Continuous flow synthesis method of low-volatile vinyl silicone oil

Abstract

The invention relates to the field of synthesis of vinyl silicone oil, and discloses a continuous flow synthesis method of low-volatile vinyl silicone oil, which comprises the following steps: (1) polymerization reaction: by taking octamethylcyclotetrasiloxane and a vinyl end-capping reagent as raw materials, reacting under the action of a phosphazene base catalyst to obtain vinyl silicone oil; carrying out ring-opening polymerization reaction in a stainless steel micro-channel reactor in which a plurality of sections of independent accurate temperature control areas are arranged; the reactor realizes accurate gradient control of the temperature of each temperature control area through an advanced PID (Proportion Integration Differentiation) algorithm, the reaction pressure is maintained at 0.3-1.0 MPa, and the retention time of materials in the reactor is 30-150 seconds; and (2) devolatilization and purification: sequentially feeding the crude product obtained in the step (1) into a combined system consisting of a first-stage film evaporator and a second-stage molecular distiller, and efficiently removing unreacted monomer and cyclosiloxane so as to reduce the volatile matter content of the product. Compared with the prior art, the method has the advantages that accurate process control can be achieved, volatile matter can be efficiently removed, and energy consumption is low.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of vinyl silicone oil synthesis, in particular to a continuous flow synthesis method of low-volatility vinyl silicone oil. BACKGROUND

[0002] Vinyl-terminated dimethyl silicone oil is an important organosilicon material, the molecular chain of which contains a vinyl functional group, can participate in cross-linking and curing through an addition reaction, and is widely used in the fields of semiconductor packaging, photoelectric display, high-temperature heat conduction and the like. High-performance application scenarios have strict requirements on the volatilization content of silicone oil, the residual metal ion content, the uniformity of the molecular weight distribution and the like.

[0003] In the prior art, the production of vinyl silicone oil is mostly implemented through a batch polymerization process, which usually uses an alkaline compound such as potassium hydroxide or sodium hydroxide as a catalyst, and has the problems of low catalyst activity and long polymerization reaction time. The vinyl termination rate of the obtained product is not easy to control, and the residual catalyst leads to a high metal ion content. In order to overcome the defects of the batch process, some technical solutions attempt to use a continuous flow reaction device to carry out silicone oil polymerization. For example, a static mixer, a screw extruder or a fixed bed reactor is used to implement continuous production. These methods improve the production efficiency to a certain extent, but there is still room for improvement in the accuracy of reaction process control, efficient removal of volatilization and system energy consumption. Especially, the prior art has not provided a perfect solution in terms of precise control of the polymerization temperature gradient, ensuring a narrow molecular weight distribution of the product and constructing a low-energy integrated purification system. SUMMARY

[0004] (I) Technical problem solved

[0005] The technical problem to be solved by the application is to provide a continuous flow synthesis method of low-volatility vinyl silicone oil, which can realize accurate process control, efficient removal of volatilization and low energy consumption.

[0006] (II) Technical solution

[0007] To solve the above technical problems, the technical solution provided by the application is as follows: a continuous flow synthesis method of low-volatility vinyl silicone oil, comprising the following steps:

[0008] (1) Polymerization reaction: octamethylcyclotetrasiloxane and a vinyl termination agent are used as raw materials, and an open ring polymerization reaction is carried out in a stainless steel micro-channel reactor with multiple independent and accurate temperature control zones built-in under the action of a phosphazene base catalyst; the reactor realizes gradient accurate control of the temperature of each temperature control zone through an advanced PID algorithm, the reaction pressure is maintained at 0.3-1.0 MPa, the residence time of the material in the reactor is 30-150 seconds, and a vinyl-terminated silicone oil crude product is obtained;

[0009] (2) Deviation purification: The crude product obtained in step (1) is sequentially fed into a combined system consisting of a primary thin-film evaporator and a secondary molecular distillation apparatus to efficiently remove unreacted monomers and cyclic siloxanes, thereby reducing the volatile content of the product.

[0010] (3) Waste heat recovery: The heat carried by the high-temperature distillate generated by the secondary molecular distillation unit is transferred to the material feed end before entering the primary thin film evaporator in step (2) through an integrated high-efficiency waste heat recovery system to preheat the material and reduce the overall energy consumption of the system.

[0011] As an improvement, the vinyl end-capping agent in step (1) is one or more of tetramethyldivinyldisiloxane and vinyl bis-end-capping agent.

[0012] As an improvement, the amount of phosphazene alkaline catalyst added in step (1) is 10 to 500 ppm of the total mass of the raw materials.

[0013] As an improvement, in step (1), the number of multi-segment precise temperature control zones of the microchannel reactor is 3 to 5, and the temperature control accuracy of each temperature control zone is ±0.5℃ achieved by the PID algorithm.

[0014] As an improvement, in step (2), the operating temperature of the first-stage thin-film evaporator is set to 150-220°C and the operating pressure is set to 100-500Pa; the operating temperature of the second-stage molecular distillation unit is set to 200-280°C and the operating pressure is set to 1-50Pa.

[0015] As an improvement, the high-efficiency waste heat recovery system in step (3) is a plate heat exchanger or a spiral plate heat exchanger.

[0016] As an improvement, the method further includes step (4): monitoring the degree of polymerization reaction and vinyl content in real time using an online viscometer and an online spectrometer, and feeding the data back to the control system, and adaptively adjusting the reaction parameters in step (1) using a multivariate statistical prediction model.

[0017] (III) Beneficial Effects

[0018] The advantages of this invention compared to existing technologies are as follows: It employs a phosphazene alkaline catalyst combined with a stainless steel microchannel reactor, utilizing its efficient mass and heat transfer characteristics to complete polymerization within a shorter residence time, which helps reduce side reactions and control the molecular weight distribution of the product. Through the combination of multiple independent temperature control zones and an advanced PID control algorithm, it achieves precise gradient control of the polymerization reaction process, providing conditions for obtaining products with predetermined molecular structures. The two-stage devolatilization process, combining thin-film evaporation and molecular distillation, effectively separates and removes low-molecular-weight volatile components, meeting the requirements for low-volatile products. Detailed Implementation

[0019] The invention will now be described in further detail with reference to specific embodiments, but this should not be construed as limiting the scope of the subject matter of the invention to the following embodiments.

[0020] Example 1

[0021] A continuous flow synthesis method for a low-volatile vinyl silicone oil includes the following steps:

[0022] (1) Polymerization reaction: Using octamethylcyclotetrasiloxane and vinyl end-capping agent as raw materials, ring-opening polymerization reaction was carried out in a stainless steel microchannel reactor with multiple independent and precise temperature control zones under the action of phosphazene alkaline catalyst. The reactor achieved precise gradient control of the temperature of each temperature control zone through an advanced PID algorithm. The reaction pressure was maintained at 0.3 MPa, and the residence time of the material in the reactor was 30 seconds, resulting in crude vinyl-end-capped silicone oil. The vinyl end-capping agent was tetramethyldivinyldisiloxane, and the amount of phosphazene alkaline catalyst added was 10 ppm of the total mass of the raw materials. The microchannel reactor had 3 precise temperature control zones, and the temperature control accuracy of each temperature control zone was ±0.5℃ achieved by the PID algorithm.

[0023] (2) Deviation purification: The crude product obtained in step (1) is sequentially fed into a combined system consisting of a primary thin-film evaporator and a secondary molecular distillation unit to efficiently remove unreacted monomers and cyclic siloxanes, thereby reducing the volatile content of the product. The operating temperature of the primary thin-film evaporator is set to 150°C and the operating pressure is 100Pa; the operating temperature of the secondary molecular distillation unit is set to 200°C and the operating pressure is 1Pa.

[0024] (3) Waste heat recovery: The heat carried by the high-temperature distillate generated by the secondary molecular distillation unit is transferred to the material feed end before entering the primary thin film evaporator in step (2) through an integrated high-efficiency waste heat recovery system to preheat the material and reduce the overall energy consumption of the system. The high-efficiency waste heat recovery system is a plate heat exchanger or a spiral plate heat exchanger.

[0025] (4) The degree of polymerization reaction and vinyl content are monitored in real time by online viscometer and online spectrometer, and the data is fed back to the control system. The reaction parameters in step (1) are adaptively controlled by multivariate statistical prediction model.

[0026] Example 2

[0027] A continuous flow synthesis method for a low-volatile vinyl silicone oil includes the following steps:

[0028] (1) Polymerization reaction: Using octamethylcyclotetrasiloxane and vinyl end-capping agent as raw materials, ring-opening polymerization reaction was carried out in a stainless steel microchannel reactor with multiple independent and precise temperature control zones under the action of phosphazene alkaline catalyst. The reactor achieved precise gradient control of the temperature of each temperature control zone through an advanced PID algorithm. The reaction pressure was maintained at 0.6 MPa, and the residence time of the material in the reactor was 100 seconds, resulting in crude vinyl-terminated silicone oil. The vinyl end-capping agent was tetramethyldivinyldisiloxane and a vinyl dual end-capping agent. The amount of phosphazene alkaline catalyst added was 200 ppm of the total mass of the raw materials. The microchannel reactor had 4 precise temperature control zones, and the temperature control accuracy of each temperature control zone was ±0.5℃ through the PID algorithm.

[0029] (2) Deviation purification: The crude product obtained in step (1) is sequentially fed into a combined system consisting of a primary thin-film evaporator and a secondary molecular distillation unit to efficiently remove unreacted monomers and cyclic siloxanes, thereby reducing the volatile content of the product. The operating temperature of the primary thin-film evaporator is set to 200℃ and the operating pressure is 300Pa; the operating temperature of the secondary molecular distillation unit is set to 250℃ and the operating pressure is 30Pa.

[0030] (3) Waste heat recovery: The heat carried by the high-temperature distillate generated by the secondary molecular distillation unit is transferred to the material feed end before entering the primary thin film evaporator in step (2) through an integrated high-efficiency waste heat recovery system to preheat the material and reduce the overall energy consumption of the system. The high-efficiency waste heat recovery system is a plate heat exchanger or a spiral plate heat exchanger.

[0031] (4) The degree of polymerization reaction and vinyl content are monitored in real time by online viscometer and online spectrometer, and the data is fed back to the control system. The reaction parameters in step (1) are adaptively controlled by multivariate statistical prediction model.

[0032] Example 3

[0033] A continuous flow synthesis method for a low-volatile vinyl silicone oil includes the following steps:

[0034] (1) Polymerization reaction: Using octamethylcyclotetrasiloxane and vinyl end-capping agent as raw materials, ring-opening polymerization reaction was carried out in a stainless steel microchannel reactor with multiple independent and precise temperature control zones under the action of phosphazene alkaline catalyst. The reactor achieved precise gradient control of the temperature of each temperature control zone through an advanced PID algorithm. The reaction pressure was maintained at 1.0 MPa, and the residence time of the material in the reactor was 150 seconds, resulting in crude vinyl-end-capped silicone oil. The vinyl end-capping agent was a vinyl dual-end-capping agent. The amount of phosphazene alkaline catalyst added was 500 ppm of the total mass of the raw materials. The microchannel reactor had 5 precise temperature control zones, and the temperature control accuracy of each temperature control zone was ±0.5℃ achieved by the PID algorithm.

[0035] (2) Deviation purification: The crude product obtained in step (1) is sequentially fed into a combined system consisting of a primary thin-film evaporator and a secondary molecular distillation unit to efficiently remove unreacted monomers and cyclic siloxanes, thereby reducing the volatile content of the product. The operating temperature of the primary thin-film evaporator is set to 220°C and the operating pressure is 500 Pa; the operating temperature of the secondary molecular distillation unit is set to 280°C and the operating pressure is 50 Pa.

[0036] (3) Waste heat recovery: The heat carried by the high-temperature distillate generated by the secondary molecular distillation unit is transferred to the material feed end before entering the primary thin film evaporator in step (2) through an integrated high-efficiency waste heat recovery system to preheat the material and reduce the overall energy consumption of the system. The high-efficiency waste heat recovery system is a plate heat exchanger or a spiral plate heat exchanger.

[0037] (4) The degree of polymerization reaction and vinyl content are monitored in real time by online viscometer and online spectrometer, and the data is fed back to the control system. The reaction parameters in step (1) are adaptively controlled by multivariate statistical prediction model.

[0038] The final vinyl-terminated dimethyl silicone oil has a total volatile content of less than 0.1%, a metal ion residue of less than 10 ppb, and a molecular weight distribution (PDI) of less than 1.3.

[0039] Although embodiments of the present 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 present invention. The scope of the present invention is defined by the appended claims and their equivalents. In short, if those skilled in the art are inspired by these claims and design similar structural methods and embodiments without departing from the inventive spirit of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A continuous flow synthesis method for low-volatile vinyl silicone oil, characterized in that, Includes the following steps: (1) Polymerization reaction: Using octamethylcyclotetrasiloxane and vinyl end-capping agent as raw materials, ring-opening polymerization reaction is carried out in a stainless steel microchannel reactor with multiple independent and precise temperature control zones under the action of phosphazene alkaline catalyst; the reactor achieves precise gradient control of temperature in each temperature control zone through advanced PID algorithm, the reaction pressure is maintained at 0.3-1.0 MPa, the residence time of the material in the reactor is 30-150 seconds, and crude vinyl-end-capped silicone oil is obtained; (2) Deviation purification: The crude product obtained in step (1) is sequentially fed into a combined system consisting of a primary thin-film evaporator and a secondary molecular distillation apparatus to efficiently remove unreacted monomers and cyclic siloxanes, thereby reducing the volatile content of the product. (3) Waste heat recovery: The heat carried by the high-temperature distillate generated by the secondary molecular distillation unit is transferred to the material feed end before entering the primary thin film evaporator in step (2) through an integrated high-efficiency waste heat recovery system to preheat the material and reduce the overall energy consumption of the system.

2. The continuous flow synthesis method for a low-volatile vinyl silicone oil according to claim 1, characterized in that, The vinyl end-capping agent in step (1) is one or more of tetramethyldivinyldisiloxane and vinyl bis-end-capping agent.

3. The continuous flow synthesis method for a low-volatile vinyl silicone oil according to claim 1, characterized in that, In step (1), the amount of phosphazene alkaline catalyst added is 10 to 500 ppm of the total mass of the raw materials.

4. The continuous flow synthesis method for a low-volatile vinyl silicone oil according to claim 1, characterized in that, In step (1), the number of precise temperature control zones in the microchannel reactor is 3 to 5, and the temperature control accuracy of each temperature control zone is ±0.5℃ achieved by the PID algorithm.

5. The continuous flow synthesis method for a low-volatile vinyl silicone oil according to claim 1, characterized in that, In step (2), the operating temperature of the first-stage thin-film evaporator is set to 150-220℃ and the operating pressure is set to 100-500Pa; the operating temperature of the second-stage molecular distillation unit is set to 200-280℃ and the operating pressure is set to 1-50Pa.

6. The continuous flow synthesis method for a low-volatile vinyl silicone oil according to claim 1, characterized in that, The high-efficiency waste heat recovery system in step (3) is a plate heat exchanger or a spiral plate heat exchanger.

7. The continuous flow synthesis method for a low-volatile vinyl silicone oil according to claim 1, characterized in that, The method further includes step (4): monitoring the degree of polymerization reaction and vinyl content in real time using an online viscometer and an online spectrometer, and feeding the data back to the control system, and adaptively adjusting the reaction parameters in step (1) using a multivariate statistical prediction model.

8. The continuous flow synthesis method for a low-volatile vinyl silicone oil according to claim 1, characterized in that, The final vinyl-terminated dimethyl silicone oil has a total volatile content of less than 0.1%, a metal ion residue of less than 10 ppb, and a molecular weight distribution (PDI) of less than 1.3.