An end-group carbon-functionalized polysiloxane and its preparation method

Abstract

The present application discloses an end-group carbon-functionalized polysiloxane and a preparation method thereof, belonging to the technical field of silicone industry. The preparation method of the end-group carbon-functionalized polysiloxane comprises the following steps: (1) mixing a hydroxyl-terminated polysiloxane, a chlorosilane and an acid-binding agent, and stirring and reacting under nitrogen protection to obtain a reaction solution a; (2) adding an organic solvent to the reaction solution a, stirring evenly, adding an alkali solution, and stirring and reacting until the system is neutral to obtain a reaction solution b; (3) adding a desiccant to the reaction solution b, stirring and drying, and filtering to obtain a reaction solution c; (4) subjecting the reaction solution c to vacuum distillation to recover the solvent, thereby obtaining the end-group carbon-functionalized polysiloxane. The present application uses a chlorosilane to react with a hydroxyl-terminated polysiloxane to prepare the end-group carbon-functionalized polysiloxane. The preparation method is simple, the reaction is economical and efficient, and a completely capped end-group carbon-functionalized polysiloxane can be prepared in large quantities. At the same time, no waste gas or waste water is generated, and it is safe and environmentally friendly.

Description

Technical Field

[0001] The present application relates to a terminal carbon functionalized polysiloxane and a preparation method thereof, and belongs to the technical field of organic silicon industry. Background Art

[0002] Polysiloxane is a polymer containing silicon in its molecular structure and with organic groups attached to the silicon atoms. Therefore, it has the dual characteristics of organic and inorganic materials, and has excellent properties such as high and low temperature resistance, weather resistance, radiation resistance, aging resistance, corrosion resistance, electrical insulation, flame retardancy, hydrophobicity, and physiological inertness. These excellent properties of silicone products are incomparable and irreplaceable by other organic polymer materials, so they are widely used in aerospace, electronics and electrical, light industry, chemical industry, textiles, machinery, construction, transportation, medical care, and daily life.

[0003] By introducing reactive functional groups, such as silane, vinyl, chlorocarbon and other groups, at the end of the polysiloxane molecular chain, it becomes an active polysiloxane, which can be used for copolymerization modification of polymers or preparation of functional materials, greatly broadening the application scenarios of silicone materials.

[0004] At present, the preparation of polysiloxane generally adopts acidic or alkaline catalysts, and in the presence of end-capping agents, the ring bodies such as methyl ring bodies, phenyl ring bodies, trifluoropropyl ring bodies, etc. are homopolymerized or copolymerized to obtain them. Due to the different end-capping agents (such as water, vinyl double end-capping, hydrogen-containing double end-capping), hydroxyl-terminated polysiloxane, vinyl-terminated polysiloxane, and hydrogen-terminated polysiloxane are obtained, and then applied in different fields. However, the end-capping efficiency of the above-mentioned end-capping method depends on the reactivity ratio between the cyclic monomer and the end-capping agent, and the ring-opening activity of the cyclic monomer is affected by the side chain group. When one methyl group in D4 (octamethylcyclotetrasiloxane) is replaced by trifluoropropyl, the polymerization rate of cyclotetrasiloxane is 1.5 times the original; when it is replaced by a phenyl group, it is about 4 times the original; when it is replaced by a γ-cyanopropyl group, it is 440 times the original. Therefore, for methyl polysiloxane, the chain breaking or ring opening activity of the end-capping agent and the cyclic monomer is not much different, and a well-end-capped end-functionalized polysiloxane can be obtained. However, for functional monomers with special functional groups such as phenyl and trifluoropropyl in the side groups, the difference between their ring opening activity and the chain breaking activity of the end-capping agent is large, resulting in low end-capping efficiency. Therefore, the end-capping method of this type of polysiloxane has always been an industry problem. In addition, carbon functional end groups are prone to side reactions, and there are very few types of end-capping agents that can be added during the polymerization process, and only a few end-capping structures can be obtained.

[0005] Chinese patent document CN103642046A discloses a preparation method of vinyl-terminated fluorosilicone oil, which uses hydroxy-terminated fluorosilicone oil or its acetone solution to react with (N,N-dialkylamino) dimethylvinylsilane to prepare a vinyl-terminated fluorosilicone oil. However, the preparation of the above capping agent (N,N-dialkylamino) dimethylvinylsilane is relatively complex and costly, and is not suitable for industrial production. Summary of the Invention

[0006] To solve the above problems, the present application provides a carbon-functionalized polyorganosiloxane with end groups and a preparation method thereof. The carbon-functionalized polyorganosiloxane with end groups is prepared by reacting chlorosilane with hydroxy-terminated polyorganosiloxane. The preparation method is simple, the reaction is economical and efficient, and a carbon-functionalized polyorganosiloxane with completely capped end groups can be prepared in large quantities. At the same time, there is no generation of waste gas and waste water, which is safe and environmentally friendly.

[0007] According to one aspect of the present application, a preparation method of a carbon-functionalized polyorganosiloxane with end groups is provided, including the following steps:

[0008] (1) Mix hydroxy-terminated polyorganosiloxane, chlorosilane, and an acid-binding agent, and stir and react under nitrogen protection to obtain reaction solution a;

[0009] (2) Add an organic solvent to reaction solution a, stir evenly, add an alkali solution, and stir and react until the system is neutral to obtain reaction solution b;

[0010] (3) Add a desiccant to reaction solution b, stir and dry, and filter to obtain reaction solution c;

[0011] (4) Subject reaction solution c to vacuum distillation to recover the solvent and obtain a carbon-functionalized polyorganosiloxane with end groups;

[0012] The structural formula of the chlorosilane is shown in formula (1),

[0013] Formula (1),

[0014] wherein, R3, R4, and R5 are selected from one or more of methyl, ethyl, propyl, butyl, vinyl, allyl, phenyl, hydrogen, chloromethyl, chloropropyl, trifluoropropyl, and perfluorooctyl, and R3, R4, and R5 may be the same or different.

[0015] Specifically, the chlorosilane includes dimethylvinylchlorosilane, dimethylallylchlorosilane, trivinylchlorosilane, dimethylphenylchlorosilane, triphenylchlorosilane, trimethylchlorosilane, triethylchlorosilane, tributylchlorosilane, chloromethyldimethylchlorosilane, chloropropyldimethylchlorosilane, or perfluorooctyldimethylchlorosilane.

[0016] Specifically, the reaction principle is as follows:

[0017]

[0018] Among them, m, n, and x are degrees of polymerization, where m≥0, n≥0, x≥0, and 10≤(m + n + x)≤10000; R1 and R2 are selected from one or more of methyl, ethyl, phenyl, and trifluoropropyl, and R1 and R2 may be the same or different; R3, R4, and R5 are selected from one or several of methyl, ethyl, propyl, butyl, vinyl, allyl, phenyl, hydrogen, chloromethyl, chloropropyl, trifluoropropyl, and perfluorooctyl, and R3, R4, and R5 may be the same or different.

[0019] Optionally, the structural formula of the hydroxyl-terminated polysiloxane is shown in Formula (2).

[0020] Formula (2)

[0021] Among them, m, n, and x are degrees of polymerization, where m≥0, n≥0, x≥0, and 10≤(m + n + x)≤10000; R1 and R2 are selected from one or more of methyl, ethyl, phenyl, and trifluoropropyl, and R1 and R2 may be the same or different.

[0022] Preferably, 40≤(m + n + x)≤5000.

[0023] Optionally, the acid-binding agent is selected from one or several of pyridine, N,N-diisopropylethylamine, 4-dimethylaminopyridine, triethanolamine, triethylamine, potassium carbonate, ammonium carbonate, and sodium carbonate.

[0024] Optionally, the organic solvent is selected from one or several of acetone, dichloromethane, dioxane, tetrahydrofuran, petroleum ether, cyclohexane, and toluene; the alkali solution is selected from one or several of ammonia water, sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, sodium carbonate aqueous solution, and sodium bicarbonate aqueous solution.

[0025] Optionally, the desiccant is selected from one or several of anhydrous calcium chloride, anhydrous magnesium sulfate, anhydrous potassium carbonate, anhydrous magnesium sulfate, anhydrous calcium sulfate, molecular sieve, and anhydrous sodium sulfate.

[0026] Optionally, in step (1), the reaction temperature is 0°C to 100°C, and the reaction time is 0.5 h to 12 h; the mass of the chlorosilane is 0.1% to 50% of the mass of the hydroxyl-terminated polysiloxane; the mass of the acid-binding agent is 10% to 100% of the mass of the chlorosilane.

[0027] Preferably, the mass of the chlorosilane is 0.1% to 10% of the mass of the hydroxyl-terminated polysiloxane, and the mass of the acid-binding agent is 10% to 50% of the mass of the chlorosilane.

[0028] Specifically, when the mass of the chlorosilane is less than 0.1% of the mass of the hydroxyl-terminated polysiloxane, residual hydroxyl groups will be caused, making it difficult to prepare end-capped carbon-functional silicone oil with complete end-capping and good performance. When the mass of the chlorosilane is greater than 50% of the mass of the hydroxyl-terminated polysiloxane, although qualified products can also be prepared, the reaction economy will be greatly reduced.

[0029] Preferably, when (m + n + x) of the hydroxyl-terminated polysiloxane is 40, the minimum dosage of the chlorosilane is 20% of the mass of the hydroxyl-terminated polysiloxane. When (m + n + x) of the hydroxyl-terminated polysiloxane is 5000, the minimum dosage of the chlorosilane is 0.01% of the mass of the hydroxyl-terminated polysiloxane.

[0030] Optionally, in step (2), the stirring reaction time is 0.5 h to 6 h; the mass of the organic solution is 0% to 1000% of the mass of the hydroxyl-terminated polysiloxane; the mass fraction of the alkali solution is 1% to 50%.

[0031] Preferably, the mass of the organic solution is 0% to 200% of the mass of the hydroxyl-terminated polysiloxane; the mass fraction of the alkali solution is 5% to 20%.

[0032] Optionally, in step (3), the stirring and drying time is 1 h to 24 h; the mass of the desiccant is 1% to 500% of the mass of the alkali solution; in step (4), the temperature of the vacuum distillation is 30°C to 150°C, and the time is 1 h to 6 h.

[0033] Preferably, the mass of the desiccant is 20% to 200% of the mass of the alkali solution.

[0034] Specifically, the filtration step in step (3) includes vacuum filtration or pressure filtration.

[0035] Specifically, the solvent recovered in step (4) can be reused.

[0036] According to another aspect of the present application, there is also provided an end-capped carbon-functional polysiloxane prepared by the above preparation method.

[0037] The beneficial effects of the present application include but are not limited to:

[0038] 1. According to the preparation method of the end-capped carbon-functional polysiloxane of the present application, the end-capped carbon-functional polysiloxane is prepared by reacting chlorosilane with hydroxyl-terminated polysiloxane. The preparation method is simple, the reaction is economical and efficient, and end-capped complete end-capped carbon-functional polysiloxane can be prepared in large quantities. At the same time, there is no generation of waste gas and waste water, which is safe and environmentally friendly.

[0039] 2. The preparation method of the end-group carbon-functionalized polysiloxane according to the present application uses simple and readily available raw materials, can be capped quickly and efficiently under mild conditions, has good reaction controllability, and thus forms various end-group carbon-functionalized polysiloxanes. It is particularly suitable for the preparation of end-group carbon-functionalized polysiloxanes with large differences in reaction activities between cyclic monomers such as methylphenyl polysiloxane and methyltrifluoropropyl polysiloxane and capping agents. Moreover, it does not require dry solvents and silicon nitride capping agents with complex preparation processes, greatly reducing production costs and improving production efficiency.

[0040] 3. The preparation method of the end-group carbon-functionalized polysiloxane according to the present application completely hydrolyzes and neutralizes the excess chlorosilane with an alkali solution, avoiding the residue of acids or alkalis and improving the thermal stability of the product. By using a desiccant to adsorb or combine with water, the moisture in the system is removed, causing various salts to precipitate and then filtered out, avoiding the problem of generating a large amount of industrial wastewater through vacuum dehydration or multiple water washes, which is economical and environmentally friendly.

[0041] 4. The end-group carbon-functionalized polysiloxane according to the present application has a low cost, good capping effect, and can be mass-produced to meet industrial production requirements. Description of the Drawings

[0042] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation to the present application. In the drawings:

[0043] Figure 1 It is the thermogravimetric curve of the end-chloropropyl fluorosilicone oil prepared in Example 1 in air.

[0044] Figure 2 It is the 1 HNMR spectrum of the commercially available end-vinyl fluorosilicone oil.

[0045] Figure 3 It is the 1 HNMR spectrum of the end-vinyl fluorosilicone oil prepared in Example 2.

[0046] Figure 4 It is the 29 SiNMR spectrum of the end-vinyl fluorosilicone oil prepared in Example 2.

[0047] Figure 5 It is the 1 HNMR spectrum of the end-trivinyl fluorosilicone oil prepared in Example 3.

[0048] Figure 6 It is the 29 SiNMR spectrum of the end-trivinyl fluorosilicone oil prepared in Example 3.

[0049] Figure 7 1H NMR spectrum of vinyl-terminated methyl side vinyl phenyl silicone oil prepared in Example 5 1 1H NMR spectrum

[0050] Figure 8 1H NMR spectrum of terminal vinyl fluorosilicone oil prepared in Comparative Example 1 1 1H NMR spectrum Detailed implementation manners

[0051] The present application will be described in detail below with reference to the examples, but the present application is not limited to these examples.

[0052] Unless otherwise specified, the raw materials in the examples and comparative examples of the present application are all purchased through commercial channels.

[0053] Unless otherwise specified, the methods used in the examples and comparative examples of the present application are conventional methods in the prior art.

[0054] Example 1

[0055] ⑴ Pour 10 kg of hydroxyl-terminated fluorosilicone oil with a viscosity of 5000 mPa·s into a 30 L reaction kettle. After the temperature in the kettle reaches 0 °C, keep it at a constant temperature. Under nitrogen protection, add 245 g of pyridine, stir mechanically for 20 min, and then add 870 g of chloropropyl dimethyl chlorosilane. Stir and react for 1 h to obtain reaction solution a;

[0056] ⑵ Add 325.6 g of a 25% sodium hydroxide aqueous solution to reaction solution a, stir and react for 0.5 h until the system is neutral to obtain reaction solution b;

[0057] ⑶ Add 1000 g of anhydrous sodium sulfate to reaction solution b, stir and dry for 24 h, and then filter to obtain reaction solution c;

[0058] ⑷ Distill reaction solution c under reduced pressure at 150 °C for 5 h to obtain terminal chloropropyl fluorosilicone oil with a viscosity of 4800 mPa·s.

[0059] The thermogravimetric curve of the terminal chloropropyl fluorosilicone oil prepared in Example 1 in air is as Figure 1 shown. It can be seen from Figure 1 that when the sample weight loss = -4.984%, that is, when the sample weight loss is close to 5%, the temperature is 363.20 °C, indicating that the starting decomposition temperature of this sample is relatively high and it has good thermal stability; when the sample weight loss = -10.006%, that is, when the sample weight loss is close to 10%, the temperature is 401.17 °C; the temperature Tmax of the maximum weight loss rate is 454.02 °C; when the test temperature is 800.44 °C, the sample weight loss = -81.776% and the residual mass is 18.224%, indicating that the silicone oil prepared in Example 1 has good thermal stability.

[0060] Example 2

[0061] (1) Pour 10 kg of hydroxyl-terminated fluorosilicone oil with a viscosity of 20000 mPa·s into a 30 L reaction kettle. After the temperature in the kettle reaches 30 °C, keep it at a constant temperature. Under nitrogen protection, add 45 g of triethylamine, stir mechanically for 30 min, then add 331 g of dimethylvinylchlorosilane, and stir and react for 12 h to obtain reaction solution a.

[0062] (2) Add 500 g of toluene to reaction solution a, stir evenly, then add 1825 g of 20% sodium bicarbonate aqueous solution, stir and react for 0.5 h until the system is neutral to obtain reaction solution b.

[0063] (3) Add 300 g of molecular sieve to reaction solution b, stir and dry for 12 h, then filter to obtain reaction solution c.

[0064] (4) Distill reaction solution c under reduced pressure at 65 °C for 1 h to recover 498 g of toluene, and then distill it under reduced pressure at 150 °C for 3 h to obtain vinyl-terminated fluorosilicone oil with a viscosity of 18000 mPa·s.

[0065] The 1 HNMR spectrum and 29 SiNMR spectrum of the vinyl-terminated fluorosilicone oil prepared in Example 2 are as shown in Figure 3 and Figure 4 shown. It can be seen from Figure 3 and Figure 4 that the prepared vinyl-terminated fluorosilicone oil has good end-capping, and the hydroxyl peak completely disappears; Figure 2 The 1 HNMR spectrum of the commercially available vinyl-terminated fluorosilicone oil is shown in Figure 2 It can be seen that the commercially available vinyl-terminated fluorosilicone oil has an obvious hydroxyl peak and a low vinyl end-capping rate.

[0066] Example 3

[0067] (1) Pour 10 kg of hydroxyl-terminated fluorosilicone oil with a viscosity of 80000 mPa·s into a 30 L reaction kettle. After the temperature in the kettle reaches 80 °C, keep it at a constant temperature. Under nitrogen protection, add 5 g of pyridine, stir mechanically for 30 min, then add 15 g of trivinylchlorosilane, and stir and react for 4 h to obtain reaction solution a.

[0068] (2) Add 20 kg of dioxane to reaction solution a, stir evenly, then add 10 g of ammonia water, stir and react for 2 h until the system is neutral to obtain reaction solution b.

[0069] (3) Add 10 g of anhydrous magnesium sulfate to reaction solution b, stir and dry for 1 h, then filter to obtain reaction solution c.

[0070] ⑷ The reaction solution c was distilled under reduced pressure at 80 °C for 2 h to recover 19995 g of dioxane, and then distilled under reduced pressure at 150 °C for 1 h to obtain terminal trivinyl fluorosilicone oil with a viscosity of 79000 mPa•s.

[0071] The terminal trivinyl fluorosilicone oil prepared in Example 3 1 HNMR spectrum and 29 SiNMR spectrum are as Figure 5 and Figure 6 shown. From Figure 5 and Figure 6 it can be seen that the prepared terminal trivinyl fluorosilicone oil has a good end-capping, the hydroxyl peak completely disappears, and the Si connected to the trivinyl group appears at δ = 25.51, which is different from the δ = 33.69 where the Si connected to the vinyl group in the terminal vinyl silicone oil appears.

[0072] Example 4

[0073] ⑴ Pour 2 kg of terminal hydroxyl dimethyl silicone oil with 4000000 mPa•s into a 30 L reaction kettle, keep the temperature constant after reaching 60 °C in the kettle, add 0.2 g of triethylamine under nitrogen protection, stir mechanically for 30 min, add 2 g of trimethylchlorosilane, and stir and react for 2 h to obtain reaction solution a;

[0074] ⑵ Add 20 kg of tetrahydrofuran to reaction solution a, stir evenly, then add 3.3 g of 1% sodium bicarbonate aqueous solution, stir and react for 0.5 h until the system is neutral to obtain reaction solution b;

[0075] ⑶ Add 16.5 g of anhydrous magnesium sulfate to reaction solution b, stir and dry for 8 h, filter to obtain reaction solution c;

[0076] ⑷ Distill reaction solution c under reduced pressure at room temperature for 2 h to recover 19990 g of tetrahydrofuran, and then distill under reduced pressure at 150 °C for 5 h to obtain methyl-capped polydimethylsiloxane with a viscosity of 4000000 mPa•s.

[0077] Example 5

[0078] ⑴ Pour 10 kg of terminal hydroxyl methyl vinyl phenyl silicone oil (vinyl content 1%, phenyl content 20%) with 10000 mPa•s into a 30 L reaction kettle, keep the temperature constant after reaching 40 °C in the kettle, add 60 g of pyridine under nitrogen protection, stir mechanically for 2 h, add 177 g of dimethylvinylchlorosilane, and stir and react for 8 h to obtain reaction solution a;

[0079] ⑵ Add 1000 g of toluene to reaction solution a, stir evenly, then add 130 g of ammonia water, stir and react for 2 h until the system is neutral to obtain reaction solution b;

[0080] ⑶ Add 100 g of anhydrous calcium chloride to the reaction solution b, stir and dry for 10 h, then filter to obtain the reaction solution c5;

[0081] ⑷ Distill the reaction solution c under reduced pressure at 70 °C for 2 h to recover 999 g of toluene, and then distill it under reduced pressure at 150 °C for 5 h to obtain vinyl-terminated methyl vinyl phenyl silicone oil with a viscosity of 9500 mPa•s.

[0082] Figure 7 For the vinyl-terminated methyl vinyl phenyl silicone oil prepared in Example 5 1 HNMR spectrum, it can be seen that the silicone oil is well terminated.

[0083] Example 6

[0084] ⑴ Pour 10 kg of hydroxyl-terminated fluorosilicone oil with a viscosity of 2000 mPa•s into a 30 L reaction kettle, keep the temperature constant at 50 °C after reaching the temperature in the kettle, add 5000 g of 4-dimethylaminopyridine under nitrogen protection, mechanically stir for 20 min, add 5000 g of trimethylchlorosilane, and stir and react for 18 h to obtain the reaction solution a;

[0085] ⑵ Add 540.6 g of a 50% sodium carbonate aqueous solution to the reaction solution a, stir and react for 6 h until the system is neutral to obtain the reaction solution b;

[0086] ⑶ Add 5.4 g of anhydrous potassium carbonate to the reaction solution b, stir and dry for 15 h, then filter to obtain the reaction solution c;

[0087] ⑷ Distill the reaction solution c under reduced pressure at 150 °C for 4 h to obtain end-methyl fluorosilicone oil with a viscosity of 1900 mPa•s.

[0088] Example 7

[0089] ⑴ Pour 5 kg of hydroxyl-terminated fluorosilicone oil with a viscosity of 60000 mPa•s into a 30 L reaction kettle, keep the temperature constant at 25 °C after reaching the temperature in the kettle, add 250 g of pyridine under nitrogen protection, mechanically stir for 20 min, add 500 g of triethylchlorosilane, and stir and react for 3 h to obtain the reaction solution a;

[0090] ⑵ Add 10 kg of toluene to the reaction solution a, stir evenly, then add 101.9 g of a 20% sodium hydroxide aqueous solution, stir and react for 0.5 h until the system is neutral to obtain the reaction solution b;

[0091] ⑶ Add 204 g of anhydrous sodium sulfate to the reaction solution b, stir and dry for 24 h, then filter to obtain the reaction solution c;

[0092] ⑷ Distill the reaction solution c under reduced pressure at 150 °C for 5 h to obtain end-triethyl fluorosilicone oil with a viscosity of 59500 mPa•s.

[0093] Comparative Example 1

[0094] In Comparative Example 1, vinyl-terminated fluorosilicone oil was prepared by a conventional method. The specific steps are as follows:

[0095] ⑴ Pour 10 kg of trifluoropropyl cyclotrisiloxane and 2.5 g of tetramethylammonium hydroxide into a 30 L reaction kettle, dehydrate under reduced pressure at 40 °C for 1 h, then add 120 g of tetramethyldivinyldisiloxane into the kettle, raise the temperature to 100 °C and keep the temperature constant for 120 min, then raise the temperature to 145 °C and react for 1 h, and then raise the temperature to 180 °C and reduce the pressure for 5 h to remove low boilers, obtaining vinyl-terminated fluorosilicone oil with a viscosity of 15000 mPa•s.

[0096] Figure 8 For the vinyl-terminated fluorosilicone oil prepared in Comparative Example 1 1 HNMR spectrum, as can be seen from Figure 8 it that there is an obvious Si-OH peak in this silicone oil. This is because the chain-breaking of the endblocking agent tetramethyldivinyldisiloxane is more difficult than that of trifluoropropyl cyclotrisiloxane and polyfluorosilicone chain. Therefore, under the reaction conditions, the polymer chain will continuously break to form free radicals. After the polymerization reaction is completed, this part of free radicals will be transformed into Si-OH, resulting in low vinyl endblocking efficiency of the product.

[0097] Comparative Example 2

[0098] ⑴ Pour 10 kg of hydroxy-terminated fluorosilicone oil with a viscosity of 2000 mPa•s into a 30 L reaction kettle, keep the temperature constant after the temperature in the kettle reaches 50 °C, add 50 g of pyridine under nitrogen protection, stir mechanically for 20 min, add 300 g of trimethylchlorosilane, and stir and react for 18 h to obtain reaction solution a;

[0099] ⑵ Add 2000 g of water to reaction solution a, wash and stir for 1 h, then pour out the acid solution, and repeat the above washing operation 8 times until the system is neutral to obtain reaction solution b;

[0100] ⑶ Dehydrate reaction solution b under reduced pressure at 50 °C for 1 h, then raise the temperature to 150 °C and distill under reduced pressure for 4 h to obtain methyl-terminated fluorosilicone oil with a viscosity of 1960 mPa•s.

[0101] Compared with Example 6, the difference in Comparative Example 2 is that in step (2), the residual acid in the polymer is removed by washing with water instead of neutralizing with an alkali solution as in Example 6. The silicone oil prepared by this process still has good end-blocking, but a large amount of sewage is generated during the process, which is not suitable for green production.

[0102] Comparative Example 3

[0103] ⑴ Pour 10 kg of hydroxyl-terminated fluorosilicone oil with a viscosity of 30000 mPa•s into a 30 L reaction kettle. After the temperature in the kettle reaches 60 °C, keep it at a constant temperature. Under nitrogen protection, add 20 g of triethylamine, stir mechanically for 30 min, then add 70 g of dimethylvinylchlorosilane, and stir and react for 2 h to obtain reaction solution a;

[0104] ⑵ Add 500 g of tetrahydrofuran to reaction solution a, stir evenly, then add 200 g of an aqueous sodium bicarbonate solution with a mass fraction of 10%, stir and react for 1 h until the system is neutral to obtain reaction solution b;

[0105] ⑶ Carry out vacuum distillation on reaction solution b at 50 °C to remove tetrahydrofuran and water in the system to obtain reaction solution c9;

[0106] ⑷ Add 500 g of tetrahydrofuran to reaction solution c, stir evenly, and filter to remove the salts in the system to obtain reaction solution d;

[0107] ⑸ Carry out vacuum distillation on reaction solution d at room temperature for 2 h to recover 498 g of tetrahydrofuran, and then carry out vacuum distillation at 150 °C for 5 h to obtain vinyl-terminated fluorosilicone oil with a viscosity of 26500 mPa•s.

[0108] In Comparative Example 3, vacuum distillation is used to remove water and organic solvents in the reaction system, rather than the method of drying and removing water with a desiccant used in the examples of the present application. When using vacuum distillation to remove water and organic solvents in the reaction system, for high-viscosity silicone oil, it is necessary to heat again to reduce the viscosity or add an appropriate amount of solvent to reduce the viscosity during the filtration process to facilitate filtration, and the process is cumbersome.

[0109] As described above, only the embodiments of the present application are mentioned. The protection scope of the present application is not limited by these specific embodiments, but is determined by the claims of the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modifications, equivalent replacements, improvements, etc. made within the technical idea and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a terminal carbon functionalized polysiloxane, characterized in that: The following steps are involved: (1) After mixing terminal hydroxyl polysiloxane, chlorosilane and an acid binding agent, stirring and reacting under nitrogen protection to obtain a reaction solution a; (2) adding an organic solvent to the reaction solution a, stirring evenly, adding an alkali solution, stirring and reacting until the system becomes neutral, and obtaining a reaction solution b; the mass fraction of the alkali solution is 1% to 50%; (3) Add a desiccant to the reaction solution b, stir to dry, and filter to obtain a reaction solution c; (4) subjecting the reaction solution c to reduced pressure distillation to recover the solvent and obtain terminal carbon functionalized polysiloxane; The structural formula of the chlorosilane is shown in formula (1), Formula (1), Wherein, R3, R4, and R5 are selected from one of methyl, ethyl, propyl, butyl, vinyl, allyl, phenyl, hydrogen, chloromethyl, chloropropyl, trifluoropropyl, and perfluorooctyl; R3, R4, and R5 may be the same or different, and at least one of R3, R4, and R5 is one of chloromethyl, chloropropyl, trifluoropropyl, and perfluorooctyl; The mass of the chlorosilane is 0.1% to 50% of the mass of the hydroxyl-terminated polysiloxane; The structural formula of the hydroxy-terminated polysiloxane is shown in formula (2), Formula (2), Wherein, m, n, x are the degree of polymerization, m≥0, n≥0, x≥0, 10≤(m+n+x)≤10000; R1 and R2 are selected from one of methyl, ethyl, phenyl and trifluoropropyl, R1 and R2 may be the same or different, and at least one of R1 and R2 is one of phenyl and trifluoropropyl.

2. The method for preparing a terminal carbon functionalized polysiloxane according to claim 1, characterized in that: The acid binding agent is selected from one or more of pyridine, N,N-diisopropylethylamine, 4-dimethylaminopyridine, triethanolamine, tetrabutylammonium bromide, triethylamine, potassium carbonate, ammonium carbonate and sodium carbonate.

3. The method for preparing a terminal carbon functionalized polysiloxane according to claim 1, characterized in that: The organic solvent is selected from one or more of acetone, dichloromethane, dioxane, tetrahydrofuran, petroleum ether, cyclohexane, and toluene; the alkali solution is selected from one or more of ammonia water, sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, sodium carbonate aqueous solution, and sodium bicarbonate aqueous solution.

4. The method for preparing a terminal carbon functionalized polysiloxane according to claim 1, characterized in that: The desiccant is selected from one or more of anhydrous calcium chloride, anhydrous magnesium sulfate, anhydrous potassium carbonate, anhydrous magnesium sulfate, anhydrous calcium sulfate, molecular sieves, and anhydrous sodium sulfate.

5. The method for preparing a terminal carbon functionalized polysiloxane according to claim 1, characterized in that: In step (1), the reaction temperature is 0°C to 100°C, and the reaction time is 0.5h to 12h; the mass of the acid binding agent is 10% to 100% of the mass of the chlorosilane.

6. The method for preparing a terminal carbon functionalized polysiloxane according to claim 1, characterized in that: In step (2), the stirring reaction time is 0.5h~6h; the mass of the organic solution is 0%~1000% of the mass of the terminal hydroxyl polysiloxane.

7. The method for preparing a terminal carbon functionalized polysiloxane according to claim 1, characterized in that: In step (3), the stirring and drying time is 1 h to 24 h; the mass of the desiccant is 1% to 500% of the mass of the alkali solution; in step (4), the temperature of the reduced pressure distillation is 30° C. to 150° C., and the time is 1 h to 6 h.

8. A terminal carbon functionalized polysiloxane, characterized in that: The method is prepared according to any one of claims 1 to 7.

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