Method for preparing 4, 4-diisocyanate dicyclohexylmethane based on Venturi reactor

Abstract

The invention provides a method for preparing 4, 4-diisocyanate dicyclohexylmethane (HMDI) based on a Venturi reactor, and belongs to the technical field of chemical reaction engineering. According to the method, 4, 4 '-diaminodicyclohexylmethane (HMDA) is dissolved in a solvent a to obtain a substrate solution, the substrate solution passes through a preheater A, phosgene and the solvent a are mixed to obtain a phosgene solution, the phosgene solution and the solvent a are fully mixed in a jet reactor through a flowmeter, and the mixture is heated and pyrolyzed to obtain 4, 4-diisocyanate dicyclohexylmethane. The method has the advantages of accurate feeding and controllable temperature, and is mild in reaction condition, low in energy consumption, good in enhanced mixing effect, less in side reaction, high in production efficiency, stable in product quality, less in tail gas pollution and environment-friendly.

Description

Technical Field

[0001] The present invention belongs to the field of organic synthesis, and particularly relates to a method for preparing 4,4'-diisocyanatodicyclohexylmethane based on a Venturi reactor. Background Art

[0002] 4,4'-Diisocyanatodicyclohexylmethane (HMDI) is an aliphatic isocyanate, and its chemical structural formula is shown as follows:

[0003]

[0004] The polyurethane products prepared therefrom have excellent properties such as non-yellowing, light stability, weather resistance, and high mechanical properties. The polyurethane materials prepared from HMDI have excellent comprehensive properties and can be used to synthesize high-grade, yellowing-resistant, and high-temperature products, polyurethane elastomers, waterborne polyurethanes, coatings, leather, etc. HMDI is prepared from 4,4'-diaminodiphenylmethane (HMDA).

[0005] Currently, there are mainly two preparation routes. One is the non-phosgene method, mainly the urea method. HMDA first reacts with urea and alcohol to obtain carbamate, and then is pyrolyzed under the action of a catalyst to obtain HMDI. The urea method replaces highly toxic phosgene and realizes a green, environmentally friendly, and sustainable process, which conforms to the concept of modern green chemistry development. However, there are still many unsolved problems in the production equipment investment and process stability of the urea method. Currently, there is no successful operation of a thousand-ton-level device in China.

[0006] The other is the traditional phosgene method for preparation. This method is simple in preparation, high in reaction efficiency, and low in production cost. Currently, all isocyanate projects with a scale of more than a thousand tons use the phosgene method. Phosgene has irreplaceable advantages in the preparation of isocyanate products. However, how to prepare isocyanate more quickly, efficiently, and at low cost has always been a hot research topic, including the preparation of isocyanate by combining with new reactors (jet reactor, Venturi reactor, high-shear reactor). Summary of the Invention

[0007] In view of the problems in the prior art and aspects such as safety, the present invention provides a method for preparing 4,4'-diisocyanatodicyclohexylmethane based on a Venturi reactor. This method uses a Venturi reactor to strengthen the reaction process, improve the reaction activity, and at the same time can strictly control the accurate feeding of the reaction, reducing the generation of impurities.

[0008] A method for preparing 4,4'-diisocyanatodicyclohexylmethane based on a Venturi reactor, characterized in that the reaction formula is shown as follows:

[0009]

[0010] It includes the following steps:

[0011] (1) Dissolve 4,4'-diaminodicyclohexylmethane (HMDA) in solvent a to obtain a substrate solution. The substrate solution is first preheated by preheater A, and phosgene is mixed with solvent a to obtain a phosgene solution;

[0012] (2) When the substrate solution reaches a certain temperature, the substrate solution and the phosgene solution are respectively passed through flow meters and fully mixed in a jet reactor, and then heated and pyrolyzed;

[0013] (3) After the reaction is completed, cool it under temperature control to obtain a 4,4-diisocyanatodicyclohexylmethane solution, and then remove the solvent under reduced pressure to obtain 4,4-diisocyanatodicyclohexylmethane.

[0014] Furthermore, the solvent a described in step (1) is one or more of toluene, xylene, chlorobenzene, dichlorobenzene, anisole, diphenyl ether, preferably one or more of chlorobenzene and dichlorobenzene.

[0015] Furthermore, the preheating temperature of preheater A in step (1) is 15-25°C; preferably 20°C

[0016] Furthermore, the heating temperature in step (2) is 100-120°C; preferably 110°C.

[0017] Furthermore, the temperature control and cooling temperature in step (3) is 20-40°C; preferably 25°C.

[0018] Furthermore, the mass concentration of 4,4'-diaminodicyclohexylmethane in the substrate solution described in step (1) is 12wt%-20wt%, preferably 18wt%; the mass concentration of phosgene in the phosgene solution is 20wt%-50wt%, preferably 30wt%.

[0019] Furthermore, the feed flow rate of the 4,4'-diaminodicyclohexylmethane solution in step (2) is 30-50 L / h, preferably 35 L / h, and the feed flow rate of the phosgene solution is 30-50 L / h, preferably 35 L / h.

[0020] A Venturi reactor includes a jet reactor 100, an HMDA feed and a phosgene feed. The jet reactor 100 includes a reactor body 110 and a nozzle 120. A phosgene feed inlet 111 and a reactor outlet 112 are provided on the reactor body 110. The HMDA feed is injected into the reactor body 110 in a liquid form through the nozzle 120 and the spray holes 122 thereon. The phosgene feed enters the reactor body 110 in a liquid form through the phosgene feed inlet 111. The HNDA and phosgene are mixed under the action of jet entrainment and react to form the corresponding isocyanate product.

[0021] The beneficial effects of the present invention are as follows:

[0022] 1. The reaction conditions of this invention are mild and the reaction process is strengthened, increasing the reaction efficiency; precise feeding of materials is achieved, improving the selectivity of the reaction and reducing the occurrence of side reactions; through the post-treatment of vacuum distillation, 4,4-diisocyanatodicyclohexylmethane with high purity can be obtained.

[0023] 2. The Venturi reactor adopted in the present invention has good mixing effect, reduces backmixing phenomenon, and the material injection is uniform, fast and efficient. The continuous feeding method of the Venturi reactor ensures the fast inlet and outlet of materials and products, is energy-saving, green and environmentally friendly, and is suitable for large-scale industrial production. Brief Description of the Drawings

[0024] Figure 1 - One Schematic diagram of a reaction system of a Venturi reactor Detailed Embodiments

[0025] The Venturi reactor used in the examples of the present invention was ordered from Wuxi Changqing Chemical Anti-corrosion Equipment Co., Ltd. Example 1:

[0026] A method for preparing 4,4-diisocyanatodicyclohexylmethane based on a Venturi reactor, the steps are as follows:

[0027] (1) Dissolve 4,4'-diaminodicyclohexylmethane (HMDA) in chlorobenzene to obtain a substrate solution with a concentration of 18 wt%. The substrate solution is first preheated to 20 °C by a preheater A, and phosgene and chlorobenzene are mixed to obtain a substrate solution with a concentration of 30 wt%.

[0028] (2) When the substrate solution reaches the temperature, the substrate solution and the phosgene solution are respectively fed into the jet reactor at a feeding speed of 35 L / h through flow meters, heated to 110 °C for pyrolysis, and the reaction is carried out for 1 - 3 hours.

[0029] (3) After the reaction is completed, it is cooled to 25 °C to obtain a 4,4-diisocyanatodicyclohexylmethane solution, and then the solvent is removed under reduced pressure to obtain a 4,4-diisocyanatodicyclohexylmethane solution for analysis. The conversion rate of HMDA is 100%, and the selectivity of 4,4'-diaminodicyclohexylmethane is 99.4%.

[0030] Example 2:

[0031] A method for preparing 4,4-diisocyanatodicyclohexylmethane based on a Venturi reactor, the steps are as follows:

[0032] (1) 4,4′-diaminodicyclohexylmethane (HMDA) was dissolved in dichlorobenzene to obtain a substrate solution with a concentration of 18 wt %. The substrate solution was preheated to 20° C. in a preheater A. Phosgene and dichlorobenzene were mixed to obtain a substrate solution with a concentration of 30 wt %.

[0033] (2) When the substrate solution reaches the temperature, the substrate solution and the phosgene solution are fully mixed in the jet reactor at a feed rate of 35 L / h through a flow meter, and the temperature is raised to 110°C for pyrolysis and the reaction is carried out for 1 to 3 hours;

[0034] (3) After the reaction is completed, the mixture is cooled to 25° C. to obtain a 4,4-diisocyanate dicyclohexylmethane solution, and then the solvent is removed under reduced pressure to obtain a 4,4-diisocyanate dicyclohexylmethane solution for analysis. The HMDA conversion rate is 100%, and the selectivity of 4,4′-diaminodicyclohexylmethane is 99.3%.

[0035] Example 3:

[0036] A method for preparing 4,4-diisocyanate dicyclohexylmethane based on a Venturi reactor, comprising the following steps:

[0037] (1) 4,4′-diaminodicyclohexylmethane (HMDA) was dissolved in chlorobenzene to obtain a substrate solution with a concentration of 12 wt %. The substrate solution was preheated to 15° C. in a preheater A. Phosgene and chlorobenzene were mixed to obtain a substrate solution with a concentration of 20 wt %.

[0038] (2) When the substrate solution reaches the temperature, the substrate solution and the phosgene solution are fully mixed in the jet reactor at a feed rate of 30 L / h through a flow meter, and the temperature is raised to 100°C for pyrolysis, and the reaction is carried out for 1 to 3 hours;

[0039] (3) After the reaction is completed, the mixture is cooled to 20° C. to obtain a 4,4-diisocyanate dicyclohexylmethane solution, and then the solvent is removed under reduced pressure to obtain a 4,4-diisocyanate dicyclohexylmethane solution for analysis. The HMDA conversion rate is 100%, and the selectivity of 4,4′-diaminodicyclohexylmethane is 99.1%.

[0040] Example 4:

[0041] A method for preparing 4,4-diisocyanate dicyclohexylmethane based on a Venturi reactor, comprising the following steps:

[0042] (1) 4,4′-diaminodicyclohexylmethane (HMDA) was dissolved in chlorobenzene to obtain a substrate solution with a concentration of 20 wt %. The substrate solution was preheated to 25° C. in a preheater A. Phosgene and chlorobenzene were mixed to obtain a substrate solution with a concentration of 50 wt %.

[0043] (2) After the substrate solution reaches the temperature, the substrate solution and the phosgene solution are respectively fed into the jet reactor through flow meters at a feeding rate of 50 L / h and mixed thoroughly, then heated to 120 °C for pyrolysis, and the reaction is carried out for 1 - 3 hours;

[0044] (3) After the reaction is completed, it is cooled to 40 °C to obtain a solution of 4,4 - diisocyanatodicyclohexylmethane, and then the solvent is removed under reduced pressure. The obtained solution of 4,4 - diisocyanatodicyclohexylmethane is analyzed. The conversion rate of HMDA is 100%, and the selectivity of 4,4′ - diaminodicyclohexylmethane is 99.0%.

[0045] Example 5:

[0046] A method for preparing 4,4 - diisocyanatodicyclohexylmethane based on a Venturi reactor, the steps are as follows:

[0047] (1) Dissolve 4,4′ - diaminodicyclohexylmethane (HMDA) in chlorobenzene to obtain a substrate solution with a concentration of 10 wt%. The substrate solution is first preheated to 10 °C by a preheater A. After phosgene is mixed with chlorobenzene, a substrate solution with a concentration of 15 wt% is obtained;

[0048] (2) After the substrate solution reaches the temperature, the substrate solution and the phosgene solution are respectively fed into the jet reactor through flow meters at a feeding rate of 25 L / h and mixed thoroughly, then heated to 90 °C for pyrolysis, and the reaction is carried out for 1 - 3 hours;

[0049] (3) After the reaction is completed, it is cooled to 15 °C to obtain a solution of 4,4 - diisocyanatodicyclohexylmethane, and then the solvent is removed under reduced pressure. The obtained solution of 4,4 - diisocyanatodicyclohexylmethane is analyzed. The conversion rate of HMDA is 98%, and the selectivity of 4,4′ - diaminodicyclohexylmethane is 98.3%.

[0050] Example 6:

[0051] A method for preparing 4,4 - diisocyanatodicyclohexylmethane based on a Venturi reactor, the steps are as follows:

[0052] (1) Dissolve 4,4′ - diaminodicyclohexylmethane (HMDA) in chlorobenzene to obtain a substrate solution with a concentration of 25 wt%. The substrate solution is first preheated to 30 °C by a preheater A. After phosgene is mixed with chlorobenzene, a substrate solution with a concentration of 55 wt% is obtained;

[0053] (2) After the substrate solution reaches the temperature, the substrate solution and the phosgene solution are respectively fed into the jet reactor through flow meters at a feeding rate of 55 L / h and mixed thoroughly, then heated to 125 °C for pyrolysis, and the reaction is carried out for 1 - 3 hours;

[0054] (3) After the reaction was completed, it was cooled to 45 °C to obtain a solution of 4,4'-diisocyanatodicyclohexylmethane, and then the solvent was removed under reduced pressure. The resulting solution of 4,4'-diisocyanatodicyclohexylmethane was analyzed. The conversion rate of HMDA was 97%, and the selectivity of 4,4'-diaminodicyclohexylmethane was 97.5%.

[0055] Although the specific embodiments of the present invention have been described above, they do not limit the protection scope of the present invention. Those skilled in the art should understand that, based on the technical solution of the present invention, various modifications or variations that can be made without creative efforts by those skilled in the art are still within the protection scope of the present invention.

Claims

1. A method for preparing 4,4'-diisocyanatodicyclohexylmethane based on a Venturi reactor, characterized in that, The reaction formula is as follows: The following steps are involved: (1) 4,4′-diaminodicyclohexylmethane (HMDA) is dissolved in solvent a to obtain a substrate solution, the substrate solution is preheated in a preheater A, and phosgene is mixed with solvent a to obtain a phosgene solution; (2) When the substrate solution reaches a certain temperature, the substrate solution and phosgene solution are fully mixed in the jet reactor through flow meters and heated for pyrolysis; (3) After the reaction is completed, the solution of 4,4-diisocyanate dicyclohexylmethane is obtained by temperature-controlled cooling, and then the solvent is removed under reduced pressure to obtain 4,4-diisocyanate dicyclohexylmethane.

2. The method for preparing 4,4'-diisocyanatodicyclohexylmethane based on a Venturi reactor according to claim 1, characterized in that, The solvent a described in step (1) is one or more of toluene, xylene, chlorobenzene, dichlorobenzene, anisole, and diphenyl ether, preferably one or more of chlorobenzene and dichlorobenzene.

3. A method for preparing 4,4'-diisocyanatodicyclohexylmethane based on a Venturi reactor according to claim 1, characterized in that, The preheating temperature of the preheater A described in step (1) is 15-25°C, preferably 20°C.

4. A method for preparing 4,4'-diisocyanatodicyclohexylmethane based on a Venturi reactor according to claim 1, characterized in that, The heating temperature in step (2) is 100-120°C, preferably 110°C.

5. A method for preparing 4,4'-diisocyanatodicyclohexylmethane based on a Venturi reactor according to claim 1, characterized in that, The temperature of the temperature-controlled cooling in step (3) is 20-40°C, preferably 25°C.

6. A method for preparing 4,4'-diisocyanatodicyclohexylmethane based on a Venturi reactor according to claim 1, characterized in that, The mass concentration of 4,4'-diaminodicyclohexylmethane in the substrate solution of step (1) is 12wt%-20wt%, preferably 18wt%; the mass concentration of phosgene in the phosgene solution is 20wt%-50wt%, preferably 30wt%.

7. A method for preparing 4,4'-diisocyanatodicyclohexylmethane based on a Venturi reactor according to claim 1, characterized in that, The feed rate of the 4,4′-diaminodicyclohexylmethane solution in step (2) is 30-50 L / h, preferably 35 L / h, and the feed rate of the phosgene solution is 30-50 L / h, preferably 35 L / h.

8. A method for preparing 4,4'-diisocyanatodicyclohexylmethane based on a Venturi reactor according to claim 1, characterized in that, The Venturi reactor includes a jet reactor 100, HMDA feed and phosgene feed. The jet reactor 100 includes a body 110 and a nozzle 120. The body 110 is provided with a phosgene feed inlet 111 and a reactor outlet 112. The HMDA feed is sprayed into the body 110 in liquid form through the nozzle 120 and the spray holes 122 thereon. The phosgene feed enters the body 110 in liquid form through the phosgene feed inlet 111. The HMDA and phosgene are mixed and reacted under the action of jet entrainment to produce the corresponding isocyanate product.

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