CN-117186020-B - Preparation method of pentamethylene diisocyanate trimer

Abstract

The invention relates to the technical field of paint chemical industry, in particular to a preparation method of pentamethylene diisocyanate trimer, which comprises the steps of (1) pre-catalyzing, namely adding an antioxidant and a part of catalyst into pentamethylene diisocyanate, stirring at normal temperature, simultaneously carrying out negative pressure vacuum degassing, (2) self-polymerizing, namely adding the rest catalyst into the degassed monomer dropwise to initiate isocyanate self-polymerization, (3) fixed-point polymerization inhibition intervention, namely adding a small amount of polymerization inhibitor when the reaction reaches a certain specified conversion rate to realize selective inhibition of the polymerization reaction, and (4) stopping the polymerization treatment, namely supplementing the polymerization inhibitor to stop the reaction when the polymerization is stable to the end point, and purifying by a film evaporator and a short-range molecular distiller. The preparation method has the advantages of high catalysis efficiency, stable polymerization and controllable product quality, the content of trimer is higher than 60%, the content of residual monomer is lower than 0.3%, and the preparation method meets the green and environment-friendly requirements.

Inventors

• WANG HUIHUI
• SHI LIPING
• TAN WEIMIN
• WANG YAXIN
• LIU RUI
• CAO YACHENG
• RAO XINGXING
• LUO XINLIANG
• CHEN LI

Assignees

• 中海油常州涂料化工研究院有限公司
• 中海油常州环保涂料有限公司
• 中国海洋石油集团有限公司

Dates

Publication Date

20260512

Application Date

20230923

Claims (6)

1. 1. A preparation method of pentamethylene diisocyanate trimer is characterized in that the preparation method sequentially comprises the following steps of in operation order, (1) Pre-catalysis Under a vacuum environment, adding a catalyst A into the pentamethylene diisocyanate monomer, and fully mixing at normal temperature, wherein the addition amount of the catalyst A is 0.03-0.3% of the mass of the pentamethylene diisocyanate monomer; (2) Self-polymerization reaction Releasing the negative pressure in the step (1), heating the mixed system obtained in the step (1) to an initial reaction temperature of 35-75 ℃ under a protective atmosphere, and continuously and slowly adding a catalyst B into the mixed system to perform self-polymerization reaction; (3) Polymerization inhibition intervention When the isocyanate content in the reaction system of the step (2) reaches 35-55%, or when the temperature of the reaction system of the step (2) exceeds the initial reaction temperature by 5-25 ℃, adding a polymerization inhibitor A into the reaction system, wherein the adding amount of the polymerization inhibitor A is 1/40-1/4 of the sum of the mole numbers of the catalyst A and the catalyst B; (4) Reaction termination When the isocyanate content in the reaction system of the step (3) is reduced to a certain degree, adding a polymerization inhibitor B into the reaction system to terminate the reaction, wherein the addition amount of the polymerization inhibitor B is 1-2 times of the sum of the mole numbers of the catalyst A and the catalyst B, purifying the reaction system after termination to obtain the pentamethylene diisocyanate trimer, In the step (3), the polymerization inhibitor A is one or a combination of a plurality of dibutyl phosphate, monochloroacetic acid, dodecylbenzene sulfonic acid, benzoyl chloride, methane sulfonic acid and p-toluene sulfonic acid, The catalyst B may be the same as or different from the catalyst A, and the polymerization inhibitor B may be the same as or different from the polymerization inhibitor A.
2. 2. The method for preparing a pentamethylene diisocyanate trimer according to claim 1, wherein in the step (1), the catalyst A is added in the form of a diluent, the diluent of the diluent comprises one or more of butyl acetate, ethyl acetate, propylene glycol methyl ether acetate, dimethyl succinate, tetrahydrofuran, diethylene glycol dimethyl ether and xylene, and the mass percentage of the catalyst A in the diluent is 1-20%.
3. 3. The method for preparing a pentamethylene diisocyanate trimer according to claim 1, wherein in the step (1), the antioxidant is added in an amount of 0.05 to 0.5% by mass of the pentamethylene diisocyanate monomer.
4. 4. The method for preparing pentamethylene diisocyanate trimer according to claim 1, wherein in the step (2), the addition amount of the catalyst B is 1/10-1/3 of the mass of the catalyst A, the catalyst B is added dropwise in a state of a diluent, and the diluent is added at a rate of 0.3-3 g/min, wherein the diluent comprises one or more of butyl acetate, ethyl acetate, propylene glycol methyl ether acetate, dimethyl succinate, tetrahydrofuran, diethylene glycol dimethyl ether, xylene, ethanol, n-propanol, isooctanol, n-butanol, ether alcohol, ester alcohol, allyl alcohol, benzyl alcohol and 2-pyrrolidone, and the mass percentage of the catalyst B in the diluent is 5-10%.
5. 5. The method for producing a pentamethylene diisocyanate trimer according to claim 1, wherein in the step (4), after the termination of the reaction, the reaction system is passed through a thin film evaporator and a short path molecular still in this order, and the pentamethylene diisocyanate trimer is collected.
6. 6. The method for producing a pentamethylene diisocyanate trimer according to claim 5, wherein the operation temperature of the thin film evaporator and the short path molecular still are 100 to 200℃and the film scraping rotation speed is 100 to 800rpm, wherein the vacuum absolute pressure of the thin film evaporator is 100 to 1000 Pa and the vacuum absolute pressure of the short path molecular still is 5 to 500 Pa.

Description

Preparation method of pentamethylene diisocyanate trimer Technical Field The invention relates to the technical field of paint chemical industry, in particular to a preparation method of pentamethylene diisocyanate trimer. Background The polyurethane coating has the characteristics of good appearance of a coating film, excellent mechanical property and chemical resistance, is widely applied to coating and protection of woodware, automobiles, buildings, railways and the like, and has wide prospect. The isocyanate curing agent is a key component of polyurethane paint, and the pentamethylene diisocyanate trimer is one of important development directions of the isocyanate curing agent, has an isocyanurate six-membered ring structure, and has good thermal stability and good yellowing resistance. At present, the preparation of pentamethylene diisocyanate trimer has the following problems that 1) a catalyst is not properly selected, a catalysis process is complex, a large amount of catalyst is required to be dripped at a high temperature to initiate polymerization, the catalyst is low in efficiency, the system flies at a temperature, the production process is out of control, 2) the self-polymerization of isocyanate belongs to continuous exothermic reaction, the system is continuously heated, the temperature is required to be monitored manually in real time and is ready for cooling, the process is complicated, 3) when the temperature is lower than the initiation temperature of the catalyst, the self-polymerization of monomers is stopped, the reaction can be continued only by external rapid heating or additional catalyst supplement, the preparation method is low in efficiency and difficult to control, 4) the prepared trimer is low in content under normal monomer conversion rate, or the high-content trimer curing agent is required to be prepared by relying on lower conversion rate, and the production preparation is low in efficiency. Disclosure of Invention In order to solve the technical problems, the invention provides a high-efficiency and stable preparation method of pentamethylene diisocyanate trimer, which sequentially comprises the following steps of: (1) Pre-catalysis Under a vacuum environment, adding a catalyst A into the pentamethylene diisocyanate monomer, and fully mixing at normal temperature, wherein the addition amount of the catalyst A is 0.03-0.3% of the mass of the pentamethylene diisocyanate monomer; (2) Self-polymerization reaction Releasing the negative pressure in the step (1), heating the mixed system obtained in the step (1) to an initial reaction temperature of 35-75 ℃ under a protective atmosphere, and continuously and slowly adding a catalyst B into the mixed system to perform self-polymerization reaction; (3) Polymerization inhibition intervention When the isocyanate content in the reaction system of the step (2) reaches 35-55% or the temperature of the reaction system of the step (2) exceeds the initial reaction temperature by 5-25 ℃, adding a polymerization inhibitor A into the reaction system, wherein the addition amount of the polymerization inhibitor A is 1/40-1/4 of the sum of the mole numbers of the catalyst A and the catalyst B; (4) Reaction termination And (3) when the isocyanate content in the reaction system of the step (3) is reduced to a certain degree, adding a polymerization inhibitor B into the reaction system to terminate the reaction, wherein the addition amount of the polymerization inhibitor B is 1-2 times of the sum of the mole numbers of the catalyst A and the catalyst B, and purifying the reaction system after termination to obtain the pentamethylene diisocyanate trimer. Preferably, in the step (1), the addition amount of the catalyst A is 0.06-0.1% of the mass of the pentamethylene diisocyanate monomer. Preferably, in the step (1), the catalyst A is a quaternary ammonium base and/or a quaternary ammonium salt, wherein the quaternary ammonium base comprises one or a combination of a plurality of tetraethylammonium hydroxide, trimethylhydroxypropyl ammonium hydroxide and benzyltrimethyl ammonium hydroxide, and the quaternary ammonium salt comprises one or a combination of a plurality of N- (2-hydroxypropyl) -N, N, N-trimethyl ammonium-2-ethylhexyl acid salt, N- (2-hydroxypropyl) -N, N, N-trimethyl ammonium-2-formate and N, N, N-tetramethyl ammonium octyl acid salt. In the step (1), the catalyst A is added in a diluent state, wherein the diluent is a solvent inert to isocyanate groups and comprises one or more of butyl acetate, ethyl acetate, propylene glycol methyl ether acetate, dimethyl succinate, tetrahydrofuran, diethylene glycol dimethyl ether and xylene, and the mass percent of the catalyst A in the diluent is 1-20%. In the step (1), an antioxidant which is liquid and/or solid is added in addition to the catalyst A in the pentamethylene diisocyanate monomer, wherein the antioxidant comprises one or more of hindered phenol antioxidants, hindered amine antioxidan