Vinyl hydrogen-terminated silicone oil as well as preparation method and application thereof

Abstract

The invention discloses vinyl hydrogen-terminated silicone oil as well as a preparation method and application thereof, and belongs to the technical field of organic silicon. The preparation method of the vinyl hydrogen-terminated silicone oil comprises the following steps: S1, mixing a polydimethylsiloxane mixed ring body (DMC) and tetramethyl tetravinyl cyclotetrasiloxane (VMC), vacuumizing, dehydrating, adding tetramethyl dihydrodisiloxane and an acid catalyst after the dehydration is finished, and carrying out ring-opening polymerization reaction, so as to obtain a vinyl hydrogen-terminated silicone oil intermediate; and S2, increasing the reaction temperature, and carrying out low-component removal treatment on the vinyl hydrogen-terminated silicone oil intermediate to obtain the vinyl hydrogen-terminated silicone oil. The vinyl hydrogen-terminated silicone oil has multiple functions of a modifier and a chain extender, and can be widely applied to the fields of liquid silicone rubber, silica gel, pouring sealants and the like.

Description

Technical Field

[0001] This invention belongs to the field of organosilicon technology, specifically to a vinyl-terminated hydrogen silicone oil, its preparation method, and its application. Background Technology

[0002] Hydrogen-terminated silicone oils, as important intermediates for organosilicon modification or block polymers, contain Si-H active groups at one end of their molecular chains that can undergo addition reactions with unsaturated bonds such as alkenyl and alkynyl groups, thereby modifying organic polymers and imparting new properties to materials. They are widely used in plastics, silicone oil modification, resin modification, and liquid silicone rubber. Vinylsiloxanes, due to their C=C double bond structure, act as both coupling agents and crosslinking agents, making them a major raw material for addition-type liquid silicone rubbers and a key component in compound modifiers and plastic additives.

[0003] Currently, industry research on silicone oils largely focuses on optimizing single functions. For example, the production process of vinyl-terminated silicone oil uses only raw materials such as dimethyldichlorosilane hydrolysate, resulting in a product containing only a single active group at the vinyl end. This group can only be used as a crosslinking agent and cannot achieve the chain extension function of molecular chain growth. This leads to poor flowability of high-viscosity base rubber, making it difficult to mix evenly with other raw materials, ultimately affecting the tear resistance of silicone rubber. Similarly, the preparation technology of self-crosslinking vinyl hydrogen-containing silicone oil, although introducing hydrogen-containing groups, uses a combination of side-hydrogen-containing silicone oil and double-terminated vinyl silicone oil. It is only suitable for self-crosslinking scenarios to reduce oil seepage rate and still lacks the efficient chain extension ability brought by the hydrogen end group. Its application scenarios are limited to specific fields such as thermal conductive gels.

[0004] In terms of catalytic processes, existing technologies also face bottlenecks. When using alkaline catalysts (such as ethylamine and tetramethylammonium hydroxide), catalyst removal requires high temperatures of 130-200 °C, resulting in a complex and energy-intensive process. While strong acidic catalysts (such as concentrated sulfuric acid and methanesulfonic acid) can achieve catalytic polymerization, they are highly corrosive, requiring an additional neutralization step to remove acid components, increasing process costs and environmental risks. Some technologies using acidic resin catalysis also require activated carbon fixed beds for decolorization and deodorization, making the process cumbersome and reducing production efficiency. Furthermore, traditional silicone oil products have shortcomings in performance balance. They either only control the content of volatile cyclosiloxanes (e.g., some technologies control it to ≤0.5%), but the tear strength does not exceed 20 kN / m; or they fail to effectively control volatile components, failing to meet the purity requirements of high-end applications.

[0005] In summary, existing technologies cannot simultaneously achieve the dual functions of chain extension and cross-linking of silicone oil, simplify the catalytic process, and improve mechanical properties and purity. The industry urgently needs a new silicone oil preparation technology that is simple to process, comprehensive in function, and excellent in performance to solve the pain points of traditional silicone oil in the application of liquid silicone rubber, silicone gel, potting compound and other fields. Summary of the Invention

[0006] This invention aims to provide a vinyl-terminated silicone oil, its preparation method, and its application. The preparation process is simple, the reaction maintains a stable high conversion rate, and the product viscosity is controllable.

[0007] The method for preparing the vinyl-terminated silicone oil includes the following steps: S1. Polydimethylsiloxane mixed cyclic (DMC) and tetramethyltetravinylcyclotetrasiloxane (VMC) are mixed and dehydrated under vacuum. After dehydration, tetramethyldihydrodisiloxane and an acidic catalyst are added to carry out ring-opening polymerization to obtain vinyl-terminated silicone oil intermediate. S2. Increase the reaction temperature to remove the vinyl-terminated hydrogen silicone oil intermediate and obtain vinyl-terminated hydrogen silicone oil.

[0008] In a preferred embodiment, the mass ratio of the polydimethylsiloxane mixed cyclic compound, tetramethyltetravinylcyclotetrasiloxane, and tetramethyldisiloxane in step S1 is 1:0.01~0.05:0.001~0.005.

[0009] In the preferred embodiment, the dehydration temperature in step S1 is 70~90 ℃, the vacuum pressure is 0.001~0.005 MPa, and the duration is 30~50 min.

[0010] In a further preferred embodiment, the dehydration process involves a vacuum degree of 10 mbar and a duration of 30 min.

[0011] In a preferred embodiment, the acidic catalyst in step S1 is selected from trifluoromethanesulfonic acid or acidic cation exchange resin.

[0012] In a preferred embodiment, the amount of acidic catalyst added in step S1 is 5 wt% to 10 wt% of the total mass of polydimethylsiloxane mixed cyclic, tetramethyltetravinylcyclotetrasiloxane and tetramethyldisiloxane.

[0013] In a further preferred embodiment, the acidic catalyst is an acidic cation exchange resin, and the amount added is 5 wt% of the total mass of polydimethylsiloxane mixed cyclic, tetramethyltetravinylcyclotetrasiloxane and tetramethyldisiloxane.

[0014] In the preferred embodiment, the ring-opening polymerization reaction described in step S1 is carried out under normal pressure and at 60~90 ℃ for 2~6 h.

[0015] In the preferred embodiment, the de-lowering treatment in step S2 specifically involves removing low-molecular-weight compounds at a temperature of 150~200 ℃ and a vacuum pressure of 0.06~0.095 MPa for 2~6 h to remove unreacted monomers or impurities.

[0016] In a further preferred embodiment, the removal of low molecular weight compounds specifically involves removing low molecular weight compounds at a temperature of 180 °C and a vacuum pressure of 0.095 MPa for 2 hours.

[0017] The vinyl-terminated silicone oil is prepared by the method for preparing vinyl-terminated silicone oil.

[0018] The application of the aforementioned vinyl-terminated silicone oil as a modifier or chain extender in liquid silicone rubber, silicone gel, and potting compound.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The vinyl-terminated silicone oil provided by the present invention introduces vinyl groups into the terminal hydrogen silicone oil, which can increase its reactivity and performance, and has excellent properties such as high refractive index and high light transmittance.

[0020] 2. The vinyl-terminated hydrogen silicone oil provided by this invention has a novel structure of terminal hydrogen-vinyl dual active groups, which enables it to have multiple functions as a modifier and chain extender. It can be more widely used in liquid silicone rubber, silicone gel, potting compound and other fields, thereby improving the tear strength, hardness and resilience of silicone oil applied to liquid silicone rubber, compound and other fields. It can also be used as a plastic additive.

[0021] 3. When high-viscosity vinyl silicone oil is used as a base rubber, the excessively long molecular chains lead to intermolecular entanglement, resulting in poor flowability and difficulty in uniform mixing with other raw materials. This ultimately affects the performance of silicone rubber, causing drawbacks such as poor tear resistance. Furthermore, high-viscosity vinyl silicone oil is difficult to defoam when used in silicone gels, failing to meet application requirements. The vinyl-terminated hydrogen silicone oil provided by this invention can be added at lower viscosity levels to reduce the viscosity of the base rubber. The silicon-hydrogen bonds act as chain extenders in the reaction, contributing to molecular chain growth and improving tear resistance. Simultaneously, the vinyl group acts as a crosslinking agent, effectively improving the crosslinking density of silicone rubber, further enhancing the physical and mechanical properties of the compound, and exhibiting excellent flowability and workability.

[0022] 4. The vinyl-terminated silicone oil provided by this invention has low volatile content (0.25%-0.35%) and controllable viscosity. When applied to liquid silicone rubber, it increases tear strength by 27%-87% and elongation at break by 23%-56%, effectively solving the problems of poor fluidity and weak tear resistance of traditional silicone oils with high viscosity, and meeting the needs of high-end materials.

[0023] 5. The preparation method provided by the present invention is simple, the raw materials are simple and readily available, the production process is simple, the equipment requirements are not high, traditional silicone oil production equipment can be used, and there is no need to use strong acid catalysts such as concentrated sulfuric acid. The catalyst can be separated by filtration, without the need to add a neutralization step, making the process simpler and safer. Detailed Implementation

[0024] The technical solution of the present invention will be further described and illustrated below through examples. All raw materials used in the examples are commercially available or prepared using conventional methods.

[0025] Example 1 A vinyl-terminated silicone oil is prepared by the following steps: S1. Take a 2 L three-necked flask, add 1000 g of polydimethylsiloxane mixed cyclic compound and 10 g of tetramethyltetravinylcyclotetrasiloxane, heat to 80 °C, evacuate, and dehydrate under a vacuum pressure of 0.001 MPa for 30 min. Then add 5 g of tetramethyldisiloxane and 65 g of acidic resin catalyst, and stir the ring-opening polymerization reaction at 80 °C and atmospheric pressure for 5 h. S2. After the reaction is complete, the temperature is raised to 180 °C, and a vacuum is drawn. Low molecular weight molecules are removed under a vacuum pressure of 0.001 MPa for 2 h to obtain vinyl-terminated silicone oil.

[0026] The tested vinyl-terminated silicone oil had a viscosity of 5600 cp, a volatile content of 0.35%, and a vinyl content of 0.25 wt%.

[0027] Example 2 A vinyl-terminated silicone oil is prepared by the following steps: S1. Take a 2 L three-necked flask, add 1000 g of polydimethylsiloxane mixed cyclic compound and 50 g of tetramethyltetravinylcyclotetrasiloxane, heat to 80 °C, evacuate and dehydrate for 30 min under a vacuum pressure of 0.001 MPa, then add 2.0 g of tetramethyldisiloxane and 78 g of acidic resin catalyst, and stir the ring-opening polymerization reaction at 80 °C and atmospheric pressure for 5 h. S2. After the reaction is complete, the temperature is raised to 180 °C, and a vacuum is drawn. The low molecular weight molecules are removed under a vacuum pressure of 0.001 MPa for 2 hours to obtain vinyl hydrogen-containing silicone oil.

[0028] The tested vinyl-terminated silicone oil had a viscosity of 21560 cp, a volatile content of 0.26%, and a vinyl content of 0.9 wt%.

[0029] Example 3 A vinyl-terminated silicone oil is prepared by the following steps: S1. Take a 2 L three-necked flask, add 1000 g of polydimethylsiloxane mixed cyclic compound and 30 g of tetramethyltetravinylcyclotetrasiloxane, heat to 80 °C, evacuate, and dehydrate for 30 min under a vacuum pressure of 0.001 MPa. Then add 2 g of tetramethyldisiloxane and 78 g of acidic resin catalyst, and stir the ring-opening polymerization reaction at 80 °C and atmospheric pressure for 5 h. S2. After the reaction is complete, the temperature is raised to 180 °C, and a vacuum is drawn. The low molecular weight molecules are removed under a vacuum pressure of 0.001 MPa for 2 hours to obtain vinyl hydrogen-containing silicone oil.

[0030] The tested vinyl-terminated silicone oil had a viscosity of 19860 cp, a volatile content of 0.25%, and a vinyl content of 0.64 wt%.

[0031] Example 4 A liquid silicone rubber is prepared by the following steps: Take 500 g of the vinyl-terminated silicone oil prepared in Example 1, add 6 wt% hexamethyldisilazane, 1.8 wt% water, and 0.5 wt% vinylsilazane, mix evenly in a planetary mixer, add 30 wt% silica in batches, heat to 170 ℃ and stir for 4 h, and react under vacuum for 2 h; then add the remaining 500 g of the vinyl-terminated silicone oil prepared in Example 1 and dilute evenly, react under vacuum for 2 h to remove bubbles; pour into a mold and cure at 160 ℃ for 20 min, then vulcanize at 200 ℃ for 4 h to obtain liquid silicone rubber.

[0032] Example 5 A liquid silicone rubber is prepared by the following steps: Take 500 g of the vinyl-terminated silicone oil prepared in Example 2, add 6 wt% hexamethyldisilazane, 1.8 wt% water, and 0.5 wt% vinylsilazane, mix thoroughly in a planetary mixer, add 30 wt% silica in batches, heat to 170 °C and stir for 4 h, then react under vacuum for 2 h; then add the remaining 500 g of the vinyl-terminated silicone oil prepared in Example 2 and dilute evenly, react under vacuum for 2 h to remove bubbles. Pour into a mold and cure at 160 °C for 20 min, then vulcanize at 200 °C for 4 h to obtain liquid silicone rubber.

[0033] Example 6 A liquid silicone rubber is prepared by the following steps: Take 500 g of the vinyl-terminated silicone oil prepared in Example 3, add 6 wt% hexamethyldisilazane, 1.8 wt% water, and 0.5 wt% vinylsilazane, mix evenly in a planetary mixer, add 30 wt% silica in batches, heat to 170 ℃ and stir for 4 h, and react under vacuum for 2 h; then add the remaining 500 g of the vinyl-terminated silicone oil prepared in Example 3 and dilute evenly, react under vacuum for 2 h to remove bubbles; pour into a mold and cure at 160 ℃ for 20 min, then vulcanize at 200 ℃ for 4 h to obtain liquid silicone rubber.

[0034] Comparative Example 1 A liquid silicone rubber is prepared by the following steps: Take 500 g of vinyl-terminated silicone oil with a viscosity of 60000 cp, add 6 wt% hexamethyldisilazane, 1.8 wt% water, and 0.5 wt% vinylsilazane, mix evenly in a planetary mixer, add 30 wt% silica in batches, heat to 170 ℃ and stir for 4 h, then react under vacuum for 2 h; then add the remaining 500 g of vinyl-terminated hydrogen silicone oil prepared in Example 3 and dilute evenly, react under vacuum for 2 h to remove bubbles; pour into a mold and cure at 160 ℃ for 20 min, then vulcanize at 200 ℃ for 4 h to obtain liquid silicone rubber.

[0035] Testing and Analysis The mechanical properties of the above-mentioned liquid silicone rubber were tested, including: The samples were cut into right-angle shapes according to GB / T529-2008, and five parallel samples were set up for each sample to test the tear strength. According to GB / T528-2009, the samples were cut into dumbbell shapes, and five parallel samples were set up for each sample to test the elongation at break and tensile strength.

[0036] The test results are shown in Table 1.

[0037] Table 1 Performance data of liquid silicone rubber

[0038] The test results show that when the vinyl-terminated silicone oil prepared in this invention is applied to liquid silicone rubber, it is significantly superior to traditional vinyl-terminated silicone oil in terms of tear strength, elongation at break, and tensile strength, fully demonstrating its excellent application performance.

[0039] It should be understood that the above embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A method for preparing a vinyl-terminated silicone oil, characterized in that, Includes the following steps: S1. Polydimethylsiloxane mixed cyclic compound and tetramethyltetravinylcyclotetrasiloxane are mixed and dehydrated under vacuum. After dehydration, tetramethyldihydrodisiloxane and an acidic catalyst are added to carry out ring-opening polymerization to obtain vinyl-terminated silicone oil intermediate. S2. Increase the reaction temperature to remove the vinyl-terminated hydrogen silicone oil intermediate and obtain vinyl-terminated hydrogen silicone oil.

2. The method for preparing vinyl-terminated silicone oil according to claim 1, characterized in that, The mass ratio of the polydimethylsiloxane mixed cyclic compound, tetramethyltetravinylcyclotetrasiloxane and tetramethyldisiloxane mentioned in step S1 is 1:0.01~0.05:0.001~0.

005.

3. The method for preparing vinyl-terminated silicone oil according to claim 1, characterized in that, The dehydration temperature in step S1 is 70~90 ℃, the vacuum pressure is 0.001~0.005 MPa, and the time is 30~50 min.

4. The method for preparing vinyl-terminated silicone oil according to claim 1, characterized in that, The acidic catalyst mentioned in step S1 is selected from trifluoromethanesulfonic acid or acidic cation exchange resin.

5. The method for preparing vinyl-terminated silicone oil according to claim 1, characterized in that, The amount of acidic catalyst added in step S1 is 5 wt% to 10 wt% of the total mass of polydimethylsiloxane mixed cyclic, tetramethyltetravinylcyclotetrasiloxane and tetramethyldisiloxane.

6. The method for preparing vinyl-terminated silicone oil according to claim 5, characterized in that, The acidic catalyst is an acidic cation exchange resin, and the amount added is 5 wt% of the total mass of polydimethylsiloxane mixed cyclic, tetramethyltetravinylcyclotetrasiloxane and tetramethyldisiloxane.

7. The method for preparing vinyl-terminated silicone oil according to claim 1, characterized in that, The ring-opening polymerization reaction described in step S1 is carried out under normal pressure and at 60~90 ℃ for 2~6 h.

8. The method for preparing vinyl-terminated silicone oil according to claim 1, characterized in that, The de-lowering treatment described in step S2 specifically involves removing low-molecular-weight compounds at a temperature of 150~200 ℃ and a vacuum pressure of 0.06~0.095 MPa for 2~6 hours.

9. A vinyl-terminated silicone oil, characterized in that, The vinyl-terminated silicone oil is prepared by the method described in any one of claims 1 to 8.

10. The application of the vinyl-terminated silicone oil according to claim 9 as a modifier or chain extender in liquid silicone rubber, silicone gel, and potting compound.

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