Preparation method of dimethyl silicone oil
By using a self-made rutile titanium dioxide catalyst to prepare dimethyl silicone oil at low temperature, the problems of catalyst residue and high energy consumption were solved, and high-purity, low-cost dimethyl silicone oil production was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-08
- Publication Date
- 2026-04-03
AI Technical Summary
Existing methods for preparing dimethyl silicone oil suffer from problems such as catalyst residue and off-odors, resulting in low purity. Furthermore, the high energy consumption and cost of the high-cyclic pyrolysis process limit its application.
A self-made acidic catalyst was prepared using rutile titanium dioxide as raw material. The polymer was generated through vacuum dehydration and catalytic polymerization. Dimethyl silicone oil was then prepared at low temperature. After vacuum removal of low-purity components, the oil was filtered to obtain high-purity silicone oil.
This method improves the purity and added value of dimethyl silicone oil, reduces energy loss and risk, avoids metal salt residue and off-odor, and produces a clear, transparent silicone oil with controllable viscosity, with a yield of up to 90%.
Abstract
Description
Technical Field
[0001] This invention belongs to the field of organic compound preparation technology, and relates to a method for preparing dimethyl silicone oil. Background Technology
[0002] Dimethyl silicone oil is a linear organosilicon polymer with silicon-oxygen bonds as the main chain and methyl groups as the side chains. It has excellent properties such as slipperiness, hydrophobicity, resistance to high and low temperatures, chemical inertness, and electrical insulation. It is widely used in hair and skin care products, defoamers, lubricants, mold release agents, and insulating materials.
[0003] The raw materials for preparing dimethyl silicone oil are generally octamethylcyclotetrasiloxane or DMC (dimethyl carbonate), and the catalysts are generally KOH, TMAH (tetramethylammonium hydroxide), sulfuric acid, etc. However, these catalysts usually have problems such as metal residue and odor, which affect the purity of dimethyl silicone oil.
[0004] Organosilicon high-cyclic compounds are mixtures of large-molecule cyclic compounds produced by the hydrolysis, ring separation, and cyclic distillation of methylchlorosilanes. Examples include decamethylcyclopentasiloxane (D5), dodecylcyclohexasiloxane (D6), and tetradecylcycloheptasiloxane (D7). These high-cyclic mixtures are generally not sold directly but are instead cracked into DMC before being sold. The cracking process of organosilicon high-cyclic compounds is usually carried out under high temperature and pressure with catalysts. Furthermore, organosilicon high-cyclic compounds are difficult to completely crack, and catalysts are prone to deactivation. These factors result in high energy consumption, high cost, and potential hazards during the cracking process, thus limiting the application of organosilicon high-cyclic compounds. Summary of the Invention
[0005] The purpose of this invention is to provide a method for preparing dimethyl silicone oil, so as to solve the problem of low purity of dimethyl silicone oil prepared by existing methods.
[0006] To achieve the above objectives, the present invention adopts the following technical solution: This application provides a method for preparing dimethyl silicone oil, the method comprising: After vacuum dehydration of organosilicon high-cyclic compounds and hexamethyldisiloxane, a catalyst is added, and the polymerization reaction is catalyzed under a nitrogen atmosphere to generate a polymer. The polymer was vacuum-removed of low-component substances and filtered to obtain dimethyl silicone oil.
[0007] The present invention has the following beneficial effects: (1) In this application, high-purity dimethyl silicone oil is prepared by using organosilicon high-cyclic compounds and hexamethyldisiloxane as raw materials, which can improve the application range and added value of organosilicon high-cyclic compounds.
[0008] (2) In this application, an acidic catalyst is prepared using rutile titanium dioxide as raw material. This catalyst enables the preparation of clear, transparent, odorless, and precisely controllable dimethyl silicone oil with a yield of >90% by organosilicon high-cyclic compounds and hexamethyldisiloxane at low temperature. This greatly reduces energy loss and risk, and avoids problems such as metal salt residue, odor, and turbidity, thus improving the quality of dimethyl silicone oil. Detailed Implementation
[0009] This application provides a method for preparing dimethyl silicone oil, the method comprising: S01: After vacuum dehydration of organosilicon high-cyclic compounds and hexamethyldisiloxane, a catalyst is added, and the polymer is catalyzed under a nitrogen atmosphere to generate a polymer.
[0010] Organosilicon high-cyclic compounds and hexamethyldisiloxane are placed in a vacuum distillation apparatus at a mass ratio of (97-99.5):(0.5-3). The apparatus temperature is adjusted to 50-80℃ and the vacuum degree is -0.095MPa for vacuum dehydration to remove water from the organosilicon high-cyclic compounds and hexamethyldisiloxane.
[0011] After vacuum dehydration, the temperature of the organosilicon high-cyclic polymer and hexamethyldisiloxane is raised to 80-90℃, and a catalyst accounting for 0.5-2% of the total mass of the organosilicon high-cyclic polymer and hexamethyldisiloxane is added and stirred for 1-2 hours to ensure thorough mixing of the organosilicon high-cyclic polymer, hexamethyldisiloxane, and catalyst. Under a nitrogen flow rate of 200-500 mL / min, the temperature is raised to 100-120℃ for a catalytic polymerization reaction for 4-6 hours to generate the polymer. During the polymerization reaction, the active silanol salts generated by the ring-opening of the organosilicon high-cyclic polymer continuously attack the rings or segments of hexamethyldisiloxane; simultaneously, the generated linear polymer chains undergo cleavage and rearrangement reactions, eventually reaching system equilibrium, and the viscosity of the silicone oil no longer increases.
[0012] In this application, the method for preparing the catalyst includes: Rutile titanium dioxide was added to water and ultrasonically dispersed. Sodium hydroxide was then added to the uniformly dispersed rutile titanium dioxide, and the mixture was thoroughly mixed. The mixture was then placed in a rotary oven and subjected to a hydrothermal reaction at 150-180℃ for 24-36 hours. After the reaction was completed, the mixture was washed with water until neutral, and then centrifuged to obtain the solid.
[0013] Dilute nitric acid was added to the solid, and the mixture was centrifuged. This mixing and centrifugation were repeated 2-5 times to obtain an H₂TiO₅·H₂O dispersion. This H₂TiO₅·H₂O dispersion was sealed and frozen in a refrigerator for 12-24 hours, then placed in a freeze dryer and freeze-dried at -50 to -80°C for 5-10 hours. After freeze-drying, it was placed in a tube furnace and calcined at 400-500°C for 2-5 hours to obtain the precursor. The calcination process removes water molecules, increases the specific surface area of titanium dioxide, and thus reveals more active sites.
[0014] The precursor was immersed in a 1-3M sulfuric acid solution for 2-5 hours, filtered, and dried at 100-130℃. After drying, it was calcined at 300-500℃ for 2-3 hours to obtain the catalyst.
[0015] S02: The polymer is vacuum-removed of low-component substances and filtered to obtain dimethyl silicone oil.
[0016] The polymer was subjected to vacuum removal of low-boiling components for 2-4 hours at a temperature of 190-220℃ and a vacuum degree of -0.095MPa to remove low-boiling substances from the system. After the low-components were removed, the polymer was filtered through a 200-mesh filter to obtain high-purity dimethyl silicone oil.
[0017] The technical solution of the present invention will be further explained and described below through specific embodiments.
[0018] Example 1 This application provides a method for preparing dimethyl silicone oil, the method comprising: S101: Rutile titanium dioxide is added to water and ultrasonically dispersed. Sodium hydroxide is added to the uniformly dispersed rutile titanium dioxide, and after mixing, it is placed in a rotary oven and hydrothermally reacted at 150-180℃ for 24-36 hours. After the reaction, the mixture is washed with water until neutral, and then centrifuged to obtain a solid. Dilute nitric acid is added to the solid, and after mixing, it is centrifuged. This mixing and centrifugation is repeated 2-5 times to obtain an H2TiO5·H2O dispersion. This H2TiO5·H2O dispersion is sealed and frozen in a refrigerator for 12-24 hours, then placed in a freeze dryer and freeze-dried at -50~-80℃ for 5-10 hours. After freeze-drying, it is placed in a tube furnace and calcined at 400-500℃ for 2-5 hours to obtain the precursor. The precursor is immersed in a 1-3M sulfuric acid solution for 2-5 hours, filtered, and dried at 100-130℃. After drying, the catalyst is calcined at 300-500℃ for 2-3 hours to obtain the catalyst.
[0019] Organosilicon high-cyclic compounds and hexamethyldisiloxane were placed in a vacuum distillation apparatus at a mass ratio of 97:3. The apparatus was heated to 70°C and subjected to a vacuum of -0.095 MPa for dehydration. After vacuum dehydration, the temperature of the organosilicon high-cyclic compounds and hexamethyldisiloxane was raised to 80°C, and a catalyst at 0.5% of the total mass of the organosilicon high-cyclic compounds and hexamethyldisiloxane was added and stirred for 1 hour. Under a nitrogen flow rate of 500 mL / min, the temperature was raised to 100°C for 4 hours to carry out a catalytic polymerization reaction, producing the polymer.
[0020] S102: The polymer was subjected to vacuum removal of low-components for 2 hours at 200℃ and a vacuum degree of -0.095MPa. The polymer after low-component removal was filtered through a 200-mesh filter to obtain dimethyl silicone oil. This dimethyl silicone oil was neutral and had a kinematic viscosity of 180 mmHg. 2 It has a volatile content of 0.015%, a narrow molecular weight distribution, and good performance.
[0021] Example 2 This application provides a method for preparing dimethyl silicone oil, the method comprising: S201: Rutile titanium dioxide is added to water and ultrasonically dispersed. Sodium hydroxide is added to the uniformly dispersed rutile titanium dioxide, and after thorough mixing, it is placed in a rotary oven and hydrothermally reacted at 150-180℃ for 24-36 hours. After the reaction, the mixture is washed with water until neutral, and then centrifuged to obtain a solid. Dilute nitric acid is added to the solid, and after mixing and centrifugation, the mixture is repeatedly mixed and centrifuged 2-5 times to obtain an H2TiO5·H2O dispersion. This H2TiO5·H2O dispersion is sealed and frozen in a refrigerator for 12-24 hours, then placed in a freeze dryer and freeze-dried at -50~-80℃ for 5-10 hours. After freeze-drying, it is placed in a tube furnace and calcined at 400-500℃ for 2-5 hours to obtain the precursor. The precursor is immersed in a 1-3M sulfuric acid solution for 2-5 hours, filtered, and dried at 100-130℃. After drying, the catalyst is calcined at 300-500℃ for 2-3 hours to obtain the catalyst.
[0022] Organosilicon high-cyclic compounds and hexamethyldisiloxane were placed in a vacuum distillation apparatus at a mass ratio of 99.5:0.5. The apparatus was heated to 70°C and subjected to a vacuum of -0.095 MPa for dehydration. After vacuum dehydration, the temperature of the organosilicon high-cyclic compounds and hexamethyldisiloxane was raised to 80°C, and a catalyst accounting for 2% of the total mass of the organosilicon high-cyclic compounds and hexamethyldisiloxane was added and stirred for 1 hour. Under a nitrogen flow rate of 200 mL / min, the temperature was raised to 120°C for 6 hours to carry out a catalytic polymerization reaction, generating the polymer.
[0023] S202: The polymer was subjected to vacuum removal of low-components for 4 hours at a temperature of 190℃ and a vacuum degree of -0.095MPa. The polymer after low-component removal was filtered through a 200-mesh filter to obtain dimethyl silicone oil. This dimethyl silicone oil was neutral and had a kinematic viscosity of 300 mmHg. 2 It has a volatile content of 0.012%, a narrow molecular weight distribution, and good performance.
[0024] Example 3 This application provides a method for preparing dimethyl silicone oil, the method comprising: S301: Rutile titanium dioxide is added to water and ultrasonically dispersed. Sodium hydroxide is added to the uniformly dispersed rutile titanium dioxide, and after thorough mixing, it is placed in a rotary oven and hydrothermally reacted at 150-180℃ for 24-36 hours. After the reaction, the mixture is washed with water until neutral, and then centrifuged to obtain a solid. Dilute nitric acid is added to the solid, and after mixing and centrifugation, the mixture is repeatedly mixed and centrifuged 2-5 times to obtain an H2TiO5·H2O dispersion. This H2TiO5·H2O dispersion is sealed and frozen in a refrigerator for 12-24 hours, then placed in a freeze dryer and freeze-dried at -50~-80℃ for 5-10 hours. After freeze-drying, it is placed in a tube furnace and calcined at 400-500℃ for 2-5 hours to obtain the precursor. The precursor is immersed in a 1-3M sulfuric acid solution for 2-5 hours, filtered, and then dried at 100-130℃. After drying, the catalyst is calcined at 300-500℃ for 2-3 hours to obtain the catalyst.
[0025] Organosilicon high-cyclic compounds and hexamethyldisiloxane were placed in a vacuum distillation apparatus at a mass ratio of 98:2. The apparatus was dehydrated under vacuum at 50°C and -0.095 MPa. After dehydration, the temperature of the organosilicon high-cyclic compounds and hexamethyldisiloxane was raised to 90°C, and a catalyst (1% by mass of the total mass of the organosilicon high-cyclic compounds and hexamethyldisiloxane) was added and stirred for 1.5 h to ensure thorough mixing of the organosilicon high-cyclic compounds, hexamethyldisiloxane, and catalyst. Catalytic polymerization was then carried out at 110°C for 5 h under a nitrogen flow rate of 300 mL / min to generate the polymer.
[0026] S302: The polymer was subjected to vacuum removal of low-components for 2 hours at 220℃ and a vacuum degree of -0.095MPa. The polymer after low-component removal was filtered through a 200-mesh filter to obtain dimethyl silicone oil. This dimethyl silicone oil was neutral and had a kinematic viscosity of 450 mmHg. 2 It has a volatile content of 0.01%, a narrow molecular weight distribution, and good performance.
[0027] Example 4 This application provides a method for preparing dimethyl silicone oil, the method comprising: S401: Rutile titanium dioxide is added to water and ultrasonically dispersed. Sodium hydroxide is added to the uniformly dispersed rutile titanium dioxide, and after thorough mixing, it is placed in a rotary oven and hydrothermally reacted at 150-180℃ for 24-36 hours. After the reaction, the mixture is washed with water until neutral, and then centrifuged to obtain a solid. Dilute nitric acid is added to the solid, and after mixing and centrifugation, the mixture is repeatedly mixed and centrifuged 2-5 times to obtain an H2TiO5·H2O dispersion. This H2TiO5·H2O dispersion is sealed and frozen in a refrigerator for 12-24 hours, then placed in a freeze dryer and freeze-dried at -50~-80℃ for 5-10 hours. After freeze-drying, it is placed in a tube furnace and calcined at 400-500℃ for 2-5 hours to obtain the precursor. The precursor is immersed in a 1-3M sulfuric acid solution for 2-5 hours, filtered, and dried at 100-130℃. After drying, the catalyst is calcined at 300-500℃ for 2-3 hours to obtain the catalyst.
[0028] Organosilicon high-cyclic compounds and hexamethyldisiloxane were placed in a vacuum distillation apparatus at a mass ratio of 99:1. The apparatus was dehydrated under vacuum at 60°C and a vacuum degree of -0.095 MPa. After dehydration, the temperature of the organosilicon high-cyclic compounds and hexamethyldisiloxane was raised to 85°C, and a catalyst at 1.5% of the total mass of the organosilicon high-cyclic compounds and hexamethyldisiloxane was added and stirred for 2 hours. Catalytic polymerization was then carried out at 120°C for 5 hours under a nitrogen flow rate of 400 mL / min to generate the polymer.
[0029] S402: The polymer was subjected to vacuum removal of low-components for 3 hours at a temperature of 210℃ and a vacuum degree of -0.095MPa. The polymer after low-component removal was filtered through a 200-mesh filter to obtain dimethyl silicone oil. This dimethyl silicone oil was neutral and had a kinematic viscosity of 350 mmHg. 2 It has a volatile content of 0.02%, a narrow molecular weight distribution, and good performance.
[0030] Comparative Example 1 This application provides a comparative example of a method for preparing dimethyl silicone oil, the method comprising: D101: Organosilicon high-cyclic compounds and hexamethyldisiloxane were placed in a vacuum distillation apparatus at a mass ratio of 99.5:1.25. The apparatus temperature was adjusted to 70℃ and the vacuum degree to -0.095MPa for vacuum dehydration. After vacuum dehydration, the temperature of the organosilicon high-cyclic compounds and hexamethyldisiloxane was raised to 80℃, and KOH (2% of the total mass of the organosilicon high-cyclic compounds and hexamethyldisiloxane) was added and stirred for 1 hour. Under a nitrogen flow rate of 200 mL / min, the temperature was raised to 150℃ for 6 hours to carry out a catalytic polymerization reaction to generate the polymer.
[0031] D202: 0.15g of phosphoric acid was added to the polymer and stirred for 30min to neutralize KOH and deactivate it. Then, the polymer was vacuum-treated for 4h at 190℃ and -0.095MPa to remove low-components. The polymer after low-component removal was filtered through a 200-mesh filter to obtain dimethyl silicone oil. This dimethyl silicone oil is weakly acidic and has a kinematic viscosity of 180 mmHg. 2 / s, volatile matter 0.12%.
[0032] Compared with Example 2 and Comparative Example 1, when KOH was used as a catalyst, the amount of hexamethyldisiloxane increased by 2.5 times, the polymerization reaction required a high temperature of 150°C, and the metal salts in the silicone oil could not be effectively removed.
[0033] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A method for preparing dimethyl silicone oil, characterized in that, include: After vacuum dehydration of organosilicon high-cyclic compounds and hexamethyldisiloxane, a catalyst is added, and the polymerization reaction is catalyzed under a nitrogen atmosphere to generate a polymer. The polymer was vacuum-removed of low-component substances and filtered to obtain dimethyl silicone oil.
2. The method for preparing dimethyl silicone oil according to claim 1, characterized in that, The method for preparing the catalyst includes: Rutile titanium dioxide was ultrasonically dispersed, and sodium hydroxide was added. The mixture was then subjected to a hydrothermal reaction at 150-180℃ for 24-36 hours. After washing until neutral, a solid was obtained. Dilute nitric acid was added to the solid, and the mixture was then centrifuged, frozen, freeze-dried, and calcined in air to obtain the precursor. The precursor is impregnated in sulfuric acid solution, dried, and calcined to obtain the catalyst.
3. The method for preparing dimethyl silicone oil according to claim 2, characterized in that, The air-firing temperature is 400-500℃ and the time is 2-5 hours; the drying temperature is 100-130℃; and the calcination temperature is 300-500℃ and the time is 2-3 hours.
4. The method for preparing dimethyl silicone oil according to claim 1, characterized in that, The amount of catalyst used is 0.5-2% of the total mass of the organosilicon high-cyclic compound and hexamethyldisiloxane; the mass ratio of the organosilicon high-cyclic compound to hexamethyldisiloxane is (97-99.5):(0.5-3).
5. The method for preparing dimethyl silicone oil according to claim 1, characterized in that, The vacuum dehydration temperature is 50-80℃ and the vacuum degree is -0.095MPa.
6. The method for preparing dimethyl silicone oil according to claim 1, characterized in that, The organosilicon high-cyclic compound, after vacuum dehydration, is heated to 80-90°C and then the catalyst is added.
7. The method for preparing dimethyl silicone oil according to claim 1, characterized in that, The nitrogen flow rate is 200-500 mL / min.
8. The method for preparing dimethyl silicone oil according to claim 1, characterized in that, The polymerization reaction is carried out at a temperature of 100-120℃ for 4-6 hours.
9. The method for preparing dimethyl silicone oil according to claim 1, characterized in that, The vacuum removal of low-grade components is carried out at a temperature of 190-220℃, a vacuum degree of -0.095MPa, and a time of 2-4 hours.