Method for synthesizing alkyl acyloxy silane mixture from sodium acetate

Abstract

The invention relates to a method for synthesizing an alkyl acyloxy silane mixture from sodium acetate, and aims to produce a low-cost and low-crystallization-temperature cross-linking agent product for RTV (Room Temperature Vulcanization) silicone rubber. The preparation method comprises the following steps: 1) mixing and stirring alkyl acyloxy silane and sodium acetate, dropwise adding methyl trichlorosilane, supplementing sodium acetate and methyl trichlorosilane by a batch method, stirring for 1 hour without heating after dropwise adding, and then heating to react for a certain time to obtain an alkyl acyloxy silane mixture crude product; (2) further heating the reaction system, distilling out methyl trichlorosilane, a monosubstituted substance and a disubstituted substance which are not completely reacted, reacting by virtue of a tubular device filled with sodium acetate, and collecting back to the original reaction system; 3, the crude product is cooled and further filtered, and an alkyl acyloxy silane mixture product is obtained.Compared with the prior art, the synthetic route is simple, operation is convenient, the effective content of the product is high, cost is low, no organic solvent is needed, and meanwhile the difficulty that pure methyl triacetoxysilane cannot be normally used in winter is overcome.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of silane crosslinking agent synthesis, and particularly relates to a method for synthesizing an alkyl acyloxy silane mixture from sodium acetate. BACKGROUND

[0002] Methyltriacetoxysilane is a main additive of sealant and a core part of one-component room temperature vulcanized silicone rubber, has crosslinking effect, and the crosslinked silicone rubber has good heat resistance, weather resistance and mechanical properties.

[0003] The main synthesis methods of methyltriacetoxysilane include acetic anhydride method, acetic acid method and acetate method. Methyltriacetoxysilane is prepared from acetate in an inert solvent such as petroleum ether, toluene and the like, and the solvent needs to be separated and recycled for reuse. At present, the research is relatively less. The acetic anhydride method is one of the most common methods for synthesizing methyltriacetoxysilane, but the production cost of the acetic anhydride method is relatively high, and the monomer content of methyltriacetoxysilane synthesized by the acetic anhydride method is >95%, which is easy to crystallize at low temperature, and often needs to be further modified to facilitate the use of customers. In recent years, the research on the synthesis of methyltriacetoxysilane by the acetic acid method has gradually increased. The production cost of this method is relatively low, and the dimer produced in the production process can significantly improve the characteristics of the acid crosslinking agent which is easy to crystallize at low temperature. However, the reaction system is complex, and there are many side reactions. A large amount of hydrogen chloride is generated in the reaction, resulting in a large amount of polymer in the product and unstable product quality.

[0004] The invention patent with the application number 200910061452.X discloses an alkyl acyloxy mixture and a preparation method thereof. The method uses the acetic anhydride method, refluxes methyltrichlorosilane and other alkyl chlorosilanes (ethyltrichlorosilane, vinyltrichlorosilane, n-propyltrichlorosilane, etc.) with acetic anhydride at a certain temperature, and obtains an alkyl acyloxy mixture after distillation, solving the problem that the high-purity methyltriacetoxysilane is solid at room temperature. However, due to the large difference in reaction activity of different chlorosilanes and acetic anhydride, there are problems such as incomplete reaction of raw materials and high chlorine ion content in the product.

[0005] The invention patent with the application number 202210813470.4 discloses a methyl alkoxyl acetoxy silane mixture with low crystallization temperature, a preparation method and application thereof. The method reacts the synthesized methyltriacetoxysilane product with alcohol to obtain a methyl alkoxyl acetoxy silane mixture, solving the problem of low-temperature crystallization. However, it is necessary to first synthesize high-content methyltriacetoxysilane, and then further modify the product, which is complicated in synthesis process. SUMMARY

[0006] In view of this, the present application provides a method for synthesizing alkyl acyloxy silane mixture from sodium acetate, to solve the problems of high cost, complicated process and easy crystallization of the current methyl triacetoxy silane product.

[0007] To achieve the above-mentioned purpose, the method for synthesizing alkyl acyloxy silane mixture from sodium acetate of the present application comprises the following steps: (1) crude product synthesis: alkyl acyloxy silane is mixed with sodium acetate and stirred, and methyl trichlorosilane is added dropwise, and then the reaction is carried out by heating to obtain alkyl acyloxy silane mixture crude product; (2) raw material re-reaction: the alkyl acyloxy silane mixture crude product is further heated to distill off the liquid, and the obtained product is cooled and filtered to obtain alkyl acyloxy silane mixture.

[0008] The alkyl acyloxy silane comprises ethyl triacetoxy silane, propyl triacetoxy silane, vinyl triacetoxy silane or di-tert-butoxy diacetoxy silane; preferably ethyl triacetoxy silane and di-tert-butoxy diacetoxy silane.

[0009] Preferably, the di-tert-butoxy diacetoxy silane is prepared by the method with patent number 202311420752.9, and the ethyl triacetoxy silane is prepared by the method with patent number 202311420747.8.

[0010] In step (1), the molar ratio of alkyl acyloxy silane to methyl trichlorosilane is 1 / (0.7-4), and the molar ratio of methyl trichlorosilane to sodium acetate is 1 / 3-3.5. The range value refers to any value or any interval value in the interval range.

[0011] In step (1), sodium acetate and methyl trichlorosilane are added in a batch mode, and 10 batches are added according to the same molar ratio. In the first batch, after all the alkyl acyloxy silane is added to the reaction kettle, sodium acetate is added under stirring.

[0012] In step (1), when methyl trichlorosilane is added dropwise, the internal temperature is controlled below 40℃; after the addition is completed, stirring is carried out without heating for 1h, and then the temperature is raised to 60-80℃ and the reaction is carried out for 1-3h.

[0013] In step (2), the alkyl acyloxy silane mixture crude product is further heated to 100-150℃ to distill off the unreacted methyl trichlorosilane, mono-substituted product and di-substituted product, and then the product is re-reacted in a jacketed tubular reactor (jacket temperature is 100℃) filled with sodium acetate to obtain methyl triacetoxy silane product, which is returned to the original reaction system to ensure more complete reaction.

[0014] In some preferred cases, the method for synthesizing alkyl acyloxy silane mixture from sodium acetate comprises the following steps: (1) crude product synthesis: alkyl acyloxy silane and sodium acetate are mixed in a certain proportion and stirred thoroughly, methyltrichlorosilane is added dropwise, sodium acetate is added intermittently, and methyltrichlorosilane is added dropwise in proportion. After stirring at room temperature for 1 h, the reaction is carried out at an elevated temperature for a certain period of time to obtain an alkyl acyloxy silane mixture crude product.

[0015] (2) raw material re-reaction: the reaction system is further heated, the unreacted raw material is distilled, and the re-reaction is carried out through a pipe device containing sodium acetate, and the product is collected and recovered into the original reaction system.

[0016] (3) filtration: the crude product is cooled and further filtered to obtain an alkyl acyloxy silane mixture product.

[0017] Preferably, when methyltrichlorosilane is added dropwise, the temperature in the system is controlled below 40°C.

[0018] Preferably, after the three raw materials are mixed uniformly, the temperature is raised to 60-80°C and the reaction is carried out for 1-3 h.

[0019] Preferably, the temperature of the re-reaction system is raised to 100-150°C until no liquid is distilled out.

[0020] Preferably, the crude product is cooled to 20-50°C for filtration and collection.

[0021] The present application also provides an alkyl acyloxy silane mixture synthesized by sodium acetate, which is prepared by the method described above, and the mass content of methyltriacetoxysilane in the mixture is 40-70%, the mass content of other alkyltriacetoxysilanes (ethyltriacetoxysilane or di-tert-butoxydiacetoxysilane) is 30-60%, and the total effective content of the product is >90%.

[0022] The obtained alkyl acyloxy silane mixture synthesized by sodium acetate does not crystallize under the condition of -15-15°C with a crystal seed. The crystal seed is methyltriacetoxysilane.

[0023] The alkyl acyloxy silane mixture synthesized by sodium acetate does not crystallize under the condition of -15-15°C with a crystal seed, which means that after the obtained alkyl acyloxy silane mixture synthesized by sodium acetate is placed in an environment of -15-15°C (such as a refrigerator under the condition of 15°C, 0°C, -10°C and -15°C) for one day, methyltriacetoxysilane crystal seeds are added, and the product does not crystallize after being placed in the refrigerator under the corresponding temperature condition for one week. Of course, it can be understood that the alkyl acyloxy silane mixture synthesized by sodium acetate does not crystallize under the condition of -15-15°C without a crystal seed, which means that after the obtained alkyl acyloxy silane mixture synthesized by sodium acetate is placed in an environment of -15-15°C (such as a refrigerator under the condition of 15°C, 0°C, -10°C and -15°C) for 8 weeks, the product does not crystallize. A crosslinking agent comprising the sodium acetate synthetic alkyl acyloxy silane mixture.

[0024] The present application has the following advantages: (1) The present application uses sodium acetate method to synthesize alkyl acyloxy silane mixture product, the raw material sodium acetate is widely available, and the price is relatively low, which solves the problems of high cost of synthesis by acetic anhydride method and unstable product quality of synthesis by acetic acid method.

[0025] (2) The present application uses alkyl acyloxy silane as the solvent for the synthesis of sodium acetate, which not only solves the problems of using organic solvents, difficult solvent recovery, and low recovery rate in traditional sodium acetate synthesis method, but also can solve the problem of easy crystallization of methyltriacetoxysilane by using alkyl acyloxy silane as a modifier.

[0026] The numerical range described in the present application includes not only the point values listed above, but also any point values between the above numerical ranges that are not listed, and the present application does not exhaustively list the specific point values included in the range for the sake of brevity and simplicity. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 Gas chromatogram of the reaction product of di-t-butoxydiacetoxy silane and methyltrichlorosilane with a molar ratio of 1 / 1.3 in Example 2.

[0028] Figure 2 Gas chromatogram of the reaction product of ethyltriacetoxysilane and methyltrichlorosilane with a molar ratio of 1 / 1 in Example 4. DETAILED DESCRIPTION

[0029] The present application will be further described below in conjunction with specific examples. However, the scope of protection claimed by the present application is not limited to the scope of the examples.

[0030] The di-t-butoxydiacetoxy silane used in this example is prepared by the method of patent No. 202311420752.9 (Examples 1-4).

[0031] The ethyltriacetoxysilane used in this example is prepared by the method of patent No. 202311420747.8 (Example 5).

[0032] In the examples of the present application, the molar ratio relationship refers to the addition of raw materials in the relationship of mol:mol.

[0033] Example 1 A method for synthesizing an alkyl acyloxy silane mixture by sodium acetate, comprising the following steps: (1) Crude product synthesis: add di-tert-butoxydiacetoxysilane into the reaction kettle, add the first batch of sodium acetate (add 1 / 10 of the total amount of sodium acetate, add in 10 batches), and drop methyltrichlorosilane (molar ratio of di-tert-butoxydiacetoxysilane to methyltrichlorosilane is 1 / 0.9). Add sodium acetate intermittently, and drop methyltrichlorosilane in proportion (maintain the molar ratio of methyltrichlorosilane to sodium acetate at 1 / 3.2 during the supplement process). Control the internal temperature <40°C during the dropping process, and stir for 1 h after the dropping is completed. Increase the temperature to 60°C and react for 1 h to obtain the crude alkyl acyloxysilane mixture.

[0034] (2) Raw material re-reaction: further increase the temperature of the reaction system to 120°C, distill the unreacted raw materials, distill the unreacted methyltrichlorosilane, mono-substituted product and di-substituted product, and pass through a jacketed tubular reactor (jacket temperature is 100°C) filled with sodium acetate for re-reaction to obtain methyltriacetoxysilane product, and return to the original reaction system.

[0035] (3) Filtration: cool the crude product to a temperature below 25°C, and further filter to obtain the alkyl acyloxysilane mixture product.

[0036] (4) Product performance research: place the synthesized alkyl acyloxysilane mixture product at different temperatures, observe its crystallization, and measure its mechanical properties.

[0037] Example 2 A method for synthesizing an alkyl acyloxysilane mixture by sodium acetate, comprising the following steps: (1) Crude product synthesis: add di-tert-butoxydiacetoxysilane into the reaction kettle, add the first batch of sodium acetate (add 1 / 10 of the total amount of sodium acetate, add in 10 batches), and drop methyltrichlorosilane (molar ratio of di-tert-butoxydiacetoxysilane to methyltrichlorosilane is 1 / 1.3). Add sodium acetate intermittently, and drop methyltrichlorosilane in proportion (maintain the molar ratio of methyltrichlorosilane to sodium acetate at 1 / 3.2 during the supplement process). Control the internal temperature <40°C during the dropping process, and stir for 1 h after the dropping is completed. Increase the temperature to 60°C and react for 1 h to obtain the crude alkyl acyloxysilane mixture.

[0038] (2) Raw material re-reaction: further increase the temperature of the reaction system to 120°C, distill the unreacted raw materials, distill the unreacted methyltrichlorosilane, mono-substituted product and di-substituted product, and pass through a jacketed tubular reactor (jacket temperature is 100°C) filled with sodium acetate for re-reaction to obtain methyltriacetoxysilane product, and return to the original reaction system.

[0039] (3) Filtration: cool the crude product to a temperature below 25°C, and further filter to obtain the alkyl acyloxysilane mixture product.

[0040] (4) Product performance research: the synthesized alkyl acyloxy silane mixture product is placed at different temperatures, the crystallization condition is observed, and the mechanical properties are measured.

[0041] Example 3 A method for synthesizing alkyl acyloxy silane mixture by sodium acetate, comprising the following steps: (1) Crude product synthesis: add di-t-butoxy diacetoxy silane into the reaction kettle, add the first batch of sodium acetate under stirring (add 1 / 10 of the total amount of sodium acetate, add in 10 batches), add methyl trichlorosilane dropwise (molar ratio of di-t-butoxy diacetoxy silane to methyl trichlorosilane is 1 / 2), add sodium acetate intermittently, and add methyl trichlorosilane dropwise in proportion (molar ratio of methyl trichlorosilane to sodium acetate is 1 / 3.2 during the supplement process), control the internal temperature <40℃ during the dropwise addition process, and stir for 1h after the dropwise addition is completed. Increase the temperature to 60℃ and react for 1h to obtain the alkyl acyloxy silane mixture crude product.

[0042] (2) Raw material re-reaction: further increase the temperature of the reaction system to 120℃, distill the incompletely reacted raw materials, distill the incompletely reacted methyl trichlorosilane, mono-substituted product and di-substituted product, and pass through a jacketed pipe reactor filled with sodium acetate (jacket temperature is 100℃) for re-reaction to obtain methyl triacetoxy silane product, and return to the original reaction system.

[0043] (3) Filtration: cool the crude product to below 25℃, and further filter to obtain the alkyl acyloxy silane mixture product.

[0044] (4) Product performance research: the synthesized alkyl acyloxy silane mixture product is placed at different temperatures, the crystallization condition is observed, and the mechanical properties are measured.

[0045] Example 4 A method for synthesizing alkyl acyloxy silane mixture by sodium acetate, comprising the following steps: (1) Crude product synthesis: add di-t-butoxy diacetoxy silane into the reaction kettle, add the first batch of sodium acetate under stirring (add 1 / 10 of the total amount of sodium acetate, add in 10 batches), add methyl trichlorosilane dropwise (molar ratio of di-t-butoxy diacetoxy silane to methyl trichlorosilane is 1 / 2), add sodium acetate intermittently, and add methyl trichlorosilane dropwise in proportion (molar ratio of methyl trichlorosilane to sodium acetate is 1 / 3.2 during the supplement process), control the internal temperature <40℃ during the dropwise addition process, and stir for 1h after the dropwise addition is completed. Increase the temperature to 60℃ and react for 1h to obtain the alkyl acyloxy silane mixture crude product.

[0046] (2) Raw material re-reaction: The reaction system is further heated to 120°C, and the unreacted methyltrichlorosilane, monosubstituted product and disubstituted product are distilled out. The methyltriacetyloxy silane product is obtained by re-reaction through a jacketed tubular reactor (jacket temperature is 100°C) containing sodium acetate, and returned to the original reaction system.

[0047] (3) Filtration: The crude product is cooled to a temperature below 25°C, and further filtered to obtain the alkyl acyloxy silane mixture product.

[0048] (4) Product performance research: The synthesized alkyl acyloxy silane mixture product is placed at different temperatures to observe its crystallization and determine its mechanical properties.

[0049] Comparative Example 1 A method for synthesizing an alkyl acyloxy silane mixture by sodium acetate, comprising the following steps: (1) Crude product synthesis: Di-tert-butoxy diacetyloxy silane is added to the reaction kettle, and the first batch of sodium acetate (1 / 10 of the total amount of sodium acetate is added, and is added in 10 batches) is added under stirring. Methyltrichlorosilane is added dropwise (the molar ratio of di-tert-butoxy diacetyloxy silane to methyltrichlorosilane is 1 / 1.3), sodium acetate is added intermittently, and methyltrichlorosilane is added dropwise in proportion (the molar ratio of methyltrichlorosilane to sodium acetate is maintained at 1 / 3.2 during the supplement process). The internal temperature is not controlled during the dropwise addition process, and the temperature is > 40°C. After the dropwise addition is completed, stirring is carried out for 1 h. The temperature is increased to 60°C, and the reaction is carried out for 1 h to obtain the crude alkyl acyloxy silane mixture.

[0050] (2) Raw material re-reaction: The reaction system is further heated to 120°C, and the unreacted methyltrichlorosilane, monosubstituted product and disubstituted product are distilled out. The methyltriacetyloxy silane product is obtained by re-reaction through a jacketed tubular reactor (jacket temperature is 100°C) containing sodium acetate, and returned to the original reaction system.

[0051] (3) Filtration: The crude product is cooled to a temperature below 25°C, and further filtered to obtain the alkyl acyloxy silane mixture product.

[0052] (4) Product performance research: The synthesized alkyl acyloxy silane mixture product is placed at different temperatures to observe its crystallization and determine its mechanical properties.

[0053] Comparative Example 2 A method for synthesizing an alkyl acyloxy silane mixture by sodium acetate, comprising the following steps: (1) Crude product synthesis: Di-tert-butoxydiacetoxysilane was added to the reactor, and the first batch of sodium acetate (1 / 10 of the total sodium acetate was added in 10 batches) was added under stirring. Methyltrichlorosilane (the molar ratio of di-tert-butoxydiacetoxysilane to methyltrichlorosilane was 1 / 0.6) was added dropwise. Sodium acetate was added intermittently, and methyltrichlorosilane was added dropwise in proportion (the molar ratio of methyltrichlorosilane to sodium acetate was maintained at 1 / 3.2 during the addition process). The internal temperature was controlled to be <40℃ during the dropwise addition process. After the dropwise addition was completed, the mixture was stirred for 1 h. The temperature was raised to 60℃ and reacted for 1 h to obtain a crude product of alkyl acyloxysilane mixture.

[0054] (2) Re-reaction of raw materials: The reaction system is further heated to 120°C, and the unreacted raw materials are distilled off. The unreacted methyltrichlorosilane, monosubstituted and disubstituted products are distilled off and then reacted again in a jacketed tubular reactor containing sodium acetate (jacket temperature is 100°C) to obtain the methyltriacetoxysilane product, which is then returned to the original reaction system.

[0055] (3) Filtration: Cool the crude product to below 25°C and filter it further to obtain a mixture of alkyl acyloxysilanes.

[0056] (4) Product performance study: The synthesized alkyl acyl silane mixture was placed at different temperatures to observe its crystallization and to determine its mechanical properties.

[0057] To verify the changes in the performance of the modified product, this invention mainly compares the changes in product performance before and after modification in terms of crystallinity and mechanical properties.

[0058] (1) Comparison of crystallization performance: The alkyl acyloxysilane mixture products in Examples 1-4 and Comparative Examples 1 and 2 were placed in environments of 15°C, 0°C, -10°C and -15°C for one day, respectively. Then, crystallized methyltriacetoxysilane seed crystals were added, and the products were placed in the refrigerator for another week. The crystallization rate of the products before and after adding the seed crystals was observed. (2) Comparison of mechanical properties: 107 glue (viscosity 20000cp), dimethyl silicone oil (viscosity 20cp) and fumed silica were added to a planetary mixer in a ratio of 1:0.05:0.2 and stirred under normal pressure until homogeneous to obtain the base glue. After vacuum stirring for 30 min, the base glue was stirred under vacuum for 15 min in a certain ratio (base glue: crosslinking agent: dibutyltin dilaurate = 1:6%:0.2%) and made into a film to evaluate its mechanical properties. The tensile strength and elongation were tested according to GB / T 528-2009, and the hardness was tested according to HG / T2368-2011.

[0059] To verify the impact of the formulation and process of this invention on the invention's effectiveness, comparative experiments were conducted on various process parameters, and the following results were obtained, as shown in Table 1: Table 1

[0060] Note: According to GB 16776-2025 standard, the tensile strength is ≥0.60MPa, the elongation at maximum tensile strength is ≥100%, and the Shore hardness is 20-35HA (weather-resistant sealant). When the sealant is not fully cured, it will be very soft and cannot be pulled apart.

[0061] As shown in Table 1, the alkyl acyloxysilane mixture synthesized in this invention does not crystallize when seeded at a low temperature of -15℃ and exhibits excellent mechanical properties. This invention uses sodium acetate as the raw material for synthesizing methyltriacetoxysilane. Sodium acetate is widely available and relatively inexpensive, significantly reducing production costs. Furthermore, it produces fewer byproducts, has an effective content >90%, and features a simple process that is easily industrialized. This invention uses alkyl acyloxysilane as the solvent in the sodium acetate synthesis method, which not only solves the problems of using organic solvents, difficult solvent recovery, and low recovery rates in traditional sodium acetate synthesis methods, but also allows alkyl acyloxysilane to act as a modifier, lowering the product crystallization temperature.

[0062] Comparing Example 2 with Example 3 and Comparative Example 2, it is shown that when too much di-tert-butoxydiacetoxysilane is added, the product does not solidify completely, is very soft, and has poor performance. When too little di-tert-butoxydiacetoxysilane is added, the product can still crystallize at a lower temperature (-15°C). The optimal ratio of di-tert-butoxydiacetoxysilane to methyltrichlorosilane is 1 / 1.3.

[0063] Comparing Examples 1-3 with Comparative Example 1, it is shown that when di-tert-butoxydiacetoxysilane is used as a modifying solvent, the temperature of the system should be controlled below 40°C during the dropwise addition of methyltrichlorosilane to avoid the generation of byproducts. When the system temperature is above 40°C, the effective content of the product is less than 80%, which cannot meet the needs of downstream customers.

[0064] A comparison of Examples 1-3 with Example 4 shows that di-tert-butoxydiacetoxysilane has a better modification effect than ethyltriacetoxysilane because its crystallization temperature is lower than that of ethyltriacetoxysilane. It can be used at a lower temperature (-15°C), while ethyltriacetoxysilane can be used above -10°C.

[0065] The above description is only a preferred embodiment of the present invention, but not every embodiment contains only one independent technical solution. Any equivalent substitutions or changes made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the protection scope of the present invention.

Claims

1. A process for the synthesis of an alkyl acyloxy silane mixture from sodium acetate, characterized in that, The method comprises the following steps: (1) crude product synthesis: alkyl acyloxy silane is mixed with sodium acetate and stirred, methyltrichlorosilane is added dropwise, after the dropwise addition is completed, the mixture is stirred for 1 h without heating, and then the reaction is carried out at a higher temperature to obtain an alkyl acyloxy silane mixture crude product; (2) raw material re-reaction: the alkyl acyloxy silane mixture crude product is further heated and re-reacted, and the obtained product is cooled, filtered, and an alkyl acyloxy silane mixture is obtained.

2. The method of claim 1, wherein the sodium acetate is synthesized in the presence of an alkyl acyloxy silane mixture, characterized in that, The alkyl acyloxy silane comprises ethyltriacetoxysilane, propyltriacetoxysilane, vinyltriacetoxysilane or di-t-butoxydiacetoxysilane; preferably ethyltriacetoxysilane or di-t-butoxydiacetoxysilane.

3. The method of claim 2, wherein the sodium acetate is synthesized in the presence of a mixture of alkyl acyloxy silanes, characterized in that, The molar ratio of alkyl acyloxy silane to methyltrichlorosilane is 1 / (0.7-4).

4. The method for synthesizing a mixture of alkyl acyloxysilanes from sodium acetate according to claim 2, characterized in that, The molar ratio of methyltrichlorosilane to sodium acetate is 1 / 3-3.

5.

5. The method of claim 1, wherein the sodium acetate synthesis alkyl acyloxy silane mixture is characterized by, In step (1), sodium acetate and methyltrichlorosilane are added in a batch mode, and all of them are added in 5-10 batches at the same molar ratio, wherein during the addition of the first batch, the alkyl acyloxy silane is added into the reaction kettle, and then sodium acetate is added under stirring.

6. The method of claim 1, wherein the sodium acetate synthesis alkyl acyloxy silane mixture is characterized by, In step (1), when methyltrichlorosilane is added dropwise, the internal temperature is controlled below 40°C; after the dropwise addition is completed, the mixture is stirred for 1 h without heating, and then the temperature is increased to 60-80°C and the reaction is carried out for 1-3 h.

7. The method of claim 1, wherein the sodium acetate synthesis alkyl acyloxy silane mixture is characterized by, In step (2), the alkyl acyloxy silane mixture crude product is further heated to 100-150°C, and unreacted methyltrichlorosilane, mono-substituted product and di-substituted product are distilled out.

8. A sodium acetate synthesis alkyl acyloxy silane mixture characterized by, The product obtained by the method of any one of claims 1-6 has a methyltriacetoxysilane mass content of 40-70% in the mixture, other alkyltriacetoxysilane mass content of 30-60%, and total effective content of >90%, wherein the other alkyltriacetoxysilane comprises ethyltriacetoxysilane or di-t-butoxydiacetoxysilane.

9. The sodium acetate synthetic alkyl acyloxy silane mixture of claim 8, wherein, The obtained sodium acetate synthesis alkyl acyloxy silane mixture does not crystallize under the condition of -15-15°C with a crystal seed.

10. A crosslinking agent characterized by comprising: The method comprises the sodium acetate synthesis alkyl acyloxy silane mixture of claim 8 or 9.

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