Alkoxysilane-terminated polysiloxane and preparation method thereof

Abstract

The invention belongs to the technical field of silica gel, and relates to alkoxy silane-terminated polysiloxane and a preparation method thereof, and the alkoxy silane-terminated polysiloxane comprises the following components in parts by weight: (A) 80-100 parts of polysiloxane containing at least one vinyl group in a molecule; (B) 2 to 20 parts of composite hydrogen-containing alkoxy silane; (C) 0.01 to 1 part of catalyst; and (D) 0.1 to 4.5 parts of activated carbon. The alkoxy silane-terminated polysiloxane can be suitable for various formula systems such as moisture curing, addition curing and UV / moisture dual curing of organic silicon products, is particularly suitable for being applied to formula systems which contain powder and have certain thixotropy, and regulates and controls the thixotropic property and the flowing property of the products while keeping certain viscosity.

Description

Technical Field

[0001] The invention belongs to the technical field of silica gel, and in particular relates to an alkoxysilane-terminated polysiloxane and a preparation method thereof. Background Art

[0002] Alkoxy-terminated polydimethylsiloxane, as a polymer to replace 107 glue, has obvious advantages. It does not have a viscosity peak during processing and is easy to process. At the same time, it has excellent storage stability and is increasingly used in moisture-curing silicone products in the electronics manufacturing industry. Chinese invention patent CN110003842B discloses a one-component dealcoholized room temperature vulcanized organopolysiloxane composition, and Chinese invention patent CN110607074B discloses a UV / moisture dual-curing silicone resin composition with excellent weather resistance, respectively applying alkoxy-terminated polydimethylsiloxane resin to RTV moisture-curing silicone and UV / moisture dual-curing electronic silicone.

[0003] In addition, alkoxy-terminated polydimethylsiloxane, due to the presence of alkoxy groups, easily interacts with the hydroxyl groups on the surface of the powder filler, can effectively wrap the surface of the powder filler for surface treatment, can effectively reduce the viscosity after filling, and increase the filling amount. In Japanese invention patents JP2019181408 and JP2021191823A, in the formulation design of thermal conductive products, it is necessary to use monoalkoxy-terminated polydimethylsiloxane as a powder treatment agent. After the powder is treated, the filling amount of the powder filler is effectively increased to increase the thermal conductivity of the material.

[0004] In recent years, with the increasing complexity of electronic product application scenarios, more practical functional requirements have been put forward for RTV silicone, such as: ① Improving the surface dryness and deep curing speed to improve the packaging rhythm of electronic products and improve production efficiency; ② Adhesion requirements and medium resistance requirements of different materials such as fiber-reinforced PC, PBT, nickel-plated, and galvanized metals; ③ Rework requirements, etc. The traditional formula with 107 silicone oil and alkoxy-terminated polydimethylsiloxane as the main raw materials has been getting closer and closer to the limit of the product and cannot meet the more requirements put forward by customers. In addition, in the formula containing alkoxy-terminated polydimethylsiloxane, the thixotropy of the product is generally adjusted by adding appropriate powder thixotropic agents such as fumed silica, which often increases the viscosity while increasing the thixotropy and reducing the flow, and it is often difficult to achieve a balance between viscosity, thixotropy and flowability. Summary of the invention

[0005] In view of the deficiencies of the above-mentioned prior art, the present invention provides an alkoxysilane-terminated polysiloxane and a preparation method thereof. The specific technical scheme is as follows:

[0006] The first object of the present invention is to provide an alkoxysilane-terminated polysiloxane, comprising the following components in parts by weight:

[0007] (A) 80-100 parts of a polysiloxane containing at least one vinyl group in its molecule;

[0008] (B) 2-20 parts of a composite hydrogen-containing alkoxysilane, wherein a single molecule has one and only one Si-H group, at least one Si atom is bonded with an alkoxy group, and at least one Si atom is bonded with a "functional" functional group;

[0009] (C) 0.01-1 part of catalyst;

[0010] (D) 0.1-4.5 parts of activated carbon.

[0011] Furthermore, the general structural formula of the component (A) is (R 1 R 2 2SiO 1 / 2 )(R 1 R 2 SiO 2 / 2 ) a (R 2 SiO 3 / 2 ) b (SiO 4 / 2 ) c , where R 1 , R 2 R independently represent an unsubstituted or substituted monovalent hydrocarbon group; 1 and R 2 At least one of the groups is vinyl; a=0~180 (excluding 0), b=0~1, c=0~1, a+b+c=1~180.

[0012] Furthermore, R of the component (A) 1 or R 2 The number of carbon atoms is 1 to 10, preferably 1 to 6; specifically, the following can be mentioned: lower alkyl groups such as methyl, ethyl, propyl, isopropyl, cycloalkyl groups such as cyclohexyl, aryl groups such as phenyl, tolyl, xylyl, aralkyl groups such as benzyl, alkane groups containing olefinic bonds such as vinyl and propenyl, or groups in which some or all of the hydrogen atoms of the above groups are replaced by halogen atoms, cyano groups, etc., such as chloromethyl, cyanoethyl, etc. More preferably, groups selected from methyl, ethyl, vinyl, phenyl, etc. are preferred.

[0013] Further, the structure of the "functional" functional group is as follows:

[0014]

[0015] When the "functional" functional group of the present invention is structure 1, it has the function of accelerating the surface drying speed or the surface debonding speed; when it is structure 2, it has the function of enhancing the material repair performance. In addition, the "functional" functional group can also be a functional group that promotes the bonding function of different material interfaces, such as structure 3, structure 4 and structure 5, or a functional group that produces other functions.

[0016] Furthermore, the general structural formula of the component (B) is as shown in the following formula (I) or formula (II):

[0017]

[0018] Wherein, m = 1 to 10, n1 = 1 to 10, n2 = 1 to 5, R 3 is an unsubstituted or substituted monovalent hydrocarbon group, R 4 It is a "functional" functional group.

[0019] Furthermore, there is no special requirement for the catalyst of component (C), and it can be a noble metal catalyst, such as ruthenium, rhodium, palladium, platinum, etc., and complexes of these metals, as well as commonly used complexed and diluted catalysts on the market.

[0020] Furthermore, the component (D) activated carbon is one of acidic activated carbon and alkaline activated carbon.

[0021] According to the analysis of synthesis theory, in the process of organosilicon synthesis, acidic or alkaline conditions can promote the hydrolysis and chain breaking of silane alkoxy groups (Si-OR) to form Si-OH. The presence of Si-OH will increase the polarity between molecules and form hydrogen bonds. Therefore, when powder materials such as gas phase silicon are introduced, the thixotropy value of the material will increase. However, different research results were found in the experiment: the thixotropy and shape retention properties of the obtained alkoxysilane-terminated polysiloxane after adding powders treated with alkaline activated carbon were slightly better than those without activated carbon treatment; while the thixotropy and shape retention properties of the obtained alkoxysilane-terminated polysiloxane after adding powders treated with acidic activated carbon were worse than those without activated carbon treatment. Through this discovery, it is possible to control the thixotropy and flow properties of the final product by controlling the pH of activated carbon during the reaction. This can improve the adjustability of the obtained alkoxysilane-terminated polysiloxane in various formulation systems such as moisture curing, addition curing, UV / moisture dual curing, etc.

[0022] Furthermore, it also includes one or more of fluorescent agent, color paste or carbon black.

[0023] Fluorescent agents provide fluorescence detection capabilities, and color pastes and carbon black are added to adjust the appearance color.

[0024] The second object of the present invention is to provide a method for preparing the above-mentioned alkoxysilane-terminated polysiloxane, comprising the following steps:

[0025] (1) mixing the component (B) composite hydrogen-containing alkoxysilane and the component (D) activated carbon, stirring and mixing at a temperature below 40° C. for 2-6 hours for pretreatment, and filtering and removing the activated carbon after the treatment;

[0026] (2) After uniformly mixing component (A) polysiloxane containing at least one vinyl group in the molecule, component (B) composite hydrogen-containing alkoxysilane after pretreatment, and component (C) hydrosilylation catalyst, the mixture is heated to 50-100° C., kept at this temperature for 2-8 hours, cooled to room temperature, and the unreacted small molecules are removed by vacuum distillation to obtain polysiloxane capped with alkoxysilane.

[0027] At the same time, in order to facilitate the simplicity of the synthesis process, if the component (B) composite hydrogen-containing alkoxysilane is prepared by self-synthesis, step (1) can be combined with the synthesis process of component (B), and after the reaction is completed, component (D) is added for pretreatment.

[0028] The beneficial effects of the present invention are:

[0029] The alkoxysilane-terminated polysiloxane provided by the present invention can be applied to various formulation systems such as moisture curing, addition curing, UV / moisture dual curing, etc. of silicone products, and is particularly suitable for use in formulation systems containing powders and having a certain thixotropy. While maintaining a certain viscosity, the thixotropy and flow properties of the product can be regulated.

[0030] The present invention controls the structural changes of the end-capped composite hydrogen-containing alkoxysilane, so that the prepared alkoxysilane-terminated polysiloxane can meet the requirements of coating, process protection and sealing adhesive in different scenarios. At the same time, during the reaction process, by controlling the pH value of the activated carbon, the obtained alkoxysilane-terminated polysiloxane can obtain different thixotropy and flow properties after adding powder, thereby improving the adjustability of the obtained alkoxysilane-terminated polysiloxane in various formulation systems such as moisture curing, addition curing, UV / moisture dual curing, etc. DETAILED DESCRIPTION

[0031] The principles and features of the present invention are described below in conjunction with embodiments. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0032] Embodiment 1:

[0033] Synthesis of composite hydrogen-containing alkoxysilane:

[0034] 55g of vinyl trimethoxysilane, 60g of toluene and 1g of 5000ppm platinum catalyst were added to the reaction bottle, and the temperature was raised to 50°C while stirring. When the temperature reached 50°C, 100g of the molecular formula [H(CH3)2SiO 1 / 2 ]2[H(CH3)SiO 2 / 2 ][(CH3)2SiO 2 / 2 ] A mixture of hydrogen-containing siloxane and 200g toluene, pay attention to controlling the dropping speed to avoid the temperature rising to above 80°C. After the dropwise addition is completed, keep warm for reaction for 2h. Subsequently, a mixture of 44g allylbenzene and 50g toluene is added dropwise. After all the dropwise additions are completed, the temperature is raised to 80-100°C and kept warm for reaction for 4h. After the reaction is completed, the temperature is lowered to below 40°C, and 3g of activated carbon is stirred for 3h. After filtering to remove the activated carbon, the solvent toluene is removed by rotary evaporation to obtain the pretreated composite hydrogen-containing alkoxysilane B1. In order to distinguish, the one obtained by stirring and adsorbing with acidic activated carbon is recorded as B1-a, and the one obtained by stirring and adsorbing with alkaline activated carbon is recorded as B1-b.

[0035] Synthesis of Alkoxysilane-Terminated Polysiloxane Resin 1:

[0036] 100 parts of polysiloxane containing at least one vinyl group in the molecule, with a specific structural formula of (Vi(CH3)2SiO 1 / 2 )((CH3)2SiO 2 / 2 ) 150 (Vi refers to vinyl), 4.9 parts of pretreated composite hydrogen-containing alkoxysilane B1-a and 0.5 parts of 2000ppm platinum catalyst were mixed and stirred evenly, the temperature was raised to 100°C, and the reaction was kept warm for 2 hours, then cooled to room temperature, and the small molecules that were not completely reacted were removed by vacuum distillation to obtain an alkoxysilane-terminated polysiloxane resin.

[0037] The pretreated composite hydrogen-containing alkoxysilane B1-a in the above reaction process is replaced with the pretreated composite hydrogen-containing alkoxysilane B1-b to obtain an alkoxysilane-terminated polysiloxane resin II.

[0038] Embodiment 2:

[0039] Synthesis of composite hydrogen-containing alkoxysilane:

[0040] Add 61.5g of vinyltrimethoxysilane, 60g of toluene and 1g of 5000ppm of platinum catalyst to the reaction bottle, protect with nitrogen, and heat to 50°C while stirring. When the temperature reaches 50°C, slowly drop a mixture of 100g of 1,3,5,7-tetramethylcyclotetrasiloxane and 200g of toluene. Pay attention to control the drop rate to avoid the temperature rising to above 80°C. After the drop addition is completed, keep the reaction warm for 2h. Subsequently, add a mixture of 82g of heptene and 100g of toluene. After all the drop additions are completed, heat to 80-100°C and keep the reaction warm for 4h. After the reaction is completed, cool to below 40°C, stir with 6g of acidic activated carbon for 4h, filter, and remove the solvent toluene by rotary evaporation to obtain the pretreated composite hydrogen-containing alkoxysilane B2-a.

[0041] Synthesis of Alkoxysilane-Terminated Polysiloxane Resins:

[0042] 100 parts of polysiloxane containing at least one vinyl group in the molecule, with a specific structural formula of (Vi(CH3)2SiO 1 / 2 )((CH3)2SiO 2 / 2 ) 80 (Vi refers to vinyl), 10.2 parts of composite hydrogen-containing alkoxysilane B2-a and 0.5 parts of 2000ppm platinum catalyst were mixed and stirred evenly, the temperature was raised to 100°C, and the reaction was kept warm for 2 hours, then cooled to room temperature, and the small molecules that were not completely reacted were removed by vacuum distillation to obtain alkoxysilane-terminated polysiloxane resin three.

[0043] Embodiment 3:

[0044] Synthesis of composite hydrogen-containing alkoxysilane:

[0045] 61.5g of vinyl trimethoxysilane, 60g of toluene and 1g of 5000ppm platinum catalyst were added to the reaction bottle, nitrogen protection, and the temperature was raised to 50°C while stirring. When the temperature reached 50°C, a mixture of 100g of 1,3,5,7-tetramethylcyclotetrasiloxane and 200g of toluene was slowly added dropwise. Pay attention to control the dropwise addition rate to avoid the temperature rising above 80°C. After the addition was completed, the reaction was kept warm for 2h. Subsequently, a mixture of 41g of heptene, 47.5g of allyl glycidyl ether and 100g of toluene was added dropwise. After all the additions were completed, the temperature was raised to 80-100°C and the reaction was kept warm for 4h. After the reaction was completed, the temperature was lowered to below 40°C, and 6g of acidic activated carbon was stirred for 4h. After filtering, the solvent toluene was removed by rotary evaporation to obtain the pretreated composite hydrogen-containing alkoxysilane B3-a.

[0046] Synthesis of Alkoxysilane-Terminated Polysiloxane Resins:

[0047] 100 parts of polysiloxane containing at least one vinyl group in the molecule, with a specific structural formula of (Vi(CH3)2SiO 1 / 2 )((CH3)2SiO 2 / 2 ) 80 (Vi refers to vinyl), 10.6 parts of pretreated composite hydrogen-containing alkoxysilane B3-a and 0.5 parts of 2000ppm platinum catalyst were mixed and stirred evenly, the temperature was raised to 100°C, and the reaction was kept warm for 2 hours, then cooled to room temperature, and the small molecules that were not completely reacted were removed by vacuum distillation to obtain alkoxysilane-terminated polysiloxane resin four.

[0048] Comparative Example 1:

[0049] Synthesis of methyl hydrogen alkoxysilane:

[0050] 55g of vinyl trimethoxysilane, 60g of toluene and 1g of 5000ppm platinum catalyst were added to the reaction bottle, and the temperature was raised to 50°C while stirring. When the temperature reached 50°C, 100g of the molecular formula [H(CH3)2SiO 1 / 2 ]2[(CH3)2SiO 2 / 2 ]2 of hydrogen-containing siloxane and 200g of toluene, pay attention to control the drop rate to avoid the temperature rising above 80°C, after the dropwise addition is completed, keep warm for 2h. Then, heat to 80-100°C and keep warm for 4h. After the reaction is completed, cool to below 40°C, stir with 3g of alkaline activated carbon for 3h, filter, and remove the solvent toluene by rotary evaporation to obtain the pretreated methyl hydrogen-containing alkoxysilane D1-b.

[0051] Synthesis of Alkoxysilane-Terminated Polysiloxane Resins:

[0052] 100 parts of polysiloxane containing at least one vinyl group in the molecule, with a specific structural formula of (Vi(CH3)2SiO 1 / 2 )((CH3)2SiO 2 / 2 ) 150 (Vi refers to vinyl), 4.9 parts of pretreated methyl hydrogenated alkoxysilane D1-b and 0.5 parts of 2000ppm platinum catalyst were mixed and stirred evenly, and then the temperature was raised to 100°C. After the reaction was kept at this temperature for 2 hours, the temperature was lowered to room temperature, and the small molecules that were not completely reacted were removed by vacuum distillation to obtain the alkoxysilane-terminated polysiloxane resin D1.

[0053] Comparative Example 2:

[0054] Synthesis of methyl hydrogen alkoxysilane:

[0055] Add 61.5g of vinyltrimethoxysilane, 60g of toluene and 1g of 5000ppm platinum catalyst to the reaction bottle, protect with nitrogen, and heat to 50°C while stirring. When the temperature reaches 50°C, slowly drop a mixture of 100g of hexamethylcyclotetrasiloxane and 200g of toluene. Pay attention to control the drop rate to avoid the temperature rising above 80°C. After the drop is completed, keep the temperature for 2h. Heat to 80-100°C and keep the temperature for another 4h. After the reaction is completed, cool to below 40°C, stir and adsorb with 6g of acidic activated carbon for 4h, filter, and remove the solvent toluene by rotary evaporation to obtain the pretreated methyl hydrogen-containing alkoxysilane D2-a.

[0056] Synthesis of Alkoxysilane-Terminated Polysiloxane Resins:

[0057] 100 parts of polysiloxane containing at least one vinyl group in the molecule, with a specific structural formula of (Vi(CH3)2SiO 1 / 2 )((CH3)2SiO 2 / 2 ) 150 (Vi refers to vinyl), 10.0 parts of pretreated methyl hydrogenated alkoxysilane D2-a and 0.5 parts of 2000ppm platinum catalyst were mixed and stirred evenly, and then the temperature was raised to 100°C. After the reaction was kept at this temperature for 2 hours, the temperature was lowered to room temperature, and the small molecules that were not completely reacted were removed by vacuum distillation to obtain the alkoxysilane-terminated polysiloxane resin D2.

[0058] Application examples:

[0059] Application Example 1:

[0060] The alkoxysilane-terminated polysiloxane resin prepared in Example 1 and Comparative Example 1 was applied to room temperature vulcanized silicone rubber (RTV silicone composition). The application formula (by weight) and test results are shown in Table 1.

[0061] Table 1 Room temperature vulcanized silicone rubber formula and test results

[0062]

[0063] The specific test method is as follows:

[0064] 1. Viscosity: HAKKE viscometer, 25°C, C35 / 2 rotor, 20 rpm speed, record the viscosity test results;

[0065] 2. Thixotropy: HAKKE viscometer, 25°C, C35 / 2 rotor, 2rpm viscosity / 20rpm viscosity;

[0066] 3. Glue line width spreading ratio: Immediately after dispensing, record the width of the glue line as w0, and after standing for 10 minutes, test the width of the glue line again as w1. Calculate the glue line width spreading ratio = (w1-w0) / w0;

[0067] 4. Surface drying time: the time it takes to form a skin on the surface of the colloid under an environment of 25℃50%RH;

[0068] 5. Surface debonding time: Under 25℃50%RH environment, press the surface of the colloid with a rubber finger cot until the surface of the colloid is no longer sticky to the rubber finger cot. This is recorded as the surface debonding time.

[0069] From the test results in Table 1, it can be seen that the viscosity of the alkoxysilane-terminated polysiloxane resin synthesized by the composite hydrogenated alkoxysilane pretreated with acidic activated carbon or alkaline activated carbon is basically similar after reacting with the powder, with little difference; but the thixotropic performance, shape retention and positioning performance and fluidity are different. The thixotropy of formula 1 obtained by synthesizing the alkoxysilane-terminated polysiloxane resin synthesized by the composite hydrogenated alkoxysilane treated with acidic activated carbon is the lowest, the shape retention is the worst, and the corresponding flow performance, i.e., the spreading rate, is the best. The thixotropy of formula 2 obtained by synthesizing the alkoxysilane-terminated polysiloxane resin synthesized by the composite hydrogenated alkoxysilane treated with alkaline activated carbon is higher, the shape retention is better, and the corresponding spreading rate is also lower. In addition, from the comparison of the surface drying time and surface debonding time of Formula 1, Formula 2 and Formula 3, it can be seen that after the component (B) composite hydrogen-containing alkoxysilane adds the "functional" functional group of structural formula 1, the surface drying time or the surface film formation time is consistent, but the surface debonding speed is greatly accelerated.

[0070] Application Example 2:

[0071] The alkoxysilane-terminated polysiloxane resins prepared in Example 2, Example 3 and Comparative Example 2 were applied to a thermally conductive RTV silicone composition. The application formula (by weight) and test results are shown in Table 2.

[0072] Table 2 Thermally conductive RTV silicone composition formula and test results

[0073]

[0074]

[0075] The specific test method is as follows:

[0076] 1. Bonding strength: The bonding material is PCB, cured for ≥3 days at 25°C and 50% RH, the bonding area is (25±0.25)mm*(12.5±0.25)mm, the thickness is 0.15mm, and the test rate is 10mm / min;

[0077] 2.Rework performance: Bonding material is PCB, curing at 25℃, 50%RH environment for ≥3 days,

[0078] See if you can tear it off smoothly into strips.

[0079] From the test results in Table 2, it can be seen that after the "functional" functional group of structural formula 2 is added to the composite hydrogen-containing alkoxy silane component (B) in formula 4, the bonding strength decreases significantly, and after being fully cured, it can be smoothly torn off in strips, which can enhance the material's rework performance. After the composite hydrogen-containing alkoxy silane component (B) in formula 5 is added with the "functional" functional group of structural formula 3, although it also contains some of the "functional" functional groups of structural formula 2, it can increase the overall bonding strength and can be used to enhance the interface bonding of silicone, etc.

[0080] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An alkoxysilane-terminated polysiloxane, characterized in that: The composition comprises the following components in parts by weight: (A) 80-100 parts of a polysiloxane containing at least one vinyl group in its molecule; (B) 2-20 parts of a composite hydrogen-containing alkoxysilane, wherein a single molecule has one and only one Si-H group, at least one Si atom is bonded with an alkoxy group, and at least one Si atom is bonded with a "functional" functional group; (C) 0.01-1 part of catalyst; (D) 0.1-4.5 parts of activated carbon.

2. The alkoxysilane-terminated polysiloxane according to claim 1, characterized in that The general structural formula of the component (A) is (R 1 R 2 2SiO 1 / 2 )(R 1 R 2 SiO 2 / 2 ) a (R 2 SiO 3 / 2 ) b (SiO 4 / 2 ) c , where R 1 , R 2 R independently represent an unsubstituted or substituted monovalent hydrocarbon group; 1 and R 2 At least one of the groups is vinyl; a=0~180 (excluding 0), b=0~1, c=0~1, a+b+c=1~180.

3. The alkoxysilane-terminated polysiloxane according to claim 2, characterized in that The R of the component (A) 1 or R 2 The number of carbon atoms is 1 to 10.

4. The alkoxysilane-terminated polysiloxane according to claim 1, characterized in that The structure of the "functional" functional group is shown below:

5. The alkoxysilane-terminated polysiloxane according to claim 1, characterized in that The general structural formula of the component (B) is as shown in the following formula (I) or formula (II): Wherein, m = 1 to 10, n1 = 1 to 10, n2 = 1 to 5, R 3 is an unsubstituted or substituted monovalent hydrocarbon group, R 4 It is a "functional" functional group.

6. The alkoxysilane-terminated polysiloxane according to claim 1, characterized in that The component (C) catalyst is a noble metal catalyst or a noble metal complex.

7. The alkoxysilane-terminated polysiloxane according to claim 1, characterized in that: The component (D) activated carbon is one of acidic activated carbon and alkaline activated carbon.

8. The alkoxysilane-terminated polysiloxane according to claim 1, characterized in that It also includes one or more of fluorescent agent, color paste or carbon black.

9. The alkoxysilane-terminated polysiloxane according to claim 2, characterized in that: The R of the component (A) 1 or R 2 It is a methyl group, an ethyl group, a propyl group, an isopropyl group, a cycloalkyl group, an aryl group, an aralkyl group, an alkane group containing an olefinic bond, or a group in which some or all of the hydrogen atoms are substituted by a halogen atom or a cyano group.

10. The method for preparing an alkoxysilane-terminated polysiloxane according to any one of claims 1 to 9, characterized in that: The steps include: (1) mixing the component (B) composite hydrogen-containing alkoxysilane and the component (D) activated carbon, stirring and mixing at a temperature below 40° C. for 2-6 hours for pretreatment, and filtering and removing the activated carbon after the treatment; (2) After uniformly mixing component (A) polysiloxane containing at least one vinyl group in the molecule, component (B) composite hydrogen-containing alkoxysilane after pretreatment, and component (C) hydrosilylation catalyst, the mixture is heated to 50-100° C., kept at this temperature for 2-8 hours, cooled to room temperature, and the unreacted small molecules are removed by vacuum distillation to obtain polysiloxane capped with alkoxysilane.

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