Production method of diphenyl silicone oil

Abstract

The invention provides a production method of diphenyl silicone oil, which comprises the following steps: S100, carrying out chain extension on diphenyldimethoxysilane and a first chain extender dimethyl cyclosiloxane in the presence of a first catalyst, and after chain extension, carrying out decoloration treatment by using activated carbon; the dosage of the first chain extender is 30-80wt% of the mass of the diphenyldimethoxysilane; s200, an alcohol solvent and an inorganic acid aqueous solution are added, hydrolysis is carried out under the condensation reflux condition, a hydrolysis product is washed with water, the solvent is removed, and low-viscosity hydroxyl-terminated diphenyl silicone oil is obtained; and S300, carrying out second-time chain extension on the low-viscosity hydroxyl-terminated diphenyl silicone oil and a second chain extender in the presence of a second catalyst to obtain the product diphenyl silicone oil. No toxic organic solvent is used, the viscosity of an intermediate product is low, decoloration is facilitated, and the product is colorless and transparent in appearance. Diphenyl silicone oil products with different viscosities and different functional group end caps can be conveniently prepared.

Description

Technical Field

[0001] The invention belongs to the technical field of organic silicon, and particularly relates to a method for preparing diphenyl silicone oil. Background Art

[0002] It is well known that when preparing methylphenyl silicone oil, octaphenylcyclotetrasiloxane or tetraphenylcyclotetrasiloxane is used to react with the corresponding end-capping agent, and the corresponding hydroxy-terminated methylphenyl silicone oil, M-terminated methylphenyl silicone oil, vinyl-terminated methylphenyl silicone oil, and hydrogen-terminated methylphenyl silicone oil prepared have a colorless and transparent product appearance; while using diphenyldimethylsilane (diphenyldichlorosilane) or methylphenyldimethoxysilane (or methylphenyldichlorosilane) for hydrolysis, the viscosity of the product is large, and even a ring-back phenomenon occurs, so that part of the hydrolysis product adheres to the wall of the reactor, the position of the stirring rod, etc., which not only makes the phenyl content of the target product low, but also at this time, it is difficult to use activated carbon for decolorization, and the corresponding hydroxy-terminated methylphenyl silicone oil, M-terminated methylphenyl silicone oil, vinyl-terminated methylphenyl silicone oil, and hydrogen-terminated methylphenyl silicone oil prepared by it have a light yellow product appearance.

[0003] It can be seen from the two patents of Jiangxi Beiteli New Materials Co., Ltd. (CN202311644215.2-A method for synthesizing diphenylsilanediol, a method for preparing octaphenylcyclotetrasiloxane) that the product after hydrolysis of diphenyldimethoxysilane is a powdered solid of diphenylsilanediol (melting point 144-147°C) or a powdered solid of octaphenylcyclotetrasiloxane (melting point 196-198°C). Obviously, if diphenylsilanediol or octaphenylcyclotetrasiloxane is used to prepare methylphenyl silicone oil products, the cost will surge.

[0004] CN201310003581.X discloses a method for preparing a hydroxy-terminated polymethylphenyl silicone oil, which uses diphenyldichlorosilane and dimethyldichlorosilane for hydrolysis to prepare small-molecule hydroxydiphenyl silicone oil. Dimethyldichlorosilane is flammable, volatile (boiling point is only 70.3°C), and easily hydrolyzed to produce HCl, which is harmful to the human body and the environment. Its vapor and liquid can cause skin burns. Inhalation is not only toxic, but also irritates the throat, causing breathing difficulties and even life-threatening. The reactor must use a more expensive enamel reactor. Because dimethyldichlorosilane will produce hydroxyl groups in the subsequent hydrolysis process, the patent adopts acetylation and then performs a second hydrolysis to obtain a small-molecule hydroxy-terminated phenylmethyl silicone oil. It should be pointed out that the decolorization process of this patent is based on the second hydrolysis after acylation to obtain a small-molecule hydroxy-terminated phenylmethyl silicone oil with lower viscosity.

[0005] CN201711208626.1 discloses a method for preparing methylphenyl vinyl silicone oil, comprising: using a mixture of diphenyldimethoxysilane, octamethylcyclotetrasiloxane, dimethylvinylethoxysilane, concentrated sulfuric acid and toluene, stirring at 30-45°C for 1h, then keeping the temperature at 35-50°C, adding deionized water dropwise within 1-2h, heating and reflux for 4h after the addition is completed to carry out a hydrolysis condensation reaction to obtain a hydrolysis mixture, then standing and cooling the hydrolysis mixture to room temperature, separating an organic layer and washing the organic layer with deionized water until neutral, adding 0.1-1g potassium hydroxide to the organic layer, heating and azeotropic reflux for 4h to obtain an azeotropic reflux liquid, and then stirring and neutralizing with 20-80g of a cationic resin, sampling and determining the potassium ion content in the mixture while stirring, then filtering, and removing the remaining toluene and low-boiling substances under vacuum at a vacuum degree of 0.075MPa and a temperature of 200°C for 2-4h to obtain methylphenyl vinyl silicone oil. Toluene can reduce the viscosity of the system, but toluene still needs to be removed eventually, and the use of toluene is not green and environmentally friendly, as it is a toxic reagent.

[0006] In summary, the traditional hydrolysis process of diphenyldimethoxysilane (or diphenyldichlorosilane) is generally co-hydrolyzed with dimethyl dichloride, which not only corrodes the equipment, but also poses a hidden danger of harm to the human body. During the hydrolysis process, hydroxyl groups are produced. In the acidic system, some of the hydroxyl groups will condense, resulting in a high viscosity of the hydrolyzed material after hydrolysis, which is not conducive to the decolorization and filtration of activated carbon, and will also cause the final product to have a light yellow appearance. Summary of the invention

[0007] In view of this, the purpose of the present invention is to address the shortcomings of the prior art in preparing methylphenyl silicone oil, which uses toxic organic solvents (such as toluene), has high viscosity of the intermediate product, is not conducive to decolorization, and has a yellow appearance. The present invention provides a method for producing methylphenyl silicone oil, which can conveniently prepare diphenyl silicone oil products with different viscosities and different functional groups, does not use toxic organic solvents such as toluene, has a colorless and transparent product appearance, and does not cause white paste to hang on the wall during the production process.

[0008] The objectives of the present invention are achieved through the following technical solutions.

[0009] A method for producing diphenyl silicone oil comprises the following steps:

[0010] S100, diphenyldimethoxysilane and the first chain extender dimethylcyclosiloxane are chain extended in the presence of a first catalyst, and after chain extension, activated carbon is used for decolorization; the first chain extender is dimethylcyclosiloxane, and the amount of the first chain extender is 30-80wt% of the mass of diphenyldimethoxysilane;

[0011] S200, adding an alcohol solvent and an inorganic acid aqueous solution, hydrolyzing under condensation reflux conditions, washing the hydrolyzate with water, and removing the solvent to obtain a low-viscosity hydroxyl-terminated diphenyl silicone oil;

[0012] S300, low viscosity hydroxyl-terminated diphenyl silicone oil and a second chain extender, a second chain extension is carried out in the presence of a second catalyst to obtain a product diphenyl silicone oil; the second chain extender is selected from at least one of low viscosity α, ω-dihydroxy polydimethylsiloxane or low viscosity hydroxyl-terminated diphenyl silicone oil and dimethylcyclosiloxane.

[0013] The present invention uses diphenyldimethoxysilane as a starting material. After the first chain extension, the product viscosity is low, and it is convenient to carry out decolorization treatment at this time. The final product diphenyl silicone oil is a colorless and transparent product. During the entire preparation process, especially after concentration, there will be no white paste on the inner wall of the reactor to affect production. During the second chain extension, diphenyl silicone oils with different viscosities and different functional group end-capping can be prepared by adding various end-capping agents. During the first chain extension, the amount of the first chain extender is crucial, and the amount of the first chain extender is preferably 30-80wt% of the mass of diphenyldimethoxysilane. If the amount of the first chain extender is too little, a white paste will be produced on the inner wall of the reactor after concentration, and there will be turbidity; if the amount of the chain extender is too much, the viscosity after hydrolysis will be too large, and after washing, the separation speed of the separatory funnel will slow down.

[0014] Further, in step S100, the first chain extender dimethylcyclosiloxane is selected from at least one of octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6), such as a dimethylcyclosiloxane mixed ring (DMC, wherein D4 is about 75% to 85%, D5 is 10% to 15%, and D6 is about 5-10%); the first catalyst is selected from trifluoromethanesulfonic acid or tetramethylammonium hydroxide silicon alkoxide, or potassium hydroxide silicon alkoxide.

[0015] Furthermore, when the first catalyst is trifluoromethanesulfonic acid, the reaction temperature is 40-70°C and the reaction time is 2-6h; when the first catalyst is tetramethylammonium hydroxide siliconate, the reaction temperature is set to 90-125°C and the reaction time is 2-6h. After the reaction is completed, the temperature is raised to 140-150°C and the catalyst is kept warm for 1-2h to break the catalyst. The tetramethylammonium hydroxide catalyst will be thermally decomposed and volatilized; when the first catalyst is potassium hydroxide siliconate, the reaction temperature is 140-160°C and the reaction time is 3-7h.

[0016] Furthermore, in step S100, the amount of the first chain extender is 30-80wt% of the mass of diphenyldimethoxysilane, and the amount of the first catalyst is 20-300ppm, preferably 30-100ppm, of the mass of diphenyldimethoxysilane.

[0017] Furthermore, in step S100, the amount of activated carbon is 0.5-3wt% of the mass of diphenyldimethoxysilane, preferably 1-2wt%. The specific surface area of ​​the activated carbon is 900-1500m 2 / g.

[0018] Furthermore, in step S200, the alcohol solvent is selected from at least one of methanol, ethanol, and isopropanol, and the amount of the alcohol solvent added is 20-80wt% of the mass of the diphenyldimethoxysilane in step S100, preferably 20-55wt%; the inorganic acid aqueous solution is dilute sulfuric acid with a pH of 1-4, or dilute hydrochloric acid with a pH of 1-4; the amount of the inorganic acid aqueous solution is 20-30wt% of the mass of the diphenyldimethoxysilane in step S100.

[0019] Furthermore, in step S200, the hydrolysis reaction temperature is 50-70°C, the reaction time is 4-7h, and the alcohol solvent is removed at 50-90°C and a vacuum degree of -0.07 to -0.1 MPa.

[0020] In step S200, the viscosity of the intermediate product low-viscosity hydroxyl-terminated diphenyl silicone oil is 400-1000 mm 2 / s.

[0021] Further, in step 300, the definition of dimethylcyclosiloxane is the same as that in step S100, that is, at least one selected from octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6); the viscosity of the low-viscosity α, ω-dihydroxy polydimethylsiloxane is 50 to 140 mPa.s, and the viscosity of the low-viscosity hydroxyl-terminated diphenyl silicone oil is 300 to 600 mm 2 / s; further, the amount of the second chain extender is 100-200wt% of the mass of the low-viscosity hydroxyl-terminated diphenyl silicone oil in step S200.

[0022] Furthermore, in step 300, a capping agent is also added; when it is necessary to prepare trimethylsilyl-terminated (M-terminated) diphenyl silicone oil, the capping agent is selected from hexamethyldisiloxane (MM), or a viscosity of 5-40 mm 2 / s of dimethyl silicone oil; when it is necessary to prepare alkenyl-terminated diphenyl silicone oil, the end-capping agent is selected from tetramethyl divinyl silane, or a viscosity of 5-40mm 2 / s vinyl silicone oil; when it is necessary to prepare active hydrogen-terminated diphenyl silicone oil, the end-capping agent is selected from tetramethyldihydrosilane, or a viscosity of 5-40mm 2 / s of hydrogen-containing silicone oil. The amount of the end-capping agent is 5-15wt% of the mass of the low-viscosity hydroxyl-terminated diphenyl silicone oil described in step S200, preferably 8-11wt%; the second catalyst is selected from trifluoromethanesulfonic acid or tetramethylammonium hydroxide silicon alkoxide, or potassium hydroxide silicon alkoxide or phosphinothionite chloride. The selection range of the second catalyst is the same as that of the first catalyst, and the reaction temperature and reaction time are also as described above.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] 1. The dimethylcyclosiloxane used in the present invention does not generate additional hydroxyl groups, so the viscosity of the product after the first chain extension is low, less than 10 mm 2 / s, at this time, it is more convenient to use activated carbon for decolorization, rather than decolorization after hydrolysis. And the product after the first chain extension has low viscosity, which is not only conducive to decolorization, but also hydrolyzed in an alcohol solvent, and then washed with water to obtain a hydrolyzate. The stratification speed after each water washing is fast and can be completed within 20 minutes. The hydrolyzate can be further chain extended to prepare hydroxyl-terminated diphenyl silicone oil, methyl-terminated diphenyl silicone oil, vinyl-terminated diphenyl silicone oil, hydrogen-terminated diphenyl silicone oil and other products with different viscosities.

[0025] Second, in the whole process of the present invention, no white (paste-like) solid attached to the kettle wall or the stirring rod will appear. After the production is enlarged, the product can be smoothly transferred in the pipeline, which is suitable for large-scale production.

[0026] 3. The present invention adopts diphenyldimethoxysilane and dimethyl ring body to prepare various functional group-terminated diphenyl silicone oils. The raw materials used not only do not involve dimethyldichlorosilane that is corrosive to production equipment, but also do not produce HCl gas harmful to the human body during the production process. In addition, the first chain extension of the present invention can use tetramethylammonium hydroxide silicon alkoxide or potassium hydroxide silicon alkoxide, and the reaction kettle does not need to use an enamel kettle.

[0027] Fourth, the hydrolysis process involved in the present invention uses an alcohol solvent as the organic solvent, rather than toxic reagents such as toluene, and the viscosity of the diphenyl dimethoxyalkyl and dimethyl cyclosiloxane after chain extension, decolorization, hydrolysis, and solvent removal is 1000mm 2 / s, the preferred embodiment can reach 500mm 2 / s, there is no need to reduce the viscosity by toluene, and it can further react with chain extender 2 and corresponding end-capping agent to prepare hydroxyl-terminated diphenyl silicone oil, M-terminated diphenyl silicone oil, vinyl-terminated diphenyl silicone oil, and hydrogen-terminated diphenyl silicone oil of different viscosities. Compared with the use of diphenylsilanediol or octaphenylcyclotetrasiloxane, it has a significant low-cost advantage. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is further explained below with reference to specific embodiments.

[0029] Diphenyldimethoxysilane was purchased from Jiangxi Hongbai New Materials Co., Ltd.;

[0030] D4 and DMC (D4 about 75%, D5 15%, D6 about 10%) were purchased from Jiangxi Lanxing Xinghuo Silicone Co., Ltd.;

[0031] Example 1

[0032] (S100) Add 150 g of diphenyldimethoxysilane and 45 g of octamethylcyclotetrasiloxane (D4) to the reactor, raise the temperature to 50° C., -0.1 MPa, dehydrate for 1 h, change to condensation reflux, and raise the temperature to 150° C., add 0.0394 g of 15% potassium hydroxide silicon alkoxide, react for 4 h; cool to 30° C., add 2 g of activated carbon for decolorization for 1 h, and filter;

[0033] (S200) 50 g of isopropanol and 30 g of hydrochloric acid solution with a pH of 2 were added to the filtrate, and the mixture was condensed and refluxed at 60° C. for 5 h; the product was transferred to a separatory funnel and washed with water twice; the material was transferred to a reactor, the temperature was set to 60° C., the vacuum degree was -0.1 MPa, the solvent was removed, and a viscosity of 402 mm was obtained. 2 / s low viscosity hydroxyl-terminated diphenyl silicone oil, no solid particles remain on the wall of the reactor.

[0034] Example 2

[0035] (S100) Add 150 g of diphenyldimethoxysilane and 80 g of DMC to the reactor, raise the temperature to 60° C., -0.09 MPa, dehydrate for 1 hour, change to condensation reflux, and raise the temperature to 110° C., add 0.7666 g of 3% tetramethylammonium hydroxide silicon alkoxide, react for 3.5 hours, raise the temperature to 150° C., keep the temperature for 1 hour; after cooling to 30° C., add 2 g of activated carbon for decolorization for 1 hour, and filter;

[0036] (S200) 70 g of n-butanol and 35 g of hydrochloric acid solution with a pH of 2 were added to the filtrate, and the mixture was condensed and refluxed at 60° C. for 5 h; the product was transferred to a separatory funnel and washed with water three times; the material was transferred to a reactor, the temperature was set to 60° C., the vacuum degree was -0.1 MPa, the solvent was removed, and a viscosity of 458 mm was obtained. 2 / s low viscosity hydroxyl-terminated diphenyl silicone oil, no solid particles remain on the wall of the reactor.

[0037] Example 3

[0038] (S100) 150 g of diphenyldimethoxysilane and 120 g of DMC were added to the reactor, the temperature was raised to 60° C., -0.09 MPa, dehydrated for 1 h, then condensed and refluxed, and the temperature was raised to 75° C., 0.405 g of a 2% trifluoromethanesulfonic acid toluene solution was added, and the reaction was continued for 3.5 h; after cooling to 30° C., 2 g of activated carbon was added for decolorization for 1 h, and filtered;

[0039] (S200) 80g of ethanol and 35g of hydrochloric acid solution with pH=2 were added to the filtrate, and the mixture was condensed and refluxed at 60°C for 5h; the product was transferred to a separatory funnel and washed with water 3 times; the material was transferred to a reactor, the temperature was set to 60°C, the vacuum degree was -0.1MPa, the solvent was removed, and the viscosity was 675mm 2 / s low viscosity hydroxyl-terminated diphenyl silicone oil, no solid particles remain on the wall of the reactor.

[0040] Comparative Example 1

[0041] The other conditions are the same as those in Example 1, except that in step (S100), the amount of D4 added is 40 g.

[0042] Comparative Example 2

[0043] The other conditions are the same as those in Example 1, except that in step (S100), the amount of D4 added is 30 g.

[0044] Comparative Example 3

[0045] 150 g of diphenyldimethoxysilane, 80 g of ethanol, and 35 g of hydrochloric acid solution with a pH of 2 were added to the reactor, and the mixture was condensed and refluxed at 60° C. for 5 h. The product was transferred to a separatory funnel, and the lower oil layer had difficulty in flowing.

[0046] Comparative Example 4

[0047] The other conditions are the same as those in Example 1, except that in step (S100), the amount of D4 added is 150 g.

[0048] The product characteristics of the above examples and comparative examples are shown in Table 1 below.

[0049] Table 1 Characterization of low viscosity hydroxyl-terminated diphenyl silicone oil

[0050]

[0051] The product of Example 1 was used to further prepare diphenyl silicone oils with different functionalities:

[0052] Application Example 1: Preparation of Hydroxyl-Terminated Diphenyl Silicone Oil

[0053] 140 g of the low-viscosity hydroxyl-terminated diphenyl silicone oil of Example 1 was placed in a reaction kettle, heated to 75° C., 0.014 g of 1% trifluoromethanesulfonic acid catalyst (toluene as solvent) was added, reacted for 2 h, 0.016 g of 1% NaHCO3 aqueous solution was added, neutralized for 1 h, and then heated to 170° C. and degassed for 2 h to obtain a 24500 mm thick silica gel. 2 / s hydroxy-terminated diphenyl silicone oil.

[0054] Application Example 2: Preparation of M-terminated diphenyl silicone oil

[0055] 47 g of the low-viscosity hydroxyl-terminated diphenyl silicone oil of Example 1, 87.5 g of DMC, and 5 g of a 20 mm 2 / s dimethyl silicone oil was placed in a reactor, heated to 50°C, dehydrated at -0.1MPa for 1h, then heated to 160°C, 0.028g of 15% KOH silicon alkoxide was added, reacted for 5h, 0.0558g of 15% silicon-based phosphate was added, neutralized for 1h, then heated to 220°C, dehydrated for 2h, and a viscosity of 623mm was obtained. 2 / s of M-terminated diphenyl silicone oil.

[0056] Application Example 3: Preparation of Vinyl-Terminated Diphenyl Silicone Oil

[0057] 47 g of the product of Example 1, 87.5 g of D4, 5 g of a viscosity of 24 mm 2 / s of vinyl-terminated silicone oil was placed in a reactor, heated to 50°C, dehydrated at -0.1MPa for 1h, then heated to 110°C, 1.4g of 3% tetramethylammonium hydroxide silicon alkoxide was added, reacted for 5h, heated to 150°C, broken for 1h, then heated to 220°C, dehydrated for 2h, and a viscosity of 710mm was obtained. 2 / s vinyl terminated diphenyl silicone oil.

[0058] Application Example 4: Preparation of Hydrogen-Terminated Diphenyl Silicone Oil

[0059] 83 g of the product of Example 1 and 83 g of a viscosity of 90 mm 2 / s of α,ω-dihydroxypolydimethylsiloxane, 7g of viscosity is 7mm 2 / s of terminal hydrogen silicone oil was placed in a reactor, heated to 55°C, dehydrated at -0.1MPa for 1h, 0.0035g of phosphinothionyl chloride was added, reacted for 3h, 0.007g of triamylamine was added, neutralized for 1h, heated to 205°C, dehydrated for 2h, and a viscosity of 150mm was obtained. 2 / s hydrogen-terminated diphenyl silicone oil.

[0060] Application Characterization:

[0061]

Claims

1. A method for producing diphenyl silicone oil, characterized in that: The following steps are involved: S100, diphenyldimethoxysilane and the first chain extender dimethylcyclosiloxane are chain extended in the presence of a first catalyst, and after chain extension, activated carbon is used for decolorization; the first chain extender is dimethylcyclosiloxane, and the amount of the first chain extender is 30-80wt% of the mass of diphenyldimethoxysilane; S200, adding an alcohol solvent and an inorganic acid aqueous solution, hydrolyzing under condensation reflux conditions, washing the hydrolyzate with water, and removing the solvent to obtain a low-viscosity hydroxyl-terminated diphenyl silicone oil; S300, low viscosity hydroxyl-terminated diphenyl silicone oil and a second chain extender, a second chain extension is carried out in the presence of a second catalyst to obtain a product diphenyl silicone oil; the second chain extender is selected from at least one of low viscosity α, ω-dihydroxy polydimethylsiloxane or low viscosity hydroxyl-terminated diphenyl silicone oil and dimethylcyclosiloxane.

2. The production method according to claim 1, characterized in that In step S100, the dimethylcyclosiloxane is selected from at least one of octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6); and the first catalyst is selected from trifluoromethanesulfonic acid or tetramethylammonium hydroxide silicon alkoxide, or potassium hydroxide silicon alkoxide.

3. The production method according to claim 2, characterized in that: When the first catalyst is trifluoromethanesulfonic acid, the reaction temperature is 40-70°C and the reaction time is 2-6h; when the first catalyst is tetramethylammonium hydroxide siliconate, the reaction temperature is set to 90-125°C, the reaction time is 2-6h, and after the reaction is completed, the temperature is raised to 140-150°C and the catalyst is kept warm for 1-2h; when the first catalyst is potassium hydroxide siliconate, the reaction temperature is 140-160°C and the reaction time is 3-7h.

4. The production method according to claim 1, characterized in that In step S100, the amount of the first chain extender is 30-80wt% of the mass of diphenyldimethoxysilane, and the amount of the first catalyst is 20-300ppm, preferably 30-100ppm, of the mass of diphenyldimethoxysilane.

5. The production method according to claim 1, characterized in that: In step S100, the amount of activated carbon is 0.5-3wt% of the mass of diphenyldimethoxysilane, preferably 1-2wt%; the specific surface area of ​​the activated carbon is 900-1500m 2 / g.

6. The production method according to claim 1, characterized in that: In step S200, the alcohol solvent is selected from at least one of methanol, ethanol, and isopropanol, and the amount of the alcohol solvent added is 20-80wt% of the mass of the diphenyldimethoxysilane in step S100, preferably 20-55wt%; the inorganic acid aqueous solution is dilute sulfuric acid with a pH of 1-4, or dilute hydrochloric acid with a pH of 1-4; the amount of the inorganic acid aqueous solution is 20-30wt% of the mass of the diphenyldimethoxysilane in step S100.

7. The production method according to claim 1, characterized in that: In step S200, the hydrolysis reaction temperature is 50-70°C and the reaction time is 4-7h; the removal of the alcohol solvent is carried out at 50-90°C and a vacuum degree of -0.07 to -0.1 MPa.

8. The production method according to claim 1, characterized in that: In step S200, the viscosity of the intermediate product low-viscosity hydroxyl-terminated diphenyl silicone oil is 400-1000 mm 2 / s.

9. The production method according to claim 1, characterized in that: In step 300, the viscosity of the low-viscosity α,ω-dihydroxy polydimethylsiloxane is 50-140 mPa.s, and the viscosity of the low-viscosity hydroxyl-terminated diphenyl silicone oil is 300-600 mm 2 / s; Further, the amount of the second chain extender is 100-200 wt % of the mass of the low-viscosity hydroxyl-terminated diphenyl silicone oil in step S200.

10. The production method according to claim 1, characterized in that: In step 300, a capping agent is also added; when it is necessary to prepare trimethylsilyl-terminated (M-terminated) diphenyl silicone oil, the capping agent is selected from hexamethyldisiloxane (MM), or a viscosity of 5-40 mm 2 / s of dimethyl silicone oil; when it is necessary to prepare alkenyl-terminated diphenyl silicone oil, the end-capping agent is selected from tetramethyl divinyl silane, or a viscosity of 5-40mm 2 / s vinyl silicone oil; when it is necessary to prepare active hydrogen-terminated diphenyl silicone oil, the end-capping agent is selected from tetramethyldihydrosilane, or a viscosity of 5-40mm 2 / s of hydrogen-containing silicone oil. The amount of the end-capping agent is 5-15wt% of the mass of the low-viscosity hydroxyl-terminated diphenyl silicone oil in step S200, preferably 8-11wt%; and / or The second catalyst is selected from trifluoromethanesulfonic acid, tetramethylammonium hydroxide siliconate, potassium hydroxide siliconate or phosphonitrile chloride.

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