Preparation method of low-volatile silicone oil

Abstract

The present invention discloses a method for preparing low-volatile silicone oil, and relates to the technical field of silicone oil. Its technical scheme is: adding silanol-terminated polydimethylsiloxane, monosilanol-terminated agent, and catalyst to a reactor, reacting at 70-90°C for 2-3h under negative pressure, adding a terminator, and obtaining low-volatile silicone oil; wherein, the amount of catalyst added is 0.0005-0.001% of the total mass of silanol-terminated polydimethylsiloxane and monosilanol-terminated agent. The preparation method of low-volatile silicone oil of the present invention can utilize the condensation reaction of silanol to obtain a low-volatile silicone oil product, the reaction temperature is low, the amount of catalyst used is small, the backbiting of the siloxane segment will not be caused, there is no production of small molecule dimethylcyclosiloxane, no need to carry out a de-lowing process, low production cost, and more environmentally friendly.

Description

Technical Field

[0001] The invention relates to the technical field of silicone oil, and in particular to a method for preparing low-volatile silicone oil. Background Art

[0002] Silicone oil is a very important organosilicon product, and its structure is end-capped linear polydimethylsiloxane, and the side chain and the end group are hydrocarbon groups. Silicone oil has many special properties, such as low temperature viscosity coefficient, high and low temperature resistance, oxidation resistance, high flash point, good insulation and low surface tension, so it is widely used in daily chemicals, textiles, food and other fields.

[0003] However, the traditional process for preparing silicone oil mainly adopts the acid method and the alkaline method, and the reaction mechanism is respectively the ring-opening polymerization reaction of dimethylcyclosiloxane catalyzed by cation or anion. However, in the ring-opening polymerization reaction of both mechanisms, the back-biting reaction of the silicon-oxygen chain will occur, thereby producing new dimethylcyclosiloxane, making the product volatile matter 10-12wt.%, so to obtain low-volatile silicone oil products, it is necessary to go through a high-energy consumption low-molecular-weight removal process. With the development of market demand and the improvement of environmental protection needs, the requirements for the volatile matter in silicone oil products are getting higher and higher, and the energy consumption of obtaining low-volatile silicone oil through the low-molecular-weight removal process is also getting higher and higher. Therefore, it is very valuable to develop a low-volatile silicone oil synthesis process.

[0004] Chinese invention patent CN108102100B discloses a production method and production system for low-volatile vinyl silicone oil. When preparing low-volatile end-vinyl silicone oil, this invention patent successively undergoes dehydration, polymerization, centrifugal extraction, deoxidation and other processes. In the production process, organic solvents need to be used for extraction and the organic solvents need to be recovered. The production process is complicated and energy-intensive.

[0005] Chinese invention patent CN117209763A discloses a method for preparing ultra-low volatility vinyl silicone oil using a circulating de-lowering device. This invention patent removes low molecular weight products through multiple treatments to finally obtain a low volatility end vinyl product. The process also has high energy consumption.

[0006] In summary, there is an urgent need to provide a new method for preparing silicone oil to solve the problems existing in the current synthesis process. Summary of the invention

[0007] The technical problem to be solved by the present invention is: to overcome the shortcomings of the prior art, to provide a preparation method for low-volatile silicone oil, to utilize the condensation reaction of silanol groups to obtain a low-volatile silicone oil product, to have a low reaction temperature, to use a small amount of catalyst, to not cause backbiting of the siloxy chain segments, to not produce small molecular weight dimethylcyclosiloxane, to not require a de-lowering process, to have a low production cost, and to be more environmentally friendly.

[0008] The technical solution of the present invention is:

[0009] The preparation method of low-volatile silicone oil comprises the following steps: adding silanol-terminated polydimethylsiloxane, monosilanol-terminated agent and catalyst into a reaction kettle, reacting at 70-90° C. for 2-3 hours under negative pressure, and adding a terminator to obtain low-volatile silicone oil; wherein the amount of the catalyst added is 0.0005-0.001% of the total mass of the silanol-terminated polydimethylsiloxane and the monosilanol-terminated agent.

[0010] Preferably, the structural formula of the low volatility silicone oil is as follows:

[0011] ,

[0012] Where n is 79-1500, R 1 Methyl or vinyl.

[0013] Preferably, the structural formula of the monosilanol capping agent is as follows:

[0014] ,

[0015] R 1 Methyl or vinyl.

[0016] Preferably, the monosilanol capping agent is 1-hydroxy-1,1,3,3,5,5,7,7,7-nonamethyltetrasiloxane or 1-vinyl-7-hydroxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane.

[0017] Preferably, the catalyst is sodium hydroxide or potassium hydroxide.

[0018] Preferably, the terminator is lauric acid, acetic acid or phosphoric acid gum.

[0019] Preferably, the volatility of the low-volatile silicone oil measured at 150° C. for 3 hours is less than 0.3 wt.%.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The preparation method of the low-volatile silicone oil of the present invention comprises the following steps: a dehydration condensation reaction of silanol groups occurs in silanol-terminated polydimethylsiloxane and a monosilanol-terminated agent under the catalysis of a catalyst, thereby obtaining a low-volatile silicone oil product; the system only undergoes a dehydration condensation reaction of silanol groups without causing backbiting of the siloxane segments; the reaction temperature is low, the amount of catalyst used is small, and no small-molecule dimethylcyclosiloxane is generated; the low-volatile silicone oil product can be obtained without dehydration, and the production cost is low and the product is more environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1The 1-hydroxy-1,1,3,3,5,5,7,7,7-nonamethyltetrasiloxane prepared by the present invention 1 H NMR spectrum.

[0023] Figure 2 The 1-vinyl-7-hydroxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane prepared by the present invention 1 HNMR spectrum.

[0024] Figure 3 The low volatility methyl silicone oil prepared in Example 1 of the present invention is 1 H NMR spectrum.

[0025] Figure 4 The low-volatile vinyl silicone oil prepared in Example 2 of the present invention is 1 H NMR spectrum. DETAILED DESCRIPTION

[0026] In order to enable persons skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0027] Unless otherwise specified, all raw materials used in the following examples are commercially available products; the volatile matter of the silanol-terminated polydimethylsiloxane used in the examples measured at 150° C. for 3 h is less than 0.1 wt.%.

[0028] In the following examples, the synthesis method of 1-hydroxy-1,1,3,3,5,5,7,7,7-nonamethyltetrasiloxane is as follows:

[0029] (1) Synthesis of 1-chloro-1,1,3,3,5,5,7,7,7-nonamethyltetrasiloxane

[0030] The structural formula of 1-chloro-1,1,3,3,5,5,7,7,7-nonamethyltetrasiloxane is as follows:

[0031] ;

[0032] Its synthetic route is as follows:

[0033] .

[0034] The synthesis process is as follows:

[0035] 108.64 g of trimethylchlorosilane, 222.46 g of hexamethylcyclotrisiloxane and 2 g of N,N-dimethylformamide were added to a flask, and the mixture was reacted at 25°C for 2 h under nitrogen protection. The solid was completely dissolved to obtain a reaction solution, and the reaction was completed. The yield of 1-chloro-1,1,3,3,5,5,7,7,7-nonamethyltetrasiloxane was 77.12% as measured by GC.

[0036] (2) Synthesis of 1-hydroxy-1,1,3,3,5,5,7,7,7-nonamethyltetrasiloxane

[0037] Its synthetic route is as follows:

[0038] .

[0039] The synthesis process is as follows:

[0040] Add 54g of water, 50g of toluene and 106.25g of triethylamine into a flask, cool to 10°C, protect with nitrogen, start stirring, and drop the reaction solution obtained in step (1) into the flask, keeping the reaction temperature below 60°C. After the addition is completed, continue the reaction for 0.5h, then add 100g of water to dissolve the generated solid salt; at -0.095MPa, collect the 68°C fraction by distillation to obtain 239.54g of the target product. According to GC measurement, the purity of 1-hydroxy-1,1,3,3,5,5,7,7,7-nonamethyltetrasiloxane is 99.92%, and the total yield is 76%. 1 The product was characterized by H NMR. Figure 1 As shown, 1 H NMR (400MHz, CDCl3, ppm): 0.05-0.17 (m, 27H), 2.59 (s, 1H).

[0041] The synthesis method of 1-vinyl-7-hydroxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane is as follows:

[0042] (1) Synthesis of 1-vinyl-7-chloro-1,1,3,3,5,5,7,7-octamethyltetrasiloxane

[0043] The structural formula of 1-vinyl-7-chloro-1,1,3,3,5,5,7,7-octamethyltetrasiloxane is as follows:

[0044] ;

[0045] Its synthetic route is as follows:

[0046] .

[0047] The synthesis process is as follows:

[0048] 120.65 g of vinyldimethylchlorosilane, 222.46 g of hexamethylcyclotrisiloxane and 2 g of N,N-dimethylformamide were added to a flask, and the mixture was reacted at 25°C for 2 h under nitrogen protection. The solid was completely dissolved to obtain a reaction solution, and the reaction was completed. The yield of 1-vinyl-7-chloro-1,1,3,3,5,5,7,7-octamethyltetrasiloxane was 74.33% as measured by GC.

[0049] (2) Synthesis of 1-vinyl-7-hydroxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane

[0050] Its synthetic route is as follows:

[0051] .

[0052] Add 54g of water, 50g of toluene and 106.25g of triethylamine into a flask, cool to 10°C, protect with nitrogen, start stirring, and drop the reaction solution obtained in step (1) into the flask, keeping the reaction temperature below 60°C. After the addition is completed, continue the reaction for 0.5h, then add 100g of water to dissolve the generated solid salt; at -0.095MPa, collect the 70°C fraction by distillation to obtain 237.29g of the target product. According to GC measurement, the purity of 1-vinyl-7-hydroxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane is 99.88%, and the total yield is 73%. 1 The product was characterized by H NMR. Figure 2 As shown, 1 H NMR (400MHz, CDCl3, ppm): 0.05-0.17 (m, 24H), 2.59 (s, 1H), 5.73 (dd, J1=20.4Hz, J2=4 .4Hz, 1H), 5.93 (dd, J1=15.1Hz, J2=3.7Hz, 1H), 6.12 (dd, J1=20.4Hz, J2=15.1Hz, 1H).

[0053] Example 1

[0054] The structural formula of the low volatility methyl silicone oil of the present embodiment is as follows:

[0055] .

[0056] The preparation method is as follows:

[0057] Add 4478.9 g of silanol-terminated polydimethylsiloxane and 521.1 g of 1-hydroxy-1,1,3,3,5,5,7,7,7-nonamethyltetrasiloxane into a flask, stir and heat up to 70°C, keep the temperature constant, dissolve 0.025 g of sodium hydroxide in water and add it into the flask, remove the water produced by the reaction at -0.095 MPa, react for 3 h, add 0.128 g of lauric acid and continue stirring for 30 min, cool down to obtain a colorless transparent liquid, i.e., methyl silicone oil, with a viscosity of 127.12 mm 2 / s. Its volatile content was measured at 150°C for 3 hours and was 0.11wt.%. 1 The product was characterized by H NMR. Figure 3 shown.

[0058] Example 2

[0059] The structural formula of the low-volatile vinyl silicone oil of this embodiment is as follows:

[0060] .

[0061] The preparation method is as follows:

[0062] Add 4783.55g of silanol-terminated polydimethylsiloxane and 216.45g of 1-vinyl-7-hydroxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane into a flask, stir and heat up to 80°C, keep the temperature constant, dissolve 0.03g of potassium hydroxide in water and add it into the flask, remove the water produced by the reaction at -0.095MPa, react for 2h, add 0.033g of acetic acid and continue stirring for 30min, cool down to obtain a colorless transparent liquid, i.e. vinyl silicone oil, with a viscosity of 640.14mm 2 / s. Its volatile content was measured at 150°C for 3 hours and was 0.13wt.%. 1 The product was characterized by H NMR. Figure 4 As shown, 1 H NMR (400MHz, CDCl3, ppm): 0.05-0.25 (m, 1220H), 5.73 (dd, J1=20.4Hz, J2=4.4Hz , 1H), 5.93 (dd, J1=15.1Hz, J2=3.7Hz, 1H), 6.12 (dd, J1=20.4Hz, J2=15.1Hz, 1H).

[0063] Example 3

[0064] The structural formula of the low volatility methyl silicone oil of the present embodiment is as follows:

[0065] .

[0066] The preparation method is as follows:

[0067] 4895.78g of silanol-terminated polydimethylsiloxane and 104.22g of 1-hydroxy-1,1,3,3,5,5,7,7,7-nonamethyltetrasiloxane were added to the flask, stirred and heated to 80°C, kept constant temperature, 0.04g of sodium hydroxide was dissolved in water and added to the flask, the water produced by the reaction was removed at -0.095MPa, reacted for 2.5h, 0.33g of 15wt.% phosphate gum was added and stirred for 30min, cooled, and a colorless transparent liquid, i.e. methyl silicone oil, was obtained, and the product viscosity was 3550mPa·s. Its volatile content was 0.16wt.% under the conditions of 150°C and 3h.

[0068] Example 4

[0069] The structural formula of the low volatility methyl silicone oil of the present embodiment is as follows:

[0070] .

[0071] The preparation method is as follows:

[0072] 4971.92g of silanol-terminated polydimethylsiloxane and 28.08g of 1-hydroxy-1,1,3,3,5,5,7,7,7-nonamethyltetrasiloxane were added to the flask, stirred and heated to 90°C, kept constant temperature, 0.05g of sodium hydroxide was dissolved in water and added to the flask, the water produced by the reaction was removed at -0.095MPa, reacted for 2.5h, 0.42g of 15wt.% phosphate gum was added and stirred for 30min, cooled, and a colorless transparent liquid, i.e. methyl silicone oil, was obtained, and the product viscosity was 110500mPa·s. Its volatile content was 0.24wt.% under the conditions of 150°C and 3h.

[0073] Comparative Example 1

[0074] The structural formula of the methyl silicone oil of Comparative Example 1 is as follows:

[0075] .

[0076] The preparation method is as follows:

[0077] 4687.34 g of silanol-terminated polydimethylsiloxane and 312.66 g of 1-hydroxy-1,1,3,3,5,5,7,7,7-nonamethyltetrasiloxane were added to a flask, and the temperature was raised to 90°C and kept constant. 0.075 g of sodium hydroxide was dissolved in water and added to the flask. The water produced by the reaction was removed at -0.095 MPa. The reaction was continued for 2.5 h. 0.63 g of 15 wt.% phosphate gum was added and the stirring was continued for 30 min. The temperature was lowered to obtain a colorless transparent liquid, i.e., methyl silicone oil. The product viscosity was 311.78 mm 2 / s. The volatile content was determined to be 0.53 wt.% at 150°C for 3 h.

[0078] Comparative Example 2

[0079] The structural formula of the methyl silicone oil of Comparative Example 2 is as follows:

[0080] .

[0081] The preparation method is as follows:

[0082] 4759.49 g of silanol-terminated polydimethylsiloxane and 240.51 g of 1-hydroxy-1,1,3,3,5,5,7,7,7-nonamethyltetrasiloxane were added to a flask, and the temperature was raised to 95°C with stirring. 0.05 g of sodium hydroxide was dissolved in water and added to the flask. The water produced by the reaction was removed at -0.095 MPa. The reaction was continued for 2.5 h. 0.42 g of 15 wt.% phosphate gum was added and stirring was continued for 30 min. The temperature was lowered to obtain a colorless transparent liquid, i.e., methyl silicone oil. The product viscosity was 410.88 mm 2 / s. The volatile content was determined to be 0.51 wt.% at 150°C for 3 h.

[0083] Comparative Example 3

[0084] The structural formula of the methyl silicone oil of Comparative Example 3 is as follows:

[0085] .

[0086] The preparation method is as follows:

[0087] Add 4843.67 g of silanol-terminated polydimethylsiloxane and 156.33 g of 1-hydroxy-1,1,3,3,5,5,7,7,7-nonamethyltetrasiloxane into a flask, start stirring and heat up to 80°C. Keep the temperature constant, dissolve 0.02 g of sodium hydroxide in water and add it into the flask, remove the water produced by the reaction at -0.095 MPa, and react for 4 hours. The materials do not react.

[0088] Comparative Example 4

[0089] The structural formula of the methyl silicone oil of Comparative Example 4 is as follows:

[0090] .

[0091] Octamethylcyclotetrasiloxane was heated at 80°C and nitrogen was bubbling to remove water. 1091.88 g of dehydrated octamethylcyclotetrasiloxane and 8.12 g of hexamethyldisiloxane were added to a flask. Stirring was started and the temperature was raised to 130°C. 0.55 g of potassium hydroxide gelatin with a potassium hydroxide content of 20 wt.% was added. The reaction was continued for 6 hours. Phosphoric acid gel was added to neutralize the reaction. The viscosity of the obtained methyl silicone oil was 762.33 mm 2 / s, and the volatile content was 11.22wt.% under the conditions of 150℃ and 3h. At 150℃ and -0.095MPa, nitrogen bubbling was used to remove low molecular weight, and the viscosity of the obtained methyl silicone oil was 1134mm 2 / s, and its volatile content was measured at 150℃ for 3h and was 0.23wt.%.

Claims

1. A method for preparing low-volatile silicone oil, characterized in that: Add silanol-terminated polydimethylsiloxane, monosilanol-terminated agent and catalyst into a reaction kettle, react at 70-90° C. for 2-3 hours under negative pressure, add terminator to obtain low-volatile silicone oil; wherein the added amount of catalyst is 0.0005-0.001% of the total mass of silanol-terminated polydimethylsiloxane and monosilanol-terminated agent; the monosilanol-terminated agent is 1-hydroxy-1,1,3,3,5,5,7,7,7-nonamethyltetrasiloxane or 1-vinyl-7-hydroxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane.

2. The method for preparing low-volatile silicone oil according to claim 1, characterized in that: The structural formula of the low-volatile silicone oil is as follows: ， Where n is 79-1500, R 1 Methyl or vinyl.

3. The method for preparing low-volatile silicone oil according to claim 1, characterized in that: The catalyst is sodium hydroxide or potassium hydroxide.

4. The method for preparing low-volatile silicone oil according to claim 1, characterized in that: The terminator is lauric acid, acetic acid or phosphoric acid glue.

5. The method for preparing low-volatile silicone oil according to claim 1, characterized in that: The volatility of low-volatile silicone oil measured at 150°C for 3 hours is less than 0.3wt.%.

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