A catalyst for synthesizing fluorosilicone gum and a preparation method thereof
The problem of poor catalyst uniformity was solved by reacting sodium hydroxide with D3F in an organic solvent, thus achieving high molecular weight and narrow molecular weight distribution of fluorosilicone raw rubber and improving its quality.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- 江西晨光新材料股份有限公司
- Filing Date
- 2024-03-20
- Publication Date
- 2026-07-10
AI Technical Summary
In existing processes for preparing fluorosilicone raw rubber, the catalyst has poor uniformity and is prone to leaving behind white insoluble particles, resulting in uneven dispersion of the reaction system, making it difficult to control the molecular weight distribution and affecting the quality of the fluorosilicone raw rubber.
The catalyst prepared by dissolving sodium hydroxide in organic solvents and water and reacting it with D3F has good uniformity, high storage stability, and is easy to disperse in the reaction system. By controlling the reaction time window to regulate the ring-opening polymerization of D3F, high molecular weight fluorosilicone raw rubber with a narrow molecular weight distribution is obtained.
This method achieves uniform dispersion of the catalyst in the reaction system, provides a wider time window, facilitates control of the polymerization reaction, and yields high molecular weight fluorosilicone raw rubber with a narrow molecular weight distribution, thereby improving product quality.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of fluorosilicone raw rubber synthesis technology, and more specifically, to a catalyst for synthesizing fluorosilicone raw rubber and its preparation method. Background Technology
[0002] Most fluorosilicone raw rubber is made from 1,3,5-trimethyl-1,3,5-tris(3',3',3'-trifluoropropyl)cyclotrisiloxane (D3 F D3 is a linear high molecular weight polymer formed by ring-opening polymerization. Studies have found that D3... F Anionic ring-opening polymerization involves a "biting-back" reaction, producing low-molecular-weight cyclic compounds alongside high-molecular-weight polymers. The presence of these low-molecular-weight cyclic compounds significantly impacts the performance of fluorosilicone raw materials; therefore, improving D3... F Conversion rate is of great significance for improving polymerization efficiency and reducing product separation.
[0003] In the synthesis of fluorosilicone raw rubber, ring-opening polymerization is typically carried out using a catalyst. However, the catalyst concentration is generally low, resulting in a limited number of active sites and making the process highly sensitive to impurities. For example, acidic compounds can destroy the active sites, halting the polymerization, while water and CO2 can coordinate with the active sites, hindering the reaction process. Therefore, using a suitable catalytic system can yield high conversion rates and high molecular weight fluorosilicone raw rubber within a wider "time window." However, in existing technologies, the catalysts used in the fluorosilicone raw rubber preparation process exhibit poor catalyst uniformity, easily leaving behind white insoluble particles that are difficult to disperse uniformly in the reaction system. This makes it difficult to control the molecular weight of the raw rubber, resulting in a wider molecular weight distribution and directly affecting the quality of the obtained fluorosilicone raw rubber. Summary of the Invention
[0004] The primary objective of this invention is to provide a method for preparing a catalyst for the synthesis of fluorosilicone raw rubber. This method yields a catalyst with good uniformity, good storage stability, and excellent dispersion in the reaction system, enabling effective catalytic regulation of D3 over a relatively wide time window. F High molecular weight fluorosilicone raw rubber was prepared by ring-opening polymerization.
[0005] The method for preparing a catalyst for synthesizing fluorosilicone raw rubber provided by the present invention includes the following steps:
[0006] Sodium hydroxide was added to an organic solvent and water and dissolved completely. Then D3 was added. F Under N2 protection, after removing the organic solvent and water, the reaction is carried out at 110–150 °C for 2–4 h.
[0007] In this invention, D3 FIt is 1,3,5-trimethyl-1,3,5-tris(3',3',3'-trifluoropropyl)cyclotrisiloxane.
[0008] In this invention, sodium hydroxide is dissolved in an organic solvent and water, and D3 is added after complete dissolution. F This is one of the core inventive points of this invention. In a specific embodiment of this invention, sodium hydroxide can be added to an organic solvent and water in a certain proportion and dissolved completely by stirring (or other methods commonly used in the art). In a specific embodiment of this invention, the water can be deionized water, purified water, or mineral water, etc. In a preferred embodiment of this invention, the organic solvent is an alcohol solvent such as methanol, ethanol, isopropanol, or n-propanol. To obtain a more uniform, transparent catalyst with better catalytic effect, the organic solvent is further preferably ethanol. In this invention, when the catalyst obtained using ethanol is used to prepare fluorosilicone raw rubber, it is easily and uniformly dispersed in the reaction system, and high molecular weight fluorosilicone raw rubber with a narrow molecular weight distribution can be obtained.
[0009] In a preferred embodiment of the present invention, in order to improve the catalytic effect of the obtained catalyst, the mass ratio of sodium hydroxide to organic solvent and water is 1:(5-25):(0.5-2.5), preferably 1:(8-15):(0.8-1.5).
[0010] In a preferred embodiment of the present invention, in order to make the obtained catalyst more homogeneous and improve the catalytic effect of the catalyst, sodium hydroxide and D3... F The mass ratio is 1:(30-250), preferably 1:(50-125).
[0011] In specific embodiments of the present invention, methods commonly used in the art can be used to remove organic solvents and water, such as vacuum distillation.
[0012] The catalyst prepared using the method provided in this invention can effectively catalyze and regulate D3. F High molecular weight fluorosilicone raw rubber is prepared by ring-opening polymerization. Fluorosilicone raw rubber with a molecular weight of 800,000 to 1,500,000 can be prepared using the catalyst of this invention.
[0013] Another object of the present invention is to provide a catalyst obtained by the above preparation method.
[0014] Another object of the present invention is to provide the application of the catalyst obtained by the above preparation method in the synthesis of fluorosilicone raw rubber.
[0015] In one specific embodiment of the present invention, the raw materials in the synthetic fluorosilicone raw rubber include D3. F D3 vi 、 vi MM vietc. Among them, D3 vi It is 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane. vi MM vi It is 1,1,3,3-tetramethyl-1,3-divinyldisilazane. In a specific embodiment of the present invention, the raw material includes D3. F D3 vi 、 vi MM vi The synthesis reaction of fluorosilicone raw rubber in this invention will be described in detail later.
[0016] In a preferred embodiment of the present invention, the amount of catalyst provided by the present invention is such that the alkali content in the catalytic reaction system is 0.001 wt% to 0.003 wt% of the total mass of the raw materials. In a specific embodiment of the present invention, the raw materials include D3. F D3 vi 、 vi MM vi In the synthesis reaction of fluorosilicone raw rubber, the amount of catalyst can be calculated according to the following formula:
[0017]
[0018] Where C% is the base content in the reaction system, m(Cat) is the catalyst mass, and A% is the base content in the catalyst, m(D3) is the catalyst mass. F —D3 F Mass, m(D3) vi —D3 vi mass, m( vi MM vi )— vi MM vi quality.
[0019] The catalyst prepared by the method provided by this invention exhibits good uniformity, effectively avoids alkaline solid residues, demonstrates good storage stability, and shows excellent dispersion in the reaction system. Under non-equilibrium polymerization conditions, the catalyst provided by this invention can provide a wide (40–60 min) termination reaction "time window" (referring to the time from the start of polymerization to the addition of the terminating neutralizing agent), and D3 is easily controlled. F By maintaining the high-conversion linear polysiloxane as the absolute main component after ring-opening polymerization, the resulting fluorosilicone raw rubber has a higher molecular weight, is easier to control, and has a narrower molecular weight distribution range, effectively improving the quality of the fluorosilicone raw rubber. Detailed Implementation
[0020] The specific embodiments of the present invention will be described in further detail below with reference to the examples. These examples are for illustrative purposes only and are not intended to limit the scope of the invention.
[0021] Unless otherwise specified in the examples, the conditions should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products. In this invention, unless otherwise specified, "parts" refers to parts by weight, and "%" refers to percentages.
[0022] Example 1
[0023] In a 250mL three-necked flask equipped with a stirrer, nitrogen purging tube, and thermometer, first add 1 part NaOH to 12 parts ethanol and 1 part deionized water and stir until completely dissolved. Then add 100 parts D3. F After removing the organic solvent and water under N2 and stirring conditions at 55℃ / -0.096MPa, the temperature was further increased to 130℃ and reacted for 3 hours to obtain a viscous catalyst, which was then cooled and sealed for storage.
[0024] Example 2
[0025] In a 250mL three-necked flask equipped with a stirrer, nitrogen purging tube, and thermometer, first add 1 part NaOH to 8 parts ethanol and 1.5 parts deionized water and stir until completely dissolved. Then add 50 parts D3. F After removing the organic solvent and water under N2 and stirring conditions at 55℃ / -0.096MPa, the temperature was further increased to 120℃ and reacted for 3 hours to obtain a viscous catalyst, which was then cooled and sealed for storage.
[0026] Example 3
[0027] In a 250mL three-necked flask equipped with a stirrer, nitrogen purging tube, and thermometer, first add 1 part NaOH to 15 parts ethanol and 0.8 parts deionized water and stir until completely dissolved. Then add 125 parts D3. F After removing the organic solvent and water under N2 and stirring conditions at 55℃ / -0.096MPa, the temperature was further increased to 140℃ and reacted for 3 hours to obtain a viscous catalyst, which was then cooled and sealed for storage.
[0028] Example 4
[0029] In a 250mL three-necked flask equipped with a stirrer, nitrogen purging tube, and thermometer, first add 1 part NaOH to 5 parts ethanol and 2.5 parts deionized water and stir until completely dissolved. Then add 30 parts D3. F After removing the organic solvent and water under N2 and stirring conditions at 55℃ / -0.096MPa, the temperature was further increased to 130℃ and reacted for 3 hours to obtain a viscous catalyst, which was then cooled and sealed for storage.
[0030] Example 5
[0031] In a 250mL three-necked flask equipped with a stirrer, nitrogen purging tube, and thermometer, first add 1 part NaOH to 25 parts ethanol and 0.5 parts deionized water and stir until completely dissolved. Then add 250 parts D3. F After removing the organic solvent and water under N2 and stirring conditions at 55℃ / -0.096MPa, the temperature was further increased to 150℃ and reacted for 2 hours to obtain a viscous catalyst, which was then cooled and sealed for storage.
[0032] Example 6
[0033] The preparation method provided in this embodiment is the same as that in Example 1, the only difference being that the organic solvent is methanol.
[0034] Example 7
[0035] The preparation method provided in this embodiment is the same as that in Example 1, the only difference being that the organic solvent is isopropanol.
[0036] Comparative Example 1
[0037] In a 250mL three-necked flask equipped with a stirrer, nitrogen purging tube, and thermometer, add 1 part NaOH to 100 parts D3. F In the process, under N2 and stirring conditions, the catalyst was dehydrated at 55℃ / -0.096MPa, and then the temperature was further increased to 130℃ for 3 hours to obtain a viscous catalyst, which was then cooled and sealed for storage.
[0038] Comparative Example 2
[0039] In a 250mL three-necked flask equipped with a stirrer, nitrogen purging tube, and thermometer, add 1 part NaOH to 50 parts D3. F In a medium atmosphere, after dehydration at 55℃ / -0.096MPa under N2 purging and stirring, the temperature was further increased to 120℃ and reacted for 3 hours to obtain a viscous catalyst, which was then cooled and sealed for storage.
[0040] Comparative Example 3
[0041] In a 250mL three-necked flask equipped with a stirrer, nitrogen purging tube, and thermometer, first add 1 part NaOH to 125 parts D3. F After dehydration at 55℃ / -0.096MPa under N2 and stirring conditions, the temperature was further increased to 140℃ and reacted for 3 hours to obtain the catalyst, which was then cooled and sealed for storage.
[0042] Experimental Example
[0043] The appearance and stability of the catalysts provided in the examples and comparative examples are shown in Table 1. The alkali content in the catalysts was determined by acid-base titration; the stability of the catalysts was determined by retesting the alkali content after storing the catalysts at room temperature in a sealed container for one month and calculating the alkali content loss ratio.
[0044] Table 1. Performance of the catalysts provided in the examples and comparative examples.
[0045]
[0046] Catalytic performance of catalysts provided in the examples and comparative examples
[0047] A certain ratio of D3 F and D3 Vi Add to the reactor and dehydrate at 55℃ / -0.096MPa for 0.5h, then add an appropriate amount of vi MM vi The catalyst prepared in the above examples or comparative examples was heated to 140°C with N2 and stirred for 50 min to polymerize. Then, fluorinated silicon-based phosphate ester (abbreviated as P-FSi) was added and stirred to neutralize for 0.5 h. Finally, the temperature was raised to 200°C / -0.096 MPa and maintained for 3 h to remove low-boiling substances. After cooling, the product was discharged to obtain colorless and transparent fluorosilicone raw rubber. The fluorinated silicon-based phosphate ester was prepared in-house, with a mass ratio of phosphoric acid:D3. F The product was obtained by polymerization at 1:70 at 130℃ for 3 hours, and the phosphoric acid content was determined to be 1.45%.
[0048] For effective comparison, in experiments 1-10 of Tables 2 and 3, fluorosilicone raw rubber was prepared by catalysis with an alkali content of 0.002 wt% in the reaction system, and the catalyst was prepared and used immediately. The feed amounts of each substance in experiments 1-10 are shown in Table 2.
[0049] Table 2. Feeding Table for the Preparation of Fluorosilicone Raw Rubber
[0050]
[0051] The molecular weight determination method for fluorosilicone raw rubber is as follows: Ubbelohde viscometer is used at a constant temperature of 30℃, with ethyl acetate as the solvent. The vinyl content determination method for fluorosilicone raw rubber is a modified iodometric method, using trifluorotrichloroethane-butyl acetate as the solvent system; the reaction mechanism is the same as that of the iodometric method.
[0052] Method for determining the molecular weight distribution of fluorosilicone raw rubber: A 1525 gel permeation chromatograph was used, with tetrahydrofuran as the mobile phase, a flow rate of 1.0 mL / min, a column temperature of 40 ℃, and a sample mass fraction of 0.3%.
[0053] Method for determining the volatile matter of fluorosilicone raw rubber: The volatile matter is determined by thermal loss method. Test conditions: 150℃, 3h.
[0054] The properties of the obtained fluorosilicone raw rubber are shown in Table 3.
[0055] Table 3 Performance of Fluorosilicone Raw Rubber
[0056]
[0057] As shown in Table 3, the molecular weight of the fluorosilicone raw rubber prepared using the catalyst obtained in Comparative Example 1 is lower than that prepared using the catalyst obtained in Example 1; the molecular weight of the fluorosilicone raw rubber prepared using the catalyst obtained in Comparative Example 2 is lower than that prepared using the catalyst obtained in Example 2; and the molecular weight of the fluorosilicone raw rubber prepared using the catalyst obtained in Comparative Example 3 is lower than that prepared using the catalyst obtained in Example 3. Furthermore, the fluorosilicone raw rubber prepared using the catalysts obtained in the comparative examples exhibits a wider molecular weight distribution, while the vinyl content and volatile matter content show little difference. The catalysts obtained in the comparative examples have poor uniformity and are not evenly dispersed in the reaction system, easily leading to excessively high local alkali concentrations, imbalances in mass and heat transfer, and difficulty in controlling the equilibrium reaction during polymerization, resulting in a decrease in the molecular weight and a wider molecular weight distribution of the raw rubber.
[0058] Finally, the method of this invention is merely a preferred embodiment and is not intended to limit the scope of protection of this invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.
Claims
1. A method for preparing a catalyst for synthesizing fluorosilicone raw rubber, characterized in that, Includes the following steps: Sodium hydroxide was added to an organic solvent and water and dissolved completely. Then 1,3,5-trimethyl-1,3,5-tris(3',3',3'-trifluoropropyl)cyclotrisiloxane was added. Under N2 protection, after removing the organic solvent and water, the reaction was carried out at 110-150°C for 2-4 hours. The organic solvent is ethanol; The mass ratio of sodium hydroxide, organic solvent, and water is 1:(5~25):(0.5~2.5). The mass ratio of sodium hydroxide to 1,3,5-trimethyl-1,3,5-tris(3',3',3'-trifluoropropyl)cyclotrisiloxane is 1:(30~250).
2. The preparation method according to claim 1, characterized in that, The mass ratio of sodium hydroxide to organic solvent and water is 1:(8~15):(0.8~1.5).
3. The preparation method according to claim 1 or 2, characterized in that, The mass ratio of sodium hydroxide to 1,3,5-trimethyl-1,3,5-tris(3',3',3'-trifluoropropyl)cyclotrisiloxane is 1:(50~125).
4. The application of the catalyst obtained by the preparation method according to any one of claims 1 to 3 in the synthesis of fluorosilicone raw rubber, characterized in that, The raw materials for the synthetic fluorosilicone raw rubber include 1,3,5-trimethyl-1,3,5-tris(3',3',3'-trifluoropropyl)cyclotrisiloxane, 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane and 1,1,3,3-tetramethyl-1,3-divinyldisiloxane.
5. The application according to claim 4, characterized in that, The amount of catalyst used is such that the alkali content in the catalytic reaction system is 0.001 wt% to 0.003 wt% of the total mass of the raw materials.