Preparation method of vinyl tri (2-methoxyethoxy) silane

Abstract

The invention discloses a preparation method of vinyltris (2-methoxyethoxy) silane, which can effectively reduce the accumulation of hydrogen chloride by adding an amino-modified ceramic filler into a reactor, and avoid the generation of polysilane by chain reaction due to the existence of a large amount of hydrogen chloride, thereby enhancing the conversion rate of esterification reaction. And a new path is provided for industrially improving the product competitiveness.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of vinyl silane coupling agent synthesis, in particular to a preparation method of vinyl tris (2-methoxyethoxy) silane. BACKGROUND

[0002] Vinyl tris (2-methoxyethoxy) silane (abbreviated as A-172) is a bifunctional silane coupling agent containing vinyl and ether type alkoxy groups, and the molecular formula is C 11 H 24 O6Si. In the structure, the vinyl group provides an unsaturated bond to participate in organic polymerization such as free radical copolymerization, and the 2-methoxyethoxy group has hydrolytic activity and can form a Si-O-M covalent bond with inorganic glass fibers, metal oxide fillers and other materials, thereby bridging the organic-inorganic interface. The compound has hydrophilicity and solubility due to the introduction of ether bonds, significantly improves the surface coating efficiency of inorganic powders, and becomes a key additive for modifying composite materials.

[0003] Vinyl tris (2-methoxyethoxy) silane can not only be used as an interfacial modifier for glass fiber reinforced resins to improve the wet strength of epoxy resin composites, but also can improve the dispersibility of white carbon black fillers in the rubber industry and reduce the viscosity of the rubber compound. In recent years, it has also been applied in some emerging fields such as photovoltaic products and electronic packaging to make solar cell backsheet coatings resistant to heat and aging, as an additive for waterproof and anti-pollution functional textiles, or as a flame-retardant filler modifier for flammable polymer products.

[0004] In the 1960s, Dow Corning, Wacker and other companies in the United States and Germany developed vinyl silane coupling agents for the first time. In the early stage, direct esterification of vinyl trichlorosilane was mainly used, but due to strong corrosion and side reaction problems, it was gradually replaced by ester exchange process. After 2000, through the optimization of complex salt catalyst ester exchange method by the Institute of Chemistry of the Chinese Academy of Sciences, Zhejiang Xin'an Chemical and other institutions, high-purity (>99%) ViSi (OCH2CH2OCH3) 3 was realized, which promoted its application in high-end fields such as cable insulation layer and solar packaging film.

[0005] There are two routes for the traditional synthesis process of vinyl tris (2-methoxyethoxy) silane. The first is to carry out ester exchange reaction of vinyl trimethoxysilane and ethylene glycol monomethyl ether at about 100 DEG C to produce vinyl tris (2-methoxyethoxy) silane and by-product methanol; the second is to first react vinyl trichlorosilane with methanol at 80 DEG C to produce vinyl trimethoxysilane, and then carry out ester exchange with ethylene glycol monomethyl ether at about 100 DEG C.

[0006] The problem of the ester exchange method is that it is difficult to produce in large quantities, and the intermittent ester exchange operation mode leads to low production efficiency and cannot meet the demand for large-scale continuous production. However, if a continuous reactor is used, the catalyst suspension system is easy to block the pipeline, increasing the equipment maintenance requirements. The catalyst separation of this method is difficult, and the product is easy to be contaminated. The traditional process uses strong alkali such as sodium hydroxide as catalyst, and after reaction, neutralization treatment is needed, which is difficult to reduce the purity of the product, and the catalyst cannot be recovered, increasing the cost of waste liquid treatment and catalyst consumption; if a strong acid catalyst such as p-toluenesulfonic acid is used, it is easy to cause the polymerization side reaction of olefinic bond, which leads to the deepening of product color and yellowing, and additional purification operation is needed, further increasing the energy consumption. Another problem is that the ester exchange reaction is a reversible reaction based on esterification mechanism, and the presence of by-product methanol will reduce the conversion efficiency, and methanol needs to be removed or excess ethylene glycol monomethyl ether raw material needs to be added to promote the high-yield forward reaction, increasing the equipment cost or raw material cost.

[0007] The problem of the two-step esterification method is that hydrogen chloride gas is generated in the alcoholysis stage, which may cause corrosion to the equipment, and the residual hydrogen chloride is easy to cause the hydrolysis and condensation of the intermediate vinyltrimethoxysilane, generating by-products such as D3 and D4, reducing the yield of the intermediate produced by alcoholysis; and the trace Si-H impurities such as hydrogen-containing trimethoxysilane contained in the raw material vinyltrichlorosilane may cause skinning during storage, blocking the pipeline and affecting the downstream customer products, which need to be treated by additional rectification or using the commonly used alkali metal alcoholate treatment agent to eliminate impurities, further increasing the reaction steps and cost. And both steps of the reaction need to be purified by distillation independently, and the intermediate is obtained by distillation after neutralization and layering after alcoholysis; the final product is obtained by secondary distillation after ester exchange. The multi-step operation leads to further reduction of the total yield and further increase of the energy consumption, and the mixture of by-product methanol, reactant ethylene glycol monomethyl ether and hydrogen chloride is easy to generate various chlorinated compounds, which need to be set up additional separation facilities, otherwise the VOC emission will exceed the standard.

[0008] Patent CN106349276A reports a method for preparing vinyltri(2-methoxyethoxy)silane by ester exchange method. The method adds anhydrous aluminum potassium sulfate as catalyst to catalyze and promote the ester exchange reaction of ethylene glycol monomethyl ether and vinyltrimethoxysilane at 70-80°C, and after 2h reaction, the methanol is removed by heating, and then the anhydrous aluminum potassium sulfate is recovered by cooling. This method solves the problem of catalyst recovery by selecting a new catalyst, and to some extent, reduces the cost consumption.

[0009] Patent document CN115317941A reports a process method for preparing vinyltri(2-methoxyethoxy)silane by setting a catalytic tower and a rectifying tower for ester exchange reaction, by setting a catalytic rectifying filler tower, filling solid alkali catalyst K2CO3 / Al2O3, and inputting materials at a raw material ratio of about 3.5:1, and carrying out ester exchange reaction at about 100℃. The advantage is that the purity of the product in the rectifying tower kettle is high, but the yield still needs to be improved.

[0010] Mamehong, Wang Yugang, Tan Jun, et al. (2011) "Synthesis process of vinyltri(β-methoxyethoxy)silane" reports a two-step preparation process, which is carried out by adding vinyltrichlorosilane to the upper part and introducing methanol into the lower part of a continuous tower type device for alcoholysis reaction. After neutralization with sodium methoxide solution, vinyltrimethoxysilane is obtained by filtration and distillation, and then vinyltri(2-methoxyethoxy)silane is obtained by adding ethylene glycol monomethyl ether and self-made catalyst at one time. Although this method has mild process conditions and good product properties, the reaction time is too long, the process is complex, and the problem of supplementing excess ethylene glycol monomethyl ether raw material in the ester exchange process has not been solved.

[0011] Therefore, it is necessary to propose a preparation method of vinyltri(2-methoxyethoxy)silane to solve the problem of low selectivity of esterification reaction and improve the conversion rate of product. SUMMARY

[0012] The present application provides a preparation method of vinyltri(2-methoxyethoxy)silane to improve the conversion rate of esterification reaction.

[0013] In view of this, the scheme of the present application is: A preparation method of vinyltri(2-methoxyethoxy)silane, wherein vinyltrichlorosilane is fed into a reactor provided with a condensing exhaust outlet, heated to a temperature above its vaporization and provided with reflux, ethylene glycol monomethyl ether is added dropwise into the reactor and fully reacted to obtain vinyltri(2-methoxyethoxy)silane; the reactor is filled with amino-modified filler, which is prepared by modifying ceramic filler with amino silane coupling agent.

[0014] Further, the amino silane coupling agent is selected from one or more of γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-n-butyl-3-aminopropyltrimethoxysilane, N-n-butyl-3-aminopropyltriethoxysilane, and N-(2-aminoethyl)-3-aminoisobutylmethyldimethoxysilane.

[0015] Further, the preparation method of the amino-modified filler is as follows: the ceramic filler is placed in an amino-based silane coupling agent solution, reacted at 35-75 DEG C for 1-3 hours, then separated, and the separated ceramic filler is solidified at 80-110 DEG C for 3-6 hours to obtain the amino-modified filler.

[0016] Preferably, the ceramic filler is pretreated before the reaction, including surface drying and acid pickling to remove metal impurities; and the ceramic filler is spherical or cylindrical.

[0017] Preferably, the concentration of the amino-based silane coupling agent solution is 0.75-4 wt%.

[0018] Preferably, the amino loading of the amino-modified filler is 0.7-1.2 mmol / g.

[0019] Further, the use amount ratio of the amino-modified filler to vinyltrichlorosilane is (50-100) g: 1 mol.

[0020] Further, the molar ratio of the vinyltrichlorosilane to ethylene glycol monomethyl ether is 1: (3-3.3).

[0021] Further, the heating temperature is 100-140 DEG C, and the reaction time is 0.5-2 hours.

[0022] Further, the method further comprises a step of post-treating the reaction product, and the target boiling range fraction of the vinyltris (2-methoxyethoxy) silane product is obtained by distillation.

[0023] Compared with the prior art, the present application has the following beneficial effects: The preparation method provided by the present application can effectively reduce the accumulation of hydrogen chloride, avoid the generation of polysilane caused by the existence of a large amount of hydrogen chloride, thereby improving the conversion rate of esterification reaction, and providing a new path for industrialization to improve product competitiveness. DETAILED DESCRIPTION

[0024] The technical solutions of the present application will be described clearly and completely below in combination with preferred embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0025] Vinyltris (2-methoxyethoxy) silane is usually prepared by esterification reaction of vinyltrichlorosilane and ethylene glycol monomethyl ether, and the specific reaction is as follows:

[0026] The above reaction route has the following defects: the alcoholysis rate of organohalosilane is different with the structure of alcohol and the change of hydrocarbon group on silicon atom. Generally, with the complication of alcohol structure, the steric hindrance gradually increases, resulting in the decrease of alcoholysis rate. Ethylene glycol monomethyl ether, as a high-level alcohol with large steric hindrance, has a poor conversion rate when directly alcoholized with chlorosilane. Further, due to the slow reaction conversion rate, a large amount of hydrogen chloride generated in the main reaction may react with ethylene glycol monomethyl ether at high temperature to generate chloroethyl methyl ether and water, and the water will preferentially and rapidly react with vinyltrichlorosilane to generate polysiloxane. This is one of the important problems in the preparation of vinyltris(2-methoxyethoxy)silane product.

[0027] To solve the above problems, the embodiment provides a preparation method of vinyltris(2-methoxyethoxy)silane. Modified amino filler is filled in the reactor, a condensation system and a gas discharge port are arranged, a metered vinyltrichlorosilane is put into the reactor, heating is carried out at 100-140°C, the temperature of the condensation outlet inside the reactor is controlled to be between 50-75°C, to ensure that hydrogen chloride can be smoothly discharged from the system, the vinyltrichlorosilane is vaporized and refluxed in the reactor at this temperature, then ethylene glycol monomethyl ether is added dropwise, the dropwise adding speed is controlled to ensure sufficient gas-liquid contact and avoid liquid overflow or local overheating, after the dropwise adding is completed, reaction is carried out, the overall reaction time is controlled to be 0.5-2h, and when the material in the flask no longer boils, the reaction is stopped. At this time, the reaction bottle contains crude vinyltris(2-methoxyethoxy)silane. Then, negative pressure distillation is carried out, residual hydrogen chloride and a small amount of low-boiling substances are first extracted, then vacuum distillation is continued, and the target fraction (such as boiling range 142°C / 10mmHg) is collected, to obtain the vinyltris(2-methoxyethoxy)silane product.

[0028] In the above embodiment, by adding the amino-modified ceramic filler in the reactor, the accumulation of hydrogen chloride can be effectively reduced, and the chain reaction to generate polysilane caused by the large amount of hydrogen chloride can be avoided, thereby improving the esterification reaction conversion rate. In some specific embodiments, the reaction conversion rate is above 84% based on vinyltrichlorosilane, and the purity is above 99%.

[0029] In the above embodiment, part of the hydrogen chloride produced in the reaction process is discharged through the condensation outlet, and the other part is converted into ammonium salt, so that the amount of hydrogen chloride gas participating in the reaction system is greatly reduced. The reaction temperature is set to be above the boiling point of vinyltrichlorosilane and below the boiling point of the product, such as 100-140°C. The esterification reaction generates the product in the process of vaporization and reflux counter-mass transfer. As the reaction proceeds, the reflux amount gradually decreases. Under the premise of the theoretical molar ratio of the raw material, when there is little or no reflux in the reactor, it indicates that the raw material has undergone sufficient esterification reaction.

[0030] In a preferred embodiment, the method for preparing the amino-modified filler is as follows: the ceramic filler is placed in an excess of 0.75-4 wt% amino silane coupling agent solution, reacted at 35-75°C for 1-3 h, then separated, and the separated ceramic filler is solidified at 80-110°C for 3-6 h to obtain the amino-modified filler. Through this method, the amino loading can reach 1.2 mmol / g, the bonding is firm, and the chemical stability is good. The amino loading can be controlled by controlling parameters such as reaction time.

[0031] In a preferred embodiment, the amino silane coupling agent is selected from one or more of γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-n-butyl-3-aminopropyltrimethoxysilane, N-n-butyl-3-aminopropyltriethoxysilane, and N-(2-aminoethyl)-3-aminoisobutylmethyldimethoxysilane, and more preferably γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, and N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane.

[0032] In a preferred embodiment, the ceramic filler is spherical or cylindrical, preferably spherical, with a diameter of 5-20 mm. The amount of the amino-modified filler used is (50-100) g: 1 mol of vinyltrichlorosilane. By controlling the amount of the amino-modified filler added, the supply of amino groups that can react with hydrogen chloride is ensured, and hydrogen chloride is eliminated in a timely manner.

[0033] Preparation Example 1

[0034] 1) The spherical ceramic filler (5 mm in diameter) was dried at 125°C for 4 h, and a 5% dilute hydrochloric acid solution was prepared in a 500 mL beaker that was dried and purged with nitrogen. Then the dried long cylindrical ceramic filler particles were soaked in the dilute hydrochloric acid solution, soaked for 1 h, and then washed with pure water until neutral.

[0035] 2) A certain amount of γ-aminopropyltriethoxysilane was taken and prepared into a 3 wt% solution. The washed filler was quickly immersed in the silane solution, heated to 60°C, stirred and reacted for 2 h. The treated filler was then centrifuged and solidified at 100°C for 6 h to form a stable surface-grafted amine group structure. The amino loading was measured to be 1.2 mmol / g.

[0036] Preparation Example 2

[0037] 1) Dry the spherical ceramic packing (5 mm in diameter) at 125 °C for 4 h, and prepare a 5% dilute hydrochloric acid solution in a 500 mL beaker that has been dried and purged with nitrogen. Then immerse the dried cylindrical ceramic packing particles in the dilute hydrochloric acid solution for 1 h, and rinse the packing with pure water until it is neutral.

[0038] 2) Take a certain amount of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane and prepare a 4wt% solution. Quickly immerse the rinsed filler in the silane solution, heat to 70℃, stir and react for 1.5h. Then centrifuge the treated filler and cure it at 100℃ for 6h to form a stable filler with a surface-grafted amine structure. The amino loading was measured to be 1.1mmol / g.

[0039] Preparation Example 3

[0040] 1) Dry the spherical ceramic packing (5 mm in diameter) at 125 °C for 4 h, and prepare a 5% dilute hydrochloric acid solution in a 500 mL beaker that has been dried and purged with nitrogen. Then immerse the dried cylindrical ceramic packing particles in the dilute hydrochloric acid solution for 1 h, and rinse the packing with pure water until it is neutral.

[0041] 2) Take a certain amount of N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane and prepare a 1wt% solution. Quickly immerse the rinsed filler in the silane solution, heat to 65℃, stir and react for 2h. Then centrifuge the treated filler and cure it at 100℃ for 6h to form a stable filler with a surface-grafted amine structure. The amino loading was measured to be 0.8mmol / g.

[0042] Example 1

[0043] A 500 mL single-necked flask, dried and purged with nitrogen, was filled with 48 g of the packing material prepared in Preparation Example 1. 129.2 g (0.8 mol) of vinyltrichlorosilane was added, the temperature was raised and controlled at 100 °C, and a reflux condenser was set up with a condenser outlet temperature of 55 °C. 187.6 g (2.44 mol) of ethylene glycol monomethyl ether was weighed and added dropwise over 35 min. Hydrogen chloride was discharged from the condenser outlet into a collecting flask. The reaction was stopped 1 h after the addition of ethylene glycol monomethyl ether, when no further reflux occurred in the system. A small amount of low-boiling-point substances were removed by vacuum distillation, and the fraction was collected to obtain 188.5 g (0.672 mol, yield 84.0%, purity 99.1%) of vinyltris(2-methoxyethoxy)silane.

[0044] Example 2

[0045] A 500 mL single-necked flask, dried and purged with nitrogen, was filled with 50 g of the packing material prepared in Preparation Example 2. 129.2 g (0.8 mol) of vinyltrichlorosilane was added, the temperature was raised and controlled at 120 °C, and a reflux condenser was set up with a condenser outlet temperature of 65 °C. 196.8 g (2.56 mol) of ethylene glycol monomethyl ether was weighed and added dropwise over 40 min. Hydrogen chloride was discharged from the condenser outlet into a collection flask. One hour after the addition of ethylene glycol monomethyl ether was completed, the reaction was stopped. A small amount of low-boiling substances was removed by vacuum distillation, yielding 188.3 g (0.672 mol, yield 83.9%, purity 99.4%) of vinyltris(2-methoxyethoxy)silane.

[0046] Example 3

[0047] A 500 mL single-necked flask, dried and purged with nitrogen, was filled with 72 g of the packing material prepared in Preparation Example 3. 129.2 g (0.8 mol) of vinyltrichlorosilane was added, the temperature was raised and controlled at 110 °C, and a reflux condenser was set up with a condenser outlet temperature of 60 °C. 202.93 g (2.67 mol) of ethylene glycol monomethyl ether was weighed and added dropwise over 1 hour. Hydrogen chloride was discharged from the condenser outlet into a collection flask. One hour after the addition of ethylene glycol monomethyl ether, the reaction was stopped. A small amount of low-boiling substances was removed under negative pressure, and the mixture was distilled under reduced pressure to obtain 188.8 g (0.673 mol, yield 84.1%, purity 99.5%) of vinyltris(2-methoxyethoxy)silane.

[0048] Comparative Example 1

[0049] In Example 3, 72 g of ungrafted packing material (not grafted in step 2) was added to a dry, nitrogen-purged 500 mL single-necked flask. 129.2 g (0.8 mol) of vinyltrichlorosilane was added, and the mixture was heated to 100 °C for vaporization. The vaporization was then passed through a condenser system, with the condenser outlet temperature at 60 °C. 202.93 g (2.67 mol) of ethylene glycol monomethyl ether was weighed and added dropwise over 1 hour. Hydrogen chloride was discharged from the condenser system opening into a collection flask. One hour after the addition of ethylene glycol monomethyl ether, the reaction was stopped. A small amount of low-boiling material was removed under negative pressure, and the mixture was distilled under reduced pressure to obtain 167.3 g (0.597 mol, yield 74.6%, purity 92.3%) of vinyltris(2-methoxyethoxy)silane.

[0050] It is evident from Examples 1-3 above that the esterification reaction yield can reach 84% after adding amino-modified filler, which is significantly higher than that of Comparative Example 1 without modified filler. This indicates that amino-modified filler has a significant effect on reducing hydrogen chloride accumulation and preventing the raw materials from being converted into impurities.

[0051] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing vinyltris(2-methoxyethoxy)silane, characterized in that, Vinyltrichlorosilane is fed into a reactor equipped with a condenser exhaust outlet, heated to a temperature above its vaporization temperature and reflux is set. Ethylene glycol monomethyl ether is added dropwise to the reactor and reacted completely to obtain vinyltris(2-methoxyethoxy)silane. The reactor is filled with amino-modified packing material, which is prepared by modifying ceramic packing material with an aminosilane coupling agent.

2. The preparation method according to claim 1, characterized in that, The aminosilane coupling agent is selected from one or more of γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, 3-ureapropyltrimethoxysilane, 3-ureapropyltriethoxysilane, N-n-butyl-3-aminopropyltrimethoxysilane, N-n-butyl-3-aminopropyltriethoxysilane, and N-(2-aminoethyl)-3-aminoisobutylmethyldimethoxysilane.

3. The preparation method according to claim 1, characterized in that, The preparation method of the amino-modified filler is as follows: place the ceramic filler in an amino-based silane coupling agent solution, react at 35~75℃ for 1-3 hours, and then separate it. After separation, the ceramic filler is cured at 80~110℃ for 3-6 hours to obtain the amino-modified filler.

4. The preparation method according to claim 3, characterized in that, The ceramic filler is pretreated before the reaction, including surface drying and acid washing to remove metal impurities; And / or, the ceramic filler is spherical or cylindrical.

5. The preparation method according to claim 3, characterized in that, The concentration of the amino-based silane coupling agent solution is 0.75~4wt%.

6. The preparation method according to claim 3, characterized in that, The amino loading of the amino-modified filler is 0.7~1.2 mmol / g.

7. The preparation method according to claim 1, characterized in that, The ratio of the amino-modified filler to vinyltrichlorosilane is (50~100) g: 1 mol.

8. The preparation method according to claim 1, characterized in that, The molar ratio of vinyltrichlorosilane to ethylene glycol monomethyl ether is 1:(3~3.3).

9. The preparation method according to claim 1, characterized in that, The heating temperature is 100~140℃, and the reaction time is 0.5~2h.

10. The preparation method according to claim 1, characterized in that, It also includes a step of post-processing the reaction product, in which the target boiling range fraction is collected by distillation to obtain the vinyltris(2-methoxyethoxy)silane product.

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