Preparation method of alkoxy modified organic silicon end sealing agent

Abstract

The invention relates to a preparation method of an alkoxy modified organic silicon end sealing agent, which comprises the following reaction steps: S1, carrying out nitrogen displacement on a reactor, and then adding tetramethyldisiloxane and a copper salt catalyst to carry out primary reaction; s2, aldehyde monomers are added into the reactor for a secondary reaction; s3, after the secondary reaction is completed, cooling the reactor, and then filtering a product; and S4, sequentially washing, distilling and removing impurities and water from the product obtained in the step S3 to obtain the alkoxy modified organic silicon end sealing agent. According to the preparation method, the raw materials are easy to obtain, the product selectivity is high, the product is easy to separate, the raw material conversion rate is high, the obtained product is stable in performance, the mechanical property retention rate of the organic silicon sealant can be effectively increased, and the yellowing problem is solved.

Description

Technical Field

[0001] The invention relates to a method for preparing an organosilicon capping agent, in particular to a method for preparing an alkoxy-modified organosilicon capping agent. Background Art

[0002] Alkoxy-modified silicone capping agents are an important class of chemical intermediates. The properties of silicone capping agents are adjusted by introducing alkoxy groups at the ends of polysiloxane chains. Specifically, alkoxy-modified silicone capping agents are generally compounds that introduce alkoxy groups (such as methoxy, ethoxy, etc.) to the ends of polysiloxane chains through chemical reactions. They are mainly used to control and terminate the growth of polysiloxane chains, thereby adjusting the molecular weight and physical and chemical properties of polymers. However, the preparation method of alkoxy-modified silicone capping agents in the prior art has low raw material conversion rate and product yield, and the product is not easy to separate. Summary of the invention

[0003] In view of the above problems, the main purpose of the present invention is to provide a method for preparing an alkoxy-modified organosilicon capping agent, in which the raw materials are easily available, the product selectivity is high, the product is easy to separate, and the raw material conversion rate is high.

[0004] In order to achieve the above-mentioned purpose, the preparation method of the alkoxy-modified silicone capping agent of the present invention comprises the following steps: step S1, nitrogen replacement of the reactor, and then adding tetramethyldisiloxane and copper salt catalyst for preliminary reaction; step S2, adding aldehyde monomer to the reactor for secondary reaction; tetramethyldisiloxane and aldehyde monomer react under the action of copper salt catalyst, and the reaction formula is as follows:

[0005]

[0006] Step S3, after the secondary reaction is completed, the reactor is cooled and the product is filtered; Step S4, the product obtained in step S3 is washed and distilled to remove impurities and water in sequence to obtain an alkoxy-modified organosilicon capping agent.

[0007] Furthermore, the copper salt catalyst is copper sulfate, cupric chloride or cuprous chloride, and the amount of the copper salt catalyst is 5% to 20% of the mass of tetramethyldisiloxane.

[0008] Furthermore, the aldehyde monomer is formaldehyde or acetaldehyde.

[0009] Furthermore, the molar ratio of the aldehyde monomer to tetramethyldisiloxane is 1-1.1:1.

[0010] Furthermore, in step S1, the reaction temperature of the preliminary reaction is 140-160° C., and the reaction time is 1-3 h.

[0011] Furthermore, the reaction temperature of the secondary reaction in step S2 is 150-200° C., the reaction time is 1-3 h, and the reaction system pressure is 0.2-0.6 MPa.

[0012] Furthermore, after the cooling temperature in step S3 is lower than 40° C., filtering is performed.

[0013] Furthermore, in the washing process in step S4, the volume ratio of soft water to product is 2 to 3:1, the washing times are 1 to 2 times, and the temperature of distillation for impurity removal and water removal is 100 to 140°C.

[0014] Through the above technical solution, the beneficial effects achieved by the present invention include:

[0015] The preparation method of the alkoxy-modified silicone head-sealing agent of the present invention specifically comprises the following steps: tetramethyldisiloxane and an aldehyde monomer are reacted under the action of a copper salt catalyst to obtain the alkoxy-modified silicone head-sealing agent, wherein the conversion rate of tetramethyldisiloxane is high, the yield of the alkoxy-modified silicone head-sealing agent product is high, and the finished product is easier to separate. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the present invention are described clearly and completely below in conjunction with the embodiments of the present invention. In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0017] The preparation method of the alkoxy-modified organic silicon capping agent of the present invention comprises the following steps:

[0018] Step S1, the reactor is purged with nitrogen, and then tetramethyldisiloxane and a copper salt catalyst are added to carry out a preliminary reaction;

[0019] Step S2, adding aldehyde monomers to the reactor for secondary reaction; tetramethyldisiloxane and aldehyde monomers react under the action of a copper salt catalyst, and the reaction formula is as follows:

[0020]

[0021] Step S3, after the secondary reaction is completed, the reactor is cooled and the product is filtered;

[0022] Step S4, washing and distilling the product obtained in step S3 to remove impurities and water in sequence to obtain an alkoxy-modified organic silicon capping agent.

[0023] The reaction principle of the present invention is that since the silicon-hydrogen bond (Si-H) in silane itself has high reactivity and has the ability to undergo addition reaction with double bonds, compounds containing silicon-hydrogen bonds, such as tetramethyldisiloxane ((CH3)2SiHOSiH(CH3)2), can undergo addition reaction with unsaturated bonds such as carbon-carbon double bonds, carbon-oxygen double bonds, and carbon-nitrogen double bonds; in addition, affected by the atomic polarity, Si on Si-H is positively charged and H is negatively charged, while C in aldehyde (-COH) is positively charged and O is negatively charged. Therefore, in the reaction process of the present invention, the H of Si-H can attack the C atom of -COH, and the Si atom of Si-H combines with the O atom of -COH, and the reaction results in obtaining alkoxysilane.

[0024] According to the preparation method steps and principles of the present invention, a number of examples and comparative examples were tested, and the test results were analyzed, as follows:

[0025] Example 1

[0026] The specific steps of the preparation method in Example 1 of the present invention are as follows:

[0027] Step S1, first replace the reactor with nitrogen, then add tetramethyldisiloxane and a copper salt catalyst for preliminary reaction, the copper salt catalyst is copper sulfate, the amount of copper sulfate catalyst is 10% of the mass of tetramethyldisiloxane, the reaction temperature is 160° C., and the reaction time is 2 hours;

[0028] Step S2, after the reaction in the above steps is completed, formaldehyde is added to the reactor for a secondary reaction, the molar ratio of tetramethyldisiloxane to formaldehyde is 1:1, the reaction temperature is 150°C, the reaction time is 2h, and the reaction system pressure is 0.6MPa

[0029] Step S3, after the secondary reaction is completed, the reactor is cooled to less than 40° C., and then the product is filtered;

[0030] Step S4, washing and distilling the product obtained in step S3 in sequence to remove impurities and water, wherein the washing process is carried out according to a volume ratio of soft water to product of 2:1, the number of washing times is 1, and the temperature of distillation to remove impurities and water is 120°C, and finally an alkoxy-modified silicone capping agent is obtained.

[0031] Embodiment 2 to Embodiment 6

[0032] The difference between Examples 2 to 6 and Example 1 is that the reaction condition parameters in their preparation methods are different, as shown in the following table:

[0033] Table 1 Comparison of reaction conditions in the preparation methods of various embodiments

[0034]

[0035] The experimental results obtained in the preparation methods of Examples 1 to 6 are analyzed, and the specific information is as follows:

[0036] Table 2 Comparison table of preparation results of various embodiments

[0037]

[0038] Comparative Example 1 to Comparative Example 7

[0039] During the development of the preparation method of the present invention, a number of comparative experiments were screened, and the specific information is as follows:

[0040] Table 3 Comparison of reaction conditions of Example 1 and the preparation methods of the comparative examples

[0041]

[0042] Table 4 Comparison of the results of Example 1 and the preparation methods of the comparative examples

[0043]

[0044] The above Tables 1 to 4 are analyzed as follows:

[0045] By comparing the experimental data of Example 1 and Example 4, it is found that the aldehyde monomer in the preparation method of the present invention can be formaldehyde or acetaldehyde, and no matter which one of the two is selected to participate in the secondary reaction, it has no significant effect on the preparation result; in addition, please refer to the experimental data of Example 1 and Comparative Example 1, Example 4 and Comparative Example 4, and Comparative Example 2 and Comparative Example 4. From the experimental results, it can be analyzed that if the preparation method of the present invention uses ternary copper as a catalyst for the reaction, no matter whether the raw material is formaldehyde or acetaldehyde, it is impossible to react to obtain an alkoxy-modified organosilicon capping agent, and the alkoxy-modified organosilicon capping agent is obtained. It can be seen that the copper salt can be copper sulfate, copper chloride or cuprous chloride, that is, divalent copper ions can be used as the catalyst of the preparation method, and the copper salt is used as the catalyst, tetramethyldisiloxane and aldehyde monomers are fully reacted under the catalytic action of the copper salt. It is not difficult to see from the experimental results of Examples 1 to 6 that the conversion rate of tetramethyldisiloxane is as high as 80% or more, the product purity is greater than 95%, and the impurity content is low. According to gas chromatography analysis, the low component content in the alkoxy-modified silicone capping agent is less than 3%. The entire preparation method is easy to operate and the finished product is easier to separate.

[0046] Please continue to refer to the experimental data of Example 1, Example 6 and Comparative Example 3. The content of the catalyst is adjusted in Comparative Example 3. The mass ratio of the catalyst to the raw material, i.e., tetramethyldisiloxane, in Comparative Example 3 is 30%, which is much higher than 5% in Example 1 and 20% in Example 6. Although the catalyst content is greatly increased, from the experimental results, the raw material product conversion rate is not increased, nor is the final product yield. Therefore, the catalyst content of the present invention is preferably 5% to 20%. Please refer to the experimental data of Comparative Example 5 and Example 1 again. The molar ratio of aldehydes to raw materials is slightly increased in Comparative Example 5. From the experimental results, it can be seen that both the conversion rate of tetramethyldisiloxane and the content of the alkoxy-modified organosilicon capping agent are reduced. It can be seen that the molar ratio of raw materials to aldehyde monomers is better when it is between 1 and 1.1:1.

[0047] In addition, the reaction temperature of step S1 and step S2 is lowered in comparative example 6 relative to example 1, and the reaction time of the two steps is increased in comparative example 7 relative to example 1. After lowering the reaction temperature, it is obvious in the experimental results that the material reaction is not sufficient, and the conversion rate and product purity are both reduced. In addition, although comparative example 7 increases the reaction time of the two steps, it does not have a significant impact on the experimental results. Therefore, 2h is the best reaction time.

[0048] Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

1. A method for preparing an alkoxy-modified silicone capping agent, characterized in that: The following steps are involved: Step S1, the reactor is purged with nitrogen, and then tetramethyldisiloxane and a copper salt catalyst are added to carry out a preliminary reaction; Step S2, adding aldehyde monomer to the reactor for secondary reaction; The tetramethyldisiloxane and the aldehyde monomer react under the action of a copper salt catalyst, and the reaction formula is as follows: Step S3, after the secondary reaction is completed, the reactor is cooled and the product is filtered; Step S4, washing and distilling the product obtained in step S3 in sequence to remove impurities and water, to obtain an alkoxy-modified organic silicon capping agent.

2. The method for preparing the alkoxy-modified silicone capping agent according to claim 1, characterized in that: The copper salt catalyst is copper sulfate, cupric chloride or cuprous chloride, and the amount of the copper salt catalyst is 5% to 20% of the mass of the tetramethyldisiloxane.

3. The method for preparing the alkoxy-modified silicone capping agent according to claim 1, characterized in that: The aldehyde monomer is formaldehyde or acetaldehyde.

4. The method for preparing the alkoxy-modified silicone capping agent according to claim 3, characterized in that: The molar ratio of the aldehyde monomer to tetramethyldisiloxane is 1-1.1:

1.

5. The method for preparing the alkoxy-modified silicone capping agent according to claim 1, characterized in that: In the step S1, the reaction temperature of the preliminary reaction is 140-160° C., and the reaction time is 1-3 hours.

6. The method for preparing the alkoxy-modified silicone capping agent according to claim 1, characterized in that: The reaction temperature of the secondary reaction in step S2 is 150-200° C., the reaction time is 1-3 hours, and the reaction system pressure is 0.2-0.6 MPa.

7. The method for preparing the alkoxy-modified silicone capping agent according to claim 1, characterized in that: After the cooling temperature in step S3 is lower than 40° C., filtering is performed.

8. The method for preparing the alkoxy-modified silicone capping agent according to claim 1, characterized in that: In the washing process in step S4, the volume ratio of soft water to product is 2 to 3:1, the washing is performed 1 to 2 times, and the temperature of the distillation for impurity removal and water removal is 100 to 140°C.

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