Method for modifying 1, 2-bis (trimethoxysilyl) ethane and application of 1, 2-bis (trimethoxysilyl) ethane

Abstract

The invention relates to the technical field of vinyltrimethoxysilane by-products, in particular to a method for modifying 1, 2-bis (trimethoxysilyl) ethane and application of the 1, 2-bis (trimethoxysilyl) ethane. The method comprises the following steps: dehydrating a vinyltrimethoxysilane by-product 1, 2-bis (trimethoxysilyl) ethane through a molecular sieve, mixing the vinyltrimethoxysilane by-product 1, 2-bis (trimethoxysilyl) ethane with acetoxysilane, and discharging water through the molecular sieve. Compared with 1, 2-bis (trimethoxysilyl) ethane, the obtained modified product is higher in hydrolysis speed, lower in acid value and longer in preservation time, so that the modified product can be better applied to the fields of buildings, sealants and the like, and due to the low acid value, the modified product is expected to be expanded to the fields with higher requirements, such as metals, electronic materials and the like.

Description

Technical Field

[0001] This invention relates to the technical field of vinyltrimethoxysilane byproducts, and more specifically to a method for modifying 1,2-bistrimethoxysilylethane and its application. Background Technology

[0002] The formation of 1,2-bistrimethoxysilylethane as a byproduct in the industrial preparation of vinyltrimethoxysilane has long been a technical problem. The formation of this byproduct is closely related to the pathway control of the silanization reaction in the vinyltrimethoxysilane synthesis process. Current technologies mainly suppress its formation by optimizing the catalyst system or reaction conditions, but this is difficult to completely avoid. However, 1,2-bistrimethoxysilylethane is difficult to hydrolyze due to steric hindrance, electronic effects, the inertness of substituents, and product stability, thus affecting its resource utilization. Acetic acid is typically added during hydrolysis to accelerate it, but this results in an acidic post-hydrolysis product, hindering its application in the metal and electronics industries. Therefore, solving the hydrolysis rate problem without affecting the acid value can effectively improve its economic value. Summary of the Invention

[0003] This invention discloses a method for modifying 1,2-bistrimethoxysilyl ethane and its application. This method not only solves the problem of byproducts in the preparation of vinyltrimethoxysilane, but also accelerates the hydrolysis rate of these byproducts, lowers their acid value, and extends their shelf life. This makes it more suitable as a bifunctional silane coupling agent for applications in material interface modification, composite material preparation, coating function optimization, and other fields.

[0004] According to a first aspect of the present invention, a method for modifying 1,2-bis(trimethoxysilyl)ethane is provided, characterized in that the 1,2-bis(trimethoxysilyl)ethane is a byproduct of the preparation of vinyltrimethoxysilane, and the method comprises:

[0005] The 1,2-bistrimethoxysilyl ethane was subjected to a first dehydration process.

[0006] The 1,2-bis(trimethoxysilyl)ethane that has undergone the first dehydration is mixed with acetoxysilane, the acid value is adjusted to <0.1, and the temperature is controlled at 50-60℃;

[0007] The mixture obtained by mixing with acetoxysilane is subjected to a second dehydration.

[0008] In some embodiments, the first water removal includes the step of mixing 1,2-bis(trimethoxysilyl)ethane with a water removal molecular sieve.

[0009] In some embodiments, after the first water removal, the moisture content in the 1,2-bistrimethoxysilyl ethane is controlled to be below 200 ppm.

[0010] In some embodiments, the acetoxysilane is selected from at least one of methyltriacetoxysilane, ethyltriacetoxysilane, propyltriacetoxysilane, tetraacetoxysilane, and dimethyldiacetoxysilane.

[0011] In some embodiments, the molar ratio of the acetoxysilane to the 1,2-bis(trimethoxysilyl)ethane is 1:40000-60000.

[0012] In some embodiments, the second dewatering includes the step of mixing a mixture obtained by mixing with acetoxysilane with a dewatering molecular sieve.

[0013] In some embodiments, the moisture content in the product obtained by the second dehydration is controlled to be below 200 ppm.

[0014] In some embodiments, the water-removing molecular sieve is selected from at least one of 3A molecular sieve, 4A molecular sieve, 5A molecular sieve, and 13A molecular sieve.

[0015] According to a first aspect of the present invention, the 1,2-bistrimethoxysilyl ethane prepared by the method of the first aspect is provided as a bifunctional silane coupling agent.

[0016] This invention creatively modifies 1,2-bis(trimethoxysilyl)ethane using acetoxysilane. Introducing the acetoxy group accelerates hydrolysis and lowers the acid value. In contrast, existing technologies primarily use acetoxysilane as a crosslinking agent or synthetic raw material (e.g., patent CN102321114A for the preparation of methyltriacetoxysilane), without modifying byproducts. Furthermore, the modified 1,2-bis(trimethoxysilyl)ethane exhibits faster hydrolysis, lower acid value, and longer shelf life, making it more suitable as a bifunctional silane coupling agent for applications in material interface modification, composite material preparation, and coating function optimization.

[0017] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. In the drawings:

[0019] Figure 1 The infrared spectrum of unmodified 1,2-bistrimethoxysilylethane is shown.

[0020] Figure 2 The infrared spectrum of 1,2-bistrimethoxysilylethane modified in Comparative Example 1 is shown.

[0021] Figure 3 The infrared spectrum of 1,2-bistrimethoxysilyl ethane modified in Example 1 is shown. Detailed Implementation

[0022] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application. The reagents used in the embodiments are all commercially available and legally purchasable.

[0023] Example 1

[0024] Add 1 kg of 1,2-bis(trimethoxysilyl)ethane to a 2 L three-necked flask, then add 50 g of 3A molecular sieve in batches, mixing thoroughly with magnetic stirring. Measure the moisture content. Repeat this process until the moisture content is below 200 ppm, then filter. Pour the filtrate into a 2 L round-bottom flask, add 16 g of methyltriacetoxysilane, seal the flask, and turn on magnetic stirring and heating to 50-60 °C for 15 min. After cooling to room temperature, take a sample and measure the acid value; it should be 0.0810. Add 50 g of 3A molecular sieve in batches, mixing thoroughly with magnetic stirring. Measure the moisture content. Repeat this process until the moisture content is below 200 ppm, then filter to obtain modified 1,2-bis(trimethoxysilyl)ethane A.

[0025] Example 2

[0026] 1 kg of 1,2-bis(trimethoxysilyl)ethane was added to a 2 L three-necked flask, followed by the addition of 50 g of 3A molecular sieve in batches. The mixture was thoroughly stirred with magnetic stirring, and the moisture content was measured. This process was repeated until the moisture content was below 200 ppm, then filtered. The filtrate was poured into a 2 L round-bottom flask, 17 g of ethyltriacetoxysilane was added, the flask was sealed, and magnetic stirring was started. The temperature was raised to 50-60 °C and maintained for 15 min. After cooling to room temperature, a sample was taken, and the acid value was measured to be 0.0789. 50 g of 3A molecular sieve was added in batches, and the mixture was thoroughly stirred with magnetic stirring. The moisture content was measured, and this process was repeated until the moisture content was below 200 ppm, then filtered to obtain modified 1,2-bis(trimethoxysilyl)ethane B.

[0027] Example 3

[0028] 1 kg of 1,2-bis(trimethoxysilyl)ethane was added to a 2 L three-necked flask, followed by the addition of 50 g of 3A molecular sieve in batches. The mixture was thoroughly stirred with magnetic stirring, and the moisture content was measured. This process was repeated until the moisture content was below 200 ppm, then filtered. The filtrate was poured into a 2 L round-bottom flask, 18 g of propyltriacetoxysilane was added, and the flask was sealed. Magnetic stirring was then turned on, and the temperature was raised to 50-60 °C and maintained for 15 min. After cooling to room temperature, a sample was taken, and the acid value was measured to be 0.0854. 50 g of 13A molecular sieve was added in batches, and the mixture was thoroughly stirred with magnetic stirring. The moisture content was measured, and this process was repeated until the moisture content was below 200 ppm, then filtered to obtain the modified 1,2-bis(trimethoxysilyl)ethane C.

[0029] Comparative Example 1

[0030] The procedure was the same as in Example 1, except that 16g of methyltriacetoxysilane was replaced with 5g of acetic acid, and the modified 1,2-bistrimethoxysilylethane D was finally obtained.

[0031] Comparative Example 2

[0032] The procedure was the same as in Example 1, and the water content of 1,2-bis(trimethoxyethane) was measured to be 2000 ppm, thus omitting the dehydration step. Modified 1,2-bis(trimethoxyethane) E was obtained.

[0033] Hydrolysis time test

[0034] Take 5g of each of the modified 1,2-bistrimethoxysilyl ethane and unmodified 1,2-bistrimethoxysilyl ethane samples prepared in Examples 1-3 and Comparative Example 1, and mix them with 95g of water in a beaker. Immediately turn on the magnetic stirrer at a stirring speed of 700 rpm, observe the state of the mixture, and record the clarification time. A clarification time of less than 5 minutes is optimal.

[0035] Acid value test after hydrolysis

[0036] The test method refers to GB12008.5-89, and the acid value of the modified 1,2-bistrimethoxysilyl ethane and the unmodified 1,2-bistrimethoxysilyl ethane samples prepared in Examples 1-3 and Comparative Example 1 were tested after hydrolysis.

[0037] Storage test

[0038] Take 250g each of the modified 1,2-bistrimethoxysilyl ethane and unmodified 1,2-bistrimethoxysilyl ethane samples prepared in Examples 1-3 and Comparative Example 1, seal them in transparent reagent bottles and place them in a cool and ventilated place. Observe the material status and test the hydrolysis time once every five days.

[0039] Table 1

[0040] sample Hydrolysis time Acid value after hydrolysis Storage time Unmodified >30min ＜＜0.1 No change after 30 days A 1 minute 58 seconds ＜＜0.1 No change after 30 days B 2 minutes 30 seconds ＜＜0.1 No change after 30 days C 2min10s ＜＜0.1 No change after 30 days D 1 minute 30 seconds ＜＜0.1 Crystals appeared at the bottom of the material after 15 days, and the hydrolysis time was extended to 4 minutes. E 1 minute 48 seconds ＜＜0.1 Crystallization appeared at the bottom of the material after 25 days, and the hydrolysis time was extended to 3 minutes.

[0041] As shown in Table 1 and Figure 3 It can be seen that the hydrolysis rate of the modified 1,2-bis(trimethoxysilyl)ethane is significantly improved without affecting its shelf life. However, changing the modifier to acetic acid also increases the hydrolysis rate, but it affects the shelf life; after a period of time, crystallization occurs, further impacting the hydrolysis rate.

[0042] 1,2-Ditrimethoxysilylethane suffers from steric hindrance due to the two large trimethoxysilane groups linked by a short chain. Furthermore, the methoxy group, being an electron-donating group, reduces the positive charge of the silicon atom, severely hindering the nucleophilic attack of water molecules on the silicon atom. The hydroxyl group in acetic acid is a potentially electronegative group. During the reaction, the hydroxyl oxygen atom of acetic acid attacks the silicon atom, forming a five-coordinate transition state. The methoxy group then departs as methanol, ultimately producing acetoxysilane and methanol. While the substitution of one or two methoxy groups in 1,2-ditrimethoxysilylethane does not weaken the steric hindrance, the electron-withdrawing acetoxy group enhances the positive charge of the silicon atom, making it more susceptible to nucleophilic attack by water molecules. The hydrolyzed acetic acid also acts as an autocatalytic catalyst, thus accelerating the hydrolysis process.

[0043] like Figure 1 and 2 It can be seen that the infrared spectrum of sample D is located at 1700-1750 cm⁻¹. -1 1260-1195 cm -1 The presence of multiple peaks indicates the presence of Si-OAc, based on the characteristic absorption frequencies of organosilicon compounds. This suggests that acetic acid reacted with 1,2-bis(trimethoxysilyl)ethane to produce acetoxysilane and methanol. However, because it readily undergoes hydrolysis and polymerization to form crystals, replacing acetic acid with methyltriacetoxysilane avoids substitution and subsequent hydrolysis and polymerization, effectively extending its retention time.

[0044] The above description is merely an embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method for modifying 1,2-bis(trimethoxysilyl)ethane, characterized in that, The 1,2-bis(trimethoxysilyl)ethane is a byproduct of the preparation of vinyltrimethoxysilane, and the method includes: The 1,2-bistrimethoxysilyl ethane was subjected to a first dehydration process. The 1,2-bis(trimethoxysilyl)ethane that has undergone the first dehydration is mixed with acetoxysilane, the acid value is adjusted to <0.1, and the temperature is controlled at 50-60℃; The mixture obtained by mixing with acetoxysilane is subjected to a second dehydration.

2. The method according to claim 1, characterized in that, The first water removal includes the step of mixing 1,2-bis(trimethoxysilyl)ethane with a water removal molecular sieve.

3. The method according to claim 1 or 2, characterized in that, After the first water removal, the moisture content in the 1,2-bistrimethoxysilyl ethane is controlled to be below 200 ppm.

4. The method according to claim 1, characterized in that, The acetoxysilane is selected from at least one of methyltriacetoxysilane, ethyltriacetoxysilane, propyltriacetoxysilane, tetraacetoxysilane, and dimethyldiacetoxysilane.

5. The method according to claim 1, characterized in that, The molar ratio of the acetoxysilane to the 1,2-bis(trimethoxysilyl)ethane is 1:40000-60000.

6. The method according to claim 1, characterized in that, The second water removal includes the step of mixing the mixture obtained by mixing with acetoxysilane with a water removal molecular sieve.

7. The method according to claim 1 or 6, characterized in that, The moisture content of the product obtained after the second dehydration is controlled to be below 200 ppm.

8. The method according to claim 2 or 6, characterized in that, The water removal molecular sieve is selected from at least one of 3A molecular sieve, 4A molecular sieve, 5A molecular sieve, and 13A molecular sieve.

9. The application of 1,2-bistrimethoxysilylethane prepared by the method according to any one of claims 1 to 9 as a bifunctional silane coupling agent.

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