Synthesis method of 1, 3, 5-tri (trialkoxysilylpropyl) isocyanurate

Abstract

The invention discloses a synthesis method of 1, 3, 5-tri (trialkoxysilylpropyl) isocyanurate, and the 1, 3, 5-tri (trialkoxysilylpropyl) isocyanurate is obtained by reacting gamma-chloropropyl trialkoxysilane with isocyanuric acid in the presence of an acid-binding agent. The method is simple in process, convenient to operate, mild in reaction and suitable for industrial production.

Description

Technical Field

[0001] This invention relates to a method for synthesizing 1,3,5-tris(trialkoxysilylpropyl)isocyanurate, belonging to the field of organosilicon synthesis technology. Background Technology

[0002] Silane coupling agents, acting as molecular bridges connecting inorganic and organic materials, have wide applications in the automotive, aerospace, medical, construction, and electronics industries. For example, in the automotive tire industry, silica can be used as a reinforcing agent and filler for rubber. However, due to the significant differences in their physicochemical properties, silica exhibits poor dispersibility in rubber. The introduction of silane coupling agents effectively solves this problem, significantly improving the processing and performance of tires.

[0003] Most of the silane coupling agents used in tires are one or two ethoxy groups. When mixing rubber, the amount of silane coupling agent added to improve silica is usually 8 to 10% of the silica mass, which is a large amount.

[0004] 1,3,5-Tris(trialkoxysilylpropyl)isocyanurate contains three major alkoxy groups, which can improve the dispersibility of silica and is also highly compatible with resins. When used as a silane coupling agent, it requires a small amount and can also improve the thermal stability, oxidation resistance, and flame retardancy of rubber. Therefore, it is a promising silane coupling agent.

[0005] Currently, there are few reports on the preparation of 1,3,5-tris(trialkoxysilylpropyl)isocyanurate. CN105693758A discloses a method for synthesizing triisocyanurate silane. This method uses sodium cyanate and chloroalkylalkoxysilane as raw materials, and carries out a polycondensation reaction in the presence of a phase transfer catalyst and a polymerization accelerator. After the chloroalkylsilane is completely converted, the reaction solution is filtered to remove the generated sodium chloride salt, thus obtaining the triisocyanurate silane. In this method, sodium cyanate is insoluble in chloroalkylalkoxysilane, and the reaction is a liquid-solid reaction. However, the tetrabutylammonium bromide used in this patent is commonly used in liquid-liquid reactions, but its catalytic effect is not obvious, the reaction time is too long, and many side reactions are generated in the polymerization accelerator. CN108570069A discloses a method for preparing tris[3-(alkoxysilyl)propyl]isocyanurate, which involves hydrosilylating 1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H9-trione) with hydrogenated trialkoxysilane, hydrogenated alkyldialkoxysilane, and / or hydrogenated dialkylalkoxysilane in the presence of a Pt-catalyst, a carboxylic acid, and another co-catalyst. The Pt-catalyst used in this method is expensive, and the reaction involves numerous products and side reactions. The byproducts cannot be removed from the target product by distillation, resulting in high production costs. Summary of the Invention

[0006] The purpose of this invention is to provide a method for synthesizing 1,3,5-tris(trialkoxysilylpropyl)isocyanurate. This method is simple to operate, produces fewer by-products, and has a high product yield, showing great promise for industrial application.

[0007] The specific technical solution of this invention is as follows: A method for synthesizing 1,3,5-tris(trialkoxysilylpropyl)isocyanurate, which is obtained by reacting γ-chloropropyltrialkoxysilane and isocyanuric acid in the presence of an acid-binding agent.

[0008] Furthermore, the 1,3,5-tris(trialkoxysilylpropyl)isocyanurate includes 1,3,5-tris(trimethoxysilylpropyl)isocyanurate and 1,3,5-tris(triethoxysilylpropyl)isocyanurate. The corresponding γ-chloropropyltrialkoxysilane raw materials for each product are γ-chloropropyltrimethoxysilane and γ-chloropropyltriethoxysilane, respectively.

[0009] Furthermore, the acid-binding agent is triethylamine, dimethylaniline, or diethylaniline, etc., and triethylamine is preferred from a cost perspective.

[0010] Furthermore, the molar ratio of the acid-binding agent to isocyanuric acid is 3.2~3.3:1.

[0011] Furthermore, the molar ratio of γ-chloropropyltrialkoxysilane to isocyanuric acid is 1.02~1.05:1.

[0012] Furthermore, the reaction is carried out in a solvent, which serves as the reaction medium, and its amount can be adjusted as required. The solvent is at least one of dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone. Experiments have shown that isocyanuric acid reacts optimally in a mixture of dimethylformamide and dimethyl sulfoxide; therefore, a mixture of dimethylformamide and dimethyl sulfoxide is preferred as the solvent, with a preferred mass ratio of 3-5:1.

[0013] Furthermore, the reaction is carried out under a protective gas, such as nitrogen or argon.

[0014] Furthermore, the reaction is preferably carried out under a certain pressure, which is 0.4~0.5 MPa, provided by a protective gas.

[0015] Further, the preferred reaction steps are as follows: first, mix isocyanuric acid, solvent and half of the acid-binding agent, then add γ-chloropropyltrialkoxysilane and the other half of the acid-binding agent dropwise under controlled pressure and temperature under gas protection, ensuring that the acid-binding agent is added dropwise faster than γ-chloropropyltrialkoxysilane, and continue the reaction at the temperature after the γ-chloropropyltrialkoxysilane has been added.

[0016] Furthermore, the reaction temperature is 80-90℃, for example 80℃, 81℃, 82℃, 83℃, 84℃, 85℃, 86℃, 87℃, 88℃, 89℃, and 90℃.

[0017] Furthermore, the γ-chloropropyltrialkoxysilane is added dropwise over a period of 30-45 minutes, and the reaction is continued at a constant temperature for 3-4 hours after the addition is complete.

[0018] The present invention has the following beneficial effects: 1. The 1,3,5-tris(trialkoxysilylpropyl)isocyanurate of this invention contains three major alkoxy groups, which can react with the hydroxyl groups on silica. The isocyanurate groups are also highly compatible with most resins, making the silica more evenly dispersed on the tire tread. At the same time, the carbonyl groups in this product can also undergo addition reactions with resins and rubbers, improving the thermal stability, oxidation resistance, and flame retardancy of rubber.

[0019] 2. The 1,3,5-tris(trialkoxysilylpropyl)isocyanurate obtained by this invention can be added as a rubber additive to rubber compounds containing silica, with an addition amount of 4-7%. Compared with other existing silane coupling agents, the usage amount is reduced by about 1 / 3. Therefore, 1,3,5-tris(trialkoxysilylpropyl)isocyanurate has great application potential in the rubber field.

[0020] 2. This invention adopts a homogeneous method, which allows the raw materials to react in the same system. The preparation method is simple, convenient to operate, and environmentally friendly. The resulting product has a high yield and high purity, with a yield of over 98% and a purity of over 97%, which meets the requirements of industrial production.

[0021] 3. This invention adopts a homogeneous method, which allows the raw materials to be in the same system, reduces the use of catalysts, introduces acid-binding agents, and enables the reaction to proceed in the direction of the target product. In addition, it involves fewer types of raw materials with large differences in boiling points, and simplifies purification. Detailed Implementation

[0022] The present invention will be further described below with reference to specific embodiments, but the following embodiments are merely exemplary and do not limit its content.

[0023] In the following examples and comparative examples, the product yield w is calculated using the following formula: .

[0024] The purity of the product was determined by GC chromatography. The impurities were mainly γ-chloropropyltrialkoxysilane, solvent, and acid-binding agent.

[0025] Example 1 A method for synthesizing 1,3,5-tris(triethoxysilylpropyl)isocyanurate, the reaction formula is as follows: The steps are as follows: Add 308g of dimethylformamide and 77g of dimethyl sulfoxide to a 2000mL high-pressure reactor, then add 193.6g of isocyanuric acid, heat and stir, and control the system temperature at 40℃. After the solid is completely dissolved, add 246.5g of triethylamine, purge the air in the reactor with nitrogen to make the pressure in the reactor between 0.4 and 0.5MPa, and then add 372g of γ-chloropropyltriethoxysilane dropwise at 80-85℃ for 35min. While adding γ-chloropropyltriethoxysilane, add 246.5g of triethylamine dropwise, ensuring that it is added faster than the γ-chloropropyltriethoxysilane. The burette for triethylamine should be inserted below the liquid surface. After the reaction was completed under nitrogen protection, the mixture was kept at a constant temperature and stirred for 3 hours. After the reaction was completed, the pressure was released, and the triethylamine hydrochloride was removed by filtration. Then, the solvent was removed by vacuum distillation at 50-140℃ and -0.097MPa. During the distillation, the temperature was slowly increased and maintained at 130-140℃ for 30 minutes to obtain 911.7g of 1,3,5-tris(triethoxysilylpropyl)isocyanurate, which was a yellow transparent liquid with a yield of 98.7% based on isocyanuric acid, a product purity of 98.7%, and an impurity content of 0.9%, of which γ-chloropropyltriethoxysilane content was 0.3%.

[0026] Example 2 1,3,5-tris(triethoxysilylpropyl)isocyanurate was prepared according to the method in Example 1, except that "308g of dimethylformamide and 77g of dimethyl sulfoxide" were replaced with "385g of dimethyl sulfoxide". After removing the solvent by vacuum distillation, 870.1g of 1,3,5-tris(triethoxysilylpropyl)isocyanurate was finally obtained. The product was a yellow transparent liquid with a yield of 94.2% based on isocyanuric acid, a purity of 97.2%, and an impurity content of 1.9%, of which γ-chloropropyltriethoxysilane content was 0.9%.

[0027] Example 3 1,3,5-tris(triethoxysilylpropyl) isocyanurate was prepared according to the method in Example 1, except that "308g of dimethylformamide and 77g of dimethyl sulfoxide" were replaced with "404g of dimethylformamide". After removing the solvent by vacuum distillation, 874.2g of 1,3,5-tris(triethoxysilylpropyl) isocyanurate was finally obtained. The product was a yellow transparent liquid with a yield of 94.7% based on isocyanuric acid, a purity of 97.8%, and an impurity content of 1.5%, of which the content of γ-chloropropyltriethoxysilane was 0.74%.

[0028] Example 4 1,3,5-tris(triethoxysilylpropyl)isocyanurate was prepared according to the method in Example 1, except that 493g of triethylamine was replaced with 600g of dimethylaniline. A final yield of 910.8g of 1,3,5-tris(triethoxysilylpropyl)isocyanurate was obtained as a yellow transparent liquid with a yield of 98.6% based on isocyanuric acid, a product purity of 97.4%, and an impurity content of 1.2%, including 0.63% γ-chloropropyltriethoxysilane. Due to the higher price and lower economic viability of dimethylaniline, triethylamine was preferred.

[0029] Example 5 1,3,5-Tris(triethoxysilylpropyl)isocyanurate was prepared according to the method in Example 1, except that the addition of γ-chloropropyltriethoxysilane was performed dropwise and the reaction temperature was maintained at 90°C. 887.2 g of 1,3,5-tris(triethoxysilylpropyl)isocyanurate was finally obtained. It was a yellow, transparent liquid with a yield of 96.1% based on isocyanuric acid, a purity of 97.9%, and an impurity content of 1.7%, of which γ-chloropropyltriethoxysilane accounted for 0.73%.

[0030] Example 6 In a 2000 mL high-pressure reactor, 308 g of dimethylformamide and 77 g of dimethyl sulfoxide were added, followed by 193.6 g of isocyanuric acid. The mixture was heated and stirred, maintaining the temperature at 40 °C. After the solids were completely dissolved, 493 g of triethylamine was added in one go. Nitrogen gas was then introduced to purge the air from the reactor, bringing the pressure inside to between 0.4 and 0.5 MPa. Then, 372 g of γ-chloropropyltriethoxysilane was added dropwise at 80–85 °C over a period of 35 min. After the addition was complete under nitrogen protection, the mixture was kept at this temperature and stirred for 3 h. After the reaction was completed, the pressure was released, and the triethylamine hydrochloride was removed by filtration. Then, the solvent was removed by vacuum distillation at 50-140℃ and -0.097MPa. During the distillation, the temperature was slowly increased and maintained at 130-140℃ for 30 min to obtain 856.8 g of 1,3,5-tris(triethoxysilylpropyl)isocyanurate, which was a yellow transparent liquid with a yield of 92.8% based on isocyanuric acid, a product purity of 90.7%, and an impurity content of 8.3%, of which γ-chloropropyltriethoxysilane content was 6.4%.

[0031] Comparative Example 1 1,3,5-tris(triethoxysilylpropyl)isocyanurate was prepared according to the method of Example 1, except that the reaction was carried out under nitrogen protection at atmospheric pressure. The final product yield was 78.7% based on isocyanuric acid, and the impurity content in the product was 21.4%, of which γ-chloropropyltriethoxysilane content was 20.5%.

[0032] Comparative Example 2 1,3,5-Tris(triethoxysilylpropyl)isocyanurate was prepared according to the method of Example 1, except that the γ-chloropropyltriethoxysilane was added dropwise and the reaction temperature was maintained at 65°C. The final product yield was 85.3% based on isocyanuric acid, the product purity was 84.3%, the impurity content was 15.4%, and the γ-chloropropyltriethoxysilane content was 14.3%.

[0033] Comparative Example 3 1,3,5-tris(triethoxysilylpropyl)isocyanurate was prepared according to the method in Example 1, except that triethylamine was not added. Upon observation, after 3 hours of reaction, the product was a turbid liquid; further testing revealed that no product had formed.

[0034] Application examples The product 1,3,5-tris(triethoxysilylpropyl)isocyanurate obtained in Example 1 was compared with commonly available tetrasulfide and disulfide silanes. They were applied to tread rubber compounds, and the compound formulations are shown in Table 1 below: Table 1 The mixing, open milling, and vulcanization of the above-mentioned rubber compounds were all carried out in accordance with GB / T 6038-2006. First stage of intensive mixing: Put the weighed rubber compound into the intensive mixer, mix at 40 r / min for 60 s, then lift the top plug for 10 s and add the silane coupling agent, silica, carbon black and remaining small ingredients from the formula. Mix at 40 r / min for 60 s, then lift the top plug for 10 s to clean. Finally, mix at 40 r / min for 50 s, then lift the middle plug twice for 10 s to turn the rubber. The discharge temperature is about 149℃.

[0035] Two-stage open mill: Adjust the roller gap of the open mill so that there is an appropriate amount of accumulated rubber above the open mill, then roll and mix for about 1 minute. Add accelerator and sulfur. After the material is fully absorbed, cut the left and right sides three times and then produce sheets. Adjust the roller gap of the open mill to the appropriate level, make 3 triangular wraps and 5 rolls, then adjust the roller gap and produce sheets for testing.

[0036] The performance test results of the obtained rubber compounds are shown in Table 2 below: Table 2 All properties in Table 2 are based on 100% of the properties in Example 1. The thermal stability of the rubber compound was characterized by the heat generated during compression; a higher value indicates less heat generation and better thermal stability. The thermal stability and oxidation resistance of the rubber compound were characterized by the tensile properties after heat and oxidation; a higher value indicates better thermal stability and oxidation resistance. The dispersion performance of silica was characterized by the RPA test simulating the Payne effect; a higher value indicates a smaller ΔG' and better silica dispersion. The flame retardant properties of the rubber composition were characterized by GB / T 2408; a higher value indicates better flame retardancy.

[0037] The vulcanization characteristics at 151℃ were tested according to GB / T 16584-1996, tensile strength, stress at a given elongation, and elongation at break were tested according to GB / T 528-2009, flame retardancy was tested according to the testing standard GB / T 2408, compression heat generation was tested using a rubber dynamic viscoelasticity analyzer, and Payne effect was tested using an RPA tester.

[0038] The performance tests and comparisons of the rubber compounds show that the silane coupling agent prepared using this invention has a better dispersion effect on silica, and the dosage is less, reducing costs. The rubber compounds obtained using the silane coupling agent of this invention have more obvious advantages, and can improve the stability, oxidation resistance, and flame retardancy of tire tread compounds.

Claims

1. A method for synthesizing 1,3,5-tris(trialkoxysilylpropyl)isocyanurate, characterized in that: It is obtained by reacting γ-chloropropyltrialkoxysilane and isocyanuric acid in the presence of an acid-binding agent.

2. The synthesis method according to claim 1, characterized in that: The γ-chloropropyltrialkoxysilane is γ-chloropropyltrimethoxysilane or γ-chloropropyltriethoxysilane; preferably, the acid-binding agent is triethylamine, dimethylaniline or diethylaniline.

3. The synthesis method according to claim 1, characterized in that: The molar ratio of γ-chloropropyltrialkoxysilane to isocyanuric acid is 1.02~1.05:

1.

4. The synthesis method according to claim 1, characterized in that: The molar ratio of the acid-binding agent to isocyanuric acid is 3.2~3.3:

1.

5. The synthesis method according to any one of claims 1-4, characterized in that: The reaction takes place in a solvent.

6. The synthesis method according to claim 5, characterized in that: The solvent is at least one of dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone, preferably a mixture of dimethylformamide and dimethyl sulfoxide.

7. The synthesis method according to claim 5 or 6, characterized in that: First, mix isocyanuric acid, solvent, and half of the acid-binding agent. Then, under gas protection, control the pressure and temperature to add γ-chloropropyltrialkoxysilane and the other half of the acid-binding agent dropwise, ensuring that the acid-binding agent is added faster than γ-chloropropyltrialkoxysilane. After the γ-chloropropyltrialkoxysilane is added, continue to keep the reaction at the temperature.

8. The synthesis method according to claim 1 or 7, characterized in that: The reaction is carried out under gas protection; the reaction pressure is 0.4~0.5MPa.

9. The synthesis method according to claim 1 or 7, characterized in that: The reaction temperature is 80-90℃.

10. The synthesis method according to claim 7, characterized in that: The addition time for γ-chloropropyltrialkoxysilane is 30-45 min, and the reaction is continued at the temperature for 3-4 h after the addition is complete.

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