Low-acid-value high-hydrogen silicone oil and method for producing the same

Abstract

This application discloses a low-acid-value, high-hydrogen-content silicone oil and its preparation method, belonging to the field of organosilicon technology. The preparation method first involves hydrolyzing a raw material containing methyldichlorosilane, followed by drying to remove water and then polymerizing with a polymerizing agent to obtain polymerized silicone oil. Subsequently, the polymerized silicone oil is kept at 140–160 °C for 30–90 min, and then subjected to reduced pressure treatment to remove low-molecular-weight volatiles, promoting the conversion of residual bound chlorine in the silicone oil into free chlorine, which is simultaneously removed. Finally, a chemical dechlorinating agent and matching additives are added to the dechlorinated silicone oil for refining, and the finished product is obtained after filtration. This application eliminates the need for water washing and organic solvents in the subsequent refining and deacidification process, simultaneously removing both free and bound chlorine from the high-hydrogen-content silicone oil, thus solving the problem of acid reversion during product storage.

Description

Technical Field

[0001] This application relates to the field of organosilicon technology, specifically to a low-acid-value, high-hydrogen-content silicone oil and its preparation method. Background Technology

[0002] High-hydrogen-content silicone oil refers to polysiloxanes with a large number of highly reactive silicon-hydrogen bonds (Si-H) on their molecular backbone. Due to its unique reactivity, it is widely used in silicone rubber crosslinking agents, fabric waterproofing agents, polyurethane foam leveling agents, paper release agents, and other fields. High-hydrogen-content silicone oil is usually prepared from methyldichlorosilane as the main raw material through processes such as hydrolysis.

[0003] However, during the synthesis process using methyldichlorosilane as the main raw material, trace amounts of chloride ions are easily left behind. These chloride ions are mainly divided into two categories: one is "free chloride," which is free acid existing in the form of hydrogen chloride (HCl); the other is "bound chloride," which is incompletely hydrolyzed silicon-chlorine bonds (Si-Cl). The residual acidic substances will catalyze the decomposition and cross-linking reaction of the high-hydrogen-content silicone oil itself, causing the product to gradually increase in viscosity or even gel (commonly known as "dead glue") during storage, seriously affecting its application performance and storage stability.

[0004] Even more serious is the problem of "acid reversion": the product's acid value is qualified when it leaves the factory, but after 1-3 months of storage, the acid value rebounds sharply, causing the product to become ineffective. The root cause of acid reversion is that improper water control or incomplete reaction during hydrolysis generates products containing Si-Cl bonds. These hidden "bound chlorine" compounds are difficult to completely remove in conventional post-processing. When the product is stored, the bound chlorine slowly absorbs trace amounts of moisture from the air and undergoes secondary hydrolysis, releasing HCl and causing the acid value to rebound.

[0005] Existing technologies have the following drawbacks when removing residual acid values ​​from high-hydrogen-content silicone oils: First, incomplete acid removal can easily lead to "acid rebound." Most existing patented technologies target free HCl and cannot remove hidden "bound chlorine." The product may have a qualified acid value when it leaves the factory, but after 1 to 3 months, the "bound chlorine" will slowly absorb trace amounts of moisture from the air and undergo secondary hydrolysis, releasing HCl and causing the acid value to rebound significantly.

[0006] Secondly, the introduction of organic solvents increases environmental and cost pressures. Existing technologies use methods such as adding toluene or heptane. Although these methods can alleviate the acid value problem to some extent, the presence of solvents not only limits production capacity and increases energy consumption and solvent recovery costs, but also the residual solvents affect product purity and odor, which is inconsistent with the development direction of green chemistry.

[0007] Third, the water washing process has limitations. For example, Chinese patent CN118930863A discloses a method of washing with hot brine to break the emulsion, followed by preliminary neutralization with dilute alkali and then secondary neutralization with magnesium oxide and organic alkali. Although this method can reduce the acid return rate, it has the following problems: (1) The multi-stage water washing process is complex, generates a large amount of wastewater, and has high environmental treatment costs; (2) The amount of magnesium oxide used is relatively large (0.5%-2%), and it needs to be used in conjunction with organic alkali, which increases the cost; (3) The loss rate of silicone oil during the water washing process is relatively high, which affects the yield.

[0008] Therefore, how to remove as much "free chlorine" and "bound chlorine" as possible from high-hydrogen-content silicone oil without using organic solvents or washing with water, so as to obtain high-hydrogen-content silicone oil with low acid value and no acid reversion during long-term storage, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0009] The purpose of this application is to provide a method for preparing a high-hydrogen-content silicone oil with low acid value that does not cause acid backflow during long-term storage.

[0010] To achieve the above objectives, the technical solution adopted in this application is as follows: This application provides a method for preparing a low-acid-value, high-hydrogen-content silicone oil, comprising the following preparation steps: S1: Hydrolyzing a raw material containing methyldichlorosilane with water, allowing it to stand and separate into layers, then taking the silicone oil layer and drying it to remove water; adding a polymerization regulator to the dried silicone oil to carry out a polymerization reaction, and filtering after the reaction to obtain the polymerized silicone oil; S2: Heating the polymerized silicone oil to 140~160 ℃ and holding it at that temperature for 30~90 min, and then subjecting it to vacuum treatment to remove low-molecular-weight volatiles; S3: Adding a chemical dechlorinating agent and other additives to the dechlorinated silicone oil for further purification, and filtering to obtain the low-acid-value, high-hydrogen-content silicone oil.

[0011] As a preferred embodiment, the raw material containing methyldichlorosilane is methyldichlorosilane and trimethylchlorosilane, and the mass ratio of methyldichlorosilane to trimethylchlorosilane is (20~30):1.

[0012] As a preferred embodiment, the hydrolysis reaction is carried out at a temperature of 0~15 ℃.

[0013] As a preferred embodiment, the polymerization agent is any one or a combination of activated clay, acid clay, or sulfuric acid.

[0014] As a preferred embodiment, the amount of the chemical dechlorinating agent used is 0.005% to 0.02% of the mass of the dechlorinated silicone oil.

[0015] As a preferred embodiment, in step S3, the chemical dechlorinating agent is any one of magnesium oxide, calcium oxide, or sodium bicarbonate.

[0016] As a preferred embodiment, the other additives include activated carbon, which is used for the physical adsorption of chlorine.

[0017] As a preferred embodiment, the other additives include diatomaceous earth, wherein the amount of diatomaceous earth added is 0.05% to 0.5% of the mass of the de-descaled silicone oil.

[0018] As another preferred option, in step S2, the reduced pressure treatment can be carried out by rotary evaporation or thin-film evaporation to remove low molecular weight volatiles from the telomerized silicone oil under negative pressure conditions of vacuum degree above -98 kPa and heating conditions of 150~160 ℃.

[0019] This application also provides a low-acid-value, high-hydrogen-content silicone oil, prepared using any of the above-described preparation methods.

[0020] Compared with the prior art, the beneficial effects of this application are as follows: (1) The preparation method of this application can promote the conversion of the "bound chlorine" in the silicone oil into the easily removed "free chlorine" by setting a specific heating and heat preservation process after telomerization. Combined with the subsequent refining process to remove it at the same time, it can not only significantly reduce the initial acid value of the product, but also avoid the problem of acid value rebound during storage from the root, and greatly improve the long-term storage stability of the product. (2) The preparation method of this application does not introduce organic solvents throughout the process and does not require a water washing process, thus avoiding the burden of generating a large amount of wastewater and recycling solvents, reducing environmental protection costs and material losses. (3) The preparation method of this application will not cause significant damage to the silicon-hydrogen bond. The core performance indicators of the product, such as viscosity, hydrogen content, and volatile matter, can be maintained at an excellent level. The final product has no solvent residue, high transparency, and no odor, which can meet the quality requirements of high-end application fields. Detailed Implementation

[0021] The present application will be further described below with reference to specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0022] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0023] This application provides a method for preparing a low-acid-value, high-hydrogen-content silicone oil, comprising the following preparation steps: S1: The raw material containing methyldichlorosilane is hydrolyzed with water. After standing and separating into layers, the silicone oil layer is taken and dried to remove water. A polymerization activator is added to the dried silicone oil to carry out a polymerization reaction. After the reaction is completed, the polymerized silicone oil is obtained by filtration. S2: Heat the polymerized silicone oil to 140~160 ℃ and keep it at that temperature for 30~90 min. After the temperature is maintained, perform a pressure reduction treatment to remove low molecular weight volatiles. S3: Add chemical dechlorinating agent and other additives to the dechlorinated silicone oil for further refining, and filter to obtain the low acid value, high hydrogen content silicone oil of this application.

[0024] This application designs a reaction process where, after polymerizing silicone oil, the temperature is raised to 140-160 °C and held for 30-90 min. This process promotes the hydrolysis of "bound chlorine" in the residual silicon-chlorine bonds of the silicone oil. Trace amounts of incompletely hydrolyzed "bound chlorine" (Si-Cl bonds) in the silicone oil are forcibly activated. Through residual trace amounts of water or through a thermal rearrangement reaction, the Si-Cl bonds break, releasing free hydrogen chloride (HCl) gas. This released hydrogen chloride is then removed in subsequent refining steps, further reducing the acid value of the high-hydrogen-content silicone oil and enabling stable storage for a period without "acid reversion," thus facilitating the long-term storage and transportation of high-hydrogen-content silicone oil.

[0025] In the low-temperature insulation step of this application, it was found that the silicone oil molecular chain is relatively stable in the specific stage of "polymerization of silicone oil". At this time, heating in the temperature range of 140~160 ℃ can selectively promote the breaking of Si-Cl bonds to release bound chlorine, while the thermal cross-linking reaction of Si-H bonds has not yet occurred on a large scale. This condition makes it possible to reduce the acid value under the waterless washing condition of this application.

[0026] If the temperature is too low or the holding time is insufficient, the Si-Cl bond activation may be incomplete, and the "bound chlorine" may not be fully released. While excessively high temperatures or excessively long holding times can promote the release of "bound chlorine," they increase the risk of thermal cross-linking of Si-H bonds, leading to an abnormal increase in silicone oil viscosity and a decrease in hydrogen content. In the preferred technical solution, the heating temperature of the polymerized silicone oil is 150 °C, and the heating holding time is 60 min. Under these conditions, the full release of bound chlorine is ensured, while the risk of thermal cross-linking of Si-H bonds is controlled within an acceptable range.

[0027] In some embodiments, a raw material containing methyldichlorosilane is hydrolyzed with water. The raw material containing methyldichlorosilane further includes trimethylchlorosilane, and the mass ratio of methyldichlorosilane to trimethylchlorosilane is (20-30):1. Preferably, the mass ratio of methyldichlorosilane to trimethylchlorosilane is 25:1. Trimethylchlorosilane can be used as a capping agent to control the degree of polymerization and viscosity of silicone oil.

[0028] In some embodiments, the hydrolysis reaction temperature is 0–15 °C, and more preferably 5–10 °C. Within this low-temperature range, the hydrolysis rate can be effectively controlled, preventing the breaking of silane-hydrogen bonds due to localized overheating, while reducing the formation of cyclic oligomers and improving product quality.

[0029] In some specific preparation methods, after standing and separating into layers, the silicone oil layer is taken out and a desiccant is added to it. The desiccant can be a commonly used desiccant such as calcium chloride, anhydrous sodium sulfate, or molecular sieves, with calcium chloride being preferred. The purpose of drying is to remove free water from the silicone oil, creating anhydrous conditions for the subsequent telomerization reaction.

[0030] In some specific preparation methods, the polymerization modifier can be commonly used modifiers such as activated clay, acid clay, and sulfuric acid, with activated clay being preferred. The purpose of the polymerization reaction is to adjust the molecular weight distribution of the silicone oil, making it more uniform, while reducing the content of low-molecular-weight cyclic compounds. After the polymerization reaction is completed, the polymerization modifier is removed by means of filtration or other methods.

[0031] In some embodiments, the telomerized silicone oil after heat preservation is subjected to depressurization treatment. This depressurization treatment can be performed using methods such as rotary evaporation or thin-film evaporation. Under negative pressure conditions (above -98 kPa) and heating conditions of 150–160 °C, low-molecular-weight volatiles and most of the hydrogen chloride gas released in step S2 are removed from the silicone oil. After this depressurization treatment, the free HCl content in the silicone oil is significantly reduced.

[0032] In some embodiments, a chemical dechlorinating agent is added to the dechlorinated silicone oil for dechlorination. The chemical dechlorinating agent is any one of magnesium oxide, calcium oxide, or sodium bicarbonate. Among them, magnesium oxide (MgO) is a weakly alkaline solid that can neutralize the residual trace amounts of HCl. The magnesium chloride and trace amounts of water generated by this reaction have minimal impact on the silicone oil, and the magnesium chloride is in dry powder form, which is easy to remove by subsequent filtration.

[0033] The amount of magnesium oxide added is 0.005%~0.02% of the mass of the de-lowered silicone oil. The amount of magnesium oxide used is much lower than that used in existing conventional technologies. The main reason is that in step S2, the heating and heat preservation reaction promotes the hydrolysis of silicon chloride bonds, which has converted most of the "bound chlorine" into "free chlorine" and removed it in the subsequent de-lowering step. Therefore, only a small amount of magnesium oxide needs to be added in the refining step to react further with the residual trace amount of hydrogen chloride.

[0034] Preferably, the amount of magnesium oxide added is 0.01% of the mass of the de-alkaliened silicone oil. At this amount, it can effectively neutralize the residual HCl without triggering the side reaction of Si-H bonds due to excessive use of alkaline substances.

[0035] In some specific preparation steps, other additives include activated carbon and diatomaceous earth. Activated carbon, as a physical adsorbent, has a high specific surface area and abundant pore structure, which can adsorb impurities such as magnesium chloride, trace pigments, and odor substances, further improving the purity and transparency of silicone oil. Diatomaceous earth, as a filter aid, can form a loose filter cake, prevent filter cloth clogging, and improve filtration efficiency, making it particularly suitable for large-scale industrial production.

[0036] In a preferred embodiment, the amounts of activated carbon and diatomaceous earth added range from 0.05% to 0.5% of the mass of the degraded silicone oil. In a more preferred preparation method, magnesium oxide is added to the degraded silicone oil and the mixture is stirred for 20-40 minutes, followed by the addition of activated carbon and stirring for another 20-40 minutes, and then the addition of diatomaceous earth and stirring for another 20-40 minutes. Sufficient stirring time ensures that the magnesium oxide and HCl react fully and that the activated carbon effectively adsorbs impurities.

[0037] The method for preparing low-acid-value, high-hydrogen-content silicone oil disclosed in this application does not use organic solvents, is green and environmentally friendly, leaves no solvent residue, has a simple process and low energy consumption, and uses inexpensive and readily available industrial raw materials such as magnesium oxide, activated carbon and diatomaceous earth, which effectively reduces production costs, results in high product yield and low silicone oil loss.

[0038] This application also provides a low-acid-value, high-hydrogen-content silicone oil product, prepared by any of the above-described methods. The high-hydrogen-content silicone oil product prepared by this application has a high hydrogen content, a low acid value, does not exhibit acid reversion during long-term storage, has good transparency, and is odorless, thus meeting the application requirements of high-end fields such as electronic-grade silicone rubber and medical-grade silicone rubber.

[0039] Example 1 To prepare a low-acid-value, high-hydrogen-content silicone oil, follow these steps: S1: Methyldichlorosilane and trimethylchlorosilane are mixed at a mass ratio of 25:1. The mixture is slowly added dropwise to pure water to carry out a hydrolysis reaction, and the hydrolysis temperature is controlled at 5 ℃. After the hydrolysis reaction is completed, the mixture is allowed to stand and separate into layers, and the oil and water are separated. The upper silicone oil layer is taken. Calcium chloride at a mass of 3% of the silicone oil mass is added to the silicone oil layer, and the mixture is dried to remove water under stirring. Activated clay at a mass of 1.5% of the silicone oil mass is added to the dried silicone oil as a polymerization modifier to carry out a polymerization reaction. The polymerization temperature is 60℃ and the polymerization reaction time is 3 hours. After the reaction is completed, the mixture is filtered to obtain polymerized silicone oil. S2: Heat the polymerized silicone oil to 150 ℃ and keep it at that temperature for 60 min. After the holding time is over, do not cool down and directly perform decompression treatment. Remove low molecular weight volatiles under vacuum conditions of -98 kPa or higher and temperature of 150~160 ℃. S3: Add magnesium oxide to the dehydrogenated silicone oil, with the mass of magnesium oxide accounting for 0.01% of the mass of the dehydrogenated silicone oil. After stirring for 30 min, add activated carbon and diatomaceous earth, and continue stirring for 30 min. The mass of activated carbon and diatomaceous earth are 0.1% of the mass of the dehydrogenated silicone oil, respectively. After stirring, filter the mixture to obtain colorless and transparent high-hydrogen silicone oil.

[0040] Example 2 The heat preservation time of the polysiloxane in step S2 was adjusted to 30 min, and the other preparation steps, unless otherwise specified, were consistent with the preparation steps in Example 1.

[0041] Example 3 The heat preservation time of the polysiloxane in step S2 was adjusted to 90 min, and the other preparation steps, unless otherwise specified, were consistent with the preparation steps in Example 1.

[0042] Example 4 The heating temperature of the polysiloxane in step S2 was adjusted to 160 °C, and the other preparation steps, unless otherwise specified, remained the same as those in Example 1.

[0043] Example 5 The heating temperature of the polysiloxane in step S2 was adjusted to 140 °C, and the other preparation steps, unless otherwise specified, remained the same as those in Example 1.

[0044] Example 6 The amount of magnesium oxide added in step S3 was adjusted to 0.005% of the mass of the de-silicone oil, and the other preparation steps, unless otherwise specified, were consistent with the preparation steps in Example 1.

[0045] Example 7 The amount of magnesium oxide added in step S3 was adjusted to 0.02% of the mass of the de-silicone oil, and the other preparation steps, unless otherwise specified, were consistent with the preparation steps in Example 1.

[0046] Example 8 In step S3, magnesium oxide is replaced with calcium oxide, and the amount of calcium oxide added is 0.01% of the mass of the de-saturated silicone oil. Other preparation steps, unless otherwise specified, are consistent with the preparation steps in Example 1.

[0047] Example 9 In step S3, magnesium oxide is replaced with sodium bicarbonate, and the amount of sodium bicarbonate added is 0.01% of the mass of the degraded silicone oil. Other preparation steps, unless otherwise specified, are consistent with the preparation steps in Example 1.

[0048] Comparative Example 1 The telomerized silicone oil was prepared according to step S1 of Example 1. The telomerized silicone oil was directly subjected to vacuum treatment. Under vacuum conditions of -98 kPa or higher and temperature of 150~160 °C, low molecular weight volatiles were removed. Then, magnesium oxide, activated carbon and diatomaceous earth were added sequentially according to step S3 of Example 1. After filtration, the high hydrogen content silicone oil of Comparative Example 1 was obtained.

[0049] That is, compared with the preparation steps of Example 1, the heating and heat preservation treatment step of the polypolymer silicone oil was omitted in the preparation steps of Comparative Example 1, and the other preparation steps, unless otherwise specified, are consistent with the preparation steps in Example 1.

[0050] Comparative Example 2 The dehydrogenated silicone oil was prepared according to the preparation steps S1 and S2 in Example 1. Activated carbon and diatomaceous earth were added to the dehydrogenated silicone oil and stirred for 30 min, wherein the mass of activated carbon and diatomaceous earth were 0.1% of the mass of the dehydrogenated silicone oil, respectively. After stirring, the mixture was filtered by pressure to obtain the high hydrogen content silicone oil of Comparative Example 2.

[0051] That is, compared with the preparation steps of Example 1, the preparation steps of Comparative Example 2 omitted the magnesium oxide treatment step, and the other preparation steps, unless otherwise specified, were consistent with the preparation steps in Example 1.

[0052] Comparative Example 3 Using a conventional water washing process, following the preparation steps of S1 in Example 1, telomerized silicone oil was prepared and then subjected to a conventional water washing and alkali washing process: it was washed with 5% hot water at a temperature of about 70 °C to remove acidic water in layers, and then washed with 5% dilute alkali solution (1% NaOH solution) to remove alkaline wastewater in layers after washing. Finally, 0.1% activated carbon was added for adsorption, and after filtration, high hydrogen-containing silicone oil of Comparative Example 3 was obtained.

[0053] Performance testing The high-hydrogen-content silicone oils prepared in the above embodiments and comparative examples were subjected to the following performance tests: Viscosity: measured at 25 °C using an Ubbelohde viscometer according to GB / T 265-1988 standard, unit is mm. 2 / s; Hydrogen content: determined by hydrogen generation method according to GB / T6370-2008 standard, unit is %; Volatile matter: determined by mass loss after heating at 150 ℃ for 1.5 h according to GB / T 10700-2006 standard, unit is wt%; Acid value: determined by potentiometric titration method, expressed as HCl, unit is ppm (mg / kg); Acid value after 3 months: after sealing and storing the sample at room temperature (25 ℃) for 3 months, the acid value is determined according to the above method.

[0054] Table 1 Performance test results of each embodiment and each comparative example

[0055] The high-hydrogen-content silicone oil prepared in this application has a low acid value, which remains stable after 3 months of storage at room temperature. Furthermore, the product exhibits excellent viscosity, hydrogen content, and volatile matter content. Specifically, the high-hydrogen-content silicone oil prepared in Example 1 has a hydrogen content of 1.6% and a viscosity of 20.5 mm. 2 The product has the highest quality, with an initial acid value of 0.5 ppm and no increase in acid value after 3 months of storage.

[0056] Analysis of the test results from Examples 1 to 5 reveals an optimal range for heating temperature and time in telomerized silicone oil. Insufficient temperature or holding time may lead to inadequate activation of Si-Cl bonds, preventing the complete release of "bound chlorine." Conversely, excessively high temperature or excessively long holding time, while promoting the release of "bound chlorine," increases the risk of thermal cross-linking of Si-H bonds, resulting in an abnormal increase in silicone oil viscosity and a decrease in hydrogen content.

[0057] Analysis of the test results of Examples 6 and 7 shows that there is a lower limit to the amount of magnesium oxide used. If the amount is too low, it may not be able to completely neutralize the residual HCl, resulting in a higher initial acid value and slight acid backflow.

[0058] Analysis of Examples 8 and 9 shows that while calcium oxide has a good acid removal effect, it clogs the filter cloth and is not suitable for industrial use; sodium bicarbonate releases moisture and triggers Si-H bond cross-linking, leading to a decline in product quality. Therefore, magnesium oxide is the optimal dechlorination agent.

[0059] Comparative Example 1, lacking high-temperature heating, failed to remove "bound chlorine" from the product, resulting in severe "acid reversion." Comparative Example 2, lacking the chemical dechlorination step of magnesium oxide, relied solely on subsequent activated carbon adsorption of "free chlorine," which could not completely remove hydrogen chloride, leading to a high acid value in the product.

[0060] Comparative Example 3 used a conventional water washing process, which could not remove the "bound chlorine" present in the product. After 3 months, the acid value increased significantly, and the water washing process generated a large amount of wastewater, resulting in a significant loss of hydrogen-containing silicone oil.

[0061] In summary, this application provides a method for preparing a high-hydrogen-content silicone oil with low acid value. Under conditions of no water washing and no solvent, the method achieves the removal of acid from the high-hydrogen-content silicone oil, reduces the initial acid value, and prevents acid reversion after 3 months of storage at room temperature. It has the advantages of simple process, low cost, good environmental performance, and suitability for industrialization.

[0062] The basic principles, main features, and advantages of this application have been described above. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely the principles of this application. Various changes and modifications can be made to this application without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection claimed by this application is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a low-acid-value, high-hydrogen-content silicone oil, characterized in that, The preparation steps include the following: S1: The raw material containing methyldichlorosilane is hydrolyzed with water. After standing and separating into layers, the silicone oil layer is taken and dried to remove water. A polymerization activator is added to the dried silicone oil to carry out a polymerization reaction. After the reaction is completed, the polymerized silicone oil is obtained by filtration. S2: Heat the polymerized silicone oil to 140~160 ℃ and keep it at that temperature for 30~90 min. After the temperature is maintained, perform a pressure reduction treatment to remove low molecular weight volatiles. S3: Add chemical dechlorinating agent and other additives to the dechlorinated silicone oil for further refining, and obtain the low acid value high hydrogen content silicone oil after filtration.

2. The preparation method according to claim 1, characterized in that, The raw materials containing methyldichlorosilane are methyldichlorosilane and trimethylchlorosilane, and the mass ratio of methyldichlorosilane to trimethylchlorosilane is (20~30):

1.

3. The preparation method according to claim 1, characterized in that, The hydrolysis reaction is carried out at a temperature of 0~15 ℃.

4. The preparation method according to claim 1, characterized in that, The polymerization agent is any one or a combination of activated clay, acid clay, or sulfuric acid.

5. The preparation method according to claim 1, characterized in that, The amount of the chemical dechlorinating agent used is 0.005% to 0.02% of the mass of the dechlorinated silicone oil.

6. The preparation method according to claim 1, characterized in that, In step S3, the chemical dechlorinating agent is any one of magnesium oxide, calcium oxide, or sodium bicarbonate.

7. The preparation method according to claim 1, characterized in that, The other additives include activated carbon, which is used for the physical adsorption of chlorine.

8. The preparation method according to claim 7, characterized in that, The other additives include diatomaceous earth, and the amount of diatomaceous earth added is 0.05% to 0.5% of the mass of the degraded silicone oil.

9. The preparation method according to claim 1, characterized in that, In step S2, the reduced pressure treatment can be performed by rotary evaporation or thin-film evaporation to remove low-molecular-weight volatiles from the telomerized silicone oil under negative pressure conditions of -98 kPa or higher and heating conditions of 150~160 ℃.

10. A low-acid-value, high-hydrogen-content silicone oil, characterized in that, It is prepared by any one of the preparation methods described in claims 1 to 9.

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