Process for preparing silicone rubber with low residual amount of low-vinyl silicone oil ring

Abstract

The application discloses a kind of low vinyl silicone oil ring body residual amount of silicone rubber preparation process, comprising: dimethylsiloxane mixed ring body is heated and stirred, and vacuum device dehydration;Vinyl end cap is added to dimethylsiloxane mixed ring body, stirring is heated, while nitrogen is imported, after reaction, composite catalyst is added, and it is 3-4h after balance and is polymerized, then it is heated and broken, after filtration, it is obtained that end vinyl silicone oil is removed by low vacuum;End vinyl silicone oil and structural treatment agent are added to kneader and stirred uniformly, then batched gas phase white carbon black is added, after stirring, vacuum is extracted, after dilution, liquid glue base glue is obtained;Liquid glue base glue is ground and dispersed to form glue base fine powder;Then glue base fine powder, vinyl silicone oil, low hydrogen-containing silicone oil and inhibitor are reacted to obtain silicone rubber.The application utilizes dimethylsiloxane mixed ring body to prepare low dimethylsiloxane ring body residual end vinyl silicone oil, realizes the low residual of dimethylsiloxane mixed ring body in silicone rubber.

Description

Technical Field

[0001] This invention belongs to the field of silicone rubber technology, specifically relating to a process for preparing silicone rubber with low vinyl silicone oil cyclic residue. Background Technology

[0002] Silicone oil is an essential raw material in the preparation of silicone rubber. Silicone oil is formed by the catalytic polymerization of dimethylsiloxane cyclic compounds, and therefore contains varying amounts of these compounds. Studies have shown that dimethylsiloxane cyclic compounds exhibit proliferative toxicity and adversely affect the human nervous system. The Stockholm Convention has listed them as suspected or potential persistent organic pollutants. Therefore, the preparation of silicone rubber with low levels of residual dimethylsiloxane cyclic compounds is of great significance for product quality control, environmental protection, and human health. Summary of the Invention

[0003] To address the problems in the prior art, this invention provides a method for preparing silicone rubber with low vinyl silicone oil cyclic residue. The method utilizes vacuum dehydration and vacuum de-oxidation to remove water molecules from the dimethylsiloxane mixed cyclic structure. Furthermore, the synergistic effect of an alkaline catalyst and temperature promotes the ring-opening reaction of the cyclic structure, achieving an effective treatment effect. Simultaneously, a high-temperature de-oxidation system is used to remove small molecule materials and cyclic structures, effectively reducing the residual amount of dimethylsiloxane mixed cyclic structure.

[0004] To achieve the above technical objectives, the technical solution of the present invention is as follows: A method for preparing silicone rubber with low vinyl silicone oil cyclic residue includes the following steps: Step 1: The dimethylsiloxane mixed ring is added to the reaction vessel, heated and stirred, and dehydrated using a vacuum device to remove trace amounts of water; the dimethylsiloxane mixed ring is purchased from Zhejiang Hengyecheng Organosilicon Co., Ltd.; the heating and stirring temperature is 65-105℃; this step involves heating and vacuum dehydration of the dimethylsiloxane mixed ring to achieve rapid removal of water molecules and achieve the desired removal effect; Step 2: Add the vinyl end-capping agent to the above-mentioned dimethylsiloxane mixed ring, stir and heat to 100-130℃, simultaneously introducing nitrogen gas, react for 15 minutes, then add the composite catalyst, and after equilibrium polymerization for 3-4 hours, heat to 140-180℃ for catalyst breaking for 1 hour. After filtration, remove the end-vinyl silicone oil under vacuum; the vinyl end-capping agent is a mixture of divinyltetramethyldisiloxane and tetramethyltetravinylcyclotetrasiloxane, and the divinyltetramethyldisiloxane and tetramethyltetravinylcyclotetrasiloxane... The mass ratio of alkenylcyclotetrasiloxane is 1-2:2, and the mass ratio of the vinyl end-capping agent to the dimethylsiloxane mixed ring is 10-25:100. The composite catalyst is a mixture of tetramethylammonium hydroxide and potassium hydroxide, and the amount of potassium hydroxide used is 2% of the mass of tetramethylammonium hydroxide. The vacuum desorption temperature is 150-180℃, and the pressure is -0.5kPa. In this step, the vinyl end-capping agent is added to the dimethylsiloxane mixed ring and heated, and nitrogen is used to desorb... Impurity gases are removed to create a nitrogen inert atmosphere. Simultaneously, a composite catalyst is added and reacted at a constant temperature to form vinyl silicone oil. Tetramethylammonium hydroxide is decomposed and removed by heating. Finally, small molecule materials are removed using a de-oxidation device, resulting in a vinyl silicone oil material with low cyclic content (below 300 ppm). In this step, both tetramethylammonium hydroxide and potassium hydroxide exhibit good catalytic activity. When tetramethylammonium hydroxide forms the catalytic system, potassium hydroxide also produces a corresponding catalytic effect. After the catalytic reaction is complete, and the tetramethylammonium hydroxide is decomposed by heating, the activity of potassium hydroxide is enhanced, further catalyzing the remaining cyclic compounds. This further reaction of the cyclic compounds reduces the residual cyclic compounds in the vinyl silicone oil. At the same time, potassium hydroxide is filtered out in the reaction system, achieving good removal of the composite catalyst and solving the problem of difficult separation and removal of the composite catalyst. Step 3: Add the above-mentioned vinyl-terminated silicone oil and structuring agent to a kneader and stir evenly. Then, add fumed silica in batches and stir with gradient heating. After stirring, vacuum for 2-3 hours. After dilution, discharge to obtain liquid adhesive. The structuring agent is hydroxyl silicone oil, and the mass ratio of the vinyl-terminated silicone oil to the structuring agent is 100:2-15. The stirring speed for even stirring is 100-200 r / min. The amount of fumed silica added is 20-40% of the mass of the vinyl-terminated silicone oil. The gradient heating and stirring adopts a dual-gradient stirring method, with the first gradient temperature at 120℃ and stirring time at 1 hour, and the second gradient temperature at 150℃ and stirring time at 2 hours. The vacuum pressure is not greater than 1 kPa. The dilution uses vinyl silicone oil with a vinyl content of 5%, and the mass ratio of vinyl silicone oil to vinyl-terminated silicone oil during the dilution process is 80:3-20. Step 4: Grind and disperse the liquid adhesive base in a grinder to obtain a fine powder of the base adhesive; then add the fine powder of the base adhesive, vinyl silicone oil, low-hydrogen silicone oil and inhibitor to a reaction vessel, stir at room temperature for 40 minutes, and then degas under vacuum for 5 minutes to obtain silicone rubber. The amount of vinyl silicone oil added is 10-20% of the mass of the fine powder of the base adhesive, the hydrogen content of the low-hydrogen silicone oil is 0.36%, and the amount of the low-hydrogen silicone oil added is 5-10% of the mass of the fine powder of the base adhesive. The inhibitor is a polyvinyl polysiloxane, and the amount of the inhibitor added is 0.2-0.5% of the mass of the fine powder of the base adhesive.

[0005] In this technical solution, silica, as one of the raw materials for liquid adhesive base, contains a small amount of alcohol hydroxyl groups on its surface, ensuring stable bonding with other materials. However, the hydroxyl groups on the silica surface do not react with vinyl groups, causing a decrease in its bonding stability within the base adhesive. To improve the stability of silica in liquid adhesive base, silica undergoes surface modification treatment. This modification treatment utilizes trichlorosilane to form a porous structure on the silica surface, effectively increasing the content of silanol hydroxyl groups and silane-hydrogen bonds, promoting the formation of multidimensional chemical bonds in the base adhesive. The modification treatment includes the following steps: a1, adding trichlorosilane to benzene and stirring until uniform to form a solution, then adding ethyl cellulose and ultrasonically treating for 20-40 minutes to obtain a mixed solution; the concentration of trichlorosilane in benzene is... The concentration of ethyl cellulose in the solution is 20-50 g / L, and the stirring speed is 100-300 r / min. The amount of ethyl cellulose added is 10-20% of the mass of trichlorosilane. The ultrasonic treatment frequency is 60-80 kHz, and the temperature is 10-20℃. This step utilizes the solubility of benzene in trichlorosilane and ethyl cellulose to form a stable and dispersed homogenized solution. Next, fumed silica is added to the solution and ultrasonically treated for 20-30 min. After filtration, the precipitate is sprayed into the reaction vessel to settle, yielding coated silica. The concentration of fumed silica in the solution is 100-300 g / L. The ultrasonic treatment frequency is 60-80 kHz, and the temperature is 20-30℃. The spraying speed is 5-10 g / min, and the spraying area is 100-400 cm². 2 The atmosphere inside the reactor is a mixture of water vapor and nitrogen, with a volume ratio of water vapor to nitrogen of 1:12-15, and the settling temperature is 85-90℃. This step utilizes ultrasonic dispersion of fumed silica in a solution to ensure uniform distribution of benzene on the surface area of ​​the fumed silica. Simultaneously, trichlorosilane and ethyl cellulose are deposited on the surface. After filtration, a liquid film forms on the silica surface. Following spraying, water molecules directly react with trichlorosilane to form a trihydroxysilane structure, and in-situ hydroxyl condensation occurs under temperature conditions, achieving an excellent surface shell structure. a3. The coated silica is placed in the reactor and light-treated for 1-2 hours to obtain modified silica. The light treatment uses infrared light, with an intensity of 2-5 W / cm². 2 The temperature is 200-230℃. This step utilizes light treatment to stabilize and decompose ethyl cellulose and promote the stability of trihydroxysilane hydroxyl condensation. The modified silica prepared by this process uses ethyl cellulose as a surface porogen, ensuring the formation of porous trihydroxysilane condensates on the silica surface. At this point, the modified silica surface contains silanol groups and silane-hydrogen bonds, effectively improving the surface activity of the silica. During use, the silane-hydrogen bonds can react with the vinyl groups on the silicone oil, effectively improving the stability of the silica.

[0006] As can be seen from the above description, the present invention has the following advantages: 1. This invention utilizes vacuum dehydration and vacuum de-lowering to remove water molecules from the dimethylsiloxane mixed rings, and promotes the ring-opening reaction of the rings under the synergistic effect of alkaline catalyst and temperature to achieve effective treatment. At the same time, the high-temperature de-lowering system removes small molecule materials and evaporates the rings, effectively reducing the residual amount of dimethylsiloxane mixed rings.

[0007] 2. This invention utilizes dimethylsiloxane mixed cyclic compounds to prepare terminal vinyl silicone oil with low dimethylsiloxane cyclic compound residue, effectively achieving low residue of dimethylsiloxane mixed cyclic compounds in silicone rubber.

[0008] 3. This invention utilizes the silicon-hydrogen bond modification of silica to form vinyl consumption in vinyl silicone oil within the base rubber, thereby improving the stability of silica within the base rubber and achieving the performance of silicone rubber. Detailed Implementation

[0009] The present invention will be described in detail with reference to the embodiments, but the claims of the present invention are not intended to limit the scope of the invention.

[0010] Example 1 A method for preparing silicone rubber with low vinyl silicone oil cyclic residue includes the following steps: Step 1: Surface modification treatment of silica includes the following steps: a1. Adding trichlorosilane to benzene and stirring until homogeneous to form a solution, then adding ethyl cellulose and ultrasonically treating for 20 min to obtain a mixture; the concentration of trichlorosilane in benzene is 20 g / L, the stirring speed is 100 r / min, the amount of ethyl cellulose added is 10% of the mass of trichlorosilane, the ultrasonic frequency of the ultrasonic treatment is 60 kHz, and the temperature is 10℃; a2. Adding fumed silica to the solution and ultrasonically treating for 20 min, filtering, and then spraying the precipitate into a reaction vessel for settling to obtain coated silica; the concentration of fumed silica in the solution is 100 g / L, the ultrasonic frequency of the ultrasonic treatment is 60 kHz, and the temperature is 20℃; the spraying speed is 5 g / min, and the spraying area is 100 cm². 2 The atmosphere inside the reactor is a mixture of water vapor and nitrogen, with a volume ratio of water vapor to nitrogen of 1:12, and the settling temperature is 85℃; a3, coated silica is placed in the reactor and phototreated for 1 hour to obtain modified silica. The phototreatment is infrared phototreatment with an intensity of 2 W / cm². 2 The temperature is 200℃; Step 2: Add the dimethylsiloxane mixed cyclic compound to the reactor, heat and stir, and dehydrate using a vacuum device to remove trace amounts of moisture; the dimethylsiloxane mixed cyclic compound was purchased from Zhejiang Hengyecheng Organosilicon Co., Ltd.; the temperature for heating and stirring was 65°C. Step 3: Add the vinyl end-capping agent to the above-mentioned dimethylsiloxane mixed ring, stir and heat to 100°C, simultaneously introducing nitrogen gas. After reacting for 15 minutes, add the composite catalyst, and after equilibration and polymerization for 3 hours, heat to 140°C for catalyst breaking for 1 hour. After filtration, remove the end-vinyl silicone oil under vacuum to obtain the final vinyl end-capping agent. The vinyl end-capping agent is a mixture of divinyltetramethyldisiloxane and tetramethyltetravinylcyclotetrasiloxane, with a mass ratio of 1:2. The mass ratio of the vinyl end-capping agent to the dimethylsiloxane mixed ring is 10:100. The composite catalyst is a mixture of tetramethylammonium hydroxide and potassium hydroxide, with the amount of potassium hydroxide being 2% of the mass of tetramethylammonium hydroxide. The vacuum removal temperature is 150°C, and the pressure is -0.5 kPa. Step 4: Add the above-mentioned vinyl-terminated silicone oil and structuring agent to a kneader and stir evenly. Then, add fumed silica in batches and stir with gradient heating. After stirring, vacuum for 2 hours. After dilution, discharge to obtain liquid adhesive. The structuring agent is hydroxyl silicone oil, the mass ratio of the vinyl-terminated silicone oil to the structuring agent is 100:2, the stirring speed is 100 r / min, the amount of fumed silica added is 20% of the mass of the vinyl-terminated silicone oil, the gradient heating and stirring adopts dual gradient stirring, the temperature of the first gradient is 120℃ and the stirring time is 1 hour, the temperature of the second gradient is 150℃ and the stirring time is 2 hours; the vacuum pressure is not greater than 1 kPa; the dilution uses vinyl silicone oil, the vinyl content of the vinyl silicone oil is 5%, and the mass ratio of vinyl silicone oil to vinyl-terminated silicone oil in the dilution process is 80:3. Step 5: Grind and disperse the liquid adhesive base in a grinder to obtain a fine powder of the base adhesive; then add the fine powder of the base adhesive, vinyl silicone oil, low-hydrogen silicone oil and inhibitor to a reaction vessel, stir at room temperature for 40 minutes, and then degas under vacuum for 5 minutes to obtain silicone rubber. The amount of vinyl silicone oil added is 10% of the mass of the fine powder of the base adhesive, the hydrogen content of the low-hydrogen silicone oil is 0.36%, and the amount of the low-hydrogen silicone oil added is 5% of the mass of the fine powder of the base adhesive. The inhibitor is a polyvinyl polysiloxane, and the amount of the inhibitor added is 0.2% of the mass of the fine powder of the base adhesive.

[0011] Example 2 A method for preparing silicone rubber with low vinyl silicone oil cyclic residue includes the following steps: Step 1: Surface modification treatment of silica, comprising the following steps: a1, adding trichlorosilane to benzene and stirring until homogeneous to form a solution, then adding ethyl cellulose and ultrasonically treating for 40 min to obtain a mixture; the concentration of trichlorosilane in benzene is 50 g / L, the stirring speed is 300 r / min, the amount of ethyl cellulose added is 20% of the mass of trichlorosilane, the ultrasonic frequency of the ultrasonic treatment is 80 kHz, and the temperature is 20℃; a2, adding fumed silica to the solution and ultrasonically treating for 20-30 min, filtering, and then spraying the precipitate into a reaction vessel for settling to obtain coated silica; the concentration of fumed silica in the solution is 300 g / L, the ultrasonic frequency of the ultrasonic treatment is 80 kHz, and the temperature is 30℃; the spraying speed is 10 g / min, and the spraying area is 400 cm². 2 The atmosphere inside the reactor is a mixture of water vapor and nitrogen, with a volume ratio of water vapor to nitrogen of 1:15, and the settling temperature is 90℃; a3, coated silica is placed in the reactor and phototreated for 2 hours to obtain modified silica. The phototreatment is infrared phototreatment with an intensity of 5 W / cm². 2 The temperature is 230℃; Step 2: Add the dimethylsiloxane mixed cyclic compound to the reactor, heat and stir, and dehydrate using a vacuum device to remove trace amounts of water; the dimethylsiloxane mixed cyclic compound was purchased from Zhejiang Hengyecheng Organosilicon Co., Ltd.; the temperature for heating and stirring was 105℃. Step 3: Add the vinyl end-capping agent to the above-mentioned dimethylsiloxane mixed ring, stir and heat to 130°C, simultaneously introduce nitrogen gas, react for 15 minutes, add the composite catalyst, and after equilibrium polymerization for 4 hours, heat to 180°C for catalyst breaking for 1 hour. After filtration, remove the end vinyl silicone oil under vacuum. The vinyl end-capping agent is a mixture of divinyltetramethyldisiloxane and tetramethyltetravinylcyclotetrasiloxane, and the mass ratio of divinyltetramethyldisiloxane to tetramethyltetravinylcyclotetrasiloxane is 2:2. The mass ratio of the vinyl end-capping agent to the dimethylsiloxane mixed ring is 25:100. The composite catalyst is a mixture of tetramethylammonium hydroxide and potassium hydroxide, and the amount of potassium hydroxide used is 2% of the mass of tetramethylammonium hydroxide. The vacuum removal temperature is 180°C and the pressure is -0.5 kPa. Step 4: Add the above-mentioned vinyl-terminated silicone oil and structuring agent to a kneader and stir evenly. Then, add fumed silica in batches and stir with gradient heating. After stirring, vacuum for 3 hours. After dilution, discharge to obtain liquid adhesive. The structuring agent is hydroxyl silicone oil, and the mass ratio of the vinyl-terminated silicone oil to the structuring agent is 100:15. The stirring speed for even stirring is 200 r / min. The amount of fumed silica added is 40% of the mass of the vinyl-terminated silicone oil. The gradient heating and stirring adopts a dual-gradient stirring method, with the first gradient temperature at 120℃ and stirring time at 1 hour, and the second gradient temperature at 150℃ and stirring time at 2 hours. The vacuum pressure is not greater than 1 kPa. The dilution uses vinyl silicone oil with a vinyl content of 5%, and the mass ratio of vinyl silicone oil to vinyl-terminated silicone oil during the dilution process is 80:20. Step 5: Grind and disperse the liquid adhesive base in a grinder to obtain a fine powder of the base adhesive; then add the fine powder of the base adhesive, vinyl silicone oil, low-hydrogen silicone oil and inhibitor to a reaction vessel, stir at room temperature for 40 minutes, and then degas under vacuum for 5 minutes to obtain silicone rubber. The amount of vinyl silicone oil added is 20% of the mass of the fine powder of the base adhesive, the hydrogen content of the low-hydrogen silicone oil is 0.36%, and the amount of the low-hydrogen silicone oil added is 10% of the mass of the fine powder of the base adhesive. The inhibitor is a polyvinyl polysiloxane, and the amount of the inhibitor added is 0.5% of the mass of the fine powder of the base adhesive.

[0012] Example 3 A method for preparing silicone rubber with low vinyl silicone oil cyclic residue includes the following steps: Step 1: Surface modification treatment of silica includes the following steps: a1. Adding trichlorosilane to benzene and stirring until homogeneous to form a solution, then adding ethyl cellulose and ultrasonically treating for 30 min to obtain a mixture; the concentration of trichlorosilane in benzene is 40 g / L, the stirring speed is 200 r / min, the amount of ethyl cellulose added is 10-20% of the mass of trichlorosilane, the ultrasonic frequency of the ultrasonic treatment is 70 kHz, and the temperature is 15℃; a2. Adding fumed silica to the solution and ultrasonically treating for 25 min, filtering, and then spraying the precipitate into a reaction vessel for settling to obtain coated silica; the concentration of fumed silica in the solution is 200 g / L, the ultrasonic frequency of the ultrasonic treatment is 70 kHz, and the temperature is 25℃; the spraying speed is 8 g / min, and the spraying area is 200 cm². 2 The atmosphere inside the reactor is a mixture of water vapor and nitrogen, with a volume ratio of water vapor to nitrogen of 1:14, and the settling temperature is 90℃; a3, coated silica is placed in the reactor and phototreated for 2 hours to obtain modified silica. The phototreatment is infrared irradiation, and the infrared irradiation intensity is 4 W / cm².2 The temperature is 220℃; Step 2: Add the dimethylsiloxane mixed cyclic compound to the reactor, heat and stir, and dehydrate using a vacuum device to remove trace amounts of water; the dimethylsiloxane mixed cyclic compound was purchased from Zhejiang Hengyecheng Organosilicon Co., Ltd.; the temperature for heating and stirring was 80℃. Step 3: Add the vinyl end-capping agent to the above-mentioned dimethylsiloxane mixed ring, stir and heat to 120°C, simultaneously introduce nitrogen gas, react for 15 minutes, add the composite catalyst, and after equilibrium polymerization for 4 hours, heat to 160°C for catalyst breaking for 1 hour. After filtration, remove the end vinyl silicone oil under vacuum. The vinyl end-capping agent is a mixture of divinyltetramethyldisiloxane and tetramethyltetravinylcyclotetrasiloxane, and the mass ratio of divinyltetramethyldisiloxane to tetramethyltetravinylcyclotetrasiloxane is 1:2. The mass ratio of the vinyl end-capping agent to the dimethylsiloxane mixed ring is 15:100. The composite catalyst is a mixture of tetramethylammonium hydroxide and potassium hydroxide, and the amount of potassium hydroxide used is 2% of the mass of tetramethylammonium hydroxide. The vacuum removal temperature is 170°C and the pressure is -0.5 kPa. Step 4: Add the above-mentioned vinyl-terminated silicone oil and structuring agent to a kneader and stir evenly. Then, add fumed silica in batches and stir with gradient heating. After stirring, vacuum for 3 hours. After dilution, discharge to obtain liquid adhesive. The structuring agent is hydroxyl silicone oil, and the mass ratio of the vinyl-terminated silicone oil to the structuring agent is 100:10. The stirring speed for even stirring is 150 r / min. The amount of fumed silica added is 20-40% of the mass of the vinyl-terminated silicone oil. The gradient heating and stirring adopts a dual-gradient stirring method, with the first gradient temperature at 120℃ and stirring time at 1 hour, and the second gradient temperature at 150℃ and stirring time at 2 hours. The vacuum pressure is not greater than 1 kPa. The dilution uses vinyl silicone oil with a vinyl content of 5%, and the mass ratio of vinyl silicone oil to vinyl-terminated silicone oil during the dilution process is 80:10. Step 5: Grind and disperse the liquid adhesive base in a grinder to obtain a fine powder of the base adhesive; then add the fine powder of the base adhesive, vinyl silicone oil, low-hydrogen silicone oil and inhibitor to a reaction vessel, stir at room temperature for 40 minutes, and then degas under vacuum for 5 minutes to obtain silicone rubber. The amount of vinyl silicone oil added is 15% of the mass of the fine powder of the base adhesive, the hydrogen content of the low-hydrogen silicone oil is 0.36%, and the amount of the low-hydrogen silicone oil added is 8% of the mass of the fine powder of the base adhesive. The inhibitor is a polyvinyl polysiloxane, and the amount of the inhibitor added is 0.4% of the mass of the fine powder of the base adhesive.

[0013] Example 4 A method for preparing silicone rubber with low vinyl silicone oil cyclic residue includes the following steps: Step 1: Add the dimethylsiloxane mixed cyclic compound to the reaction vessel, heat and stir, and dehydrate using a vacuum device to remove trace amounts of water; the dimethylsiloxane mixed cyclic compound was purchased from Zhejiang Hengyecheng Organosilicon Co., Ltd.; the temperature for heating and stirring was 80℃. Step 2: Add the vinyl end-capping agent to the above-mentioned dimethylsiloxane mixed ring, stir and heat to 120°C, simultaneously introduce nitrogen gas, react for 15 minutes, add the composite catalyst, and after equilibrium polymerization for 4 hours, heat to 160°C for catalyst breaking for 1 hour. After filtration, remove the end vinyl silicone oil under vacuum. The vinyl end-capping agent is a mixture of divinyltetramethyldisiloxane and tetramethyltetravinylcyclotetrasiloxane, and the mass ratio of divinyltetramethyldisiloxane to tetramethyltetravinylcyclotetrasiloxane is 1:2. The mass ratio of the vinyl end-capping agent to the dimethylsiloxane mixed ring is 15:100. The composite catalyst is a mixture of tetramethylammonium hydroxide and potassium hydroxide, and the amount of potassium hydroxide used is 2% of the mass of tetramethylammonium hydroxide. The vacuum removal temperature is 170°C and the pressure is -0.5 kPa. Step 3: Add the above-mentioned vinyl-terminated silicone oil and structuring agent to a kneader and stir evenly. Then, add fumed silica in batches and stir with gradient heating. After stirring, vacuum for 3 hours. After dilution, discharge to obtain liquid adhesive. The structuring agent is hydroxyl silicone oil, and the mass ratio of the vinyl-terminated silicone oil to the structuring agent is 100:10. The stirring speed for even stirring is 150 r / min. The amount of fumed silica added is 20-40% of the mass of the vinyl-terminated silicone oil. The gradient heating and stirring adopts a dual-gradient stirring method, with the first gradient temperature at 120℃ and stirring time at 1 hour, and the second gradient temperature at 150℃ and stirring time at 2 hours. The vacuum pressure is not greater than 1 kPa. The dilution uses vinyl silicone oil with a vinyl content of 5%, and the mass ratio of vinyl silicone oil to vinyl-terminated silicone oil during the dilution process is 80:10. Step 4: Grind and disperse the liquid adhesive base in a grinder to obtain a fine powder of the base adhesive; then add the fine powder of the base adhesive, vinyl silicone oil, low-hydrogen silicone oil and inhibitor to a reaction vessel, stir at room temperature for 40 minutes, and then degas under vacuum for 5 minutes to obtain silicone rubber. The amount of vinyl silicone oil added is 15% of the mass of the fine powder of the base adhesive, the hydrogen content of the low-hydrogen silicone oil is 0.36%, and the amount of the low-hydrogen silicone oil added is 8% of the mass of the fine powder of the base adhesive. The inhibitor is a polyvinyl polysiloxane, and the amount of the inhibitor added is 0.4% of the mass of the fine powder of the base adhesive.

[0014] Comparative Example A method for preparing silicone rubber includes the following steps: Step 1: Add the terminal vinyl silicone oil and the structuring agent to a kneader and stir evenly. Then, add fumed silica in batches and stir with gradient heating. After stirring, vacuum for 3 hours. After dilution, discharge to obtain liquid adhesive. The structuring agent is hydroxyl silicone oil. The mass ratio of the terminal vinyl silicone oil to the structuring agent is 100:10. The stirring speed for even stirring is 150 r / min. The amount of fumed silica added is 20-40% of the mass of the terminal vinyl silicone oil. The gradient heating and stirring adopts a dual gradient stirring method. The temperature of the first gradient is 120℃ and the stirring time is 1 hour. The temperature of the second gradient is 150℃ and the stirring time is 2 hours. The vacuum pressure is not greater than 1 kPa. The dilution uses vinyl silicone oil with a vinyl content of 5%. The mass ratio of vinyl silicone oil to terminal vinyl silicone oil in the dilution process is 80:10. Step 2: Grind and disperse the liquid adhesive base in a grinder to obtain a fine powder of the base adhesive; then add the fine powder of the base adhesive, vinyl silicone oil, low-hydrogen silicone oil and inhibitor to a reaction vessel, stir at room temperature for 40 minutes, and then degas under vacuum for 5 minutes to obtain silicone rubber. The amount of vinyl silicone oil added is 15% of the mass of the fine powder of the base adhesive, the hydrogen content of the low-hydrogen silicone oil is 0.36%, and the amount of the low-hydrogen silicone oil added is 8% of the mass of the fine powder of the base adhesive. The inhibitor is a polyvinyl polysiloxane, and the amount of the inhibitor added is 0.4% of the mass of the fine powder of the base adhesive.

[0015] Performance testing

[0016] It is understood that the above detailed description of the present invention is for illustrative purposes only and is not intended to limit the technical solutions described in the embodiments of the present invention. Those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention to achieve the same technical effects; as long as the usage requirements are met, they are all within the protection scope of the present invention.

Claims

1. A method for preparing silicone rubber with low vinyl silicone oil cyclic residue, characterized in that: Includes the following steps: Step 1: Add the dimethylsiloxane mixed ring to the reaction vessel, heat and stir, and dehydrate using a vacuum device to remove trace amounts of water; Step 2: Add the vinyl end-capping agent to the above-mentioned dimethylsiloxane mixed ring, stir and heat to 100-130℃, while simultaneously introducing nitrogen gas. After reacting for 15 minutes, add the composite catalyst, and after equilibrium polymerization for 3-4 hours, heat to 140-180℃ for catalyst destruction for 1 hour. After filtration, remove the vinyl end-capping agent under vacuum to obtain the vinyl-terminated silicone oil. The vinyl end-capping agent is a mixture of divinyltetramethyldisiloxane and tetramethyltetravinylcyclotetrasiloxane; the composite catalyst is a mixture of tetramethylammonium hydroxide and potassium hydroxide. Step 3: Add the above-mentioned vinyl-terminated silicone oil and structuring agent to a kneader and stir evenly. Then add fumed silica in batches and stir with gradient heating. After stirring, vacuum for 2-3 hours. After dilution, discharge to obtain liquid adhesive. Step 4: Grind and disperse the liquid adhesive base in a grinder to obtain fine powder of the base; then add the fine powder of the base, vinyl silicone oil, low hydrogen content silicone oil and inhibitor to a reaction vessel, stir at room temperature for 40 minutes, and then degas under vacuum for 5 minutes to obtain silicone rubber; The fumed silica undergoes surface modification treatment, which includes the following steps: a1, adding trichlorosilane to benzene and stirring until homogeneous to form a solution, then adding ethyl cellulose and ultrasonically treating for 20-40 minutes to obtain a mixture; the concentration of trichlorosilane in benzene is 20-50 g / L, the stirring speed is 100-300 r / min, the amount of ethyl cellulose added is 10-20% of the mass of trichlorosilane, and the ultrasonic frequency of the ultrasonic treatment is... The ultrasonic frequency is 60-80 kHz, and the temperature is 10-20℃; a2, fumed silica is added to the solution and ultrasonically treated for 20-30 min, filtered, and the precipitate is sprayed into the reaction vessel to settle, obtaining coated fumed silica. The concentration of fumed silica in the solution is 100-300 g / L, the ultrasonic frequency of the ultrasonic treatment is 60-80 kHz, and the temperature is 20-30℃; the spraying speed is 5-10 g / min, and the spraying area is 100-400 cm². 2 The atmosphere inside the reactor is a mixture of water vapor and nitrogen, with a volume ratio of water vapor to nitrogen of 1:12-15, and the settling temperature is 85-90℃; a3, coated fumed silica is placed in the reactor and phototreated for 1-2 hours to obtain modified fumed silica. The phototreatment uses infrared light, and the infrared light intensity is 2-5 W / cm². 2 The temperature is 200-230℃.

2. The method for preparing silicone rubber with low vinyl silicone oil cyclic residue according to claim 1, characterized in that: The dimethylsiloxane mixed cyclic compound in step 1 was purchased from Zhejiang Hengyecheng Organosilicon Co., Ltd.; the temperature for heating and stirring was 65-105℃.

3. The method for preparing silicone rubber with low vinyl silicone oil cyclic residue according to claim 1, characterized in that: The mass ratio of divinyltetramethyldisiloxane to tetramethyltetravinylcyclotetrasiloxane in step 2 is 1-2:

2.

4. The method for preparing silicone rubber with low vinyl silicone oil cyclic residue according to claim 1, characterized in that: The mass ratio of the vinyl end-capping agent to the dimethylsiloxane mixed ring in step 2 is 10-25:

100.

5. The method for preparing silicone rubber with low vinyl silicone oil cyclic residue according to claim 1, characterized in that: The amount of potassium hydroxide used in step 2 is 2% of the mass of tetramethylammonium hydroxide, and the vacuum desorption temperature is 150-180℃ and the pressure is -0.5kPa.

6. The method for preparing silicone rubber with low vinyl silicone oil cyclic residue according to claim 1, characterized in that: The structuring agent in step 3 is hydroxyl silicone oil, and the mass ratio of the terminal vinyl silicone oil to the structuring agent is 100:2-15. The stirring speed for uniform mixing is 100-200 r / min.

7. The method for preparing silicone rubber with low vinyl silicone oil cyclic residue according to claim 1, characterized in that: The amount of fumed silica added in step 3 is 20-40% of the mass of the vinyl-terminated silicone oil. The gradient heating and stirring adopts a dual-gradient stirring method, with the first gradient temperature being 120℃ and the stirring time being 1h, and the second gradient temperature being 150℃ and the stirring time being 2h. The vacuum pressure is not greater than 1kPa.

8. The method for preparing silicone rubber with low vinyl silicone oil cyclic residue according to claim 1, characterized in that: The dilution in step 3 uses vinyl silicone oil, and the vinyl content of the vinyl silicone oil is 5%. The mass ratio of vinyl silicone oil to end vinyl silicone oil in the dilution process is 80:3-20.

9. The method for preparing silicone rubber with low vinyl silicone oil cyclic residue according to claim 1, characterized in that: In step 4, the amount of vinyl silicone oil added is 10-20% of the mass of the base silicone powder. The hydrogen content of the low-hydrogen silicone oil is 0.36%, and the amount of the low-hydrogen silicone oil added is 5-10% of the mass of the base silicone powder. The inhibitor is a polyvinyl polysiloxane, and the amount of the inhibitor added is 0.2-0.5% of the mass of the base silicone powder.

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