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

Abstract

The invention provides a method for continuously preparing 4, 4-diisocyanate dicyclohexylmethane (HMDI) based on a jet 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 jet 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 from it 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 pyrolyzes 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 device with an annual output of more than a thousand tons operating successfully in China.

[0006] The other is the traditional phosgene method for preparation. This method is simple to prepare, has high reaction efficiency, and low production cost. Currently, all isocyanate projects with an output 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, which includes the preparation of isocyanate in combination with new reactors (jet reactors, Venturi reactors, high-shear reactors). Summary of the Invention

[0007] Aiming at the problems in the prior art and safety, etc., the present invention provides a method for preparing 4,4'-diisocyanatodicyclohexylmethane based on a jet reactor. This method uses a jet-type powerful mixer to strengthen the reaction process, improve the reaction activity, and at the same time can strictly control the precise feeding of the reaction, reducing the generation of impurities.

[0008] A method for preparing 4,4'-diisocyanatodicyclohexylmethane based on a jet 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, control the temperature and cool to obtain a 4,4-diisocyanatodicyclohexylmethane solution, and then carry out post-treatment to obtain the product.

[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 described in step (1) is 15-20°C; preferably 18°C.

[0016] Furthermore, the heating temperature described in step (2) is 100-130°C; preferably 120°C.

[0017] Furthermore, the temperature control and cooling temperature described in step (3) is 20-40°C; preferably 30°C.

[0018] Furthermore, the mass concentration of 4,4′-diaminodicyclohexylmethane in the substrate solution described in step (1) is 10wt%-15wt%, preferably 12wt%; the mass concentration of phosgene in the phosgene solution is 20wt%-60wt%, preferably 35wt%.

[0019] Furthermore, the feed flow rate of the 4,4′-diaminodicyclohexylmethane solution described in step (2) is 30-50 L / h, preferably 40 L / h, and the feed flow rate of the phosgene solution is 30-50 L / h, preferably 40 L / h.

[0020] Furthermore, the post-treatment described in step (3) includes the steps of: carrying out vacuum rectification on the mixed solution to obtain 4,4-diisocyanatodicyclohexylmethane.

[0021] Furthermore, in the vacuum rectification process, the pressure is 0.1-0.2 MPa, and the fraction product at 180-190°C is collected to obtain the 4,4-diisocyanatodicyclohexylmethane.

[0022] Further, in the vacuum distillation process, the pressure is 0.15 MPa, and the fraction product at 185 °C is collected to obtain the 4,4-diisocyanatodicyclohexylmethane.

[0023] The present invention also provides an injection reactor, comprising: an internal feed pipe, an external feed pipe coaxial with the internal feed pipe, and an annular space defined between the two feed pipes. Wherein, the connection between the external feed pipe and the internal feed pipe is a liquid one-way valve, the upstream of the internal feed pipe is coaxially connected with a liquid one-way valve, and injection holes are formed on the wall of the upstream part of the internal feed pipe.

[0024] The beneficial effects of the present invention are as follows:

[0025] 1. The reaction conditions of this invention are mild, the reaction process is strengthened, and the reaction efficiency is increased; precise feeding of materials is achieved, the selectivity of the reaction is improved, and the occurrence of side reactions is reduced; through the post-treatment of vacuum distillation, high-purity 4,4-diisocyanatodicyclohexylmethane can be obtained.

[0026] 2. The injection reactor adopted in the present invention has good mixing effect, reduces backmixing phenomenon, and the materials are sprayed evenly, quickly and efficiently. The continuous feeding method by injection 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. Description of the Drawings

[0027] Figure 1 - Longitudinal sectional view of the injection reactor implementation scheme Detailed Embodiments

[0028] The injection reactor used in the embodiment of the present invention was purchased from Wuxi Changqing Chemical Anti-Corrosion Equipment Co., Ltd.

[0029] Example 1:

[0030] A method for preparing 4,4-diisocyanatodicyclohexylmethane based on an injection reactor comprises the following steps:

[0031] (1) 4,4′-Diaminodicyclohexylmethane (HMDA) is dissolved in chlorobenzene to obtain a substrate solution with a concentration of 12 wt%. The substrate solution is first preheated to 18 °C by a preheater A, and phosgene is mixed with chlorobenzene to obtain a substrate solution with a concentration of 35 wt%.

[0032] (2) When the substrate solution reaches the temperature, the substrate solution and the phosgene solution are respectively fed into the injection reactor at a feeding speed of 40 L / h through flow meters, heated to 120 °C for pyrolysis, and reacted for 1 - 3 hours.

[0033] (3) After the reaction is completed, it is cooled to 30 °C to obtain a solution of 4,4-diisocyanatodicyclohexylmethane. Then, it is subjected to vacuum distillation to collect the fraction product at 185 °C / 0.15 MPa for analysis. The conversion rate of HMDA is 100%, and the product selectivity is 99.5%.

[0034] Example 2:

[0035] A method for preparing 4,4-diisocyanatodicyclohexylmethane based on a jet reactor, the steps are as follows:

[0036] (1) Dissolve 4,4'-diaminodicyclohexylmethane (HMDA) in dichlorobenzene to obtain a substrate solution with a concentration of 12 wt%. The substrate solution is first preheated to 18 °C by preheater A. Phosgene is mixed with dichlorobenzene to obtain a substrate solution with a concentration of 35 wt%.

[0037] (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 rate of 40 L / h through flow meters, and are fully mixed, heated to 120 °C for pyrolysis, and the reaction is carried out for 1 - 3 hours.

[0038] (3) After the reaction is completed, it is cooled to 30 °C to obtain a solution of 4,4-diisocyanatodicyclohexylmethane. Then, it is subjected to vacuum distillation to collect the fraction product at 185 °C / 0.15 MPa for analysis. The conversion rate of HMDA is 100%, and the product selectivity is 99.4%.

[0039] Example 3:

[0040] A method for preparing 4,4-diisocyanatodicyclohexylmethane based on a jet reactor, the steps are as follows:

[0041] (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 15 °C by preheater A. Phosgene is mixed with chlorobenzene to obtain a substrate solution with a concentration of 20 wt%.

[0042] (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 rate of 30 L / h through flow meters, and are fully mixed, heated to 100 °C for pyrolysis, and the reaction is carried out for 1 - 3 hours.

[0043] (3) After the reaction is completed, it is cooled to 20 °C to obtain a solution of 4,4-diisocyanatodicyclohexylmethane. Then, it is subjected to vacuum distillation to collect the fraction product at 180 °C / 0.10 MPa for analysis. The conversion rate of HMDA is 100%, and the product selectivity is 99.1%.

[0044] Example 4:

[0045] A method for preparing 4,4'-diisocyanatodicyclohexylmethane based on a jet reactor, the steps are as follows:

[0046] (1) Dissolve 4,4'-diaminodicyclohexylmethane (HMDA) in chlorobenzene and mix to obtain a substrate solution with a concentration of 15 wt%. The substrate solution is first preheated to 20 °C by preheater A. Phosgene and chlorobenzene are mixed to obtain a substrate solution with a concentration of 60 wt%.

[0047] (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 rate of 50 L / h through flow meters, heated to 130 °C for pyrolysis, and reacted for 1 - 3 hours;

[0048] (3) After the reaction is completed, it is cooled to 40 °C to obtain a 4,4'-diisocyanatodicyclohexylmethane solution. Then, it is subjected to vacuum distillation to collect the fraction product at 190 °C / 0.20 MPa for analysis. The conversion rate of HMDA is 100%, and the product selectivity is 99.0%.

[0049] Example 5:

[0050] A method for preparing 4,4'-diisocyanatodicyclohexylmethane based on a jet reactor, the steps are as follows:

[0051] (1) Dissolve 4,4'-diaminodicyclohexylmethane (HMDA) in chlorobenzene and mix to obtain a substrate solution with a concentration of 5 wt%. The substrate solution is first preheated to 12 °C by preheater A. Phosgene and chlorobenzene are mixed to obtain a substrate solution with a concentration of 15 wt%.

[0052] (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 rate of 20 L / h through flow meters, heated to 90 °C for pyrolysis, and reacted for 1 - 3 hours;

[0053] (3) After the reaction is completed, it is cooled to 15 °C to obtain a 4,4'-diisocyanatodicyclohexylmethane solution. Then, it is subjected to vacuum distillation to collect the fraction product at 170 °C / 0.05 MPa for analysis. The conversion rate of HMDA is 97%, and the product selectivity is 96.3%.

[0054] Example 6:

[0055] A method for preparing 4,4'-diisocyanatodicyclohexylmethane based on a jet reactor, the steps are as follows:

[0056] (1) Dissolve 4,4'-diaminodicyclohexylmethane (HMDA) in chlorobenzene and mix to obtain a substrate solution with a concentration of 20 wt%. The substrate solution is first preheated to 25 °C by preheater A. Phosgene and chlorobenzene are mixed to obtain a substrate solution with a concentration of 65 wt%.

[0057] (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, heated to 135 °C for pyrolysis, and reacted for 1 to 3 hours;

[0058] (3) After the reaction is completed, it is cooled to 45 °C to obtain a solution of 4,4-diisocyanatodicyclohexylmethane. Then, vacuum distillation is carried out to collect the fraction product at 200 °C / 0.25 MPa for analysis. The conversion rate of HMDA is 96%, and the product selectivity is 95.7%.

[0059] Although the specific implementation manners of the present invention are 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 solutions of the present invention, various modifications or deformations 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 jet reactor, characterized in that, The reaction formula is as follows: It includes the following steps: (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; (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; (3) After the reaction is completed, after controlling the temperature and cooling, a 4,4-diisocyanatodicyclohexylmethane solution is obtained, and then post-treatment is carried out to obtain the product.

2. The method for preparing 4,4'-diisocyanatodicyclohexylmethane based on a jet 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, diphenyl ether, preferably one or more of chlorobenzene and dichlorobenzene.

3. The method for preparing 4,4'-diisocyanatodicyclohexylmethane based on a jet reactor according to claim 1, wherein The preheating temperature of preheater A described in step (1) is 15-20 °C; preferably 18 °C.

4. A method for preparing 4,4 - diisocyanatodicyclohexylmethane based on a jet reactor according to claim 1, characterized in that, The heating temperature described in step (2) is 100-130 °C; preferably 120 °C.

5. A method for preparing 4,4'-diisocyanatodicyclohexylmethane based on a jet reactor according to claim 1, characterized in that, The temperature control and cooling temperature described in step (3) is 20-40 °C; preferably 30 °C.

6. A method for preparing 4,4'-diisocyanatodicyclohexylmethane based on a jet reactor according to claim 1, characterized in that, The mass concentration of 4,4'-diaminodicyclohexylmethane in the substrate solution described in step (1) is 10 wt%-15 wt%, preferably 12 wt%; the mass concentration of phosgene in the phosgene solution is 20 wt%-60 wt%, preferably 35 wt%.

7. The method for preparing 4,4-diisocyanate dicyclohexylmethane based on a jet reactor according to claim 1, characterized in that: The feed flow rate of the 4,4'-diaminodicyclohexylmethane solution described in step (2) is 30-50 L / h, preferably 40 L / h, and the feed flow rate of the phosgene solution is 30-50 L / h, preferably 40 L / h.

8. The method for preparing 4,4-diisocyanate dicyclohexylmethane based on a jet reactor according to claim 1, characterized in that: The post-treatment described in step (3) includes the steps of: subjecting the mixed solution to vacuum rectification to obtain 4,4-diisocyanatodicyclohexylmethane.

9. A method for preparing 4,4'-diisocyanatodicyclohexylmethane based on a jet reactor according to claim 8, characterized in that, During the vacuum rectification process, the pressure is 0.1-0.2 MPa, and the fraction product at 180-190 °C is collected to obtain the 4,4-diisocyanatodicyclohexylmethane.

10. A method for preparing 4,4'-diisocyanatodicyclohexylmethane based on a jet reactor, characterized in that, The jet reactor includes: an internal feed pipe, an external feed pipe coaxial with the internal feed pipe, and an annular space defined between the two feed pipes. Among them, the connection between the external feed pipe and the internal feed pipe is a liquid one-way valve, the upstream of the internal feed pipe is coaxially connected with a liquid one-way valve, and spray holes are formed on the wall of the upstream part of the internal feed pipe.

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