovery tower.

8. The process for the production of methyl isobutyl ketone diimine for one-component polyurethane according to claim 1, characterized in that The rectifying section II and the distillation section II of the recovery tower are both filled with θ ring type fillers.

9. The process for the production of methyl isobutyl ketone diimine for one-component polyurethane according to claim 1, characterized in that The tower kettle II is heated by the heat exchanger in normal operation, is heated by the heater in the initial preparation stage, adopts an electric heating jacket form, and the heating power recovered by the tower kettle of the recovery tower is 1000-2000W.

10. The process for the production of methyl isobutyl ketone diimine for one-component polyurethane according to claim 1, characterized in that The reaction rectification tower and the recovery tower are externally wound with electric heating wires for heat preservation.

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