Preparation method of Zn-Co double-metal cyanide catalyst, and catalyst and application thereof

Abstract

The invention discloses a preparation method of a Zn-Co double-metal cyanide catalyst, the catalyst and application of the catalyst, the Zn-Co double-metal cyanide catalyst is prepared from cobalt cyanic acid and zinc 2-ethylhexanoate in a methanol solvent, the Zn-Co double-metal cyanide catalyst is utilized to catalyze a cyclosiloxane monomer to perform a bulk ring-opening polymerization reaction, and the Zn-Co double-metal cyanide catalyst is obtained. After the reaction is finished, adding dichloromethane to dissolve a polymerization product, and centrifuging to remove the catalyst; adding the dichloromethane solution of the polymer into a large amount of methanol, centrifuging to obtain a polymer precipitate, and carrying out vacuum drying to remove methanol and a small amount of unreacted monomers to obtain a final product; by controlling the dosage of the catalyst, the reaction temperature and the reaction time, the conversion rate and the efficiency of the polymerization reaction can be effectively improved. The double-metal cyanide catalyst disclosed by the invention has the advantages of high catalytic activity, small dosage, no corrosion, low cost, easiness in recovery and the like; the method provided by the invention can realize efficient synthesis of polysiloxane, and is suitable for the fields of material science, electronic industry and the like.

Description

Technical Field

[0001] The invention relates to the technical field of polymer synthesis, and in particular to a preparation method of a Zn-Co double metal cyanide catalyst, the catalyst and application thereof. Background Art

[0002] Polysiloxane is a class of polymers with typical organic-inorganic characteristics, whose main chain is composed of alternating silicon and oxygen atoms (-Si-O-Si-). Due to the large bond angle of Si-O-Si bond (about 140°) and the easy rotation of Si-O bond, polysiloxane exhibits extremely high flexibility. This type of polymer has many excellent properties, including excellent thermal stability, low surface energy, high elasticity, extremely low glass transition temperature, and excellent resistance to ozone, ultraviolet rays and chemical corrosion. It is widely used in defense, aerospace, automobile, construction, textile and other fields.

[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: A method for preparing a 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 using a rotary evaporator, and further completely drying by vacuum treatment at 60-65°C for 3-3.5 hours; (3) Add icy ethanol to form a slurry, and stir overnight at -5°C. Then add icy ethanol and centrifuge to obtain pale yellow solid cobalt cyanate. Dissolve the pale yellow solid cobalt cyanate and zinc 2-ethylhexanoate in methanol respectively, then quickly mix and stir for 24 to 28 hours to separate and obtain a white gel. Dry under vacuum at 50 to 55°C for 24 to 28 hours and grind to obtain a white solid powder Zn-Co double metal cyanide catalyst.

[0006] Preferably, the Zn-Co double metal cyanide catalyst is a composite of cobalt cyanate and zinc 2-ethylhexanoate.

[0007] Preferably, the molar ratio of Zn:Co in the Zn-Co double metal cyanide catalyst is 3:1.

[0008] The present application also provides a Zn-Co double metal cyanide catalyst, which is prepared by the above-mentioned preparation method of the Zn-Co double metal cyanide catalyst.

[0009] The present application also claims a method for ring-opening polymerization of cyclosiloxane using the above-mentioned Zn-Co double metal cyanide catalyst, comprising the following steps: 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, and the obtained polysiloxane is dissolved in dichloromethane, and centrifuged to obtain a solid catalyst and a dissolving solution, and an excess of methanol solution is added to the dissolving solution, and centrifuged to obtain a polymer precipitate, which is then vacuum dried to remove methanol and a small amount of unreacted monomers in the polymer.

[0010] Preferably, the cyclosiloxane is hexamethylcyclotrisiloxane (D3).

[0011] Specifically, the Zn-Co double metal cyanide catalyst is a compound represented by formula I; (Formula I); wherein, ; Due to the application of the above technical solution, the present invention has the following beneficial effects compared with the prior art: 1. The conventional liquid acid-catalyzed cyclosiloxane ring-opening polymerization requires cumbersome post-treatments such as neutralization and water washing, and these liquid acids seriously corrode equipment, pollute the environment, are difficult to operate, and have high production costs. Compared with the conventional liquid acid-catalyzed cyclosiloxane ring-opening polymerization, the present invention adopts a heterogeneous double metal cyanide catalyst, and can prepare polysiloxane with a high conversion rate by controlling the reaction conditions. The catalyst has the advantages of no corrosion to equipment, no environmental pollution, low cost, and easy catalyst recovery. 2. Traditional DMC catalysts are usually prepared using potassium cobalt cyanate and zinc chloride as precursors. However, during the catalyst synthesis process, potassium chloride byproducts 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. Under the conditions of 2wt% to 4wt% catalyst dosage, reaction temperature of 120°C, and reaction time of 10h, the ring-opening conversion rate of D3 is 21.04% to 25.27%, and the yield is only 5.43% to 6.01%. Under the conditions of 0.1wt% to 0.5wt% catalyst dosage, reaction temperature of 120°C, and reaction time of 1.5h, the ring-opening conversion rate of D3 is 65.75% to 99.54%, and the yield is as high as 56.16% to 87.14%. 3. The present invention compounds cobalt cyanate and zinc 2-ethylhexanoate in a methanol solvent in a specific ratio to form a complex catalyst, thereby avoiding the disadvantage of mixing potassium chloride and water in the preparation process of the traditional DMC catalyst. The conversion rate of the catalytic ring-opening polymerization of cyclosiloxane is as high as 99%, and it has the advantages of small dosage, high conversion rate and high activity. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, some of the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be made based on these drawings without paying any creative work.

[0013] Figure 1 This is an infrared spectrum (FT-IR) image of the double metal cyanide catalyst of Example 1 of the present invention; Figure 2 is an X-ray diffraction (XRD) image of the double metal cyanide catalyst of Example 1 of the present invention; Figure 3 The double metal cyanide catalyst of Example 1 of the present invention is 0.1wt% catalytic D3 ring-opening polymerization NMR ( 1 H-NMR) images; Figure 4 The double metal cyanide catalyst of Example 4 of the present invention is 0.5wt% catalytic D3 ring-opening polymerization NMR ( 1 H-NMR) images. DETAILED DESCRIPTION

[0014] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, a specific implementation scheme is now described in detail.

[0015] The present invention is further described below in conjunction with the examples, but the present invention is not limited to the following examples. The implementation conditions used in the examples can be further adjusted according to the different requirements of specific use, and the implementation conditions not indicated are conventional conditions in the industry. The technical features involved in each embodiment of the present invention can be combined with each other as long as they do not conflict with each other.

[0016] Synthesis example 1 This synthesis example provides a method for preparing a Zn-Co double metal cyanide catalyst, comprising the following steps: (1) Dissolve potassium cobalt cyanide in distilled water at 50°C, add sulfuric acid dropwise to form a white solid precipitate, stir for 3 hours, add cold ethanol, and continue stirring for 30 minutes; (2) removing the white precipitate by centrifugation, removing the solvent from the filtrate using a rotary evaporator, and further completely drying by vacuum treatment at 60 °C for 3 h; (3) adding icy ethanol to form a slurry, stirring at -5°C overnight, 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 rapidly mixing and stirring for 24 hours to obtain a white gel, which was vacuum dried at 50°C for 24 hours and ground to obtain a white solid powder Zn-Co double metal cyanide catalyst; the Zn:Co molar ratio of the Zn-Co double metal cyanide catalyst is 3:1.

[0017] Example 1 See attached Figures 1 to 3 This embodiment provides a method for ring-opening polymerization of cyclosiloxane using the Zn-Co double metal cyanide catalyst prepared in the above-mentioned Synthesis Example 1, comprising the following steps: S1. In an anhydrous and oxygen-free glove box, add 0.1 wt% Zn-Co double metal cyanide catalyst and 20 g hexamethylcyclotrisiloxane (D3) into a 100 ml two-necked reaction flask that has been dried; S2, introducing nitrogen, heating to 100°C and reacting at a constant temperature for 1.5 hours to carry out a bulk ring-opening polymerization reaction. During the reaction, sampling was performed at regular intervals and nuclear magnetic hydrogen spectrum analysis was performed to obtain the monomer conversion rate and yield of each sampling point; S3. After the polymerization reaction is completed, polysiloxane is obtained, and the obtained polysiloxane is dissolved in dichloromethane, and centrifuged to obtain a solid catalyst and a dissolving solution, and 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 final monomer conversion rate is 35.9%, and the reaction yield is 28.85%.

[0018] Example 2 This embodiment provides a method for ring-opening polymerization of cyclosiloxane using the Zn-Co double metal cyanide catalyst prepared in Synthesis Example 1, comprising the following steps: 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 100 ml two-necked reaction flask that has been dried; S2, introducing nitrogen, heating to 100°C and reacting at a constant temperature for 1.5 hours to carry out a bulk ring-opening polymerization reaction. During the reaction, sampling was performed at regular intervals and nuclear magnetic hydrogen spectrum analysis was performed to obtain the monomer conversion rate and yield of each sampling point; S3. After the polymerization reaction is completed, polysiloxane is obtained, and the obtained polysiloxane is dissolved in dichloromethane, and centrifuged to obtain a solid catalyst and a dissolving solution, and an excess of methanol solution is added to the dissolving solution, and centrifuged to obtain a polymer precipitate, which is then vacuum dried to remove methanol and a small amount of unreacted monomers in the polymer; the final monomer conversion rate is 53.05%, and the reaction yield is 42.78%.

[0019] Example 3 This embodiment provides a method for ring-opening polymerization of cyclosiloxane using the Zn-Co double metal cyanide catalyst prepared in Synthesis Example 1, comprising the following steps: 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 100 ml two-necked reaction flask that has been dried; S2, introducing nitrogen, heating to 100°C and reacting at a constant temperature for 1.5 hours to carry out a bulk ring-opening polymerization reaction. During the reaction, sampling was performed at regular intervals and nuclear magnetic hydrogen spectrum analysis was performed to obtain the monomer conversion rate and yield of each sampling point; S3. After the polymerization reaction is completed, polysiloxane is obtained, and 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, which is then vacuum dried to remove methanol and a small amount of unreacted monomers in the polymer; the final monomer conversion rate is 95.39%, and the reaction yield is 77.14%.

[0020] Example 4 This embodiment provides a method for ring-opening polymerization of cyclosiloxane using the Zn-Co double metal cyanide catalyst prepared in Synthesis Example 1, comprising the following steps: 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 100 ml two-necked reaction flask that has been dried; S2, introducing nitrogen, heating to 100°C and reacting at a constant temperature for 1.5 hours to carry out a bulk ring-opening polymerization reaction. During the reaction, sampling was performed at regular intervals and nuclear magnetic hydrogen spectrum analysis was performed to obtain the monomer conversion rate and yield of each sampling point; S3. After the polymerization reaction is completed, polysiloxane is obtained, and the obtained polysiloxane is dissolved in dichloromethane, and centrifuged to obtain a solid catalyst and a dissolving solution, and 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 final monomer conversion rate is 99.83%, and the reaction yield is 82.01%.

[0021] Example 5 This embodiment provides a method for ring-opening polymerization of cyclosiloxane using the Zn-Co double metal cyanide catalyst prepared in Synthesis Example 1, comprising the following steps: S1. In an anhydrous and oxygen-free glove box, add 0.1 wt% Zn-Co double metal cyanide catalyst and 20 g hexamethylcyclotrisiloxane (D3) into a 100 ml two-necked reaction flask that has been dried; S2, introducing nitrogen, heating to 110° C. and reacting at a constant temperature for 1.5 hours to carry out a bulk ring-opening polymerization reaction. During the reaction, sampling was performed at regular intervals and nuclear magnetic hydrogen spectrum analysis was performed to obtain the monomer conversion rate and yield of each sampling point; S3. After the polymerization reaction is completed, polysiloxane is obtained, and 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, which is then vacuum dried to remove methanol and a small amount of unreacted monomers in the polymer; the final monomer conversion rate is 53.27%, and the reaction yield is 45.33%.

[0022] Example 6 This embodiment provides a method for ring-opening polymerization of cyclosiloxane using the Zn-Co double metal cyanide catalyst prepared in Synthesis Example 1, comprising the following steps: 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 100 ml two-necked reaction flask that has been dried; S2, introducing nitrogen, heating to 110° C. and reacting at a constant temperature for 1.5 hours to carry out a bulk ring-opening polymerization reaction. During the reaction, sampling was performed at regular intervals and nuclear magnetic hydrogen spectrum analysis was performed to obtain the monomer conversion rate and yield of each sampling point; S3. After the polymerization reaction is completed, polysiloxane is obtained, and the obtained polysiloxane is dissolved in dichloromethane, and centrifuged to obtain a solid catalyst and a dissolving solution, and 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 final monomer conversion rate is 97.33%, and the reaction yield is 75.53%.

[0023] Example 7 This embodiment provides a method for ring-opening polymerization of cyclosiloxane using the Zn-Co double metal cyanide catalyst prepared in Synthesis Example 1, comprising the following steps: 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 100 ml two-necked reaction flask that has been dried; S2, introducing nitrogen, heating to 110° C. and reacting at a constant temperature for 1.5 hours to carry out a bulk ring-opening polymerization reaction. During the reaction, sampling was performed at regular intervals and nuclear magnetic hydrogen spectrum analysis was performed to obtain the monomer conversion rate and yield of each sampling point; S3. After the polymerization reaction is completed, polysiloxane is obtained, and the obtained polysiloxane is dissolved in dichloromethane, and centrifuged to obtain a solid catalyst and a dissolving solution, and 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 final monomer conversion rate is 99.31%, and the reaction yield is 84.51%.

[0024] Example 8 This embodiment provides a method for ring-opening polymerization of cyclosiloxane using the Zn-Co double metal cyanide catalyst prepared in Synthesis Example 1, comprising the following steps: 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 100 ml two-necked reaction flask that has been dried; S2, introducing nitrogen, heating to 110° C. and reacting at a constant temperature for 1.5 hours to carry out a bulk ring-opening polymerization reaction. During the reaction, sampling was performed at regular intervals and nuclear magnetic hydrogen spectrum analysis was performed to obtain the monomer conversion rate and yield of each sampling point; S3. After the polymerization reaction is completed, polysiloxane is obtained, and the obtained polysiloxane is dissolved in dichloromethane, and centrifuged to obtain a solid catalyst and a dissolving solution, and 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 final monomer conversion rate is 99.13%, and the reaction yield is 86.82%.

[0025] Example 9 This embodiment provides a method for ring-opening polymerization of cyclosiloxane using the Zn-Co double metal cyanide catalyst prepared in Synthesis Example 1, comprising the following steps: S1. In an anhydrous and oxygen-free glove box, add 0.1 wt% Zn-Co double metal cyanide catalyst and 20 g hexamethylcyclotrisiloxane (D3) into a 100 ml two-necked reaction flask that has been dried; S2, introducing nitrogen, heating to 120° C. and reacting at a constant temperature for 1.5 hours to carry out a bulk ring-opening polymerization reaction. During the reaction, sampling was performed at regular intervals and nuclear magnetic hydrogen spectrum analysis was performed to obtain the monomer conversion rate and yield of each sampling point; S3. After the polymerization reaction is completed, polysiloxane is obtained, and the obtained polysiloxane is dissolved in dichloromethane, and centrifuged to obtain a solid catalyst and a dissolving solution, and 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 final monomer conversion rate is 65.75%, and the reaction yield is 56.16%.

[0026] Example 10 This embodiment provides a method for ring-opening polymerization of cyclosiloxane using the Zn-Co double metal cyanide catalyst prepared in Synthesis Example 1, comprising the following steps: 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 100 ml two-necked reaction flask that has been dried; S2, introducing nitrogen, heating to 120° C. and reacting at a constant temperature for 1.5 hours to carry out a bulk ring-opening polymerization reaction. During the reaction, sampling was performed at regular intervals and nuclear magnetic hydrogen spectrum analysis was performed to obtain the monomer conversion rate and yield of each sampling point; S3. After the polymerization reaction is completed, polysiloxane is obtained, and the obtained polysiloxane is dissolved in dichloromethane, and centrifuged to obtain a solid catalyst and a dissolving solution, and 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 final monomer conversion rate is 98.87%, and the reaction yield is 82.32%.

[0027] Embodiment 11 This embodiment provides a method for ring-opening polymerization of cyclosiloxane using the Zn-Co double metal cyanide catalyst prepared in Synthesis Example 1, comprising the following steps: 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 100 ml two-necked reaction flask that has been dried; S2, introducing nitrogen, heating to 120° C. and reacting at a constant temperature for 1.5 hours to carry out a bulk ring-opening polymerization reaction. During the reaction, sampling was performed at regular intervals and nuclear magnetic hydrogen spectrum analysis was performed to obtain the monomer conversion rate and yield of each sampling point; S3. After the polymerization reaction is completed, polysiloxane is obtained, and the obtained polysiloxane is dissolved in dichloromethane, and centrifuged to obtain a solid catalyst and a dissolving solution, and 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 final monomer conversion rate is 99.45%, and the reaction rate constant is 84.36%.

[0028] Example 12 This embodiment provides a method for ring-opening polymerization of cyclosiloxane using the Zn-Co double metal cyanide catalyst prepared in Synthesis Example 1, comprising the following steps: 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 100 ml two-necked reaction flask that has been dried; S2, introducing nitrogen, heating to 120° C. and reacting at a constant temperature for 1.5 hours to carry out a bulk ring-opening polymerization reaction. During the reaction, sampling was performed at regular intervals and nuclear magnetic hydrogen spectrum analysis was performed to obtain the monomer conversion rate and yield of each sampling point; S3. After the polymerization reaction is completed, polysiloxane is obtained, and the obtained polysiloxane is dissolved in dichloromethane, and centrifuged to obtain a solid catalyst and a dissolving solution, and 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 final monomer conversion rate is 99.54%, and the reaction yield is 87.14%.

[0029] Comparative Example 1 This comparative example provides a method for ring-opening polymerization of cyclosiloxane using the Zn-Co double metal cyanide catalyst prepared in the above-mentioned Synthesis Example 1, comprising the following steps: S1. In an anhydrous and oxygen-free glove box, add 0.1 wt% Zn-Co double metal cyanide catalyst and 20 g hexamethylcyclotrisiloxane (D3) into a 100 ml two-necked reaction flask that has been dried; S2, introducing nitrogen, heating to 90°C and reacting at a constant temperature for 1.5 hours to carry out bulk ring-opening polymerization. During the reaction, sampling was performed at regular intervals and nuclear magnetic hydrogen spectrum analysis was performed to obtain the monomer conversion rate and yield of each sampling point; S3. After the polymerization reaction is completed, polysiloxane is obtained, and 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, which is then vacuum dried to remove methanol and a small amount of unreacted monomers in the polymer; the final monomer conversion rate is 16.24%, and the reaction yield is 9.76%.

[0030] Comparative Example 2 This comparative example provides a method for ring-opening polymerization of cyclosiloxane using the Zn-Co double metal cyanide catalyst prepared in the above-mentioned Synthesis Example 1, comprising the following steps: 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 100 ml two-necked reaction flask that has been dried; S2, introducing nitrogen, heating to 90°C and reacting at a constant temperature for 1.5 hours to carry out bulk ring-opening polymerization. During the reaction, sampling was performed at regular intervals and nuclear magnetic hydrogen spectrum analysis was performed to obtain the monomer conversion rate and yield of each sampling point; S3. After the polymerization reaction is completed, polysiloxane is obtained, and 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, which is then vacuum dried to remove methanol and a small amount of unreacted monomers in the polymer; the final monomer conversion rate is 23.60%, and the reaction yield is 15.75%.

[0031] Comparative Example 3 This comparative example provides a method for ring-opening polymerization of cyclosiloxane using the Zn-Co double metal cyanide catalyst prepared in the above-mentioned Synthesis Example 1, comprising the following steps: S1. In an anhydrous and oxygen-free glove box, add 0.1 wt% Zn-Co double metal cyanide catalyst and 20 g hexamethylcyclotrisiloxane (D3) into a 100 ml two-necked reaction flask that has been dried; S2, introducing nitrogen, heating to 130° C. and reacting at a constant temperature for 1.5 hours to carry out a bulk ring-opening polymerization reaction. During the reaction, sampling was performed at regular intervals and nuclear magnetic hydrogen spectrum analysis was performed to obtain the monomer conversion rate and yield of each sampling point; S3. After the polymerization reaction is completed, polysiloxane is obtained, and the obtained polysiloxane is dissolved in dichloromethane, and centrifuged to obtain a solid catalyst and a dissolving solution. An excess amount of methanol solution is added to the dissolving solution, and centrifuged to obtain a polymer precipitate, which is then vacuum dried to remove methanol and a small amount of unreacted monomers in the polymer; the final monomer conversion rate is 30.76%, and the reaction yield is 21.94%.

[0032] Comparative Example 4 This comparative example provides a method for ring-opening polymerization of cyclosiloxane using the Zn-Co double metal cyanide catalyst prepared in the above-mentioned Synthesis Example 1, comprising the following steps: 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 100 ml two-necked reaction flask that has been dried; S2, introducing nitrogen, heating to 130° C. and reacting at a constant temperature for 1.5 hours to carry out a bulk ring-opening polymerization reaction. During the reaction, sampling was performed at regular intervals and nuclear magnetic hydrogen spectrum analysis was performed to obtain the monomer conversion rate and yield of each sampling point; S3. After the polymerization reaction is completed, polysiloxane is obtained, and the obtained polysiloxane is dissolved in dichloromethane, and centrifuged to obtain a solid catalyst and a dissolving solution. An excess amount of methanol solution is added to the dissolving solution, and centrifuged to obtain a polymer precipitate, which is then vacuum dried to remove methanol and a small amount of unreacted monomers in the polymer; the final monomer conversion rate is 34.87%, and the reaction yield is 25.62%.

[0033] Figure 3 This is the nuclear magnetic resonance spectrum of the polymethylsiloxane synthesized in Example 1; it can be seen from the spectrum that the chemical shift of hydrogen in the product is consistent with the spectrum. Figure 1 Correspondingly, nuclear magnetic resonance hydrogen spectrum analysis showed that this product was the target product polymethylsiloxane.

[0034] In Examples 1, 2, 3, and 4, the polymerization temperature was 100° C., and the amount of the double metal cyanide catalyst was adjusted. The results showed that when the catalyst content was in the range of 0.1 wt % to 0.5 wt %, as the amount of the catalyst increased, the D3 ring-opening conversion rate and the reaction rate increased; In Examples 5, 6, 7, and 8, the polymerization temperature was 110° C., and the amount of the double metal cyanide catalyst was adjusted while keeping other conditions unchanged. The results showed that when the catalyst content was in the range of 0.1 wt % to 0.5 wt %, as the amount of the catalyst increased, the D3 ring-opening conversion rate and the reaction rate increased; In Examples 9, 10, 11, and 12, the polymerization temperature was 120° C. while keeping other conditions unchanged. By adjusting the amount 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 %, as the amount of the catalyst increased, the D3 ring-opening conversion rate and the reaction rate increased; In Examples 1, 5, and 9, the catalyst content was 0.1 wt % while keeping other conditions unchanged. By adjusting the polymerization temperature, the results showed that when the polymerization temperature was in the range of 100°C to 120°C, the D3 ring-opening conversion rate and reaction rate increased with the increase of the polymerization temperature.

[0035] It can be seen from the examples and comparative examples that the polymerization temperature below 100° C. or above 120° C. will affect the D3 ring-opening conversion rate and reaction rate.

[0036] The invention adopts cobalt cyanate and zinc 2-ethylhexanoate to synthesize a novel Zn-Co double metal cyanide catalyst in a methanol solvent for ring-opening polymerization of epoxysilane; compared with traditional DMC catalysts and liquid acid catalysts, the catalyst has mild polymerization conditions, high catalytic performance, short reaction time and low energy consumption, and has obvious advantages over traditional methods; 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 if the catalyst dosage is small, the catalytic efficiency is still high, which can significantly improve production efficiency and save costs. This method is in line with the concept of green chemistry. The catalyst is recyclable and non-corrosive, which reduces equipment damage and waste generation, and has a lower environmental impact. Overall, the present invention has significant technical advantages. It not only improves product performance and production efficiency, but also has good environmental performance. It is suitable for the preparation of high-performance polysiloxanes and related fields and has broad application prospects.

[0037] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a Zn-Co double metal cyanide catalyst, characterized in that: The steps include: (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) Add icy ethanol to form a slurry, and stir overnight at -5°C. Then add icy ethanol and centrifuge to obtain pale yellow solid cobalt cyanate. Dissolve the pale yellow solid cobalt cyanate and zinc 2-ethylhexanoate in methanol respectively, then quickly mix and stir for 24 to 28 hours to separate and obtain a white gel. Dry under vacuum at 50 to 55°C for 24 to 28 hours and grind to obtain a white solid powder Zn-Co double metal cyanide catalyst.

2. The method for preparing the Zn-Co double metal cyanide catalyst according to claim 1, characterized in that: The Zn-Co double metal cyanide catalyst is composited from cobalt cyanate and zinc 2-ethylhexanoate.

3. The method for preparing the Zn-Co double metal cyanide catalyst according to claim 1, characterized in that: The molar ratio of Zn:Co in the Zn-Co double metal cyanide catalyst is 3:

1.

4. A Zn-Co double metal cyanide catalyst, characterized in that: The catalyst is prepared by the method for preparing the Zn-Co double metal cyanide catalyst according to any one of claims 1 to 3.

5. A method for ring-opening polymerization of cyclosiloxane using a Zn-Co double metal cyanide catalyst, characterized in that: A method for ring-opening polymerization of cyclosiloxane using the Zn-Co double metal cyanide catalyst prepared by the preparation method of the Zn-Co double metal cyanide catalyst according to any one of claims 1 to 3 or the Zn-Co double metal cyanide catalyst according to claim 4, comprising the following steps: 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, and the obtained polysiloxane is dissolved in dichloromethane, and centrifuged to obtain a solid catalyst and a dissolving solution, and an excess of methanol solution is added to the dissolving solution, and centrifuged to obtain a polymer precipitate, which is then vacuum dried to remove methanol and a small amount of unreacted monomers in the polymer.

6. The method for ring-opening polymerization of cyclosiloxane using a Zn-Co double metal cyanide catalyst according to claim 5, characterized in that: The cyclosiloxane is hexamethylcyclotrisiloxane.

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