Preparation method of high-selectivity single-ended vinyl silicone oil

Abstract

The invention provides a preparation method of high-selectivity single-ended vinyl silicone oil, which comprises the following steps: adding a hydroxyl-terminated polydimethylsiloxane linear body into low-viscosity dimethyl silicone oil, uniformly mixing, adding linear phosphonitrile chloride for catalysis, and vacuumizing to remove water; continuously raising the temperature, adding a viscosity reduction catalyst, mixing a tetramethyl divinyl disiloxane double-end sealing agent, a dimethyl vinyl ethyoxyl silane single-end sealing agent and low-viscosity dimethyl silicone oil, dropwise adding the mixture into the reaction kettle, keeping the temperature, balancing, vacuumizing, and further removing water; then adding a hexamethyldisilazane neutralizing agent to carry out neutralization treatment; and after the neutralization is completed, entering a low-boiling-point removal process, carrying out reduced pressure distillation to remove low-boiling-point substances, and thus obtaining single-end vinyl polydimethylsiloxane. The single-ended vinyl silicone oil is applied to mold silica gel of liquid silicone rubber and can replace low-viscosity dimethyl silicone oil, the product hardness is adjusted, the oil seepage rate of the silicone oil is reduced, and the oil seepage phenomenon commonly existing in the industry is improved.

Description

Technical Field

[0001] The present invention relates to the polymerization production of organic silicon polymer materials, and in particular to a method for preparing a highly selective single-end vinyl silicone oil. The silicone oil is mainly used as a hardness regulator for mold silica gel in liquid silicone rubber to reduce the hardness of the product and solve the oil seepage rate problem. Background Art

[0002] Single-end vinyl silicone oil, with an inert methyl group at one end of the main chain and a reactive vinyl group at the other, possesses the ability to participate in addition reactions without significantly increasing the crosslink density. Therefore, it can be used as a hardness modifier for mold silicone rubber in liquid silicone rubber. Traditional mold silicone rubber primarily uses low-viscosity dimethyl silicone oil to adjust its hardness. However, due to its inertness, short molecular chain, and high addition ratio, silicone products are prone to oil leakage, a common phenomenon in the industry. To address this issue, a low-viscosity single-end vinyl silicone oil has been synthesized to replace low-viscosity dimethyl silicone oil. This significantly reduces the oil leakage rate of mold silicone rubber, effectively resolving the industry's oil leakage problem.

[0003] The traditional method for synthesizing single-end vinyl silicone oil mainly adopts octamethylcyclotetrasiloxane or dimethylsiloxane mixed ring body. Under the action of alkaline catalysts such as tetramethylammonium hydroxide, potassium hydroxide or lithium hydroxide, by regulating the addition ratio of vinyl double head and methyl double head, a "one-pot mixing" addition process is adopted. The selectivity of the silicone oil end-capping agent prepared is poor. The silicone oil product contains multiple components such as double-end vinyl silicone oil, single-end vinyl silicone oil and dimethyl silicone oil. The total yield does not exceed 90%, and the selectivity of single-end vinyl silicone oil is not high, resulting in poor application effect. Therefore, it is urgent to develop a preparation method of single-end vinyl silicone oil with high yield and good application effect to solve this problem.

[0004] Chinese patent publication number CN118085288A discloses a method for preparing monovinyl silicone oil, which uses octamethylcyclotetrasiloxane and phenylsiloxane as raw materials, hexamethyldisiloxane as a methyl end-capping agent, and tetramethyldivinyldisiloxane as a vinyl end-capping agent. The raw materials and the end-capping agent are mixed in a certain proportion, and the single-end vinyl silicone oil is prepared under the catalytic action of tetramethylammonium hydroxide alkali gel. This method adopts a "one-pot mixing" preparation method of the end-capping agent, and uses a ring body as a raw material. The proportion of the single-end vinyl silicone oil component is not high, which affects the application and quality of the single-end vinyl silicone oil; Chinese patent publication number CN111234230A Disclosed is a method for preparing single-terminal vinyl polydimethylsiloxane. The method also uses traditional dimethylsiloxane mixed ring (DMC) and octamethylcyclotetrasiloxane (D4) as raw materials. Under the catalysis of tetramethylammonium hydroxide, tetramethyldivinyldisiloxane and dimethyl silicone oil are added as capping agents, and a nano-modifier is added to accurately control the reaction temperature to prepare single-terminal vinyl silicone oil. The method is also a "one-pot" preparation process, and the nano-filler added in the process requires additional filtration treatment. For silicone oil with higher viscosity, it is more difficult to filter out the nano-material. The powder after stirring and grinding is easily dispersed and deposited in the product, affecting hidden indicators such as the product appearance.

[0005] The present invention adopts a preparation process, selects hydroxyl-terminated polydimethylsiloxane linear body as raw material, uses homemade linear chlorophosphazene as catalyst, mixes vinyl double end cap, vinyl single end cap and low viscosity methyl silicone oil in proportion, controls the continuous dripping rate of the end capping agent, and other processes to prepare highly selective single-end vinyl silicone oil. Since the prepared single-end vinyl silicone oil lacks a method for directly testing or characterizing the distribution of single-end vinyl groups, it is impossible to accurately measure the components and distribution of the single-end vinyl silicone oil. The present invention characterizes the total vinyl content index of the silicone oil and simultaneously carries out application evaluation experiments to evaluate the hardness and oil permeability index of the single-end vinyl silicone oil after being applied to the mold glue. When the double-end vinyl content in the silicone oil component is high, the total vinyl content will increase, and the hardness of the mold glue will be greatly improved. When the methyl end capping ratio in the silicone oil component is high, the oil permeability of the mold glue will be significantly increased. Therefore, the three indicators are combined to indirectly reflect the effective components of the single-end vinyl silicone oil. Summary of the Invention

[0006] The object of the present invention is to address the above technical deficiencies and provide a method for preparing a highly selective single-end vinyl silicone oil. The present invention uses hydroxyl-terminated polydimethylsiloxane as a basic raw material, linear chlorophosphazene as a high-yield catalyst, and tetramethyldivinyldisiloxane double-end capping agent, dimethylvinylethoxysilane single-end capping agent and low-viscosity dimethyl are mixed in a certain proportion, and end-capping is performed using a continuous dropwise control process to prepare a highly selective single-end vinyl silicone oil. The highly selective single-end vinyl silicone oil is used in low-hardness mold glue of liquid silicone rubber to replace methyl silicone oil as a hardness regulator, thereby significantly reducing the oil seepage rate of silicone oil.

[0007] In order to achieve the above object, the present invention provides the following technical solutions: A method for preparing a highly selective single-end vinyl silicone oil comprises the following steps: (1) After vacuum dehydration of the linear body, add low-viscosity dimethyl silicone oil and mix evenly; (2) dissolving the polycondensation catalyst in low-viscosity dimethyl silicone oil and diluting it, adding the diluted polycondensation catalyst to step (1), and performing a polycondensation reaction under vacuum; (3) The depolymerization catalyst is dissolved in low-viscosity dimethyl silicone oil and diluted. The material of step (2) is heated to the activation temperature, the diluted depolymerization catalyst is added, and the end-capping agent is slowly added dropwise to the reactor while stirring at high speed. After the addition is completed, the temperature is kept constant for 0.5 hours and the water is removed by vacuum. (4) adding a neutralizing agent to the material of step (3) for neutralization treatment; (5) The neutralized material in step (4) is subjected to a decompression treatment to obtain a single-end vinyl silicone oil.

[0008] As a preferred embodiment of the above technology, the dehydration temperature in step (1) is 60-70°C, the vacuum degree is -95~-100 kPa, the vacuuming time is 0.3-0.5 h, and stirring is performed during the vacuuming process, wherein the stirring rate is 250~300 r / min.

[0009] As a preferred embodiment of the above technology, the viscosity of the low-viscosity dimethyl silicone oil in step (1) is 10-50 cSt, and the added mass ratio is 1.0%-12.5%.

[0010] The polycondensation catalyst in step (2) and the depolymerization catalyst in step (3) are the same substance, both being homemade linear chlorophosphazene catalysts (patent CN114044904B), capable of both polycondensation and depolymerization. The catalyst dilution mass concentration is 0.5%-1.0%. During the polycondensation stage, 1-2 ppm of catalyst is added, and the polycondensation reaction is carried out under vacuum for 0.5-1.0 h. The vacuum degree is controlled at -90 to -95 kPa, and the viscosity of the polycondensation intermediate is controlled at 30,000-50,000 cP.

[0011] In step (3), the activation temperature is controlled at 90-100° C. After the temperature is reached, 3-6 ppm of linear chlorophosphazene catalyst is added for depolymerization, and the mixed end-capping agent is added dropwise while stirring under normal pressure. After the end-capping agent is added, the mixture is stirred and balanced for 0.5-1 hour.

[0012] As a preferred embodiment of the above technology, the end-capping agent in step (3) is two or three of tetramethyldivinyldisiloxane double end-capping agent, dimethylvinylethoxysilane single end-capping agent and low-viscosity dimethyl silicone oil.

[0013] In some preferred cases, when there are three end-capping agents, the mass ratio of tetramethyldivinyldisiloxane double end-capping agent, dimethylvinylethoxysilane single end-capping agent and low-viscosity dimethyl silicone oil is 0.5-5:0.5-3:0.5-13.

[0014] In some preferred cases, when there are two end-capping agents, for example, the mass ratio of tetramethyldivinyldisiloxane double end-capping agent and dimethylvinylethoxysilane single end-capping agent is 0.5-5:0.5-3.

[0015] In some preferred cases, when there are two end-capping agents, for example, the mass ratio of tetramethyldivinyldisiloxane double end-capping agent and low-viscosity dimethyl silicone oil is 0.5-5: 0.5-13.

[0016] In some preferred cases, when there are two capping agents, for example, the mass ratio of dimethylvinylethoxysilane single capping agent and low-viscosity dimethyl silicone oil is 0.5-3:0.5-13.

[0017] The flow rate of the capping agent was controlled at 0.5-3 g / min, and the stirring rate was controlled at 350-400 r / min.

[0018] As a preferred embodiment of the above technology, the vacuuming temperature in step (3) is maintained at 9-100°C, the vacuum degree is -90~-95kPa, and the vacuuming time is 1-1.5h.

[0019] As a preferred embodiment of the above technology, the neutralizing agent in step (4) is one or more of hexamethyldisilazane, tetramethyldivinyldisilazane, sodium hydroxide, and potassium hydroxide. The added mass of the neutralizing agent is 1.5-2.5 times the total mass of the linear chlorophosphazene catalyst, and the neutralization reaction time is 2-2.5 hours.

[0020] As a preferred embodiment of the above technology, the degassing temperature in step (5) is 190-210°C, and the degassing vacuum degree is -98~-100kPa.

[0021] Due to the adoption of the above technical solution, the present invention has the following beneficial effects: Compared with the traditional production process using DMC as raw material, the present invention has the following advantages: first, a hydroxyl-terminated linear body is selected as the raw material, resulting in a high product yield; second, a mixture of tetramethyldivinyldisiloxane double-capping agent, dimethylvinylethoxysilane single-capping agent and low-viscosity dimethyl silicone oil is selected in proportion as the capping agent, thereby improving the selectivity of the single end; third, by controlling the dripping process of the capping agent, the methyl capping group and the vinyl capping group can be more evenly capped at both ends of the molecular chain, thereby obtaining a highly selective single-end vinyl silicone oil; and fourth, hexamethyldisilazane is selected as the neutralizing agent, which can greatly reduce the residual hydroxyl content in the product and improve the quality of the silicone oil. DETAILED DESCRIPTION

[0022] The present invention is further explained below with reference to the following examples, but the examples do not limit the present invention in any form.

[0023] Example 1 (1) Preparation of single-ended ethylene silicone oil Add 10 kg of the linear solid into the reactor, heat to 70 ° C and dehydrate for 0.5 h before use; add 0.53 kg of 10 cSt dimethyl silicone oil at a ratio of 5.3% of the mass of the linear solid; After the mixture is evenly mixed, 1.0 g of a linear phosphazene catalyst diluted to a concentration of 1% (catalyst effective content 1 ppm, the catalyst is the product of Example 1 in patent CN114044904B) is added, and the mixture is evacuated. The mixture is reacted under vacuum for 0.5 h to carry out polycondensation reaction until no water droplets flow out. The temperature was raised to 100°C to reach the activation temperature for depolymerization, and 3.0 g of a diluted 1% concentration linear phosphazene catalyst (catalyst effective content 3 ppm, the catalyst being the product of Example 1 in patent CN114044904B) was added to carry out a depolymerization reaction; 50 g of tetramethyldivinyldisiloxane double capping agent, 250 g of dimethylvinylethoxysilane single capping agent, and 100 g of 10 cSt dimethyl silicone oil were weighed at a ratio of 0.5% of the linear mass, and 1.0% of the linear mass, respectively. After thorough mixing, the mixed capping agent was slowly added dropwise to the reactor at a flow rate of 2 g / min at 100°C, with high-speed stirring while adding, controlling the speed at 350-500 r / min. After the addition, the siloxane intermediate was kept warm and evacuated for 2 hours. 0.08 g of hexamethyldisilazane (8 ppm) was then added for neutralization for 2 hours. After qualified neutralization, the product entered the de-low-boiling process, and was de-low-boiling by reduced pressure distillation at 200°C to remove low-boiling substances to obtain a low-viscosity single-end vinyl silicone oil.

[0024] (2) Preparation of low hardness mold silicone 100 g of commercially available addition-type liquid silicone rubber base was selected, 65 g of the above-synthesized single-end vinyl silicone oil and 15 g of 10 cSt dimethyl silicone oil were added, and after mixing evenly, 0.5 g of 0.18% hydrogenated silicone oil and 0.05 g of 1-ethynylcyclohexanol inhibitor were added in sequence. After mixing evenly, 3 ppm of Custer platinum catalyst (catalyst concentration 300 ppm) was added, and after stirring and mixing evenly, it was placed in a mold, vacuumed to remove bubbles, and then placed in a 130 ° C environment for vulcanization for 10 minutes. The vulcanized samples were cut and made into sheets, and the hardness, tensile strength, tear strength and oil permeability were tested.

[0025] Example 2 (1) Preparation of single-ended ethylene silicone oil 70 g of tetramethyldivinyldisiloxane double-capping agent was weighed at a ratio of 0.7% of the linear body mass, 230 g of dimethylvinylethoxysilane single-capping agent was weighed at a ratio of 2.3% of the linear body mass, and 120 g of 10 cSt dimethyl silicone oil was weighed at a ratio of 1.2% of the linear body mass. After thorough mixing, the mixed capping agent was slowly added dropwise to the reactor at a flow rate of 2 g / min at 100°C. The remaining steps were the same as the preparation steps of (1) single-end vinyl silicone oil in Example 1.

[0026] (2) Preparation of low hardness mold silicone The vulcanization formula ratio and steps are the same as those of (2) the low-hardness mold silicone preparation step in Example 1, and the vulcanized samples are cut and made into sheets.

[0027] Example 3 (1) Preparation of single-ended ethylene silicone oil 100 g of tetramethyldivinyldisiloxane double-capping agent was weighed at a ratio of 1.0% of the linear body mass, 200 g of dimethylvinylethoxysilane single-capping agent was weighed at a ratio of 2.0% of the linear body mass, and 150 g of 10 cSt dimethyl silicone oil was weighed at a ratio of 1.5% of the linear body mass. After thorough mixing, the mixed capping agent was slowly added dropwise to the reactor at a flow rate of 2 g / min at 100°C. The remaining steps were the same as the preparation steps of (1) single-end vinyl silicone oil in Example 1.

[0028] (2) Preparation of low hardness mold silicone The vulcanization formula ratio and steps are the same as those of (2) the low-hardness mold silicone preparation step in Example 1, and the vulcanized samples are cut and made into sheets.

[0029] Example 4 (1) Preparation of single-ended ethylene silicone oil 120 g of tetramethyldivinyldisiloxane double-capping agent was weighed at a ratio of 1.2% of the linear body mass, 180 g of dimethylvinylethoxysilane single-capping agent was weighed at a ratio of 1.8% of the linear body mass, and 170 g of 10 cSt dimethyl silicone oil was weighed at a ratio of 1.7% of the linear body mass. After thorough mixing, the mixed capping agent was slowly added dropwise to the reactor at a flow rate of 2 g / min at 100°C. The remaining steps were the same as the preparation steps of (1) single-end vinyl silicone oil in Example 1.

[0030] (2) Preparation of low hardness mold silicone The vulcanization formula ratio and steps are the same as those of (2) the low-hardness mold silicone preparation step in Example 1, and the vulcanized samples are cut and made into sheets.

[0031] Example 5 (1) Preparation of single-ended ethylene silicone oil 150 g of tetramethyldivinyldisiloxane double-capping agent, 150 g of dimethylvinylethoxysilane single-capping agent, and 200 g of 10 cSt dimethyl silicone oil were weighed at a ratio of 1.5% of the linear mass, and 2.0% of the linear mass, respectively. After thorough mixing, the mixed capping agents were slowly added dropwise to the reactor at a flow rate of 2 g / min at 100°C. The remaining steps were the same as those for the preparation of single-end vinyl silicone oil (1) in Example 1.

[0032] (2) Preparation of low hardness mold silicone The vulcanization formula ratio and steps are the same as those of (2) the low-hardness mold silicone preparation step in Example 1, and the vulcanized samples are cut and made into sheets.

[0033] Example 6 (1) Preparation of single-ended ethylene silicone oil 100 g of tetramethyldivinyldisiloxane double-capping agent was weighed at a ratio of 1.0% of the linear body mass, 200 g of dimethylvinylethoxysilane single-capping agent was weighed at a ratio of 2.0% of the linear body mass, and 150 g of 10 cSt dimethyl silicone oil was weighed at a ratio of 1.5% of the linear body mass. After thorough mixing, the mixed capping agent was slowly added dropwise to the reactor at a flow rate of 1 g / min at 100°C. The remaining steps were the same as the preparation steps of (1) single-end vinyl silicone oil in Example 1.

[0034] (2) Preparation of low hardness mold silicone The vulcanization formula ratio and steps are the same as those of (2) the low-hardness mold silicone preparation step in Example 1, and the vulcanized samples are cut and made into sheets.

[0035] Example 7 (1) Preparation of single-ended ethylene silicone oil 100 g of tetramethyldivinyldisiloxane double-capping agent was weighed at a ratio of 1.0% of the linear body mass, 200 g of dimethylvinylethoxysilane single-capping agent was weighed at a ratio of 2.0% of the linear body mass, and 150 g of 10 cSt dimethyl silicone oil was weighed at a ratio of 1.5% of the linear body mass. After thorough mixing, the mixed capping agent was slowly added dropwise to the reactor at a flow rate of 3 g / min at 100°C. The remaining steps were the same as the preparation steps of (1) single-end vinyl silicone oil in Example 1.

[0036] (2) Preparation of low hardness mold silicone The vulcanization formula ratio and steps are the same as those of (2) the low-hardness mold silicone preparation step in Example 1, and the vulcanized samples are cut and made into sheets.

[0037] Comparative Example 1 (1) Preparation of single-ended ethylene silicone oil 430 g of tetramethyldivinyldisiloxane double-end capping agent was weighed at a ratio of 4.3% of the linear body mass, and the double-end capping agent was added to the reactor at one time. The remaining steps were the same as the preparation steps of (1) single-end vinyl silicone oil in Example 1.

[0038] (2) Preparation of low hardness mold silicone The vulcanization formula ratio and steps are the same as those of (2) the low-hardness mold silicone preparation step in Example 1, and the vulcanized samples are cut and made into sheets.

[0039] Comparative Example 2 (1) Preparation of single-ended ethylene silicone oil 300 g of tetramethyldivinyldisiloxane double-end capping agent was weighed at a ratio of 3.0% of the linear body mass, and the single-end capping agent was added to the reactor at one time. The remaining steps were the same as the preparation steps of (1) single-end vinyl silicone oil in Example 1.

[0040] (2) Preparation of low hardness mold silicone The vulcanization formula ratio and steps are the same as those of (2) the low-hardness mold silicone preparation step in Example 1, and the vulcanized samples are cut and made into sheets.

[0041] Comparative Example 3 (1) Preparation of single-ended ethylene silicone oil Weigh 125 g of 10 cSt dimethyl silicone oil at a ratio of 12.5% ​​of the linear volume mass and add the dimethyl silicone oil into the reactor at one time. The remaining steps are the same as those for the preparation of the single-end vinyl silicone oil (1) in Example 1.

[0042] (2) Preparation of low hardness mold silicone The vulcanization formula ratio and steps are the same as those of (2) the low-hardness mold silicone preparation step in Example 1, and the vulcanized samples are cut and made into sheets.

[0043] Comparative Example 4 (1) Preparation of single-ended ethylene silicone oil 100 g of tetramethyldivinyldisiloxane double-capping agent was weighed at a ratio of 1.0% of the linear mass, 200 g of dimethylvinylethoxysilane single-capping agent was weighed at a ratio of 2.0% of the linear mass, and 150 g of 10 cSt dimethyl silicone oil was weighed at a ratio of 1.5% of the linear mass. After thorough mixing, the mixed capping agents were added to the reactor at one time. The remaining steps were the same as the preparation steps of (1) single-end vinyl silicone oil in Example 1.

[0044] (2) Preparation of low hardness mold silicone The vulcanization formula ratio and steps are the same as those of (2) the low-hardness mold silicone preparation step in Example 1, and the vulcanized samples are cut and made into sheets.

[0045] The single-end vinyl silicone oils prepared in Examples 1-7 and Comparative Examples 1-4 were prepared by controlling the proportion and addition rate of the capping agent. The silicone oil indicators obtained are shown in the following table: Table 1 Control process parameters and product indicators of single-ended vinyl silicone oil sealing agent

[0046] The single-end vinyl silicone oils prepared in Examples 1-7 and Comparative Examples 1-4 are applied to the low-hardness mold silicone formula in liquid silicone rubber. The product test indicators are compared as follows: Table 2 Product performance test indicators

[0047] As shown in Table 2, the present invention, by screening the type, mixed ratio and addition process of capping agent, prepares highly selective single-end vinyl silicone oil, is applied to the formula of the low hardness mold silica gel in liquid silicone rubber, reduces hardness, and improves oil permeability simultaneously.By embodiment 1-5 and comparative example 1-3 contrast, it can be seen that double end ratio is higher, and mold glue hardness is higher, and oil permeability is lower, when tetramethyl divinyl disiloxane double end: dimethylvinyl ethoxysilane single end agent: when the ratio of 10cSt dimethyl silicone oil is 1:2:1.5, by dropping process, the silicone oil prepared is used for mold silica gel, and hardness and oil permeability can be significantly reduced;By comparative example 5-7 and comparative example 4 contrast, it can be seen that by controlling capping agent dropping rate, oil permeability phenomenon can be significantly improved, when rate of addition control is slower, the selectivity of single-end vinyl silicone oil is higher, the ratio of the single-end vinyl silicone oil of synthesis is higher, and the accounting of double end-capping is lower, and hardness will not have significantly improved after mold glue, and the more obvious that oil permeability phenomenon is reduced.

[0048] The specific embodiments of the present invention described above do not limit the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a highly selective single-end vinyl silicone oil, characterized in that: The following steps are involved: (1) Vacuum dehydration of hydroxyl-terminated polydimethylsiloxane linear solids, adding low-viscosity dimethyl silicone oil and mixing evenly; (2) dissolving the polycondensation catalyst in low-viscosity dimethyl silicone oil, adding the polycondensation catalyst to step (1) after dilution, and performing the polycondensation reaction under vacuum; (3) dissolving the depolymerization catalyst in low-viscosity dimethyl silicone oil, heating the material in step (2) to the activation temperature, adding the depolymerization catalyst, and slowly dropping the end-capping agent into the reactor while stirring. After the addition is completed, heat and balance, and then vacuum remove water; (4) adding a neutralizing agent to the material of step (3) for neutralization treatment; (5) The neutralized material in step (4) is subjected to a decompression treatment to obtain a single-end vinyl silicone oil.

2. The method for preparing a single-end vinyl silicone oil according to claim 1, wherein The dehydration temperature in step (1) is 60-70° C., the vacuum degree is -95-100 kPa, and stirring is performed during the vacuuming process, wherein the stirring rate is 350-400 r / min.

3. The method for preparing a single-end vinyl silicone oil according to claim 1, wherein The viscosity of the low-viscosity dimethyl silicone oil in step (1) is 10-50 cSt.

4. The method for preparing a single-end vinyl silicone oil according to claim 1, wherein The polycondensation catalyst in step (2) and the depolymerization catalyst in step (3) are the same substance, both of which are linear chlorophosphazene catalysts prepared in patent CN114044904B.

5. The method for preparing single-end vinyl silicone oil according to claim 4, wherein The dilution concentration of the polycondensation catalyst or depolymerization catalyst is 0.5%-1.0%.

6. The method for preparing a single-end vinyl silicone oil according to claim 4, wherein The amount of polycondensation catalyst added in the polycondensation stage is 1-2 ppm, the vacuuming time is 0.5-1.0 h, and the viscosity of the intermediate obtained after the polycondensation reaction is controlled at 30,000-50,000 cP; The amount of depolymerization catalyst added in the depolymerization stage is 3-6 ppm, and the activation temperature is controlled at 90-100°C.

7. The method for preparing a single-end vinyl silicone oil according to claim 1, wherein The end-capping agent in step (3) is two or three of tetramethyldivinyldisiloxane double-end-capping agent, dimethylvinylethoxysilane single-end-capping agent and low-viscosity dimethyl silicone oil. The end-capping agent addition flow rate is controlled to be 0.5-3 g / min, and the stirring speed is controlled to be 350-500 r / min.

8. The method for preparing single-end vinyl silicone oil according to claim 1, wherein In the step (4), the vacuuming temperature is maintained at 90-100°C, the vacuum degree is -90~-95kPa, and the vacuuming time is 1-1.5h.

9. The method for preparing single-end vinyl silicone oil according to claim 1, wherein The neutralizing agent in step (5) is one or two of hexamethyldisilazane, tetramethyldivinyldisilazane and hydroxide, the amount added is 1.5-2.5 times the mass of the catalyst, and the neutralization time is 2-2.5 hours.

10. The method for preparing single-end vinyl silicone oil according to claim 1, wherein The degassing temperature in step (5) is 190-210° C., and the degassing vacuum degree is -98~-100 kPa.

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