Preparation method of low-volatile epoxy-terminated polydimethylsiloxane

Abstract

The invention discloses a preparation method of low-volatile end-epoxy modified polydimethylsiloxane, and relates to the technical field of siloxane. The technical scheme is: add silanol-terminated polydimethylsiloxane, 1-glycidyloxypropyl-7-hydroxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane, and a catalyst to a reactor, react at 70-90°C under negative pressure for 2-3h, add a terminator, and obtain low-volatile end-epoxy modified polydimethylsiloxane; the amount of catalyst is 0.0005-0.001% of the total mass of silanol-terminated polydimethylsiloxane and 1-glycidyloxypropyl-7-hydroxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane; the structural formula of low-volatile end-epoxy modified polydimethylsiloxane is as follows:. The present invention can stably prepare end-epoxy modified polydimethylsiloxane with a number average molecular weight of about 100,000, without the need for deoxidation, and at low cost.

Description

Technical Field

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

[0002] Epoxy-terminated polydimethylsiloxane, also known as epoxy silicone oil, is a very important silicone intermediate. Its structure is polydimethylsiloxane modified by epoxy groups at the end. It is mainly used in the synthesis of block silicone oil, fabric fiber finishing agent and coating additive, etc.

[0003] At present, there are two main processes for synthesizing epoxy silicone oil: acid method and alkaline method. The acid method synthesizes epoxy silicone oil by hydrosilylation reaction of terminal hydrogen silicone oil and allyl glycidyl ether under the catalysis of platinum catalyst. Due to the limitation of hydrosilylation reaction itself, when synthesizing high molecular weight (number average molecular weight greater than 20,000) epoxy silicone oil, the hydrosilylation reaction is not complete, and there is a certain amount of residual silicon and hydrogen in the system, which greatly reduces the performance and stability of epoxy silicone oil. Therefore, the acid method is not suitable for the preparation of high molecular weight epoxy silicone oil.

[0004] The alkaline process synthesizes epoxy silicone oil, which is prepared by ring-opening polymerization of epoxy capping agent and dimethylsiloxane ring body under the catalysis of base such as tetramethylammonium hydroxide. Since this process uses alkali as catalyst, it will damage the epoxy group and cause the loss of epoxy value of the product. When preparing high molecular weight epoxy silicone oil (number average molecular weight greater than 30,000), the product is unstable. In addition, this process uses strong alkali as catalyst, which will cause back-biting reaction of silicon oxygen chain segments, so about 12% of dimethylcyclosiloxane will be produced. To obtain low-volatile epoxy silicone oil, a high-energy consumption low-molecular removal process is also required.

[0005] In summary, there is an urgent need to provide a new method for preparing epoxy silicone oil to solve the problems existing in the current synthesis process. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method for preparing low-volatile terminal epoxy-modified polydimethylsiloxane, in which only a dehydration condensation reaction of silanol occurs without a backbiting reaction, and terminal epoxy-modified polydimethylsiloxane with a number average molecular weight of about 100,000 can be stably prepared, and a low-volatile product can be obtained without dehydration, so the production cost is low and it is more environmentally friendly.

[0007] The technical solution of the present invention is:

[0008] The invention provides a preparation method of low-volatile epoxy-terminated polydimethylsiloxane. The method comprises the following steps: adding silanol-terminated polydimethylsiloxane, 1-glycidyloxypropyl-7-hydroxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane and a 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 epoxy-terminated polydimethylsiloxane. The amount of the catalyst added is 0.0005-0.001% of the total mass of the silanol-terminated polydimethylsiloxane and the 1-glycidyloxypropyl-7-hydroxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane. The structural formula of the low-volatile epoxy-terminated polydimethylsiloxane is as follows:

[0009] ,

[0010] Where n is 76-1500.

[0011] Preferably, the structural formula of the silanol-terminated polydimethylsiloxane is as follows:

[0012] ,

[0013] Where m<n-8;

[0014] The structural formula of 1-glycidyloxypropyl-7-hydroxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane is as follows:

[0015] .

[0016] The synthetic route of the epoxy-terminated polydimethylsiloxane of the present invention is as follows:

[0017] .

[0018] Preferably, the catalyst is sodium hydroxide or potassium hydroxide.

[0019] Preferably, the terminator is lauric acid, acetic acid or phosphoric acid gum. The terminator is used to neutralize the catalyst to terminate the reaction, and the amount of the terminator is sufficient to complete the catalyst reaction when reacting with the catalyst.

[0020] Preferably, the volatility of the low-volatile epoxy-terminated polydimethylsiloxane measured at 150° C. for 3 hours is less than 0.5 wt.%.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention uses a silanol-terminated polydimethylsiloxane and 1-glycidyloxypropyl-7-hydroxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane to undergo a dehydration condensation reaction of silanol groups under the catalytic action of a catalyst, thereby obtaining a low-volatile end-epoxy modified polydimethylsiloxane product. The system only undergoes a dehydration condensation reaction of silanol groups, but does not undergo a backbiting reaction. The reaction temperature is low, the amount of catalyst used is small, and the backbiting of the siloxy chain segment will not be caused. The end-epoxy modified polydimethylsiloxane with a number average molecular weight of about 100,000 can be stably prepared, and no small molecular weight dimethylcyclosiloxane is produced. A low-volatile product can be obtained without a dehydration process, and the production cost is low and it is more environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The 1-hydrogen-7-hydroxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane prepared by the present invention 1 H NMR spectrum.

[0024] Figure 2 The 1-hydrogen-7-hydroxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane prepared by the present invention 29 SiNMR spectrum.

[0025] Figure 3 The 1-glycidyl ether oxypropyl-7-hydroxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane prepared by the present invention 1 H NMR spectrum.

[0026] Figure 4 The epoxy-terminated polydimethylsiloxane prepared in Example 1 of the present invention is 1 H NMR spectrum. DETAILED DESCRIPTION

[0027] 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.

[0028] Unless otherwise specified, all raw materials used in the following examples are commercially available products.

[0029] Silicon hydroxyl terminated polydimethylsiloxane, trade name linear, viscosity 70mm 2 / s, degree of polymerization is about 47, Shandong Dongyue Silicone Materials Co., Ltd.

[0030] Epoxy capping agent, number average molecular weight is 1000, Changzhou Guanghua Chemical New Materials Co., Ltd.

[0031] In the following examples, the synthesis method of 1-glycidyloxypropyl-7-hydroxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane is as follows:

[0032] (1) Synthesis of 1-hydrogen-7-chloro-1,1,3,3,5,5,7,7-octamethyltetrasiloxane

[0033] The structural formula of hydrogen-7-chloro-1,1,3,3,5,5,7,7-octamethyltetrasiloxane is as follows: ;

[0034] Its synthetic route is as follows:

[0035] .

[0036] The synthesis process is as follows:

[0037] 94.61 g of dimethylhydrochlorosilane, 222.46 g of hexamethylcyclotrisiloxane and 2 g of N,N-dimethylformamide were added to a flask, protected by nitrogen, and reacted at 25°C for 2 h. The solid was completely dissolved to obtain a reaction liquid, and the reaction was completed. GC measurement showed that the yield of 1-hydro-7-chloro-1,1,3,3,5,5,7,7-octamethyltetrasiloxane was 74.02%.

[0038] (2) Synthesis of 1-hydrogen-7-hydroxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane

[0039] Its synthetic route is as follows:

[0040] .

[0041] The synthesis process is as follows:

[0042] 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 65°C fraction by distillation to obtain 215g of the target product. According to GC measurement, the purity of 1-hydrogen-7-hydroxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane is 99.92%, and the total yield is 72%. 1 H NMR, 29 The product was characterized by Si NMR. Figure 1-2 As shown:

[0043] 1H NMR (400MHz, CDCl3, ppm): 0.03-0.10 (m, 12H), 0.11-0.15 (m, 6H), 0.15-0.21 (m, 6H), 2.63 (s, 1H), 4.71 (m, 1H).

[0044] 29 Si NMR (400MHz, CDCl3, ppm): -6.85 (1Si), -10.32 (1Si), -19.77 (1Si), -21.63 (1Si).

[0045] (3) Synthesis of 1-glycidyloxypropyl-7-hydroxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane

[0046] Its synthetic route is as follows:

[0047] .

[0048] The synthesis process is as follows:

[0049] 68.48 g of allyl glycidyl ether and 4 g of platinum-carbon catalyst (Pt loading is 5 wt.%) were added to the flask, and the temperature was raised to 50°C under nitrogen protection. 149.32 g of 1-hydrogen-7-hydroxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane obtained in step (2) was gradually added dropwise to the flask, and the mixture was reacted at 80°C for 2 h. The reaction was filtered and the platinum-carbon catalyst was recovered. The low molecular weight of the product was removed at 110°C and -0.095 MPa to obtain 202.27 g of colorless transparent liquid, i.e., 1-glycidyloxypropyl-7-hydroxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane. 1 The product was characterized by H NMR. Figure 3 As shown, 1 H NMR (400MHz, CDCl3, ppm): 0.03-0.10 (m, 12H), 0.11-0.15 (m, 6H), 0.15-0.21 (m, 6H), 0.53 (m, 2H), 1.62 (m , 2H), 2.60 (m, 1H), 2.63 (s, 1H), 2.78 (t, J=4.7, 1H), 3.14 (m, 1H), 3.30-3.53 (m, 3H), 3.68 (d, J=11.2, 1H).

[0050] Example 1

[0051] The structural formula of the epoxy-terminated polydimethylsiloxane of this embodiment is as follows:

[0052] .

[0053] The preparation method is as follows:

[0054] 4312.03 g of silanol-terminated polydimethylsiloxane and 687.97 g of 1-glycidyloxypropyl-7-hydroxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane were added into a flask, and the temperature was raised by stirring to 70°C and kept constant. 0.025 g of sodium hydroxide was dissolved in water and added into the flask. The generated water was removed at -0.095 MPa and reacted for 3 h. 0.128 g of lauric acid was added and the stirring was continued for 30 min. The temperature was lowered to obtain a colorless transparent liquid, i.e., epoxy-terminated polydimethylsiloxane. The viscosity of the product was 125.12 mm 2 / s. The epoxy value of the product was determined by titration to be 0.0335 mol / 100 g, and its volatile content was determined to be 0.12 wt.% at 150°C for 3 h. 1 The product was characterized by H NMR. Figure 4 As shown, 1 H NMR (400MHz, CDCl3, ppm): 0.1-0.25 (m, 470H), 0.53 (m, 4H), 1.62 (m, 4H), 2.60 (m , 2H), 2.78 (t, J=4.7, 2H), 3.14 (m, 2H), 3.30-3.53 (m, 6H), 3.68 (d, J=11.2, 2H).

[0055] Example 2

[0056] The structural formula of the epoxy-terminated polydimethylsiloxane of this embodiment is as follows:

[0057] .

[0058] The preparation method is as follows:

[0059] 4724.81 g of silanol-terminated polydimethylsiloxane and 275.19 g of 1-glycidyloxypropyl-7-hydroxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane were added to a flask, and the temperature was raised to 80°C and kept constant. 0.03 g of potassium 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 h. 0.033 g of acetic acid was added and the stirring was continued for 30 min. The temperature was lowered to obtain a colorless transparent liquid, i.e., epoxy-terminated polydimethylsiloxane. The product viscosity was 660.24 mm 2 / s. The epoxy value of the product was determined by titration to be 0.0134 mol / 100 g, and its volatile content was determined to be 0.23 wt.% at 150°C for 3 h.

[0060] Example 3

[0061] The structural formula of the epoxy-terminated polydimethylsiloxane of this embodiment is as follows:

[0062] .

[0063] The preparation method is as follows:

[0064] 4862.41g of silanol-terminated polydimethylsiloxane and 137.59g of 1-glycidyloxypropyl-7-hydroxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane 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 glue was added and stirred for 30min, cooled, and a colorless transparent liquid was obtained, i.e., epoxy-terminated polydimethylsiloxane, with a product viscosity of 3500mPa·s. The epoxy value of the product was determined by titration to be 0.0067mol / 100g, and its volatile content was determined to be 0.33wt.% under the conditions of 150°C and 3h.

[0065] Example 4

[0066] The structural formula of the epoxy-terminated polydimethylsiloxane of this embodiment is as follows:

[0067] .

[0068] The preparation method is as follows:

[0069] 4962.93g of silanol-terminated polydimethylsiloxane and 37.07g of 1-glycidyloxypropyl-7-hydroxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane 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 glue was added and stirred for 30min, cooled, and a colorless transparent liquid was obtained, i.e., epoxy-modified polydimethylsiloxane, with a product viscosity of 110000mPa·s. The epoxy value of the product was determined by titration to be 0.0018mol / 100g, and its volatile content was determined to be 0.24wt.% under the conditions of 150°C and 3h.

[0070] Comparative Example 1

[0071] The structural formula of the epoxy-terminated polydimethylsiloxane of Comparative Example 1 is as follows:

[0072] .

[0073] The preparation method is as follows:

[0074] 4587.22 g of silanol-terminated polydimethylsiloxane and 412.78 g of 1-glycidyloxypropyl-7-hydroxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane were added into 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 into 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., epoxy-terminated polydimethylsiloxane. The viscosity of the product was 320.13 mm 2 / s. The epoxy value of the product was determined by titration to be 0.0205 mol / 100 g, and its volatile content was determined to be 0.54 wt.% at 150°C for 3 h.

[0075] Comparative Example 2

[0076] The structural formula of the epoxy-terminated polydimethylsiloxane of Comparative Example 2 is as follows:

[0077] .

[0078] The preparation method is as follows:

[0079] 4682.48 g of silanol-terminated polydimethylsiloxane and 317.52 g of 1-glycidyloxypropyl-7-hydroxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane were added to a flask, and the temperature was raised to 95°C and kept constant. 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 stirred for 30 min. The temperature was lowered to obtain a colorless transparent liquid, i.e., epoxy-terminated polydimethylsiloxane. The product viscosity was 420.26 mm 2 / s. The epoxy value of the product was determined by titration to be 0.0153 mol / 100 g, and its volatile content was determined to be 0.51 wt.% at 150°C for 3 h.

[0080] Comparative Example 3

[0081] The structural formula of the epoxy-terminated polydimethylsiloxane of Comparative Example 3 is as follows:

[0082] .

[0083] The preparation method is as follows:

[0084] Add 4793.61 g of silanol-terminated polydimethylsiloxane and 206.39 g of 1-glycidyloxypropyl-7-hydroxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane 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.

[0085] Comparative Example 4

[0086] The structural formula of the epoxy-terminated polydimethylsiloxane of Comparative Example 4 is as follows:

[0087] .

[0088] The preparation method is as follows:

[0089] 166.67 g of epoxy capping agent (number average molecular weight is 1000) and 916.66 g of silanol-terminated polydimethylsiloxane were added to the flask, stirring was started, and the temperature was raised to 105°C. 0.48 g of tetramethylammonium hydroxide was added to the flask, and the temperature was maintained at 105°C. The water produced by the reaction was removed at -0.095 MPa, and the reaction was continued for 2 hours. The temperature was raised to 150°C under normal pressure and the reaction was continued for 0.5 hours to obtain a yellow transparent liquid with a product viscosity of 112.12 mm 2 / s, the epoxy value of the product was determined by titration to be 0.0300mol / 100g, and its volatile content was determined to be 12.25wt.% under the conditions of 150℃ and 3h. Nitrogen bubbling was performed at 150℃ and -0.095MPa to remove low molecular weight silicone oil with a viscosity of 126.87mm 2 / s, and its volatile content was measured at 150℃ for 3h to be 0.82wt.%.

Claims

1. A method for preparing low-volatile epoxy-terminated polydimethylsiloxane, characterized in that: Add silanol-terminated polydimethylsiloxane, 1-glycidyloxypropyl-7-hydroxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane and a catalyst into a reaction kettle, react at 70-90° C. for 2-3 hours under negative pressure, and add a terminator to obtain low-volatile end-epoxy modified polydimethylsiloxane; wherein the amount of the catalyst added is 0.0005-0.001% of the total mass of silanol-terminated polydimethylsiloxane and 1-glycidyloxypropyl-7-hydroxy-1,1,3,3,5,5,7,7-octamethyltetrasiloxane; the structural formula of the low-volatile end-epoxy modified polydimethylsiloxane is as follows: ， Where n is 76-1500; The structural formula of the silanol-terminated polydimethylsiloxane is as follows: ， Where m<n-8.

2. The method for preparing the low-volatile epoxy-terminated polydimethylsiloxane according to claim 1, characterized in that: The catalyst is sodium hydroxide or potassium hydroxide.

3. The method for preparing the low-volatile epoxy-terminated polydimethylsiloxane according to claim 1, characterized in that: The terminator is lauric acid, acetic acid or phosphoric acid glue.

4. The method for preparing low-volatile epoxy-terminated polydimethylsiloxane according to claim 1, characterized in that: The volatile matter of the low-volatile epoxy-terminated polydimethylsiloxane measured at 150°C for 3 hours is less than 0.5wt.%.

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