A method for producing high quality dimethicone

Abstract

The application provides a method for preparing dimethyl silicone oil, which comprises mixing low-molecular-weight hydroxyl-terminated polydimethylsiloxane, a methyl end-capping agent, a polycondensation telomerization agent and a phosphorus nitride catalyst, and sequentially performing normal-pressure polycondensation telomerization and negative-pressure polycondensation telomerization to obtain dimethyl silicone oil. The polycondensation telomerization agent added in the preparation method can effectively control the polycondensation rate, and dimethyl silicone oil with different viscosities can be prepared, while the viscosity peak caused by polycondensation is avoided, and the advantage is more obvious, especially for high-viscosity products. The dimethyl silicone oil prepared by the preparation method has the advantages of low ring content, especially low content of large-ring by-products, and low metal ion content, so that the application scenarios are wider. In addition, the polycondensation time of the preparation method is short, the quality is improved, the production capacity is improved, and the requirement for equipment is low.

Description

Technical Field

[0001] This invention belongs to the field of organosilicon, specifically relating to a method for preparing high-quality dimethyl silicone oil by short-path polycondensation using a batch reactor. Background Technology

[0002] Organosilicon is a fine chemical with a wide variety of products. Due to its excellent properties such as high and low temperature resistance, oxidation resistance, radiation resistance, good dielectric properties, flame retardancy, water repellency, release properties, low temperature viscosity coefficient, non-toxicity, odorlessness, and physiological inertness, it is widely used in various fields such as construction, textiles, electronics, and personal care, and is also known as "industrial MSG".

[0003] Organosilicon refers to compounds containing Si-C bonds, with at least one organic substituent directly bonded to a silicon atom. The Si-O-Si bond is the basic structural unit constituting polyorganosiloxanes, with a bond energy as high as 1014 kJ / mol, a large bond angle, and excellent thermal stability. The Si-C bond is the foundation and characteristic of organosilicon compounds; introducing Si-C bonds into the Si-O-Si chain endows organosilicon compounds with organic properties.

[0004] From 1898 to 1944, British chemist F.S. Kipping conducted extensive research on organosilicon chemistry, synthesizing hydrolyzable silanes of varying functionalities using the Grignard reaction, laying the industrial foundation for the future development of organosilicon. Organosilicon products can be broadly categorized into upstream and downstream products based on their applications and position in the product chain. Upstream products include chlorosilane monomers and primary polysiloxane intermediates, while downstream products mainly involve the further processing of primary polysiloxane intermediates into organosilicon products and finished products. Organosilicon intermediates are direct raw materials for the synthesis of silicone rubber, silicone oil, and silicone resins, including linear or cyclic siloxane oligomers such as hexamethyldisiloxane (MM), hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), and dimethylcyclosiloxane mixtures (DMC). Silicone oil is a chain-like polyorganosiloxane liquid oil with varying degrees of polymerization, mainly including dimethyl silicone oil, vinyl silicone oil, hydrogen-containing silicone oil, hydroxyl silicone oil, and phenyl silicone oil. Among them, dimethyl silicone oil is currently the most common, widely used, and most widely applied product, and it is extensively used in defoaming, mold release, lubrication, dielectric fluids, daily cosmetic additives, textile finishing, and electronic appliances.

[0005] Currently, the industrial synthesis of silicone oil is mainly a batch process, using octamethylcyclotetrasiloxane (D4) or a mixture of dimethylcyclosiloxanes (DMC), or organosilicon hydrolysates or linear forms, and methyl end-capping agents in the presence of potassium hydroxide or tetramethylammonium hydroxide and their silanoses to prepare polydimethylsiloxane products. This process does not require sophisticated synthesis equipment, but because the catalyst is an equilibrium catalyst during the catalytic process, there is a process of cracking into cyclosiloxanes during the formation of chain-like polysiloxane products. The crude product after polymerization contains approximately 15% cyclosiloxanes. The resulting macrocyclic siloxanes have high boiling points and are difficult to remove from the system, requiring sophisticated removal equipment and failing to meet the export requirements of some high-end applications, such as lubrication in the power industry, dielectric fluids in the electronics industry, and export requirements (D4 / D5 / D6 content ≤1000ppm) in daily cosmetics and textiles. Furthermore, potassium hydroxide catalyst systems suffer from the inability to separate potassium ions from the system, making them unsuitable for certain specialized applications. Tetramethylammonium hydroxide catalyst systems present odor problems, and the deactivation of tetramethylammonium hydroxide catalysts generates toxic and harmful small molecules such as trimethylamine, a problem currently unresolved in industry. Phosphazene catalysts, on the other hand, effectively address these issues. Their structural characteristics endow them with high catalytic activity, and their large size inhibits the binding between active anions and counterions during chain growth, improving chain reactivity. However, while suppressing loop side reactions, they also increase the difficulty of controlling the polymerization reaction.

[0006] The paper "Kinetics and mechanism of oligosiloxanol condensation and oligosiloxane rearrangement catalyzed with model phosphonitrile chloride catalysts" presents the kinetics and mechanism of oligosiloxane condensation and rearrangement catalyzed by model phosphonitrile chloride catalysts. "Research Progress of Phosphonitrile Catalysts" points out that the polymerization activity of phosphonitrile catalysts is more than 400 times that of KOH, making their polymerization control very difficult. In the process of preparing high-molecular-weight silicone oil using low-molecular-weight hydroxyl-terminated polydimethylsiloxane as a raw material, short-term condensation polymerization occurs, leading to viscosity peaks. The difference between the end-capping rate and the condensation rate is significant, resulting in high requirements for the stirring motor during polymerization and rearrangement, increasing the difficulty of its industrial application.

[0007] CN115676785A discloses a method for preparing silicone oil by first using a conventional catalyst to prepare hydroxyl-terminated polydimethylsiloxanes with a viscosity of 60,000 to 100,000 mPa·s, and then adding a phosphazene catalyst and a capping agent. While this method avoids the uncontrollable polymerization and viscosity peaks, it also introduces metal ions during the preparation of high-molecular-weight hydroxyl-terminated polydimethylsiloxanes. Furthermore, the high molecular weight hydroxyl-terminated polydimethylsiloxanes obtained in this process determine the quality of the subsequent silicone oil product.

[0008] CN117024744A discloses a method for preparing novel silicone oil using cyclosiloxane as a raw material and linear phosphazene catalyst. Although this method uses cyclosiloxane, which is more expensive, as a raw material to avoid the uncontrollability of polycondensation, the opening of the four siloxane chains after the ring of cyclosiloxane is completed still increases the probability of its rearrangement back into the ring. Summary of the Invention

[0009] In view of this, the purpose of this invention is to address the shortcomings of the prior art and, by utilizing existing industrial batch reactor production equipment, provide a method for preparing high-quality dimethyl silicone oil through short-path condensation polymerization in a batch reactor. The dimethyl silicone oil prepared by the method of this invention has the following characteristics: (1) low cyclic content, meeting the SVHC requirements for D4 / D5 / D6, and low content of macrocyclic byproducts; (2) low metal ion content, making it suitable for a wider range of applications; (3) the added condensation regulator can effectively control the condensation rate, resulting in a wide viscosity window for the prepared dimethyl silicone oil (i.e., methyl silicone oils of different viscosities can be prepared), and a viscosity of less than 50 mm² can be synthesized. 2 / s of dimethyl silicone oil, while avoiding the viscosity peak of polycondensation, especially for high viscosity products, this advantage is more obvious; (4) The method of the present invention prepares dimethyl silicone oil with short polycondensation time and only requires micro-devouring, which achieves the goal of quality improvement and also increases production capacity, and does not have high requirements for equipment.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] A method for preparing dimethyl silicone oil includes: mixing a low molecular weight hydroxyl-terminated polydimethylsiloxane, a methyl end-capping agent, a polycondensation tuner and a phosphazene catalyst, and sequentially subjecting the mixture to a normal compression tuner reaction and a negative compression tuner reaction to obtain dimethyl silicone oil.

[0012] The structural formula of low molecular weight hydroxyl-terminated polydimethylsiloxane is: n represents the degree of polymerization, and its viscosity is 40-120 mm. 2 / s, for example 80-100mm 2 / s.

[0013] The structural formula of the methyl end-capping agent is: m represents the degree of polymerization, and its viscosity ranges from 1.5 to 50 mm. 2 / s, for example, 1.5-20mm 2 / s.

[0014] In some embodiments of the present invention, the mass ratio of low molecular weight hydroxyl-terminated polydimethylsiloxane to methyl-terminant is (40-150):1.

[0015] The polymerization regulator is one or a mixture of two or more of the following: dimethyldimethoxysilane, dimethylmethoxyethoxysilane, dimethyldiethoxysilane, low molecular weight monomethoxy-terminated polysiloxane, and low molecular weight monoethoxy-terminated polysiloxane; the structural formula of the low molecular weight monomethoxy-terminated polysiloxane is as follows: x represents the degree of polymerization, and its viscosity ranges from 5 to 100 mm. 2 / s, for example, 5-50mm 2 / s. The structural formula of low molecular weight monoethoxylated end-capped polysiloxanes is: y represents the degree of polymerization, and its viscosity ranges from 5 to 100 mm. 2 / s, for example, 5-50mm 2 / s. Preferably, the amount of polycondensation regulator added is 2-40% of the total mass of the low molecular weight hydroxyl-terminated polydimethylsiloxane and the methyl terminator, more preferably 5-25%.

[0016] According to the present invention, the phosphazene catalyst includes phosphazene acid catalysts and phosphazene base catalysts. Among them, the phosphazene acid catalysts include, but are not limited to, [Cl3PNPCl3]. + PCl6, [Cl3PNPCl3] + SbCl6, [Cl3PNP(OEt)Cl2] + PCl6, [Cl3PNP(OEt)Cl2] + SbCl6, [Cl2(OEt)PNP(OEt)Cl2] + PCl6, [Cl2(OEt)PNP(OEt)Cl2] +SbCl6, Cl3PNP(O)Cl2, Cl2(EtO)PNP(O)Cl2, or polymers of the aforementioned linear phosphazene acids, wherein the polymers are 2-6 polymers. Phosphazene acid catalysts can be used directly, or supported on zeolite, clay, or other supporting materials to form supported catalysts, or used to form complexed catalysts with complexes such as EDTA. Phosphazene base catalysts include, but are not limited to, linear phosphazene base catalysts and their polymers with the following structural formulas, wherein the polymers are 2-6 polymers, preferably 2-3 polymers. Phosphazene base catalysts can be used directly, or supported on zeolite, clay, or other supporting materials to form supported catalysts, or used to form complexed catalysts with complexes such as EDTA.

[0017]

[0018] Among them, R1-R 45 Independently selected from H, C 1-4 Alkyl, C 3-6 Cycloalkyl, phenyl, such as: hydrogen, methyl, ethyl, propyl, butyl, cyclopentyl, cyclohexyl or phenyl.

[0019] Phosphazene catalysts can be used directly or dissolved in organic solvents such as benzene, toluene, xylene, ethyl acetate, tetrahydrofuran, n-hexane, and petroleum ether.

[0020] Preferably, the amount of phosphazene catalyst added is 0.001-0.005% of the total material mass, where the total material mass refers to the sum of the mass of low molecular weight hydroxyl-terminated polydimethylsiloxane, methyl end-capping agent and polycondensation regulator.

[0021] The normal compression polymerization is carried out at a temperature of 50-150℃ for a reaction time of 0.5-2 hours. During the reaction, no gas is introduced or an inert gas such as nitrogen is introduced.

[0022] The negative compression polymerization is carried out at a temperature of 50-150℃ and a negative pressure of -60kPa to -99kPa (gauge pressure), with a reaction time of 0.5-2h. During the reaction, no gas is introduced or an inert gas such as nitrogen is introduced.

[0023] The inventors of this invention discovered in their research that by introducing an inert gas during the polycondensation and telogenization process using the preparation method of this invention, the hydroxyl value of the product can be further reduced. Therefore, in a more preferred embodiment, an inert gas is introduced during the polycondensation and telogenization process.

[0024] This invention further discloses a method for preparing dimethyl silicone oil, comprising the following steps:

[0025] S1. In the reaction apparatus, low molecular weight hydroxyl-terminated polydimethylsiloxane and methyl-termining agent are mixed and dehydrated for 0.5-2 hours at 50-150℃ and -90kPa to -100kPa (gauge pressure).

[0026] S2. After dehydration, adjust the pressure of the reaction device to atmospheric pressure, add polycondensation regulator and phosphazene catalyst at a temperature of 50-150℃, and introduce nitrogen gas to carry out atmospheric compression polycondensation reaction for 0.5-1h.

[0027] S3. Adjust the pressure of the reaction device to -60kPa to -99kPa (gauge pressure) negative pressure conditions, and introduce nitrogen gas to carry out negative compression polymerization reaction at a temperature of 50-150℃. The reaction time is 0.5-2h to obtain crude product of dimethyl silicone oil polymerization.

[0028] S4. The crude product obtained in the previous step is post-processed (e.g., through a neutralization step and / or a micro-devouring step) to obtain the dimethyl silicone oil product.

[0029] Preferably, in step S1, the dehydration operation is carried out at 50-95℃ and -90kPa to -100kPa (gauge pressure) for 0.5-1h.

[0030] Preferably, in step S2, the amount of polycondensation regulator added is 2-40% of the total mass of the low molecular weight hydroxyl-terminated polydimethylsiloxane and the methyl terminator, and more preferably 5-25%.

[0031] Preferably, in step S2, the nitrogen flow rate is 1.9-9.5 m / s. 3 / h.

[0032] Preferably, in step S2, the polycondensation reaction temperature is 50-95℃.

[0033] Preferably, in step S3, the nitrogen flow rate is 1.9-6.5 m / s. 3 / h.

[0034] Preferably, in step S3, the polycondensation reaction temperature is 50-95℃.

[0035] In step S4, the neutralization step involves adding a neutralizing agent to neutralize the phosphazene catalyst. When using a phosphazene acid catalyst, an organic weak base is used as the neutralizing agent; when using a phosphazene base catalyst, an inorganic weak acid or an organic weak acid is used as the neutralizing agent. The inorganic weak acid or organic weak acid can be selected from one or more combinations of oxalic acid, sulfurous acid, phosphoric acid, silicone phosphate, benzoic acid, acetic acid, propionic acid, stearic acid, or citric acid. The organic weak base is selected from one or more combinations of silazane (e.g., hexamethyldisilazane), pyridine, tri-n-propylamine, or tri-n-butylamine. The amount of neutralizing agent added is adjusted according to the amount of phosphazene catalyst used, for example, 0.002-0.010% (calculated based on the total material mass). The neutralization step is preferably carried out at 50-150°C under normal pressure for 1-3 hours.

[0036] The micro-volatilization step refers to the removal of volatiles under conditions of -90kPa to -99kPa (gauge pressure) and 130-180℃ for a duration of 0.5-4h.

[0037] Furthermore, step S4 is a post-processing step and is not mandatory. Of course, a product lacking step S4 is a crude product.

[0038] In one embodiment of the present invention, the reaction apparatus used in the preparation method is a batch reactor.

[0039] In this invention, the viscosity is tested according to the capillary method in GB / T 10247-2008, using a Ping viscometer at 25°C.

[0040] definition:

[0041] Gauge pressure refers to pressure measurement based on atmospheric pressure. Its output signal is the difference between atmospheric pressure and the measured pressure, i.e.: Gauge pressure = Absolute pressure - Standard atmospheric pressure. In the vacuum industry, gauge pressure is expressed as a negative number, representing the difference between the measured gas pressure and atmospheric pressure, also called negative pressure. For example, -90 kPa indicates that the absolute pressure is standard atmospheric pressure minus 90 kPa. Unless otherwise specified, the pressure values ​​in this invention are gauge pressures.

[0042] Micro-devolatilization: In this invention, it refers to the operation of removing low-volatility substances at a short time and low temperature.

[0043] Polymer: Same meaning as "polymer".

[0044] Complex catalysts: macromolecules that exhibit catalytic activity through coordination. Detailed Implementation

[0045] The raw materials involved in the embodiments include:

[0046] Low molecular weight hydroxyl-terminated polydimethylsiloxane, viscosity approximately 90 mm. 2 / s, volatile matter ≤0.5%, Jiangxi Lanxing Xinghuo Organosilicon Co., Ltd.;

[0047] DM5 methyl end-capping agent, viscosity approximately 5 mm 2 / s, volatile matter ≤0.3%, Jiangxi Lanxing Xinghuo Organosilicon Co., Ltd., referred to as "DM5" in the following text;

[0048] Phosphanic acid catalyst, Jiangxi Lanxing Xinghuo Organosilicon Co., Ltd.;

[0049] Toluene, a reagent from China National Pharmaceutical Group.

[0050] Ethyl acetate, Guangdong Guanghua Technology Co., Ltd.;

[0051] Silicon phosphate ester, also known as acid gum used in the organosilicon industry, is obtained by reacting phosphoric acid with DMC / D4. Jiangxi Lanxing Xinghuo Organosilicon Co., Ltd.

[0052] Phosphazene alkaline catalyst, Jiangxi Lanxing Xinghuo Organosilicon Co., Ltd.;

[0053] Hexamethyldisilazane, Jiangxi Lanxing Xinghuo Organosilicon Co., Ltd., hereinafter referred to as "silazane";

[0054] If the reagents or instruments used do not specify the manufacturer, they can be purchased through legitimate channels.

[0055] The testing method in this embodiment is as follows:

[0056] Hydroxyl value test method: Performed according to the method described in Chinese patent CN 112730321B.

[0057] Volatile matter test method:

[0058] The volatile matter was measured using the oven drying method. Specifically, 2g of sample was weighed and dried at 150℃ for 2 hours. The weight of the sample before and after drying was measured, and the volatile matter was calculated using the formula: Volatile matter = (m0-m1) / m0×100%, where m0 is the weight of the sample before drying and m1 is the weight of the sample after drying.

[0059] Methods for testing cyclic content:

[0060] The content of organosilicon cyclic compounds was determined by GC-FID chromatography using the internal standard method and calculated according to the following formula I: W i =F i ×A2 / m, W i F represents the mass fraction of organosilicon cyclic compounds, in μg / g. iA represents the correction factor for organosilicon rings; A2 represents the peak area of ​​organosilicon rings in the sample; m represents the sample mass, in g.

[0061] Metal ion testing methods:

[0062] ICP-MS Analysis: The conventional ICP-MS quantitative analysis method is used. The sample is digested and then a standard curve is generated using standard solutions for quantitative detection.

[0063] Example 1

[0064] 778 g of low molecular weight hydroxyl-terminated polydimethylsiloxane and 18 g of DM5 were added to a 1000 ml reactor. The mixture was heated to 75 °C and dehydrated at -90 kPa for 1 h. After dehydration, the pressure in the reactor was adjusted to atmospheric pressure. Then, under atmospheric pressure, 40.9 g of dimethyldimethoxysilane (5.14%) was added, followed by 10 ppm of [Cl3PNPCl3]. + PCl6 catalyst, then adjust the nitrogen flow rate to 2m 3 After performing a short-range polycondensation reaction for 0.5 hours, the nitrogen flow rate is maintained at 2 m / h. 3 At a flow rate of / h, the vacuum was adjusted to -90kPa within 20 minutes, and the polycondensation reaction was carried out for 1.5 hours to obtain a polymer sample (i.e., crude product). The hydroxyl value, volatile matter, viscosity, and cyclic content of the polymer sample were tested, and the maximum torque of the reactor, the time to reach the maximum torque, experimental phenomena, and low boiling point were recorded. After polymerization, 20ppm of silazane was added for neutralization for 2 hours. After neutralization, the crude dimethyl silicone oil was subjected to micro-deglossing at -99kPa and 150℃ for 3 hours to obtain high-quality dimethyl silicone oil, and its hydroxyl value, volatile matter, viscosity, and cyclic content were tested.

[0065] Example 2

[0066] 778 g of low molecular weight hydroxyl-terminated polydimethylsiloxane and 13.4 g of DM5 were added to a 1000 ml reactor. The mixture was heated to 60 °C and dehydrated at -90 kPa for 1 h. After dehydration, the pressure in the reactor was adjusted to atmospheric pressure. Then, under atmospheric pressure, 40.67 g of dimethylmethoxyethoxysilane (5.14%) was added, followed by 15 ppm of [Cl3PNP(OEt)Cl2]. + PCl6 catalyst, then adjust the nitrogen flow rate to 2m 3 After performing a short-range polycondensation reaction for 0.5 hours, the nitrogen flow rate is maintained at 2 m / h. 3At a flow rate of / h, the vacuum was adjusted to -90kPa within 20 minutes, and the polycondensation reaction was carried out for 1.5 hours to obtain a polymer sample. The hydroxyl value, volatile matter, viscosity, and cyclic content of the polymer sample were tested, and the maximum torque of the reactor, the time to reach the maximum torque, experimental phenomena, and low boiling point were recorded. After polymerization, 20ppm of silazane was added for neutralization for 2 hours. After neutralization, the crude dimethyl silicone oil was subjected to micro-deglossing at -99kPa and 150℃ for 3 hours to obtain high-quality dimethyl silicone oil, and its hydroxyl value, volatile matter, viscosity, and cyclic content were tested.

[0067] Example 3

[0068] 778 g of low molecular weight hydroxyl-terminated polydimethylsiloxane and 13.4 g of DM5 were added to a 1000 ml reactor. The temperature was raised to 60 °C, and dehydration was carried out at -90 kPa for 1 h. After dehydration, the pressure in the reactor was adjusted to atmospheric pressure. Then, 40.67 g of dimethylmethoxyethoxysilane (5.14%) was added under atmospheric pressure, followed by 15 ppm of a phosphazene base catalyst of formula (1), R1-R8 = CH2CH3. The nitrogen flow rate was then adjusted to 2 m. 3 After performing a short-range polycondensation reaction for 0.5 hours, the nitrogen flow rate is maintained at 2 m / h. 3 At a flow rate of / h, the vacuum was adjusted to -90kPa within 20 minutes, and the polycondensation reaction was carried out for 1.5 hours to obtain a polymer sample. The hydroxyl value, volatile matter, viscosity, and cyclic content of the polymer sample were tested, and the maximum torque of the reactor, the time to reach the maximum torque, experimental phenomena, and low boiling point were recorded. After polymerization, 20ppm of phosphate silicate was added for neutralization for 2 hours. After neutralization, the crude dimethyl silicone oil product was subjected to micro-deglossing at -99kPa and 150℃ for 3 hours to obtain high-quality dimethyl silicone oil, and its hydroxyl value, volatile matter, viscosity, and cyclic content were tested.

[0069] Example 4

[0070] 778 g of low molecular weight hydroxyl-terminated polydimethylsiloxane was added to a 1000 ml reactor, followed by 13.4 g of DM5. The temperature was raised to 60 °C, and dehydration was carried out at -90 kPa for 1 h. After dehydration, the pressure in the reactor was adjusted to atmospheric pressure. Then, under atmospheric pressure, 40.67 g of dimethylmethoxyethoxysilane (5.14%) was added, followed by 15 ppm of formula (2), R9-R 14 =CH3 phosphazene alkaline catalyst, then adjust the nitrogen flow rate to 2m 3 After performing a short-range polycondensation reaction for 0.5 hours, the nitrogen flow rate is maintained at 2 m / h. 3At a flow rate of / h, the vacuum was adjusted to -90kPa within 20 minutes, and the polycondensation reaction was carried out for 1.5 hours to obtain a polymer sample. The hydroxyl value, volatile matter, and viscosity of the polymer sample were tested, and the maximum torque of the reactor, the time to reach the maximum torque, experimental phenomena, and low boiling point were recorded. After polymerization, 20ppm of phosphate silicate was added for neutralization for 2 hours. After neutralization, the crude dimethyl silicone oil product was subjected to micro-deglossing at -99kPa and 150℃ for 3 hours to obtain high-quality dimethyl silicone oil, and its hydroxyl value, volatile matter, and viscosity were tested.

[0071] Example 5

[0072] 778 g of low molecular weight hydroxyl-terminated polydimethylsiloxane and 6.17 g of DM5 were added to a 1000 ml reactor. The mixture was heated to 60 °C and dehydrated at -90 kPa for 1 h. After dehydration, the pressure in the reactor was adjusted to atmospheric pressure. Then, under atmospheric pressure, 40.31 g of dimethylmethoxyethoxysilane (5.14%) was added, followed by 15 ppm of [Cl3PNP(OEt)Cl2]. + PCl6 catalyst, then adjust the nitrogen flow rate to 2m 3 After performing a short-range polycondensation reaction for 0.5 hours, the nitrogen flow rate is maintained at 2 m / h. 3 At a flow rate of / h, the vacuum was adjusted to -90kPa within 20 minutes, and the polycondensation reaction was carried out for 1.5 hours to obtain a polymer sample. The hydroxyl value, volatile matter, and viscosity of the polymer sample were tested, and the maximum torque of the reactor, the time to reach the maximum torque, experimental phenomena, and low boiling point were recorded. After polymerization, 20ppm of silazane was added for neutralization for 2 hours. After neutralization, the crude dimethyl silicone oil product was subjected to micro-deglossing at -99kPa and 150℃ for 3 hours to obtain high-quality dimethyl silicone oil, and its hydroxyl value, volatile matter, and viscosity were tested.

[0073] Example 6

[0074] 778 g of low molecular weight hydroxyl-terminated polydimethylsiloxane and 5.40 g of DM5 were added to a 1000 ml reactor. The mixture was heated to 60 °C and dehydrated at -90 kPa for 1 h. After dehydration, the pressure in the reactor was adjusted to atmospheric pressure. Then, under atmospheric pressure, 40.27 g of dimethylmethoxyethoxysilane (5.14%) was added, followed by 15 ppm of [Cl3PNP(OEt)Cl2]. + PCl6 catalyst, then adjust the nitrogen flow rate to 2m 3 After performing a short-range polycondensation reaction for 0.5 hours, the nitrogen flow rate is maintained at 2 m / h. 3At a flow rate of / h, the vacuum was adjusted to -90kPa within 20 minutes, and the polycondensation reaction was carried out for 1.5 hours to obtain a polymer sample. The hydroxyl value, volatile matter, and viscosity of the polymer sample were tested, and the maximum torque of the reactor, the time to reach the maximum torque, experimental phenomena, and low boiling point were recorded. After polymerization, 20ppm of silazane was added for neutralization for 2 hours. After neutralization, the crude dimethyl silicone oil product was subjected to micro-deglossing at -99kPa and 150℃ for 3 hours to obtain high-quality dimethyl silicone oil, and its hydroxyl value, volatile matter, and viscosity were tested.

[0075] Example 7

[0076] 778 g of low molecular weight hydroxyl-terminated polydimethylsiloxane and 5.40 g of DM5 were added to a 1000 ml reactor. The mixture was heated to 60 °C and dehydrated at -90 kPa for 1 h. After dehydration, the pressure in the reactor was adjusted to atmospheric pressure. Then, under atmospheric pressure, 40.27 g of dimethylmethoxyethoxysilane (5.14%) was added, followed by 15 ppm of [Cl3PNP(OEt)Cl2]. + PCl6 catalyst, then adjust the nitrogen flow rate to 4m 3 After performing short-range polycondensation and polymerization for 0.5 hours, the nitrogen flow rate is maintained at 4 m / h. 3 At a flow rate of / h, the vacuum was adjusted to -90kPa within 20 minutes, and the polycondensation reaction was carried out for 1.5 hours to obtain a polymer sample. The hydroxyl value, volatile matter, and viscosity of the polymer sample were tested, and the maximum torque of the reactor, the time to reach the maximum torque, experimental phenomena, and low boiling point were recorded. After polymerization, 20ppm of silazane was added for neutralization for 2 hours. After neutralization, the crude dimethyl silicone oil product was subjected to micro-deglossing at -99kPa and 150℃ for 3 hours to obtain high-quality dimethyl silicone oil, and its hydroxyl value, volatile matter, and viscosity were tested.

[0077] Example 8

[0078] 778 g of low molecular weight hydroxyl-terminated polydimethylsiloxane and 5.40 g of DM5 were added to a 1000 ml reactor. The mixture was heated to 60 °C and dehydrated at -90 kPa for 1 h. After dehydration, the pressure in the reactor was adjusted to atmospheric pressure. Then, under atmospheric pressure, 40.27 g of dimethylmethoxyethoxysilane (5.14%) was added, followed by 15 ppm of [Cl3PNP(OEt)Cl2]. + PCl6 catalyst, then adjust the nitrogen flow rate to 8m 3 After performing a short-range polycondensation reaction for 0.5 hours, the nitrogen flow rate is maintained at 5 m / h. 3At a flow rate of / h, the vacuum was adjusted to -90kPa within 20 minutes, and the polycondensation reaction was carried out for 1.5 hours to obtain a polymer sample. The hydroxyl value, volatile matter, and viscosity of the polymer sample were tested, and the maximum torque of the reactor, the time to reach the maximum torque, experimental phenomena, and low boiling point were recorded. After polymerization, 20ppm of silazane was added for neutralization for 2 hours. After neutralization, the crude dimethyl silicone oil product was subjected to micro-deglossing at -99kPa and 150℃ for 3 hours to obtain high-quality dimethyl silicone oil, and its hydroxyl value, volatile matter, and viscosity were tested.

[0079] Example 9

[0080] 778 g of low molecular weight hydroxyl-terminated polydimethylsiloxane and 5.40 g of DM5 were added to a 1000 ml reactor. The mixture was heated to 60 °C and dehydrated at -90 kPa for 1 h. After dehydration, the pressure in the reactor was adjusted to atmospheric pressure. Then, under atmospheric pressure, 40.27 g of dimethylmethoxyethoxysilane (5.14%) was added, followed by 15 ppm of [Cl3PNP(OEt)Cl2]. + PCl6 catalyst, then adjust the nitrogen flow rate to 9m 3 After performing a short-range polycondensation reaction for 0.5 hours, the nitrogen flow rate is maintained at 5 m / h. 3 At a flow rate of / h, the vacuum regulator was brought to -90kPa within 20 minutes, and the condensation and polymerization reaction was carried out for 1.5 hours to obtain a polymer sample. The hydroxyl value, volatile matter, and viscosity of the polymer sample were tested, and the maximum torque of the reactor, the time to reach the maximum torque, experimental phenomena, and low boiling point were recorded. After polymerization, 20ppm of silazane was added for neutralization for 2 hours. After neutralization, the crude dimethyl silicone oil was subjected to micro-deglossing at -99kPa and 150℃ for 3 hours to obtain high-quality dimethyl silicone oil, and its hydroxyl value, volatile matter, and viscosity were tested.

[0081] Example 10

[0082] 778 g of low molecular weight hydroxyl-terminated polydimethylsiloxane and 5.40 g of DM5 were added to a 1000 ml reactor. The mixture was heated to 60 °C and dehydrated at -900 kPa r for 1 h. After dehydration, the pressure in the reactor was adjusted to atmospheric pressure. Then, under atmospheric pressure, 40.27 g of dimethylmethoxyethoxysilane (5.14%) was added, followed by 15 ppm of [Cl3PNP(OEt)Cl2]. + PCl6 catalyst, then adjust the nitrogen flow rate to 9m 3 After performing a short-range polycondensation reaction for 0.5 hours, the nitrogen flow rate is maintained at 6 m / h. 3At a flow rate of / h, the vacuum was slowly lowered to -90kPa within 20 minutes, and the polycondensation reaction was carried out for 1.5 hours to obtain a polymer sample. The hydroxyl value, volatile matter, and viscosity of the polymer sample were tested, and the maximum torque of the reactor, the time to reach the maximum torque, experimental phenomena, and low boiling point were recorded. After polymerization, 20ppm of silazane was added for neutralization for 2 hours. After neutralization, the crude dimethyl silicone oil product was subjected to micro-deglossing at -99kPa and 150℃ for 3 hours to obtain high-quality dimethyl silicone oil, and its hydroxyl value, volatile matter, and viscosity were tested.

[0083] Example 11

[0084] 778 g of low molecular weight hydroxyl-terminated polydimethylsiloxane and 10.1 g of DM5 were added to a 1000 ml reactor. The mixture was heated to 60 °C and dehydrated at -90 kPa for 1 h. After dehydration, the pressure in the reactor was adjusted to atmospheric pressure. Then, under atmospheric pressure, 16.2 g of dimethylmethoxyethoxysilane (2%) was added, followed by 15 ppm of [Cl3PNP(OEt)Cl2]. + PCl6 catalyst, then adjust the nitrogen flow rate to 2m 3 After performing a short-range polycondensation reaction for 0.5 hours, the nitrogen flow rate is maintained at 2 m / h. 3 At a flow rate of / h, the vacuum was adjusted to -90kPa within 20 minutes, and the polycondensation reaction was carried out for 1.5 hours to obtain a polymer sample. The hydroxyl value, volatile matter, and viscosity of the polymer sample were tested, and the maximum torque of the reactor, the time to reach the maximum torque, experimental phenomena, and low boiling point were recorded. After polymerization, 20ppm of silazane was added for neutralization for 2 hours. After neutralization, the crude dimethyl silicone oil product was subjected to micro-deglossing at -99kPa and 150℃ for 3 hours to obtain high-quality dimethyl silicone oil, and its hydroxyl value, volatile matter, and viscosity were tested.

[0085] Example 12

[0086] 778 g of low molecular weight hydroxyl-terminated polydimethylsiloxane and 10.1 g of DM5 were added to a 1000 ml reactor. The mixture was heated to 60 °C and dehydrated at -90 kPa for 1 h. After dehydration, the pressure in the reactor was adjusted to atmospheric pressure. Then, under atmospheric pressure, 40.51 g of dimethylmethoxyethoxysilane (5.14%) was added, followed by 15 ppm of [Cl3PNP(OEt)Cl2]. + PCl6 catalyst, then adjust the nitrogen flow rate to 2m 3 After performing a short-range polycondensation reaction for 0.5 hours, the nitrogen flow rate is maintained at 2 m / h. 3At a flow rate of / h, the vacuum was adjusted to -90kPa within 20 minutes, and the polycondensation reaction was carried out for 1.5 hours to obtain a polymer sample. The hydroxyl value, volatile matter, and viscosity of the polymer sample were tested, and the maximum torque of the reactor, the time to reach the maximum torque, experimental phenomena, and low boiling point were recorded. After polymerization, 20ppm of silazane was added for neutralization for 2 hours. After neutralization, the crude dimethyl silicone oil product was subjected to micro-deglossing at -99kPa and 150℃ for 3 hours to obtain high-quality dimethyl silicone oil, and its hydroxyl value, volatile matter, and viscosity were tested.

[0087] Example 13

[0088] 755 g of low molecular weight hydroxyl-terminated polydimethylsiloxane and 10.1 g of DM5 were added to a 1000 ml reactor. The mixture was heated to 60 °C and dehydrated at -90 kPa for 1 h. After dehydration, the pressure in the reactor was adjusted to atmospheric pressure. Then, 81.02 g of dimethylmethoxyethoxysilane (10.59%) was added under atmospheric pressure, followed by 15 ppm of [Cl3PNP(OEt)Cl2]. + PCl6 catalyst, then adjust the nitrogen flow rate to 2m 3 After performing a short-range polycondensation reaction for 0.5 hours, the nitrogen flow rate is maintained at 2 m / h. 3 At a flow rate of / h, the vacuum was adjusted to -90kPa within 20 minutes, and the polycondensation reaction was carried out for 1.5 hours to obtain a polymer sample. The hydroxyl value, volatile matter, and viscosity of the polymer sample were tested, and the maximum torque of the reactor, the time to reach the maximum torque, experimental phenomena, and low boiling point were recorded. After polymerization, 20ppm of silazane was added for neutralization for 2 hours. After neutralization, the crude dimethyl silicone oil product was subjected to micro-deglossing at -99kPa and 150℃ for 3 hours to obtain high-quality dimethyl silicone oil, and its hydroxyl value, volatile matter, and viscosity were tested.

[0089] Example 14

[0090] 727 g of low molecular weight hydroxyl-terminated polydimethylsiloxane and 10.1 g of DM5 were added to a 1000 ml reactor. The mixture was heated to 60 °C and dehydrated at -90 kPa for 1 h. After dehydration, the pressure in the reactor was adjusted to atmospheric pressure. Then, under atmospheric pressure, 121.53 g of dimethylmethoxyethoxysilane (16.49%) was added, followed by 15 ppm of [Cl3PNP(OEt)Cl2]. + PCl6 catalyst, then adjust the nitrogen flow rate to 2m 3 After performing a short-range polycondensation reaction for 0.5 hours, the nitrogen flow rate is maintained at 2 m / h. 3At a flow rate of / h, the vacuum was adjusted to -90kPa within 20 minutes, and the polycondensation reaction was carried out for 1.5 hours to obtain a polymer sample. The hydroxyl value, volatile matter, and viscosity of the polymer sample were tested, and the maximum torque of the reactor, the time to reach the maximum torque, experimental phenomena, and low boiling point were recorded. After polymerization, 20ppm of silazane was added for neutralization for 2 hours. After neutralization, the crude dimethyl silicone oil product was subjected to micro-deglossing at -99kPa and 150℃ for 3 hours to obtain high-quality dimethyl silicone oil, and its hydroxyl value, volatile matter, and viscosity were tested.

[0091] Example 15

[0092] 710 g of low molecular weight hydroxyl-terminated polydimethylsiloxane and 10.1 g of DM5 were added to a 1000 ml reactor. The mixture was heated to 60 °C and dehydrated at -90 kPa for 1 h. After dehydration, the pressure in the reactor was adjusted to atmospheric pressure. Then, under atmospheric pressure, 162.04 g of dimethylmethoxyethoxysilane (22.5%) was added, followed by 15 ppm of [Cl3PNP(OEt)Cl2]. + PCl6 catalyst, then adjust the nitrogen flow rate to 2m 3 After performing a short-range polycondensation reaction for 0.5 hours, the nitrogen flow rate is maintained at 2 m / h. 3 At a flow rate of / h, the vacuum was adjusted to -90kPa within 20 minutes, and the polycondensation reaction was carried out for 1.5 hours to obtain a polymer sample. The hydroxyl value, volatile matter, and viscosity of the polymer sample were tested, and the maximum torque of the reactor, the time to reach the maximum torque, experimental phenomena, and low boiling point were recorded. After polymerization, 20ppm of silazane was added for neutralization for 2 hours. After neutralization, the crude dimethyl silicone oil product was subjected to micro-deglossing at -99kPa and 150℃ for 3 hours to obtain high-quality dimethyl silicone oil, and its hydroxyl value, volatile matter, and viscosity were tested.

[0093] Example 16

[0094] 688 g of low molecular weight hydroxyl-terminated polydimethylsiloxane and 10.1 g of DM5 were added to a 1000 ml reactor. The mixture was heated to 60 °C and dehydrated at -90 kPa for 1 h. After dehydration, the pressure in the reactor was adjusted to atmospheric pressure. Then, under atmospheric pressure, 202.55 g of dimethylmethoxyethoxysilane (29.01%) was added, followed by 15 ppm of [Cl3PNP(OEt)Cl2]. + PCl6 catalyst, then adjust the nitrogen flow rate to 2m 3 After performing a short-range polycondensation reaction for 0.5 hours, the nitrogen flow rate is maintained at 2 m / h. 3At a flow rate of / h, the vacuum was adjusted to -90kPa within 20 minutes, and the polycondensation reaction was carried out for 1.5 hours to obtain a polymer sample. The hydroxyl value, volatile matter, and viscosity of the polymer sample were tested, and the maximum torque of the reactor, the time to reach the maximum torque, experimental phenomena, and low boiling point were recorded. After polymerization, 20ppm of silazane was added for neutralization for 2 hours. After neutralization, the crude dimethyl silicone oil product was subjected to micro-deglossing at -99kPa and 150℃ for 3 hours to obtain high-quality dimethyl silicone oil, and its hydroxyl value, volatile matter, and viscosity were tested.

[0095] Example 17

[0096] Add 665g of low molecular weight hydroxyl-terminated polydimethylsiloxane and 10.1g of DM5 to a 1000ml reactor. Heat to 60℃ and dehydrate at -90kPa for 1 hour. After dehydration, adjust the pressure in the reactor to atmospheric pressure. Then, under atmospheric pressure, add 243.06g of dimethylmethoxyethoxysilane (36%), followed by 20ppm of [Cl3PNP(OEt)Cl2]. + PCl6 catalyst, then adjust the nitrogen flow rate to 2m 3 After performing a short-range polycondensation reaction for 0.5 hours, the nitrogen flow rate is maintained at 2 m / h. 3 At a flow rate of / h, the vacuum was adjusted to -90kPa within 20 minutes, and the polycondensation reaction was carried out for 1.5 hours to obtain a polymer sample. The hydroxyl value, volatile matter, and viscosity of the polymer sample were tested, and the maximum torque of the reactor, the time to reach the maximum torque, experimental phenomena, and low boiling point were recorded. After polymerization, 20ppm of silazane was added for neutralization for 2 hours. After neutralization, the crude dimethyl silicone oil product was subjected to micro-deglossing at -99kPa and 150℃ for 3 hours to obtain high-quality dimethyl silicone oil, and its hydroxyl value, volatile matter, and viscosity were tested.

[0097] Comparative Example 1

[0098] Add 800g of low molecular weight hydroxyl-terminated polydimethylsiloxane and 18g of DM5 to a 1000ml reactor. Heat to 75℃ and dehydrate at -90kPa for 1 hour. After dehydration, adjust the pressure in the reactor to atmospheric pressure, and then add 10ppm of [Cl3PNPCl3] under atmospheric pressure. + PCl6 catalyst, then adjust the nitrogen flow rate to 2m 3Within 20 minutes, the vacuum was adjusted to 90 kPa, and the condensation and polymerization reaction was carried out for 2 hours to obtain a polymer sample. The hydroxyl value, volatile matter, viscosity, and cyclic content of the polymer sample were tested, and the maximum torque of the reactor, the time to reach the maximum torque, experimental phenomena, and low boiling point were recorded. After polymerization, 20 ppm of silazane was added for neutralization for 2 hours. After neutralization, the crude dimethyl silicone oil was subjected to micro-deglossing at -99 kPa and 150°C for 3 hours to obtain high-quality dimethyl silicone oil, and its hydroxyl value, volatile matter, viscosity, and cyclic content were tested.

[0099] Comparative Example 2

[0100] 800g of low molecular weight hydroxyl-terminated polydimethylsiloxane and 13.4g of DM5 were added to a 1000ml reactor. The mixture was heated to 60℃ and dehydrated at -90kPa for 1 hour. After dehydration, the pressure in the reactor was adjusted to atmospheric pressure, and then 15ppm of [Cl3PNP(OEt)Cl2] was added under atmospheric pressure. + PCl6 catalyst, then adjust the nitrogen flow rate to 2m 3 Within 20 minutes, the vacuum was adjusted to -90 kPa, and the polycondensation reaction was carried out for 2 hours to obtain a polymer sample. The hydroxyl value, volatile matter, viscosity, and cyclic content of the polymer sample were tested, and the maximum torque of the reactor, the time to reach the maximum torque, experimental phenomena, and low boiling point were recorded. After polymerization, 20 ppm of silazane was added for neutralization for 2 hours. After neutralization, the crude dimethyl silicone oil was subjected to micro-deglossing at -99 kPa and 150°C for 3 hours to obtain high-quality dimethyl silicone oil, which was then tested for hydroxyl value, volatile matter, viscosity, and cyclic content.

[0101] Comparative Example 3

[0102] Add 800g of low molecular weight hydroxyl-terminated polydimethylsiloxane and 6.17g of DM5 to a 1000ml reactor. Heat to 60℃ and dehydrate at -90kPa for 1 hour. After dehydration, adjust the pressure in the reactor to atmospheric pressure, and then add 15ppm of [Cl3PNP(OEt)Cl2] under atmospheric pressure. + PCl6 catalyst, then adjust the nitrogen flow rate to 2m 3Within 20 minutes, the vacuum was adjusted to -90 kPa, and the polycondensation reaction was carried out for 2 hours to obtain a polymer sample. The hydroxyl value, volatile matter, viscosity, and cyclic content of the polymer sample were tested, and the maximum torque of the reactor, the time to reach the maximum torque, experimental phenomena, and low boiling point were recorded. After polymerization, 20 ppm of silazane was added for neutralization for 2 hours. After neutralization, the crude dimethyl silicone oil was subjected to micro-deglossing at -99 kPa and 150°C for 3 hours to obtain high-quality dimethyl silicone oil, which was then tested for hydroxyl value, volatile matter, viscosity, and cyclic content.

[0103] Comparative Example 4

[0104] Add 800g of low molecular weight hydroxyl-terminated polydimethylsiloxane and 5.40g of DM5 to a 1000ml reactor. Heat to 60℃ and dehydrate at -90kPa for 1 hour. After dehydration, adjust the pressure in the reactor to atmospheric pressure, and then add 15ppm of [Cl3PNP(OEt)Cl2] under atmospheric pressure. + PCl6 catalyst, then adjust the nitrogen flow rate to 2m 3 Within 20 minutes, the vacuum was adjusted to -90 kPa, and the polycondensation reaction was carried out for 2 hours to obtain a polymer sample. The hydroxyl value, volatile matter, and viscosity of the polymer sample were tested, and the maximum torque of the reactor, the time to reach the maximum torque, experimental phenomena, and low boiling point were recorded. After polymerization, 20 ppm of silazane was added for neutralization for 2 hours. After neutralization, the crude dimethyl silicone oil was subjected to micro-deglossing at -99 kPa and 150°C for 3 hours to obtain high-quality dimethyl silicone oil, which was then tested for hydroxyl value, volatile matter, and viscosity.

[0105] Comparative Example 5

[0106] Add 800g of low molecular weight hydroxyl-terminated polydimethylsiloxane and 5.40g of DM5 to a 1000ml reactor. Heat to 60℃ and dehydrate at -90kPa for 1 hour. After dehydration, adjust the pressure in the reactor to atmospheric pressure, and then add 15ppm of [Cl3PNP(OEt)Cl2] under atmospheric pressure. + PCl6 catalyst, then adjust the nitrogen flow rate to 4m 3 Within 20 minutes, the vacuum was adjusted to 900 mbar, and the polycondensation reaction was carried out for 2 hours to obtain a polymer sample. The hydroxyl value, volatile matter, and viscosity of the polymer sample were tested, and the maximum torque of the reactor, the time to reach the maximum torque, experimental phenomena, and low boiling point were recorded. After polymerization, 20 ppm of silazane was added for neutralization for 2 hours. After neutralization, the crude dimethyl silicone oil was subjected to micro-deglossing at -99 kPa and 150 °C for 3 hours to obtain high-quality dimethyl silicone oil, which was then tested for hydroxyl value, volatile matter, and viscosity.

[0107] Comparative Example 6

[0108] Add 800g of low molecular weight hydroxyl-terminated polydimethylsiloxane and 5.40g of DM5 to a 1000ml reactor. Heat to 60℃ and dehydrate at -90kPa for 1 hour. After dehydration, adjust the pressure in the reactor to atmospheric pressure, and then add 15ppm of [Cl3PNP(OEt)Cl2] under atmospheric pressure. + PCl6 catalyst, nitrogen flow rate adjusted to 8m 3 Within 20 minutes, the vacuum was adjusted to -90 kPa, and the polycondensation reaction was carried out for 2 hours to obtain a polymer sample. The hydroxyl value, volatile matter, and viscosity of the polymer sample were tested, and the maximum torque of the reactor, the time to reach the maximum torque, experimental phenomena, and low boiling point were recorded. After polymerization, 20 ppm of silazane was added for neutralization for 2 hours. After neutralization, the crude dimethyl silicone oil was subjected to micro-deglossing at -99 kPa and 150°C for 3 hours to obtain high-quality dimethyl silicone oil, which was then tested for hydroxyl value, volatile matter, and viscosity.

[0109] Comparative Example 7

[0110] 778 g of low molecular weight hydroxyl-terminated polydimethylsiloxane and 5.40 g of DM5 were added to a 1000 ml reactor. The mixture was heated to 60 °C and dehydrated at -90 kPa for 1 h. After dehydration, the pressure in the reactor was adjusted to atmospheric pressure, and then 15 ppm of [Cl3PNP(OEt)Cl2] was added under atmospheric pressure. + PCl6 catalyst, then adjust the nitrogen flow rate to 9m 3 Within 20 minutes, the vacuum was adjusted to -90 kPa, and the polycondensation reaction was carried out for 2 hours to obtain a polymer sample. The hydroxyl value, volatile matter, viscosity, and cyclic content of the polymer sample were tested, and the maximum torque of the reactor, the time to reach the maximum torque, experimental phenomena, and low boiling point were recorded. After polymerization, 20 ppm of silazane was added for neutralization for 2 hours. After neutralization, the crude dimethyl silicone oil was subjected to micro-deglossing at -99 kPa and 150°C for 3 hours to obtain high-quality dimethyl silicone oil, which was then tested for hydroxyl value, volatile matter, viscosity, and cyclic content.

[0111] Comparative Example 8

[0112] Add 800g of low molecular weight hydroxyl-terminated polydimethylsiloxane and 5.40g of DM5 to a 1000ml reactor, heat to 90℃, and apply nitrogen for 2 minutes. 3Dehydration was carried out at a flow rate of / h. When the temperature reached 155℃, the nitrogen blowing was turned off, and dehydration was completed. 10 ppm of 15.6% potassium hydroxide silanol salt was added, and after 3 hours of polymerization, a polymer sample was taken to test its volatile matter, hydroxyl value, and viscosity. Then, 15 ppm of 9.7% silicone phosphate was added for neutralization for 2 hours. After neutralization, de-devouring was carried out at -99 kPa and 150℃ for 3 hours to obtain dimethyl silicone oil, which was then tested for its hydroxyl value, volatile matter, and viscosity.

[0113] Performance Characterization

[0114] The viscosity, hydroxyl value, and volatile matter of the polymerized samples and the finished samples (i.e., high-quality dimethyl silicone oil) of the methyl silicone oil prepared in each embodiment and comparative example were characterized, and the results are shown in Table 1 below.

[0115] Table 1. Viscosity, hydroxyl value, and volatile matter content of polymerized and finished samples of dimethyl silicone oil.

[0116]

[0117] Table 1 shows that the dimethyl silicone oil prepared by the method of the present invention has stable viscosity, volatile matter, and hydroxyl value with good repeatability, and the prepared dimethyl silicone oil has a significant advantage of low hydroxyl value. Examples 7-10 and Comparative Examples 5-7 show that the nitrogen flow rate exceeds 8 m / s. 3 After / h, the viscosity decreased significantly. In addition, although increasing the nitrogen flow rate can reduce the hydroxyl value of the product, the hydroxyl value of Comparative Example 7 is still around 181ppm, indicating that simply increasing the nitrogen flow rate cannot achieve the target of a low hydroxyl value.

[0118] The residual cyclic index results of the polymer samples and finished products of Examples 1-3, and the polymer samples and finished products of Comparative Examples 1-3 and 7 are shown in Table 2:

[0119] Table 2. Results of residual ring index for polymerized and finished samples of dimethyl silicone oil.

[0120]

[0121] As shown in Table 2, the macrocyclic content of the methyl silicone oil polymer sample prepared by the method of this invention, from D7 onwards, is significantly lower than that of the comparative example. This makes it easier to achieve the required low cyclic content through micro-dedipping.

[0122] The highest torque, time to reach the highest torque, experimental phenomena, and low boiling point of the methyl silicone oils prepared in the examples and comparative examples during the polymerization process are shown in Table 3:

[0123] Table 3 Torque test and response stability test data

[0124]

[0125]

[0126] As can be seen from Table 3, the addition of polycondensation regulator can significantly control the polycondensation rate, achieving the effect of slow polycondensation and regulating polymerization.

[0127] Based on the test results of the comparative examples and the comparative embodiments, the following phenomena can be observed:

[0128] Compared with Comparative Example 1, Example 1 added a polycondensation regulator. The results showed that: 1. The hydroxyl content of the polymer sample and the finished product sample of Example 1 was significantly reduced, see Table 1; 2. The macrocyclic D7 to D10 in the polymer sample and the finished product sample of Example 1 was significantly reduced, see Table 2; 3. The data on the highest torque and the time to reach the highest torque of Example 1 showed that, compared with Comparative Example 1, the method of Example 1 did not produce a viscosity peak and there was no violent reactor overflow, see Table 3.

[0129] Similarly, a similar comparative effect can be observed when comparing Examples 2 / 5 / 6 with Comparative Examples 2 / 3 / 4. Examples 3 / 4 demonstrate that using a phosphazene base catalyst also yields the same effect.

[0130] Examples 7-10, compared with Comparative Examples 5-7, show that increasing the nitrogen flow rate in the process of the present invention can further reduce the hydroxyl value. However, in the existing process, simply increasing the nitrogen flow rate cannot achieve a low hydroxyl value, nor can it play a role in polymerization regulation.

[0131] Examples 11 / 12 / 13 / 14 / 15 / 16 / 17 tested the polymerization tuning effect of different amounts of polymerization tuning agent. The test results showed that the polymerization tuning agent had a polymerization tuning effect in the range of 2-40%, but when it exceeded 25%, although it could achieve the polymerization tuning effect, the viscosity would decrease significantly and the stability would be low.

[0132] Table 4 Ion Test Results of Finished Samples

[0133]

[0134] As can be seen from Table 4, compared with Comparative Example 8, the dimethyl silicone oil prepared by phosphazene catalyst in Example 1 has the significant advantage of not introducing potassium ions, and can be applied in the power industry.

Claims

1. A method for preparing dimethyl silicone oil, characterized in that: A mixture of low molecular weight hydroxyl-terminated polydimethylsiloxane, a methyl end-capping agent, a polycondensation regulator, and a phosphazene catalyst is sequentially subjected to both normal compression polymerization and negative compression polymerization to obtain dimethyl silicone oil; wherein... The structural formula of low molecular weight hydroxyl-terminated polydimethylsiloxane is: 'n' represents the degree of polymerization, and its viscosity is 40-120 mg / L. 2 / s; The structural formula of the methyl end-capping agent is: 'm' represents the degree of polymerization, and its viscosity ranges from 1.5 to 50 mmol / L. 2 / s; The polycondensation regulator is one or a mixture of two or more of the following: dimethyldimethoxysilane, dimethylmethoxyethoxysilane, dimethyldiethoxysilane, low molecular weight monomethoxy-terminated polysiloxane, and low molecular weight monoethoxy-terminated polysiloxane; the structural formula of the low molecular weight monomethoxy-terminated polysiloxane is as follows: 'x' represents the degree of polymerization, and its viscosity is 5-100 mm² / s; the structural formula of low molecular weight monoethoxylated end-capped polysiloxanes is... y represents the degree of polymerization, and its viscosity is 5-100 mm. 2 / s; The mass ratio of low molecular weight hydroxyl-terminated polydimethylsiloxane to methyl-terminated agent is (40~150):1; The amount of polycondensation regulator added is 2-40% of the total mass of low molecular weight hydroxyl-terminated polydimethylsiloxane and methyl-terminated agent; The normal compression polymerization is carried out at a temperature of 50-150℃ for a reaction time of 0.5-2 h. During the reaction, nitrogen gas is introduced at a flow rate of 1.9-9.5 m / s. 3 / h; The negative compression polymerization is carried out at a temperature of 50-150℃ and a negative pressure of -60 kPa to -99 kPa, with a reaction time of 0.5-2 h. During the reaction, nitrogen gas is introduced at a flow rate of 1.9-6.5 m / s. 3 / h.

2. The method as described in claim 1, characterized in that, The viscosity of low molecular weight hydroxyl-terminated polydimethylsiloxane is 80-100 mm. 2 / s.

3. The method as described in claim 1, characterized in that, The viscosity of the methyl end-capping agent is 1.5-20 mm. 2 / s.

4. The method as described in claim 1, characterized in that, The viscosity of low molecular weight monomethoxy-terminated polysiloxanes is 5-50 mm. 2 / s.

5. The method as described in claim 1, characterized in that, The viscosity of low molecular weight monoethoxy-terminated polysiloxanes is 5-50 mm. 2 / s.

6. The method according to any one of claims 1-5, characterized in that, The amount of polycondensation regulator added is 5-25% of the total mass of low molecular weight hydroxyl-terminated polydimethylsiloxane and methyl end-capping agent.

7. The method according to any one of claims 1-5, characterized in that: The amount of phosphazene catalyst added is 0.001-0.005% of the total material mass, where the total material mass refers to the sum of the mass of low molecular weight hydroxyl-terminated polydimethylsiloxane, methyl end-capping agent, and polycondensation regulator.

8. The method according to any one of claims 1-5, characterized in that, Phosphazene catalysts are phosphazene acid catalysts, selected from: [Cl3PNPCl3] + PCl6, [Cl3PNPCl3] + SbCl6, [Cl3PNP(OEt)Cl2] + PCl6, [Cl3PNP(OEt)Cl2] + SbCl6, [Cl2(OEt)PNP(OEt)Cl2] + PCl6, [Cl2(OEt)PNP(OEt)Cl2] + SbCl6, Cl3PNP(O)Cl2, Cl2(EtO)PNP(O)Cl2, or polymers of the aforementioned linear phosphazene acid, wherein the polymer is a 2-6 polymer.

9. The method according to any one of claims 1-5, characterized in that, Phosphazene catalysts are phosphazene base catalysts, selected from linear phosphazene base catalysts of formula (1), (2), (3), and (4) or their polymers, wherein the polymers are 2-6 polymers: Equation (1) Equation (2), Equation (3) Equation (4); Among them, R1-R 45 Independently selected from H, C 1-4 Alkyl, C 3-6 Cycloalkyl, phenyl.

10. The method as described in claim 9, characterized in that, The polymer is a 2-3 polymer.

11. The method as described in claim 9, characterized in that, The R1-R 45 The individual components are selected independently from hydrogen, methyl, ethyl, propyl, butyl, cyclopentyl, cyclohexyl, or phenyl.

12. The method according to any one of claims 1-5, characterized in that: Includes the following steps: S1. In the reaction apparatus, low molecular weight hydroxyl-terminated polydimethylsiloxane and methyl-termining agent are mixed and dehydrated for 0.5-2 h at 50-150 °C and -90 kPa to -100 kPa. S2. After dehydration, adjust the pressure of the reaction device to atmospheric pressure, add polycondensation regulator and phosphazene catalyst at a temperature of 50-150 ℃, and introduce nitrogen gas to carry out atmospheric compression polycondensation reaction for 0.5-1 h. S3. Adjust the pressure of the reaction apparatus to a negative pressure condition of -60 kPa to -99 kPa, and introduce nitrogen gas at a temperature of 50-150 ℃ to carry out a negative compression polymerization reaction for a reaction time of 0.5-2 h to obtain crude dimethyl silicone oil polymer.

13. The method as described in claim 12, characterized in that: In step S2, the polycondensation reaction temperature is 50-95℃; in step S3, the polycondensation reaction temperature is 50-95℃.

14. The method as described in claim 12, characterized in that, In step S1, the dehydration operation is carried out at 50-95℃ and -90kPa to -100 kPa for 0.5-1 h.

15. The method as described in claim 12, characterized in that, It also includes step S4, which involves post-processing the crude product obtained in step S3 to obtain the dimethyl silicone oil product.

16. The method as described in claim 15, characterized in that, The post-treatment includes a neutralization step, in which a neutralizing agent is added to neutralize the phosphazene catalyst; when using a phosphazene acid catalyst, an organic weak base is used as the neutralizing agent; when using a phosphazene base catalyst, an inorganic weak acid or an organic weak acid is used as the neutralizing agent.

17. The method as described in claim 16, characterized in that, The inorganic or organic weak acid is selected from one or more combinations of oxalic acid, sulfurous acid, phosphoric acid, silicone phosphate, benzoic acid, acetic acid, propionic acid, stearic acid, or citric acid; the organic weak base is selected from one or more combinations of hexamethyldisilazane, pyridine, tri-n-propylamine, or tri-n-butylamine.

18. The method as described in claim 16, characterized in that, The amount of neutralizing agent added is 0.002-0.010% of the total material mass.

19. The method as described in claim 16, characterized in that, The neutralization step is carried out at 50-150 °C under normal pressure for 1-3 h.

20. The method as described in claim 15, characterized in that, The post-treatment includes a micro-volatilization step, in which volatiles are removed under conditions of -90 kPa to -99 kPa and 130-180 ℃ for 0.5-4 h.

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