Process method for producing high-purity dimethyl silicone oil by continuous method

Abstract

The invention provides a process method for producing high-purity dimethyl silicone oil by a continuous method, and belongs to the technical field of chemical production processes. Comprising the following steps: S1, continuously conveying octamethylcyclotetrasiloxane (D4) and an end-capping reagent hexamethyldisiloxane (MM) into a reaction kettle according to a certain proportion, wherein the molar ratio of D4 to MM is (10-100): 1; s2, acid clay accounting for 0.5%-5% of the total mass of D4 and MM is added into the reaction kettle to serve as a catalyst; and S3, controlling the temperature of the reaction kettle to be 100-150 DEG C, the pressure to be normal pressure and the reaction time to be 2-6 hours, carrying out ring-opening polymerization reaction, setting a temperature gradient in the reaction kettle, gradually increasing the temperature from the bottom to the top of the reaction kettle, and controlling the temperature difference to be 10-20 DEG C. According to the invention, the problems of low production efficiency, low product purity and high energy consumption in the prior art are solved, efficient and continuous production of dimethyl silicone oil is realized, and the product has excellent properties of high purity and low volatility.

Description

Technical Field

[0001] The present invention provides a process for continuously producing high-purity dimethyl silicone oil, belonging to the technical field of chemical production processes. Background Art

[0002] As an important silicone product, dimethyl silicone oil has excellent high and low temperature resistance, weather resistance, electrical insulation, physiological inertness, etc., and is widely used in many fields such as cosmetics, medicine, food, machinery, and electronics. With the continuous improvement of the quality requirements of dimethyl silicone oil in various industries, the production of high-purity and stable-performance dimethyl silicone oil has become the key to the industry's development.

[0003] Traditional dimethyl silicone oil production processes have problems such as low production efficiency, low product purity, and high energy consumption, and it is difficult to meet the market's demand for high-quality dimethyl silicone oil.

[0004] Therefore, in view of this, research and improvement are carried out on the existing structure, and a process for continuously producing high-purity dimethyl silicone oil is proposed to solve the above existing problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a process for continuously producing high-purity dimethyl silicone oil, so as to solve the problems of low production efficiency, low product purity, and high energy consumption existing in the prior art, realize the efficient and continuous production of dimethyl silicone oil, and the product has excellent properties of high purity and low volatility.

[0006] In order to solve the above problems, the technical solution proposed by the present invention is: a process for continuously producing high-purity dimethyl silicone oil, including the following steps:

[0007] S1. Octamethylcyclotetrasiloxane (D4) and endblocker hexamethyldisiloxane (MM) are continuously fed into a reaction kettle in a certain proportion, and the molar ratio of D4 to MM is (10 - 100):1;

[0008] S2. Acidic clay accounting for 0.5% - 5% of the total mass of D4 and MM is added as a catalyst in the reaction kettle;

[0009] S3. The temperature of the reaction kettle is controlled at 100 - 150°C, the pressure is normal pressure, the reaction time is 2 - 6 hours, and ring-opening polymerization reaction is carried out. A temperature gradient is set in the reaction kettle, and the temperature gradually increases from the bottom to the top of the reaction kettle, and the temperature difference is controlled at 10 - 20°C.

[0010] Furthermore, D4 and MM are continuously fed by metering pumps, and the flow accuracy of the metering pumps is controlled within ±0.5%. Before adding the catalyst, D4 and MM are dehydrated to make their water content lower than 50 ppm.

[0011] Further, in step S3, a jacketed reactor with a stirring device is used. The stirring speed is 100 - 300 r / min. During the reaction process, the temperature, pressure, and reactant concentration inside the reactor are monitored in real time by an on-line monitoring device, and the reaction conditions are automatically adjusted according to the monitoring results.

[0012] Further, after the reaction in step S3 is completed, the reaction product is continuously transported to a filtering device with a filtering precision of 1 - 5 μm to remove the catalyst. A continuous plate-and-frame filter press is used as the filtering device, and the pressure filtration pressure is 0.2 - 0.5 MPa.

[0013] Further, the continuous plate-and-frame filter press performs a low-boiling substance removal treatment on the filtered product. The low-boiling substance removal is carried out in a thin-film evaporator. The operating temperature of the thin-film evaporator is 150 - 200 °C, and the vacuum degree is 0.1 - 1 kPa.

[0014] Further, during the low-boiling substance removal treatment, a two-stage condensation system is used to recover the evaporated low-boiling substances. The temperature of the first-stage condensation is 50 - 80 °C, and the temperature of the second-stage condensation is -20 - 0 °C.

[0015] Further, the product after the low-boiling substance removal treatment is continuously transported to an adsorption tower. The adsorption tower is filled with a mixed adsorbent of activated alumina and activated carbon, and the mass ratio of activated alumina to activated carbon is (1 - 3):1.

[0016] Further, the operating temperature of the adsorption tower is 20 - 50 °C. The residence time of the product in the adsorption tower is 0.5 - 2 hours. The adsorbed product is refined through an ion-exchange resin column filled with strongly acidic cation-exchange resin and strongly basic anion-exchange resin. The tail gas generated during the production process is treated by an activated carbon adsorption device. The kinematic viscosity of the obtained high-purity dimethyl silicone oil is in the range of 20 - 1000 mm 2 / s (25 °C), the volatile content is less than 0.5%, and the purity is higher than 99%. The recovered low-boiling substances are subjected to rectification treatment. The number of theoretical plates of the rectification column is 20 - 30, and the reflux ratio is 3 - 5. The recovered D4 and MM are reused for production.

[0017] Further, the operating temperature of the ion-exchange resin column is 20 - 40 °C, and the flow rate of the product in the ion-exchange resin column is 1 - 5 BV / h.

[0018] Due to the adoption of the above technical solutions, the beneficial effects of the process method for continuously producing high-purity dimethyl silicone oil of the present invention are as follows:

[0019] 1. The present invention realizes the continuous transportation of raw materials and the continuous operation of each process through a metering pump, greatly improving the production efficiency. Compared with traditional batch production, the production cycle is significantly shortened.

[0020] 2. The present invention can effectively remove impurities and produce high-purity dimethyl silicone oil with a kinematic viscosity in the range of 20 - 1000 mm 2 / s (at 25°C), a volatile content of less than 0.5%, and a purity higher than 99% by strictly controlling the reaction conditions, precise raw material ratio, and multi-stage post-treatment processes for the product, including filtration, removal of low-boiling substances, adsorption, and purification with ion exchange resin, meeting the strict requirements of the high-end market for product quality.

[0021] 3. The present invention sets a temperature gradient in the reaction kettle, makes full use of the reaction heat, and reduces energy consumption; recovers and rectifies the low-boiling substances, reuses the recovered raw materials for production, improves the utilization rate of raw materials, reduces production costs, and conforms to the production concept of green environmental protection.

[0022] 4. During the reaction process, the present invention uses an on-line monitoring device to monitor the reaction parameters in real time and automatically adjusts the reaction conditions to ensure the stability of the reaction process, thereby guaranteeing the consistency and stability of product quality. Specific Embodiments

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0024] Example 1

[0025] Raw Material Preparation: Octamethylcyclotetrasiloxane (D4) and endblocker hexamethyldisiloxane (MM) are continuously fed into the reaction kettle by a metering pump at a molar ratio of 20:1 with a flow accuracy of ±0.5%. Before feeding, D4 and MM are dehydrated to make their water content less than 50 ppm.

[0026] Catalyst Addition: Acidic clay accounting for 1% of the total mass of D4 and MM is added to the reaction kettle as a catalyst.

[0027] Reaction Process: Control the temperature of the reaction kettle at 120°C, the pressure at atmospheric pressure, and the reaction time at 3 hours. The reaction kettle is a jacketed reaction kettle with a stirring device, and the stirring speed is 150 r / min. A temperature gradient is set in the reaction kettle, and the temperature gradually increases from the bottom to the top of the reaction kettle, with the temperature difference controlled at 15°C. The temperature, pressure, and reactant concentration in the reaction kettle are monitored in real time by an on-line monitoring device, and the reaction conditions are automatically adjusted according to the monitoring results.

[0028] Product post-treatment: After the reaction is completed, the reaction product is continuously conveyed to a continuous plate-and-frame filter press with a filtration accuracy of 3 μm, and the pressure filtration pressure is 0.3 MPa to remove the catalyst. The filtered product is subjected to low-boiling substance removal treatment in a thin-film evaporator. The operating temperature of the thin-film evaporator is 170 °C, and the vacuum degree is 0.5 kPa. A two-stage condensation system is used to recover the distilled low-boiling substances. The primary condensation temperature is 60 °C, and the secondary condensation temperature is -10 °C. The product after low-boiling substance removal treatment is continuously conveyed to an adsorption tower filled with a mixed adsorbent with a mass ratio of activated alumina to activated carbon of 2:1. The operating temperature of the adsorption tower is 30 °C, and the residence time of the product in the adsorption tower is 1 hour. The adsorbed product is refined through an ion exchange resin column filled with strongly acidic cation exchange resin and strongly basic anion exchange resin. The operating temperature of the ion exchange resin column is 30 °C, and the flow rate of the product in the ion exchange resin column is 3 BV / h. The tail gas generated during the production process is treated through an activated carbon adsorption device. After detection, the kinematic viscosity of the obtained high-purity dimethyl silicone oil is 100 mm 2 / s (25 °C), the volatile content is 0.3%, and the purity is 99.2%. The recovered low-boiling substances are subjected to rectification treatment. The number of theoretical plates of the rectification column is 25, and the reflux ratio is 4. The recovered D4 and MM are reused for production.

[0029] Example 2

[0030] Raw material preparation: Octamethylcyclotetrasiloxane (D4) and the endblocking agent hexamethyldisiloxane (MM) are continuously conveyed to the reaction kettle through a metering pump at a flow rate with an accuracy of ±0.5% according to a molar ratio of 50:1. Before conveying, D4 and MM are dehydrated to make their moisture content lower than 50 ppm.

[0031] Catalyst addition: Acidic clay accounting for 3% of the total mass of D4 and MM is added to the reaction kettle as a catalyst.

[0032] Reaction process: Control the temperature of the reaction kettle at 130 °C, the pressure at atmospheric pressure, and the reaction time at 4 hours. The reaction kettle is a jacketed reaction kettle with a stirring device, and the stirring speed is 200 r / min. A temperature gradient is set in the reaction kettle, and the temperature gradually increases from the bottom to the top of the reaction kettle, with the temperature difference controlled at 12 °C. The temperature, pressure, and reactant concentration in the reaction kettle are monitored in real time through an on-line monitoring device, and the reaction conditions are automatically adjusted according to the monitoring results.

[0033] Product post-treatment: After the reaction is completed, the reaction product is continuously transported to a continuous plate and frame filter press with a filtration accuracy of 2 μm, and the filtration pressure is 0.4 MPa to remove the catalyst. The filtered product is subjected to low-boiling substance removal treatment in a thin-film evaporator. The operating temperature of the thin-film evaporator is 180 °C, and the vacuum degree is 0.3 kPa. A two-stage condensation system is used to recover the distilled low-boiling substances. The primary condensation temperature is 70 °C, and the secondary condensation temperature is -5 °C. The product after low-boiling substance removal treatment is continuously transported to an adsorption tower filled with a mixed adsorbent with a mass ratio of activated alumina to activated carbon of 1:1. The operating temperature of the adsorption tower is 40 °C, and the residence time of the product in the adsorption tower is 1.5 hours. The adsorbed product is refined through an ion exchange resin column filled with strongly acidic cation exchange resin and strongly basic anion exchange resin. The operating temperature of the ion exchange resin column is 35 °C, and the flow rate of the product in the ion exchange resin column is 2 BV / h. The tail gas generated during the production process is treated through an activated carbon adsorption device. After detection, the kinematic viscosity of the obtained high-purity dimethyl silicone oil is 300 mm 2 / s (25 °C), the volatile content is 0.2%, and the purity is 99.5%. The recovered low-boiling substances are subjected to rectification treatment. The number of theoretical plates in the rectification column is 28, and the reflux ratio is 3.5. The recovered D4 and MM are reused for production.

[0034] Example 3

[0035] Raw material preparation: Octamethylcyclotetrasiloxane (D4) and endblocker hexamethyldisiloxane (MM) are continuously transported to the reaction kettle through a metering pump at a flow rate with an accuracy of ±0.5% according to a molar ratio of 80:1. Before transportation, D4 and MM are dehydrated to make their moisture content lower than 50 ppm.

[0036] Catalyst addition: Acidic clay accounting for 2% of the total mass of D4 and MM is added to the reaction kettle as a catalyst.

[0037] Reaction process: The temperature of the reaction kettle is controlled at 140 °C, the pressure is normal pressure, and the reaction time is 5 hours. The reaction kettle is a jacketed reaction kettle with a stirring device, and the stirring speed is 250 r / min. A temperature gradient is set in the reaction kettle, and the temperature gradually increases from the bottom to the top of the reaction kettle, with the temperature difference controlled at 18 °C. The temperature, pressure, and reactant concentration in the reaction kettle are monitored in real time through an on-line monitoring device, and the reaction conditions are automatically adjusted according to the monitoring results.

[0038] Product post-treatment: After the reaction is completed, the reaction product is continuously conveyed to a continuous plate and frame filter press with a filtration accuracy of 1 μm, and the pressure filtration pressure is 0.2 MPa to remove the catalyst. The filtered product is subjected to low-boiling substance removal treatment in a thin-film evaporator. The operating temperature of the thin-film evaporator is 190 °C, and the vacuum degree is 0.2 kPa. A two-stage condensation system is used to recover the distilled low-boiling substances. The primary condensation temperature is 55 °C, and the secondary condensation temperature is -15 °C. The product after low-boiling substance removal treatment is continuously conveyed to an adsorption tower. The adsorption tower is filled with a mixed adsorbent with a mass ratio of activated alumina to activated carbon of 3:1. The operating temperature of the adsorption tower is 25 °C, and the residence time of the product in the adsorption tower is 0.8 hours. The adsorbed product is refined through an ion exchange resin column. The ion exchange resin column is filled with strongly acidic cation exchange resin and strongly basic anion exchange resin. The operating temperature of the ion exchange resin column is 25 °C, and the flow rate of the product in the ion exchange resin column is 4 BV / h. The tail gas generated during the production process is treated through an activated carbon adsorption device. After testing, the kinematic viscosity of the obtained high-purity dimethyl silicone oil is 500 mm 2 / s (25 °C), the volatile content is 0.1%, and the purity is 99.8%. The recovered low-boiling substances are subjected to rectification treatment. The number of theoretical plates of the rectification column is 30, and the reflux ratio is 5. The recovered D4 and MM are reused for production.

[0039] As can be seen from the above examples, the process method for continuously producing high-purity dimethyl silicone oil of the present invention can stably produce dimethyl silicone oil products with high purity and low volatility, and has good application prospects.

[0040] The above describes the present invention and its implementation manners. This description is not restrictive. Generally speaking, if those of ordinary skill in the art are inspired by it and, without departing from the purpose of the present invention, design similar structural manners and embodiments to this technical solution without creative efforts, they shall fall within the protection scope of the present invention.

Claims

1. A process for continuously producing high-purity dimethyl silicone oil, characterized in that: The following steps are involved: S1, octamethylcyclotetrasiloxane (D4) and end-capping agent hexamethyldisiloxane (MM) are continuously delivered to the reaction kettle in a certain ratio, and the molar ratio of D4 to MM is (10-100):1; S2, adding 0.5%-5% of the total mass of D4 and MM into the reactor as a catalyst; S3. Control the temperature of the reactor at 100-150°C, the pressure at normal pressure, the reaction time at 2-6 hours, and carry out a ring-opening polymerization reaction. Set a temperature gradient in the reactor, gradually increase the temperature from the bottom to the top of the reactor, and control the temperature difference at 10-20°C.

2. A process for continuously producing high-purity dimethyl silicone oil according to claim 1, characterized in that: The D4 and MM are continuously delivered by a metering pump, and the flow accuracy of the metering pump is controlled within ±0.5%. Before adding the catalyst, the D4 and MM are dehydrated to make the moisture content less than 50ppm.

3. A process for continuously producing high-purity dimethyl silicone oil according to claim 1, characterized in that: In step S3, the reactor is a jacketed reactor with a stirring device, and the stirring speed is 100-300 r / min. During the reaction process, the temperature, pressure and reactant concentration in the reactor are monitored in real time by an online monitoring device, and the reaction conditions are automatically adjusted according to the monitoring results.

4. A process for continuously producing high-purity dimethyl silicone oil according to claim 1, characterized in that: After the reaction in step S3 is completed, the reaction product is continuously transported to a filtering device with a filtering accuracy of 1-5 μm to remove the catalyst. The filtering device adopts a continuous plate and frame filter press with a filtering pressure of 0.2-0.5 MPa.

5. A process for continuously producing high-purity dimethyl silicone oil according to claim 1, characterized in that: The continuous plate-and-frame filter press removes low-boiling substances from the filtered product. The removal of low-boiling substances is carried out in a thin film evaporator. The operating temperature of the thin film evaporator is 150-200° C. and the vacuum degree is 0.1-1 kPa.

6. The process for continuously producing high-purity dimethyl silicone oil according to claim 1, characterized in that: In the process of removing low-boiling-point substances, a two-stage condensation system is used to recover the evaporated low-boiling-point substances, the first-stage condensation temperature is 50-80°C, and the second-stage condensation temperature is -20-0°C.

7. The process for continuously producing high-purity dimethyl silicone oil according to claim 1, characterized in that: The product after the low-boiling-point removal treatment is continuously transported to an adsorption tower, and the adsorption tower is filled with a mixed adsorbent of activated alumina and activated carbon, and the mass ratio of activated alumina to activated carbon is (1-3):

1.

8. The process for continuously producing high-purity dimethyl silicone oil according to claim 1, characterized in that: The operating temperature of the adsorption tower is 20-50°C, the residence time of the product in the adsorption tower is 0.5-2 hours, the adsorbed product is refined by an ion exchange resin column, the ion exchange resin column is filled with a strong acid cation exchange resin and a strong basic anion exchange resin, the tail gas generated during the production process is treated by an activated carbon adsorption device, and the kinematic viscosity of the obtained high-purity dimethyl silicone oil is 20-1000mm 2 / s (25 ℃) range, the volatile content is less than 0.5%, the purity is higher than 99%, the recovered low-boiling materials are distilled, the theoretical number of plates of the distillation tower is 20-30, the reflux ratio is 3-5, and the recovered D4 and MM are reused in production.

9. The process for continuously producing high-purity dimethyl silicone oil according to claim 1, characterized in that: The operating temperature of the ion exchange resin column is 20-40° C., and the flow rate of the product in the ion exchange resin column is 1-5 BV / h.