Preparation Method of Zn-Co Bimetallic Cyanide Catalyst, Catalyst and Its Application

Abstract

The present invention discloses a preparation method of a Zn-Co double metal cyanide catalyst, the catalyst and its application. First, a Zn-Co double metal cyanide catalyst is prepared from cobalt cyanate and zinc 2-ethylhexanoate in a methanol solvent. Using the Zn-Co double metal cyanide catalyst, the cyclic siloxane monomer is catalytically subjected to bulk ring-opening polymerization reaction. After the reaction is completed, dichloromethane is added to dissolve the polymerization product, and the catalyst is removed by centrifugation; the dichloromethane solution of the polymer is added to a large amount of methanol, and the polymer precipitate is obtained by centrifugation, and methanol and a small amount of unreacted monomers are removed by vacuum drying to obtain the final product; by controlling the catalyst dosage, reaction temperature and time, the present invention can effectively improve the conversion rate and efficiency of the polymerization reaction. The double metal cyanide catalyst of the present invention has the advantages of high catalytic activity, low dosage, no corrosion, low cost, easy recovery of the catalyst, etc.; the method of the present invention can realize the efficient synthesis of polysiloxane and is applicable to fields such as materials science and electronics industry.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer synthesis, and specifically relates to a preparation method of a Zn-Co bimetallic cyanide catalyst, the catalyst and its application. Background Art

[0002] Polysiloxanes are a class of polymers with typical organic-inorganic characteristics, and their main chains are composed of alternating silicon and oxygen atoms (-Si-O-Si-). Due to the large bond angle (about 140°) of the Si-O-Si bond and the easy rotation of the Si-O bond, polysiloxanes exhibit extremely high flexibility. Such polymers have a variety of excellent properties, including excellent thermal stability, low surface energy, high elasticity, extremely low glass transition temperature, and excellent tolerance to ozone, ultraviolet light and chemical corrosion, and are widely used in the fields of national defense, aerospace, automobiles, construction, textiles, etc.

[0003] Double metal cyanide catalyst (DMC) is a highly efficient heterogeneous catalyst in the form of white or light yellow powder. The catalyst is based on a double metal cyanide complex and forms a complex complex with a variety of inorganic and organic ligands. As a catalyst in epoxy ring-opening polymerization, asymmetric catalysis and CO2 copolymerization, DMC can significantly improve the reaction rate and efficiency due to its multiphase structure, heterogeneous properties and controllable electronic properties. It has high catalytic activity, low energy consumption, environmental protection, good recyclability and a wide range of applications. At present, DMC catalyst has been studied in the ring-opening polymerization of propylene oxide (PO) and has achieved good results. It can significantly improve the conversion rate, better control the molecular weight, and has the advantages of high activity, low dosage, mild reaction conditions, non-corrosiveness and easy recovery. However, there is no information on the application of double metal cyanide catalysts in the ring-opening polymerization of cyclosiloxanes. Therefore, the present invention provides a preparation of a Zn-Co double metal cyanide catalyst (DMC) and its catalytic ring-opening polymerization of cyclosiloxanes to achieve the application of double metal cyanide catalysts in the ring-opening polymerization of cyclosiloxanes. Traditional DMC catalysts are usually prepared using potassium cobalt cyanate and zinc chloride as precursors. However, during the catalyst synthesis process, potassium chloride by-products are generated, which may inhibit subsequent polymerization reactions. In addition, the solvent used in the traditional preparation method is mainly water, and the presence of water may affect the structure of the catalyst and its catalytic performance in the ring-opening polymerization reaction of cyclosiloxane; the present invention prepares a Zn-Co double metal cyanide catalyst in a methanol solvent by using cobalt cyanate and zinc 2-ethylhexanoate, thereby avoiding the generation of potassium chloride and water that are unfavorable to subsequent reactions during the preparation process. The DMC catalyst synthesized by the preparation method is a heterogeneous catalyst with excellent catalytic performance, because its core metal uses relatively low-priced Zn and Co transition metals instead of expensive precious metals, the synthesis process is simple, no high-temperature and high-pressure equipment is required, and the amount used is small, so the catalyst has the advantages of being non-corrosive, non-polluting, low-cost, and easy to recover the catalyst; the method effectively solves the problems of equipment corrosion, environmental pollution, and difficulty in catalyst recovery that may be caused by traditional liquid acid catalysts in the reaction, while significantly improving the reaction efficiency and product quality. Summary of the invention

[0004] The purpose of the present invention is to provide a preparation method of a Zn-Co double metal cyanide catalyst, a catalyst and an application thereof, so as to realize the application of the double metal cyanide catalyst in the ring-opening polymerization of cyclosiloxane.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] A method for preparing a Zn-Co double metal cyanide catalyst comprises the following steps:

[0007] (1) Dissolve potassium hexacyanocobaltate(III) in distilled water at 50 - 55 °C, and add sulfuric acid dropwise to form a white solid precipitate. After stirring for 3 - 4 hours, add cold ethanol and continue stirring for 30 - 40 minutes;

[0008] (2) Remove the white precipitate by centrifugation, remove the solvent in the filtrate using a rotary evaporator, and perform vacuum treatment at 60 - 65 °C for 3 - 3.5 hours to further dry completely;

[0009] (3) Add ice ethanol to form a slurry, stir overnight at -5 °C, then add ice ethanol and centrifuge to obtain a pale yellow solid cobalt cyanate. Dissolve the pale yellow solid cobalt cyanate and zinc 2-ethylhexanoate in methanol respectively and then mix them quickly, stir for 24 - 28 hours, separate to obtain a white gel, dry it under vacuum at 50 - 55 °C for 24 - 28 hours, and grind to obtain a white solid powder Zn-Co double metal cyanide catalyst.

[0010] Preferably, the Zn-Co double metal cyanide catalyst is composed of cobalt cyanate and zinc 2-ethylhexanoate.

[0011] Preferably, the molar ratio of Zn:Co in the Zn-Co double metal cyanide catalyst is 3:1.

[0012] This application also provides a Zn-Co double metal cyanide catalyst prepared by the above method for preparing the Zn-Co double metal cyanide catalyst.

[0013] This application also claims to protect a method for ring-opening polymerization of cyclic siloxane using the above Zn-Co double metal cyanide catalyst, which includes the following steps:

[0014] S1. Under anhydrous and anaerobic conditions, add 0.1 wt% - 0.5 wt% of the Zn-Co double metal cyanide catalyst and cyclic siloxane monomer to a container;

[0015] S2. Pass in nitrogen, heat to 100 °C - 120 °C and keep the temperature constant for reaction for 1.5 - 2 hours to carry out bulk ring-opening polymerization reaction;

[0016] S3. After the polymerization reaction is completed, obtain polysiloxane. Dissolve the obtained polysiloxane in dichloromethane, centrifuge to separate the solid catalyst and the solution, add an excessive amount of methanol solution to the solution, centrifuge to separate the polymer precipitate, and then perform vacuum drying to remove methanol and a small amount of unreacted monomers in the polymer.

[0017] Preferably, the cyclic siloxane is hexamethylcyclotrisiloxane (D3).

[0018] Specifically, the Zn-Co double metal cyanide catalyst is the compound shown in Formula I;

[0019] (Formula I); wherein, ;

[0020] Due to the application of the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0021] 1. For the traditional liquid acid-catalyzed ring-opening polymerization of cyclic siloxanes, the reaction requires cumbersome post-treatments such as neutralization and water washing. Moreover, these liquid acids seriously corrode equipment, pollute the environment, are not easy to operate, and have high production costs. Compared with the traditional liquid acid-catalyzed ring-opening polymerization of cyclic siloxanes, the present invention uses a heterogeneous double metal cyanide catalyst. By controlling the reaction conditions, polysiloxanes with high conversion rates can be prepared. This catalyst has the advantages of not corroding equipment, no environmental pollution, low cost, and easy recovery of the catalyst;

[0022] 2. Traditional DMC catalysts are usually prepared using potassium cobalt cyanide and zinc chloride as precursors. However, during the synthesis of the catalyst, potassium chloride by-products are generated, and this by-product may have an inhibitory effect on subsequent polymerization reactions. In addition, the solvent used in the traditional preparation method is mainly water, and the presence of water may affect the structure of the catalyst and its catalytic performance in the ring-opening polymerization reaction of cyclic siloxanes. For traditional DMC catalysts, under the conditions of a catalyst dosage of 2 wt% - 4 wt%, a reaction temperature of 120 °C, and a reaction time of 10 h, the ring-opening conversion rate of D3 is 21.04% - 25.27%, and the yield is only 5.43% - 6.01%. For the DMC catalyst of the present invention, under the conditions of a catalyst dosage of only 0.1 wt% - 0.5 wt%, a reaction temperature of 120 °C, and a reaction time of 1.5 h, the ring-opening conversion rate of D3 is 65.75% - 99.54%, and the yield is as high as 56.16% - 87.14%;

[0023] 3. The present invention combines cobalt cyanate and zinc 2-ethylhexanoate in a specific ratio in a methanol solvent to form a complex catalyst, avoiding the disadvantages of mixing potassium chloride and water during the preparation of traditional DMC catalysts. The catalytic ring-opening polymerization conversion rate of cyclic siloxanes is as high as 99%, and it has the advantages of low dosage, high conversion rate, and high activity. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, some of the following drawings are embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0025] Figure 1 It is the infrared spectrum (FT-IR) picture of the double metal cyanide catalyst in Example 1 of the present invention;

[0026] Figure 2 It is the X-ray diffraction (XRD) picture of the double metal cyanide catalyst in Example 1 of the present invention;

[0027] Figure 3 It is the nuclear magnetic resonance ( 1 1H-NMR) picture of the double metal cyanide catalyst in Example 1 of the present invention with a catalytic amount of 0.1 wt% for the ring-opening polymerization of D3;

[0028] Figure 4 It is the nuclear magnetic resonance ( 1 1H-NMR) picture of the double metal cyanide catalyst in Example 4 of the present invention with a catalytic amount of 0.5 wt% for the ring-opening polymerization of D3. Detailed implementation manners

[0029] For a clearer understanding of the technical features, objectives, and effects of the present invention, the specific implementation manners will now be described in detail.

[0030] The present invention will be further described below in conjunction with embodiments, but the present invention is not limited to the following embodiments. The implementation conditions adopted in the embodiments can be further adjusted according to different requirements of specific use, and the implementation conditions not specified are conventional conditions in the industry. The technical features involved in each implementation manner of the present invention can be combined with each other as long as they do not conflict with each other.

[0031] Synthesis Example 1

[0032] This synthesis example provides a preparation method of a Zn-Co double metal cyanide catalyst, including the following steps:

[0033] (1) Dissolve potassium cobalt cyanide in distilled water at 50 °C, add sulfuric acid dropwise to form a white solid precipitate. After stirring for 3 hours, add cold ethanol and continue stirring for 30 minutes;

[0034] (2) Remove the white precipitate by centrifugation, remove the solvent in the filtrate using a rotary evaporator, and perform vacuum treatment at 60 °C for 3 hours to further dry completely;

[0035] (3) Add ice ethanol to form a slurry, stir overnight at -5 °C, then add ice ethanol and centrifuge to obtain a pale yellow solid cobalt cyanate. Dissolve the pale yellow solid cobalt cyanate and zinc 2-ethylhexanoate in methanol respectively and mix them quickly, stir for 24 hours, separate to obtain a white gel, dry it in vacuum at 50 °C for 24 hours, and grind it to obtain a white solid powder Zn-Co double metal cyanide catalyst; the molar ratio of Zn:Co of the Zn-Co double metal cyanide catalyst is 3:1.

[0036] Example 1

[0037] See the appendix Figures 1 to 3, this example provides a method for ring-opening polymerization of cyclic siloxanes using the Zn-Co double metal cyanide catalyst prepared in Synthesis Example 1 above, which includes the following steps:

[0038] S1. In an anhydrous and anaerobic glove box, add 0.1 wt% of the Zn-Co double metal cyanide catalyst and 20 g of hexamethylcyclotrisiloxane (D3) into a dried 100 ml two-neck reaction flask with a side arm;

[0039] S2. Introduce nitrogen, heat to 100 °C and keep the temperature constant for reaction for 1.5 hours to carry out bulk ring-opening polymerization reaction. During the reaction process, sample at regular intervals and conduct 1H NMR analysis to obtain the monomer conversion rate and yield at each sampling point;

[0040] S3. After the polymerization reaction is completed, prepare polysiloxane. Dissolve the prepared polysiloxane in dichloromethane, centrifuge to separate the solid catalyst and the solution. Add an excessive amount of methanol solution to the solution, centrifuge to obtain a polymer precipitate, and then conduct vacuum drying to remove methanol and a small amount of unreacted monomers in the polymer; finally, the monomer conversion rate is 35.9% and the reaction yield is 28.85%.

[0041] Example 2

[0042] , this example provides a method for ring-opening polymerization of cyclic siloxanes using the Zn-Co double metal cyanide catalyst prepared in Synthesis Example 1 above, which includes the following steps:

[0043] S1. In an anhydrous and anaerobic glove box, add 0.2 wt% of the Zn-Co double metal cyanide catalyst and 20 g of hexamethylcyclotrisiloxane (D3) into a dried 100 ml two-neck reaction flask with a side arm;

[0044] S2. Introduce nitrogen, heat to 100 °C and keep the temperature constant for reaction for 1.5 hours to carry out bulk ring-opening polymerization reaction. During the reaction process, sample at regular intervals and conduct 1H NMR analysis to obtain the monomer conversion rate and yield at each sampling point;

[0045] S3. After the polymerization reaction is completed, prepare polysiloxane. Dissolve the prepared polysiloxane in dichloromethane, centrifuge to separate the solid catalyst and the solution. Add an excessive amount of methanol solution to the solution, centrifuge to obtain a polymer precipitate, and then conduct vacuum drying to remove methanol and a small amount of unreacted monomers in the polymer; finally, the monomer conversion rate is 53.05% and the reaction yield is 42.78%.

[0046] Example 3

[0047] , this example provides a method for ring-opening polymerization of cyclic siloxanes using the Zn-Co double metal cyanide catalyst prepared in Synthesis Example 1 above, which includes the following steps:

[0048] S1. In an anhydrous and oxygen-free glove box, add 0.3 wt% of the Zn-Co double metal cyanide catalyst and 20 g of hexamethylcyclotrisiloxane (D3) into a dried 100 ml two-neck reaction flask with a side arm;

[0049] S2. Pass in nitrogen, heat to 100 °C and keep the temperature constant for reaction for 1.5 hours to carry out bulk ring-opening polymerization. During the reaction process, sample at regular intervals and conduct 1H NMR analysis to obtain the monomer conversion rate and yield at each sampling point;

[0050] S3. After the polymerization reaction is completed, the polysiloxane is obtained. Dissolve the obtained polysiloxane in dichloromethane, centrifuge to separate the solid catalyst and the solution. Add an excessive amount of methanol solution to the solution, centrifuge to obtain the polymer precipitate, and then carry out vacuum drying to remove methanol and a small amount of unreacted monomers in the polymer; finally, the monomer conversion rate is 95.39% and the reaction yield is 77.14%.

[0051] Example 4

[0052] This example provides a method for ring-opening polymerization of cyclosiloxane using the Zn-Co double metal cyanide catalyst prepared in the above Synthesis Example 1, including the following steps:

[0053] S1. In an anhydrous and oxygen-free glove box, add 0.5 wt% of the Zn-Co double metal cyanide catalyst and 20 g of hexamethylcyclotrisiloxane (D3) into a dried 100 ml two-neck reaction flask with a side arm;

[0054] S2. Pass in nitrogen, heat to 100 °C and keep the temperature constant for reaction for 1.5 hours to carry out bulk ring-opening polymerization. During the reaction process, sample at regular intervals and conduct 1H NMR analysis to obtain the monomer conversion rate and yield at each sampling point;

[0055] S3. After the polymerization reaction is completed, the polysiloxane is obtained. Dissolve the obtained polysiloxane in dichloromethane, centrifuge to separate the solid catalyst and the solution. Add an excessive amount of methanol solution to the solution, centrifuge to obtain the polymer precipitate, and then carry out vacuum drying to remove methanol and a small amount of unreacted monomers in the polymer; finally, the monomer conversion rate is 99.83% and the reaction yield is 82.01%.

[0056] Example 5

[0057] This example provides a method for ring-opening polymerization of cyclosiloxane using the Zn-Co double metal cyanide catalyst prepared in the above Synthesis Example 1, including the following steps:

[0058] S1. In an anhydrous and oxygen-free glove box, add 0.1 wt% of Zn-Co double metal cyanide catalyst and 20 g of hexamethylcyclotrisiloxane (D3) into a dried 100 ml two-neck reaction flask with a side arm;

[0059] S2. Pass in nitrogen, heat to 110 °C and keep the temperature constant for reaction for 1.5 hours to carry out bulk ring-opening polymerization reaction. During the reaction process, sample at regular intervals and conduct 1H NMR analysis to obtain the monomer conversion rate and yield at each sampling point;

[0060] S3. After the polymerization reaction is completed, obtain polysiloxane. Dissolve the obtained polysiloxane in dichloromethane, centrifuge to separate the solid catalyst and the solution. Add an excessive amount of methanol solution to the solution, centrifuge to obtain the polymer precipitate, and then conduct vacuum drying to remove methanol and a small amount of unreacted monomers in the polymer; finally, the monomer conversion rate is 53.27% and the reaction yield is 45.33%.

[0061] Example 6

[0062] This example provides a method for ring-opening polymerization of cyclosiloxane using the Zn-Co double metal cyanide catalyst prepared in Synthesis Example 1 above, including the following steps:

[0063] S1. In an anhydrous and oxygen-free glove box, add 0.2 wt% of Zn-Co double metal cyanide catalyst and 20 g of hexamethylcyclotrisiloxane (D3) into a dried 100 ml two-neck reaction flask with a side arm;

[0064] S2. Pass in nitrogen, heat to 110 °C and keep the temperature constant for reaction for 1.5 hours to carry out bulk ring-opening polymerization reaction. During the reaction process, sample at regular intervals and conduct 1H NMR analysis to obtain the monomer conversion rate and yield at each sampling point;

[0065] S3. After the polymerization reaction is completed, obtain polysiloxane. Dissolve the obtained polysiloxane in dichloromethane, centrifuge to separate the solid catalyst and the solution. Add an excessive amount of methanol solution to the solution, centrifuge to obtain the polymer precipitate, and then conduct vacuum drying to remove methanol and a small amount of unreacted monomers in the polymer; finally, the monomer conversion rate is 97.33% and the reaction yield is 75.53%.

[0066] Example 7

[0067] This example provides a method for ring-opening polymerization of cyclosiloxane using the Zn-Co double metal cyanide catalyst prepared in Synthesis Example 1 above, including the following steps:

[0068] S1. In an anhydrous and oxygen-free glove box, add 0.3 wt% of Zn-Co double metal cyanide catalyst and 20 g of hexamethylcyclotrisiloxane (D3) into a dried 100 ml two-neck reaction flask with a side arm;

[0069] S2. Pass in nitrogen, heat to 110 °C and keep the temperature constant for reaction for 1.5 hours to carry out bulk ring-opening polymerization reaction. During the reaction process, sample at regular intervals and conduct 1H NMR analysis to obtain the monomer conversion rate and yield at each sampling point;

[0070] S3. After the polymerization reaction is completed, prepare polysiloxane. Dissolve the prepared polysiloxane in dichloromethane, centrifuge to separate the solid catalyst and the solution. Add an excessive amount of methanol solution to the solution, centrifuge to obtain a polymer precipitate, and then conduct vacuum drying to remove methanol and a small amount of unreacted monomers in the polymer; finally, the monomer conversion rate is 99.31% and the reaction yield is 84.51%.

[0071] Example 8

[0072] This example provides a method for ring-opening polymerization of cyclosiloxane using the Zn-Co double metal cyanide catalyst prepared in the above Synthesis Example 1, including the following steps:

[0073] S1. In an anhydrous and oxygen-free glove box, add 0.5 wt% of Zn-Co double metal cyanide catalyst and 20 g of hexamethylcyclotrisiloxane (D3) into a dried 100 ml two-neck reaction flask with a side arm;

[0074] S2. Pass in nitrogen, heat to 110 °C and keep the temperature constant for reaction for 1.5 hours to carry out bulk ring-opening polymerization reaction. During the reaction process, sample at regular intervals and conduct 1H NMR analysis to obtain the monomer conversion rate and yield at each sampling point;

[0075] S3. After the polymerization reaction is completed, prepare polysiloxane. Dissolve the prepared polysiloxane in dichloromethane, centrifuge to separate the solid catalyst and the solution. Add an excessive amount of methanol solution to the solution, centrifuge to obtain a polymer precipitate, and then conduct vacuum drying to remove methanol and a small amount of unreacted monomers in the polymer; finally, the monomer conversion rate is 99.13% and the reaction yield is 86.82%.

[0076] Example 9

[0077] This example provides a method for ring-opening polymerization of cyclosiloxane using the Zn-Co double metal cyanide catalyst prepared in the above Synthesis Example 1, including the following steps:

[0078] S1. In an anhydrous and oxygen-free glove box, add 0.1 wt% of Zn-Co double metal cyanide catalyst and 20 g of hexamethylcyclotrisiloxane (D3) into a dried 100 ml two-neck reaction flask with a side arm;

[0079] S2. Pass in nitrogen, heat to 120 °C and keep the temperature constant for reaction for 1.5 hours to carry out bulk ring-opening polymerization reaction. During the reaction process, sample at regular intervals and conduct 1H NMR analysis to obtain the monomer conversion rate and yield at each sampling point;

[0080] S3. After the polymerization reaction is completed, obtain polysiloxane. Dissolve the obtained polysiloxane in dichloromethane, centrifuge to separate the solid catalyst and the solution. Add an excessive amount of methanol solution to the solution, centrifuge to obtain a polymer precipitate, and then conduct vacuum drying to remove methanol and a small amount of unreacted monomers in the polymer; finally, the monomer conversion rate is 65.75% and the reaction yield is 56.16%.

[0081] Example 10

[0082] This example provides a method for ring-opening polymerization of cyclosiloxane using the Zn-Co double metal cyanide catalyst prepared in Synthesis Example 1 above, including the following steps:

[0083] S1. In an anhydrous and oxygen-free glove box, add 0.2 wt% of Zn-Co double metal cyanide catalyst and 20 g of hexamethylcyclotrisiloxane (D3) into a dried 100 ml two-neck reaction flask with a side arm;

[0084] S2. Pass in nitrogen, heat to 120 °C and keep the temperature constant for reaction for 1.5 hours to carry out bulk ring-opening polymerization reaction. During the reaction process, sample at regular intervals and conduct 1H NMR analysis to obtain the monomer conversion rate and yield at each sampling point;

[0085] S3. After the polymerization reaction is completed, obtain polysiloxane. Dissolve the obtained polysiloxane in dichloromethane, centrifuge to separate the solid catalyst and the solution. Add an excessive amount of methanol solution to the solution, centrifuge to obtain a polymer precipitate, and then conduct vacuum drying to remove methanol and a small amount of unreacted monomers in the polymer; finally, the monomer conversion rate is 98.87% and the reaction yield is 82.32%.

[0086] Example 11

[0087] This example provides a method for ring-opening polymerization of cyclosiloxane using the Zn-Co double metal cyanide catalyst prepared in Synthesis Example 1 above, including the following steps:

[0088] S1. In an anhydrous and oxygen-free glove box, add 0.3 wt% of Zn-Co double metal cyanide catalyst and 20 g of hexamethylcyclotrisiloxane (D3) into a dried 100 ml two-necked reaction flask with a side arm;

[0089] S2. Pass in nitrogen, heat to 120 °C and keep the temperature constant for reaction for 1.5 hours to carry out bulk ring-opening polymerization reaction. During the reaction process, sample at regular intervals and conduct 1H NMR analysis to obtain the monomer conversion rate and yield at each sampling point;

[0090] S3. After the polymerization reaction is completed, obtain polysiloxane. Dissolve the obtained polysiloxane in dichloromethane, centrifuge to separate the solid catalyst and the solution. Add an excessive amount of methanol solution to the solution, centrifuge to obtain a polymer precipitate, and then conduct vacuum drying to remove methanol and a small amount of unreacted monomers in the polymer; finally, the monomer conversion rate is 99.45% and the reaction rate constant is 84.36%.

[0091] Example 12

[0092] This example provides a method for ring-opening polymerization of cyclosiloxane using the Zn-Co double metal cyanide catalyst prepared in the above Synthesis Example 1, including the following steps:

[0093] S1. In an anhydrous and oxygen-free glove box, add 0.5 wt% of Zn-Co double metal cyanide catalyst and 20 g of hexamethylcyclotrisiloxane (D3) into a dried 100 ml two-necked reaction flask with a side arm;

[0094] S2. Pass in nitrogen, heat to 120 °C and keep the temperature constant for reaction for 1.5 hours to carry out bulk ring-opening polymerization reaction. During the reaction process, sample at regular intervals and conduct 1H NMR analysis to obtain the monomer conversion rate and yield at each sampling point;

[0095] S3. After the polymerization reaction is completed, obtain polysiloxane. Dissolve the obtained polysiloxane in dichloromethane, centrifuge to separate the solid catalyst and the solution. Add an excessive amount of methanol solution to the solution, centrifuge to obtain a polymer precipitate, and then conduct vacuum drying to remove methanol and a small amount of unreacted monomers in the polymer; finally, the monomer conversion rate is 99.54% and the reaction yield is 87.14%.

[0096] Comparative Example 1

[0097] This comparative example provides a method for ring-opening polymerization of cyclosiloxane using the Zn-Co double metal cyanide catalyst prepared in the above Synthesis Example 1, including the following steps:

[0098] S1. In an anhydrous and oxygen-free glove box, add 0.1 wt% of Zn-Co double metal cyanide catalyst and 20 g of hexamethylcyclotrisiloxane (D3) into a dried 100 ml two-necked reaction flask with a side arm;

[0099] S2. Pass in nitrogen, heat to 90 °C and keep the temperature constant for reaction for 1.5 hours to carry out bulk ring-opening polymerization reaction. During the reaction process, sample at regular intervals and conduct 1H NMR analysis to obtain the monomer conversion rate and yield at each sampling point;

[0100] S3. After the polymerization reaction is completed, obtain polysiloxane. Dissolve the obtained polysiloxane in dichloromethane, centrifuge to separate the solid catalyst and the solution. Add an excessive amount of methanol solution to the solution, centrifuge to obtain a polymer precipitate, and then conduct vacuum drying to remove methanol and a small amount of unreacted monomers in the polymer; finally, the monomer conversion rate is 16.24% and the reaction yield is 9.76%.

[0101] Comparative Example 2

[0102] This comparative example provides a method for ring-opening polymerization of cyclosiloxane using the Zn-Co double metal cyanide catalyst prepared in the above Synthesis Example 1, including the following steps:

[0103] S1. In an anhydrous and oxygen-free glove box, add 0.5 wt% of Zn-Co double metal cyanide catalyst and 20 g of hexamethylcyclotrisiloxane (D3) into a dried 100 ml two-necked reaction flask with a side arm;

[0104] S2. Pass in nitrogen, heat to 90 °C and keep the temperature constant for reaction for 1.5 hours to carry out bulk ring-opening polymerization reaction. During the reaction process, sample at regular intervals and conduct 1H NMR analysis to obtain the monomer conversion rate and yield at each sampling point;

[0105] S3. After the polymerization reaction is completed, obtain polysiloxane. Dissolve the obtained polysiloxane in dichloromethane, centrifuge to separate the solid catalyst and the solution. Add an excessive amount of methanol solution to the solution, centrifuge to obtain a polymer precipitate, and then conduct vacuum drying to remove methanol and a small amount of unreacted monomers in the polymer; finally, the monomer conversion rate is 23.60% and the reaction yield is 15.75%.

[0106] Comparative Example 3

[0107] This comparative example provides a method for ring-opening polymerization of cyclosiloxane using the Zn-Co double metal cyanide catalyst prepared in the above Synthesis Example 1, including the following steps:

[0108] S1. In an anhydrous and oxygen-free glove box, add 0.1 wt% of Zn-Co double metal cyanide catalyst and 20 g of hexamethylcyclotrisiloxane (D3) into a dried 100 ml two-neck reaction flask with a side arm;

[0109] S2. Introduce nitrogen gas, heat to 130 °C and keep the temperature constant for reaction for 1.5 hours to carry out bulk ring-opening polymerization reaction. During the reaction process, sample at regular intervals and conduct 1H NMR analysis to obtain the monomer conversion rate and yield at each sampling point;

[0110] S3. After the polymerization reaction is completed, prepare polysiloxane. Dissolve the prepared polysiloxane in dichloromethane, centrifuge to separate the solid catalyst and the solution. Add an excessive amount of methanol solution to the solution, centrifuge to obtain a polymer precipitate, and then conduct vacuum drying to remove methanol and a small amount of unreacted monomers in the polymer; finally, the monomer conversion rate is 30.76% and the reaction yield is 21.94%.

[0111] Comparative Example 4

[0112] This comparative example provides a method for ring-opening polymerization of cyclosiloxane using the Zn-Co double metal cyanide catalyst prepared in Synthesis Example 1 above, including the following steps:

[0113] S1. In an anhydrous and oxygen-free glove box, add 0.5 wt% of Zn-Co double metal cyanide catalyst and 20 g of hexamethylcyclotrisiloxane (D3) into a dried 100 ml two-neck reaction flask with a side arm;

[0114] S2. Introduce nitrogen gas, heat to 130 °C and keep the temperature constant for reaction for 1.5 hours to carry out bulk ring-opening polymerization reaction. During the reaction process, sample at regular intervals and conduct 1H NMR analysis to obtain the monomer conversion rate and yield at each sampling point;

[0115] S3. After the polymerization reaction is completed, prepare polysiloxane. Dissolve the prepared polysiloxane in dichloromethane, centrifuge to separate the solid catalyst and the solution. Add an excessive amount of methanol solution to the solution, centrifuge to obtain a polymer precipitate, and then conduct vacuum drying to remove methanol and a small amount of unreacted monomers in the polymer; finally, the monomer conversion rate is 34.87% and the reaction yield is 25.62%.

[0116] Figure 3 1H NMR spectrum of the polymethylsiloxane synthesized in Example 1; it can be seen from this spectrum that the chemical shifts of hydrogen in the product correspond one by one to the spectrum Figure 1 After 1H NMR analysis, it shows that this product is the target product polymethylsiloxane.

[0117] In Examples 1, 2, 3, and 4, with other conditions remaining unchanged, the polymerization temperature was 100 °C. By adjusting the dosage of the double metal cyanide catalyst, the results showed that when the catalyst content was in the range of 0.1 wt% to 0.5 wt%, with the increase in the catalyst dosage, the ring-opening conversion rate of D3 and the reaction rate increased;

[0118] In Examples 5, 6, 7, and 8, with other conditions remaining unchanged, the polymerization temperature was 110 °C. By adjusting the dosage of the double metal cyanide catalyst, the results showed that when the catalyst content was in the range of 0.1 wt% to 0.5 wt%, with the increase in the catalyst dosage, the ring-opening conversion rate of D3 and the reaction rate increased;

[0119] In Examples 9, 10, 11, and 12, with other conditions remaining unchanged, the polymerization temperature was 120 °C. By adjusting the dosage of the double metal cyanide catalyst, the results showed that when the catalyst content was in the range of 0.1 wt% to 0.5 wt%, with the increase in the catalyst dosage, the ring-opening conversion rate of D3 and the reaction rate increased;

[0120] In Examples 1, 5, and 9, with other conditions remaining unchanged, the catalyst content was 0.1 wt%. By adjusting the polymerization temperature, the results showed that when the polymerization temperature was in the range of 100 °C to 120 °C, with the increase in the polymerization temperature, the ring-opening conversion rate of D3 and the reaction rate increased.

[0121] It can be seen from the examples and comparative examples that when the polymerization temperature is below 100 °C or above 120 °C, it will affect the ring-opening conversion rate of D3 and the reaction rate.

[0122] The present invention synthesizes a novel Zn-Co double metal cyanide catalyst by using cobalt cyanate and zinc 2-ethylhexanoate in a methanol solvent for the ring-opening polymerization of epoxy silane; compared with traditional DMC catalysts and liquid acid catalysts, this catalyst has mild polymerization conditions, high catalytic performance, short reaction time and low energy consumption, and has obvious advantages compared with traditional methods;

[0123] The Zn-Co double metal cyanide catalyst has high activity, low catalyst dosage, low cost, and can increase the polymerization reaction rate in a short time. Even with a small amount of catalyst, the catalytic efficiency is still high, which can significantly improve production efficiency and save costs;

[0124] This method conforms to the concept of green chemistry. The catalyst can be recycled, is non-corrosive, reduces equipment damage and waste generation, and has a low environmental impact; overall, the present invention has significant advantages technically, not only improving product performance and production efficiency, but also having good environmental protection, and is applicable to the preparation of high-performance polysiloxanes and related fields, with broad application prospects.

[0125] The above-described embodiments merely represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A method for ring-opening polymerization of cyclosiloxane using a Zn-Co double metal cyanide catalyst, characterized in that: The steps include: S1. Under anhydrous and oxygen-free conditions, 0.1wt% to 0.5wt% of Zn-Co double metal cyanide catalyst and cyclosiloxane monomer are added into a container; S2, introducing nitrogen, heating to 100°C~120°C and reacting at a constant temperature for 1.5~2 hours to carry out bulk ring-opening polymerization reaction; S3, after the polymerization reaction is completed, polysiloxane is obtained, the obtained polysiloxane is dissolved in dichloromethane, and centrifuged to obtain a solid catalyst and a dissolving solution, an excess of methanol solution is added to the dissolving solution, and centrifuged to obtain a polymer precipitate, and then vacuum drying is performed to remove methanol and a small amount of unreacted monomers in the polymer; The preparation method of the Zn-Co double metal cyanide catalyst comprises the following steps: (1) Dissolve potassium cobalt cyanide in distilled water at 50-55°C, add sulfuric acid dropwise to form a white solid precipitate, stir for 3-4 hours, add cold ethanol, and continue stirring for 30-40 minutes; (2) removing the white precipitate by centrifugation, removing the solvent from the filtrate, and further completely drying by vacuum treatment at 60-65°C for 3-3.5 hours; (3) adding icy ethanol to form a slurry, stirring overnight at -5°C, then adding icy ethanol and centrifuging to obtain pale yellow solid cobalt cyanate, dissolving the pale yellow solid cobalt cyanate and zinc 2-ethylhexanoate in methanol respectively, and then quickly mixing, stirring for 24 to 28 hours, separating to obtain a white gel, vacuum drying at 50 to 55°C for 24 to 28 hours, and grinding to obtain a white solid powder Zn-Co double metal cyanide catalyst; The Zn-Co double metal cyanide catalyst is composed of cobalt cyanate and zinc 2-ethylhexanoate; The molar ratio of Zn:Co in the Zn-Co double metal cyanide catalyst is 3:

1.

2. The method for ring-opening polymerization of cyclosiloxane using a Zn-Co double metal cyanide catalyst according to claim 1, characterized in that: The cyclosiloxane is hexamethylcyclotrisiloxane.

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