Method for synthesizing room temperature vulcanized methylphenyl silicone rubber

Abstract

The present invention relates to the field of the preparation of polymer materials, and to a method for synthesizing a room temperature vulcanized methylphenyl silicone rubber. In the present invention, the method comprises adding α,ω-dihydroxypolydimethyldiphenylsiloxane having a low degree of polymerization and a high phenyl content, dimethylcyclosiloxane, and an alkaline resin catalyst to a reaction kettle and stirring and heating the mixture for a reaction; and after the reaction is complete, removing low-boiling-point substances under vacuum to obtain the room temperature vulcanized methylphenyl silicone rubber. In the present invention, a guanidine-doped D201 ion exchange resin is obtained by means of a D201 ion exchange resin (quaternary ammonium salt type), 1-allylcyclopropylsulfonyl chloride, zinc chloride, bis(1-vinylimidazol-2-yl)ketone, mercaptoethylguanidine dihydrobromide, triethylamine, and dichloromethane; and the guanidine-doped D201 ion exchange resin is loaded into an ion exchange column for transformation to obtain the alkaline resin catalyst. The room temperature vulcanized methylphenyl silicone rubber prepared by the present invention has excellent mechanical properties.

Description

A method for synthesizing room temperature vulcanized methylphenyl silicone rubber Technical Field

[0001] This invention relates to the field of polymer material preparation, and in particular to a method for synthesizing room temperature vulcanized methylphenyl silicone rubber. Background Technology

[0002] Silicone rubber is one of the most important products of polysiloxane. Room temperature vulcanized methyl phenyl silicone rubber has excellent weather resistance, high and low temperature resistance, damping properties, and chemical resistance, and therefore has wide applications in aerospace, electronics, automotive and other fields.

[0003] Chinese Patent CN101851334A: This patent relates to the fields of new materials and fine chemicals (special polymer materials), specifically a high-temperature resistant dimethyldiphenyl room-temperature vulcanizing silicone rubber, its production process, and its applications. It is synthesized using the following four raw materials, with the following percentages by weight: (1) liquid dimethyldiphenyl mixed cyclosiloxane 20.0–34.0%, (2) dimethylcyclosiloxane 65.58–79.89%, (3) water 0.10–0.40%, and (4) tetramethylammonium hydroxide 0.008–0.015%.

[0004] Chinese Patent CN111518132A: Provides a method for preparing a methylphenyl mixed ring and a method for preparing methylphenyl silicone rubber. The method for preparing the methylphenyl mixed ring includes: catalytically cracking and rearranging polymethylphenylsiloxane, followed by stepwise vacuum fractionation. The method for preparing the methylphenyl silicone rubber includes: 1) preparing a methylphenyl mixed ring using the method for preparing methylphenyl mixed rings; 2) polymerizing one or more methylphenyl mixed rings obtained in step 1) with octamethylcyclosiloxane under a catalytic environment with a water-sealed end.

[0005] Chinese Patent CN111454453A relates to a production process for preparing room temperature vulcanizing phenyl silicone rubber raw material, comprising: a polymerization step of reactant raw materials to polymerize raw materials including diphenyldialkoxysilane and dimethyldialkoxysilane; a first vacuum treatment step to vacuum remove low-boiling-point components from the polymerized product; and a second vacuum treatment step to further remove low-boiling-point components from the product of the first vacuum treatment, wherein the purity of diphenyldialkoxysilane and dimethyldialkoxysilane is above 99.99%, the temperature of the first vacuum treatment is 170-190°C and the pressure is below 200 Pa, and the temperature of the second vacuum treatment is below 200°C and the pressure is below 100 Pa.

[0006] The mechanical properties of the room-temperature vulcanized methylphenyl silicone rubber prepared by the above patents and existing technologies need further improvement. Summary of the Invention

[0007] To address the aforementioned problems, this invention provides a method for synthesizing room-temperature vulcanized methylphenyl silicone rubber, comprising the following steps: S1: 80-100 parts by weight of α,ω-dihydroxypolydimethyldiphenylsiloxane with high phenyl content and low degree of polymerization, 30-400 parts by weight of dimethylcyclosiloxane, and 0.2-1 parts by weight of alkaline resin catalyst are added to a reaction vessel, and the mixture is stirred and heated to react; S2: After the reaction is completed, low-boiling substances are removed under vacuum to obtain room-temperature vulcanized methylphenyl silicone rubber.

[0008] The dimethylcyclosiloxane is a mixture of hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecylcyclohexasiloxane, wherein the content of octamethylcyclotetrasiloxane is not less than 75%.

[0009] The reaction temperature of S1 is 105-115℃, and the reaction time is 4-6h.

[0010] The vacuum degree of S2 is -0.09 to -0.095 MPa, and the temperature is 180-190℃.

[0011] The preparation method of the high-phenyl-content, low-polymerization-degree α,ω-dihydroxy polydimethyldiphenylsiloxane is as follows: A1: 120-148 parts of dimethyldimethoxysilane, 180-216 parts of diphenyldihydroxysilane, and 0.01-0.02 parts of hydrochloric acid are added to a reaction vessel and reacted at 60-80℃ for 3-5 hours; A2: After the reaction is completed, 20-30 parts of water are added and the hydrolysis reaction is carried out for 2-4 hours; A3: After hydrolysis, sodium hydroxide is added to adjust the pH value to neutral, and the by-product alcohol and excess water are removed by distillation to obtain the high-phenyl-content, low-polymerization-degree α,ω-dihydroxy polydimethyldiphenylsiloxane.

[0012] The preparation method of the alkaline resin catalyst includes the following steps, all in parts by mass: K1: Add 100-140 parts of D201 ion exchange resin (quaternary ammonium salt type), 1000-1200 parts of 1-allylcyclopropanesulfonyl chloride (CAS No.: 923032-59-1), and 2-5 parts of zinc chloride to a stirred tank 1, and stir and react at 30-50℃ for 3-6 hours; filter, wash with water, and dry to obtain D201 ion exchange resin containing allyl; K2: Add 0.03-0.3 parts of bis(1-vinylimidazol-2-)one (CAS No.: 168322-10-9), and 10-15 parts of mercapto... Ethyl guanidine dihydrobromide (CAS No.: 32665-11-5), 2-5 parts triethylamine, and 1000-1200 parts dichloromethane were stirred and reacted at 60-70℃ for 50-100 minutes; then 100-200 parts of allyl-containing D201 ion exchange resin were added, and the mixture was stirred and reacted at 60-70℃ for 100-150 minutes; the mixture was filtered and dried to obtain guanidine-doped D201 ion exchange resin (quaternary ammonium salt type); K3: The guanidine-doped D201 ion exchange resin and sodium hydroxide were packed into an ion exchange column for transformation to obtain hydroxide-type guanidine-doped D201 ion exchange resin (quaternary ammonium salt type), i.e., basic resin catalyst.

[0013] The K3 resin volume accounts for 25-32% of the ion exchange column volume; the amount of sodium hydroxide added is 2-4 times the resin volume, and the mass concentration of sodium hydroxide is 5-10%; the contact time is 50-100 minutes; and the forward washing flow rate is 10-20 m / h.

[0014] The reaction mechanism involves a mercapto-vinyl addition reaction between bis(1-vinylimidazol-2-)one and mercaptoethylguanidine dihydrobromide, followed by a mercapto-vinyl addition reaction with an allyl-containing D201 ion exchange resin to obtain a D201 ion exchange resin loaded with guanidine and imidazolyl groups, which is then transformed to obtain a hydroxyl resin.

[0015] The D201 ion exchange resin loaded with guanidinium and imidazole groups serves as a basic catalyst, and its catalytic mechanism involves the following aspects: Guanidinium and imidazole groups possess strong basicity, enabling them to accept protons and form stable intermediates. In the hydrolysis reaction, these basic sites can attract and stabilize protons in water molecules, making water molecules more susceptible to nucleophilic attack, thereby promoting the hydrolysis of silicon-oxygen bonds.

[0016] D201 ion exchange resin has a large specific surface area and porous structure, which facilitates sufficient contact between reactant molecules and the catalyst surface, thereby improving reaction efficiency. Simultaneously, the supported guanidine and imidazole groups may be located at specific positions on the resin, forming a spatial configuration favorable to the reaction.

[0017] Synergistic effect: Guanidinyl and imidazole groups may enhance catalyst activity through synergistic effects. For example, a basic site may first stabilize a proton in a water molecule, while another site assists in subsequent proton or electron transfer processes.

[0018] Technical Effects: This invention provides a method for synthesizing room-temperature vulcanized methylphenyl silicone rubber. Compared with existing technologies, this invention has the following significant advantages: Using a D201 ion exchange resin loaded with guanidine and imidazole groups as a catalyst, efficient hydrolysis of α,ω-dihydroxypolydimethyldiphenylsiloxane and dimethylcyclosiloxane can be achieved. This catalyst not only has high catalytic activity but also good stability and reusability. Furthermore, because the catalyst is in solid form, it is easy to separate and recover from the reaction system, reducing production costs and environmental burden.

[0019] In summary, D201 ion exchange resin loaded with guanidine and imidazole groups serves as an alkaline catalyst for the hydrolysis of α,ω-dihydroxypolydimethyldiphenylsiloxane and dimethylcyclosiloxane. This catalyst has advantages such as high efficiency, stability and reusability. Detailed Implementation

[0020] To further illustrate the technical means and effects adopted by the present invention in order to achieve the intended purpose, the following detailed description is provided in conjunction with embodiments and comparative examples: Tensile strength and elongation at break: Tested in accordance with GB / T528--2009, and the test results are shown in Table 1.

[0021] Example 1: A method for synthesizing room temperature vulcanized methylphenyl silicone rubber, the operation steps of which are as follows: S1: 80g of α,ω-dihydroxy polydimethyldiphenylsiloxane with high phenyl content and low degree of polymerization, 30g of dimethylcyclosiloxane, and 0.2g of alkaline resin catalyst are added to a reaction vessel and stirred and heated to react; S2: After the reaction is completed, the low-boiling substances are removed under vacuum to obtain room temperature vulcanized methylphenyl silicone rubber.

[0022] The dimethylcyclosiloxane is a mixture of hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecylcyclohexasiloxane, wherein the content of octamethylcyclotetrasiloxane is not less than 75%.

[0023] The reaction temperature of S1 is 105℃ and the reaction time is 4h.

[0024] The vacuum degree of S2 is -0.09MPa and the temperature is 180℃.

[0025] The preparation method of the high-phenyl-content, low-polymerization-degree α,ω-dihydroxy polydimethyldiphenylsiloxane is as follows: A1: 120g of dimethyldimethoxysilane, 180g of diphenyldihydroxysilane, and 0.01g of hydrochloric acid are added to a reaction vessel and reacted at 60℃ for 3h; A2: After the reaction is completed, 20g of water is added and the hydrolysis reaction is carried out for 2h; A3: After hydrolysis, sodium hydroxide is added, the pH is adjusted to neutral, and the by-product alcohol and excess water are removed by distillation to obtain the high-phenyl-content, low-polymerization-degree α,ω-dihydroxy polydimethyldiphenylsiloxane.

[0026] The preparation method of the alkaline resin catalyst includes the following steps, all in parts by mass: K1: Add 100g of D201 ion exchange resin (quaternary ammonium salt type), 1000g of 1-allylcyclopropanesulfonyl chloride (CAS No.: 923032-59-1), and 2g of zinc chloride to a stirred tank 1, and stir at 30°C for 3 hours; filter, wash with water, and dry to obtain D201 ion exchange resin containing allyl; K2: Add 0.03g of bis(1-vinylimidazol-2-)one (CAS No.: 168322-10-9), 10g of mercaptosulfonate, and 10g of thiosulfate to a stirred tank 2. 2g of triethylamine and 1000g of dichloromethane were reacted with methyl ethyl guanidine dihydrobromide (CAS No.: 32665-11-5) at 60°C for 50 minutes. Then, 100g of allyl-containing D201 ion exchange resin was added and reacted with the mixture at 60°C for 100 minutes. The mixture was filtered and dried to obtain guanidine-doped D201 ion exchange resin (quaternary ammonium salt type). K3: The guanidine-doped D201 ion exchange resin and sodium hydroxide were packed into an ion exchange column for transformation to obtain hydroxide-type guanidine-doped D201 ion exchange resin (quaternary ammonium salt type), i.e., basic resin catalyst.

[0027] The K3 resin volume accounts for 25% of the ion exchange column volume; the amount of sodium hydroxide added is twice the resin volume, and the mass concentration of sodium hydroxide is 5%; the contact time is 50 minutes; and the forward washing flow rate is 10 m / h.

[0028] Example 2: A method for synthesizing room temperature vulcanized methylphenyl silicone rubber, the operation steps of which are as follows: S1: 85g of α,ω-dihydroxy polydimethyldiphenylsiloxane with high phenyl content and low degree of polymerization, 100g of dimethylcyclosiloxane, and 0.4g of alkaline resin catalyst are added to a reaction vessel and stirred and heated to react; S2: After the reaction is completed, the low-boiling substances are removed under vacuum to obtain room temperature vulcanized methylphenyl silicone rubber.

[0029] The dimethylcyclosiloxane is a mixture of hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecylcyclohexasiloxane, wherein the content of octamethylcyclotetrasiloxane is not less than 75%.

[0030] The reaction temperature of S1 is 110℃ and the reaction time is 5h.

[0031] The vacuum degree of S2 is -0.09MPa and the temperature is 185℃.

[0032] The preparation method of the high-phenyl-content, low-polymerization-degree α,ω-dihydroxy polydimethyldiphenylsiloxane is as follows: A1: 130g of dimethyldimethoxysilane, 190g of diphenyldihydroxysilane, and 0.015g of hydrochloric acid are added to a reaction vessel and reacted at 65℃ for 4h; A2: After the reaction is completed, 24g of water is added and the hydrolysis reaction is carried out for 3h; A3: After hydrolysis, sodium hydroxide is added, the pH is adjusted to neutral, and the by-product alcohol and excess water are removed by distillation to obtain the high-phenyl-content, low-polymerization-degree α,ω-dihydroxy polydimethyldiphenylsiloxane.

[0033] The preparation method of the alkaline resin catalyst includes the following steps, all in parts by mass: K1: Add 110g of D201 ion exchange resin (quaternary ammonium salt type), 1050g of 1-allylcyclopropanesulfonyl chloride (CAS No.: 923032-59-1), and 3g of zinc chloride to a stirred tank 1, and stir at 35°C for 4 hours; filter, wash with water, and dry to obtain D201 ion exchange resin containing allyl; K2: Add 0.1g of bis(1-vinylimidazol-2-)one (CAS No.: 168322-10-9), 12g of mercaptosulfonate, and 12g of thiosulfate to a stirred tank 2. 3g of triethylamine and 1050g of dichloromethane were reacted with methyl ethyl guanidine dihydrobromide (CAS No.: 32665-11-5) at 65°C for 60 minutes. Then, 140g of allyl-containing D201 ion exchange resin was added and reacted with the mixture at 65°C for 110 minutes. The mixture was filtered and dried to obtain guanidine-doped D201 ion exchange resin (quaternary ammonium salt type). K3: The guanidine-doped D201 ion exchange resin and sodium hydroxide were packed into an ion exchange column for transformation to obtain hydroxide-type guanidine-doped D201 ion exchange resin (quaternary ammonium salt type), i.e., basic resin catalyst.

[0034] The K3 resin volume accounts for 27% of the ion exchange column volume; the amount of sodium hydroxide added is 3 times the resin volume, and the mass concentration of sodium hydroxide is 6%; the contact time is 70 minutes; and the forward washing flow rate is 14 m / h.

[0035] Example 3: A method for synthesizing room temperature vulcanized methylphenyl silicone rubber, the operation steps of which are as follows: S1: 95g of α,ω-dihydroxy polydimethyldiphenylsiloxane with high phenyl content and low degree of polymerization, 300g of dimethylcyclosiloxane, and 0.8g of alkaline resin catalyst are added to a reaction vessel and stirred and heated to react; S2: After the reaction is completed, the low-boiling substances are removed under vacuum to obtain room temperature vulcanized methylphenyl silicone rubber.

[0036] The dimethylcyclosiloxane is a mixture of hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecylcyclohexasiloxane, wherein the content of octamethylcyclotetrasiloxane is not less than 75%.

[0037] The reaction temperature of S1 is 110℃ and the reaction time is 5h.

[0038] The vacuum degree of S2 is -0.095MPa and the temperature is 185℃.

[0039] The preparation method of the high-phenyl-content, low-polymerization-degree α,ω-dihydroxy polydimethyldiphenylsiloxane is as follows: A1: 140g of dimethyldimethoxysilane, 200g of diphenyldihydroxysilane, and 0.015g of hydrochloric acid are added to a reaction vessel and reacted at 75℃ for 4h; A2: After the reaction is completed, 28g of water is added and the hydrolysis reaction is carried out for 3h; A3: After hydrolysis, sodium hydroxide is added, the pH is adjusted to neutral, and the by-product alcohol and excess water are removed by distillation to obtain the high-phenyl-content, low-polymerization-degree α,ω-dihydroxy polydimethyldiphenylsiloxane.

[0040] The preparation method of the alkaline resin catalyst includes the following steps, all in parts by mass: K1: Add 130g of D201 ion exchange resin (quaternary ammonium salt type), 1150g of 1-allylcyclopropanesulfonyl chloride (CAS No.: 923032-59-1), and 4g of zinc chloride to a stirred tank 1, and stir at 45°C for 5 hours; filter, wash with water, and dry to obtain D201 ion exchange resin containing allyl; K2: Add 0.2g of bis(1-vinylimidazol-2-)one (CAS No.: 168322-10-9), 14g of mercaptosulfonate, and 14g of thiosulfate to a stirred tank 2. 4g of triethylamine and 1150g of dichloromethane were reacted with methyl guanidine dihydrobromide (CAS No.: 32665-11-5) at 65°C for 90 minutes. Then, 180g of allyl-containing D201 ion exchange resin was added and reacted with the mixture at 65°C for 140 minutes. The mixture was filtered and dried to obtain guanidine-doped D201 ion exchange resin (quaternary ammonium salt type). K3: The guanidine-doped D201 ion exchange resin and sodium hydroxide were packed into an ion exchange column for transformation to obtain hydroxide-type guanidine-doped D201 ion exchange resin (quaternary ammonium salt type), i.e., basic resin catalyst.

[0041] The K3 resin volume accounts for 30% of the ion exchange column volume; the amount of sodium hydroxide added is 3 times the resin volume, and the mass concentration of sodium hydroxide is 8%; the contact time is 90 minutes; and the forward washing flow rate is 18 m / h.

[0042] Example 4: A method for synthesizing room temperature vulcanized methylphenyl silicone rubber, the operation steps of which are as follows: S1: 100g of α,ω-dihydroxy polydimethyldiphenylsiloxane with high phenyl content and low degree of polymerization, 400g of dimethylcyclosiloxane, and 1g of alkaline resin catalyst are added to a reaction vessel and stirred and heated to react; S2: After the reaction is completed, the low-boiling substances are removed under vacuum to obtain room temperature vulcanized methylphenyl silicone rubber.

[0043] The dimethylcyclosiloxane is a mixture of hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecylcyclohexasiloxane, wherein the content of octamethylcyclotetrasiloxane is not less than 75%.

[0044] The reaction temperature of S1 is 115℃ and the reaction time is 6h.

[0045] The vacuum degree of S2 is -0.095MPa and the temperature is 190℃.

[0046] The preparation method of the high-phenyl-content, low-polymerization-degree α,ω-dihydroxy polydimethyldiphenylsiloxane is as follows: A1: 148g of dimethyldimethoxysilane, 216g of diphenyldihydroxysilane, and 0.02g of hydrochloric acid are added to a reaction vessel and reacted at 80℃ for 5h; A2: After the reaction is completed, 30g of water is added and the hydrolysis reaction is carried out for 4h; A3: After hydrolysis, sodium hydroxide is added to adjust the pH value to neutral, and then the by-product alcohol and excess water are removed by distillation to obtain the high-phenyl-content, low-polymerization-degree α,ω-dihydroxy polydimethyldiphenylsiloxane.

[0047] The preparation method of the alkaline resin catalyst includes the following steps, all in parts by mass: K1: Add 140g of D201 ion exchange resin (quaternary ammonium salt type), 1200g of 1-allylcyclopropanesulfonyl chloride (CAS No.: 923032-59-1), and 5g of zinc chloride to a stirred tank 1, and stir at 50°C for 6 hours; filter, wash with water, and dry to obtain D201 ion exchange resin containing allyl groups; K2: Add 0.3g of bis(1-vinylimidazol-2-)one (CAS No.: 168322-10-9), 15g of mercapto-1... Ethyl guanidine dihydrobromide (CAS No.: 32665-11-5), 5g triethylamine, and 1200g dichloromethane were stirred at 70°C for 100 minutes. Then, 200g of allyl-containing D201 ion exchange resin was added, and the mixture was stirred at 70°C for 150 minutes. The mixture was filtered and dried to obtain guanidine-doped D201 ion exchange resin (quaternary ammonium salt type). K3: The guanidine-doped D201 ion exchange resin and sodium hydroxide were packed into an ion exchange column for transformation to obtain hydroxide-type guanidine-doped D201 ion exchange resin (quaternary ammonium salt type), i.e., a basic resin catalyst.

[0048] The K3 resin volume accounts for 32% of the ion exchange column volume; the amount of sodium hydroxide added is 4 times the resin volume, and the mass concentration of sodium hydroxide is 10%; the contact time is 100 minutes; and the forward washing flow rate is 20 m / h.

[0049] Comparative Example 1 did not add an alkaline resin catalyst, but added D201 ion exchange resin (quaternary ammonium salt type), and the rest was the same as in Example 1.

[0050] Comparative Example 2 did not include bis(1-vinylimidazol-2-)one, and was otherwise the same as in Example 1.

[0051] Comparative Example 3 did not include allylcyclopropanesulfonyl chloride, but otherwise it was the same as Example 1.

[0052] Table 1 Based on the data analysis of the above embodiments and comparative examples, the room temperature vulcanized methylphenyl silicone rubber prepared by the present invention has excellent mechanical properties.

[0053] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for synthesizing room temperature vulcanized methylphenyl silicone rubber, comprising the following steps: S1: According to the weight, add 80-100 parts of α,ω-dihydroxy polydimethyldiphenylsiloxane with high phenyl content and low degree of polymerization, 30-400 parts of dimethylcyclosiloxane, and 0.2-1 parts of alkaline resin catalyst to the reaction vessel, stir and heat to react. S2: After the reaction is complete, the low-boiling substances are removed under vacuum to obtain room temperature vulcanized methylphenyl silicone rubber; The alkaline resin is prepared by reacting allyl-containing D201 ion exchange resin, bis(1-vinylimidazol-2-)one, and mercaptoethylguanidine dihydrobromide.

2. The method for synthesizing room temperature vulcanized methylphenyl silicone rubber according to claim 1, characterized in that: The dimethylcyclosiloxane is a mixture of hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecylcyclohexasiloxane, wherein the content of octamethylcyclotetrasiloxane is not less than 75%.

3. The method for synthesizing room temperature vulcanized methylphenyl silicone rubber according to claim 1, characterized in that: The reaction temperature of S1 is 105-115℃, and the reaction time is 4-6h.

4. The method for synthesizing room temperature vulcanized methylphenyl silicone rubber according to claim 1, characterized in that: The vacuum degree of S2 is -0.09 to -0.095 MPa, and the temperature is 180-190℃.

5. The method for synthesizing room temperature vulcanized methylphenyl silicone rubber according to claim 1, characterized in that: The preparation method of the high-phenyl-content, low-polymerization-degree α,ω-dihydroxypolydimethyldiphenylsiloxane is as follows: A1: Add 120-148 parts of dimethyldimethoxysilane, 180-216 parts of diphenyldihydroxysilane, and 0.01-0.02 parts of hydrochloric acid to a reaction vessel and react at 60-80℃ for 3-5 hours; A2: After the reaction is complete, add 20-30 parts of water and allow the hydrolysis reaction to proceed for 2-4 hours; A3: After hydrolysis, sodium hydroxide is added to adjust the pH to neutral. Then, the by-product alcohol and excess water are removed by distillation to obtain α,ω-dihydroxypolydimethyldiphenylsiloxane with high phenyl content and low degree of polymerization.

6. The method for synthesizing room temperature vulcanized methylphenyl silicone rubber according to claim 1, characterized in that: The method for preparing the alkaline resin catalyst, The following steps are included: all measured in parts by weight: K1: Add 100-140 parts of D201 ion exchange resin, 1000-1200 parts of 1-allylcyclopropanesulfonyl chloride, and 2-5 parts of zinc chloride to a stirred tank 1, and stir the reaction at 30-50℃ for 3-6 hours; filter, wash with water, and dry to obtain D201 ion exchange resin containing allyl. K2: Add 0.03-0.3 parts of bis(1-vinylimidazol-2-)one, 10-15 parts of mercaptoethylguanidine dihydrobromide, 2-5 parts of triethylamine, and 1000-1200 parts of dichloromethane to stirred tank 2, and stir at 60-70℃ for 50-100 minutes; then add 100-200 parts of allyl-containing D201 ion exchange resin, and stir at 60-70℃ for 100-150 minutes; filter, dry, and obtain guanidine-doped D201 ion exchange resin; K3: Guanidine-doped D201 ion exchange resin and sodium hydroxide are packed into an ion exchange column for transformation to obtain hydroxyl-type guanidine-doped D201 ion exchange resin, i.e., basic resin catalyst.

7. The method for synthesizing room temperature vulcanized methylphenyl silicone rubber according to claim 6, characterized in that: The K3 resin volume accounts for 25-32% of the ion exchange column volume; the amount of sodium hydroxide added is 2-4 times the resin volume, and the mass concentration of sodium hydroxide is 5-10%; the contact time is 50-100 minutes; and the forward washing flow rate is 10-20 m / h.

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