CN112266743B

CN112266743B - Modified silane end-capping agent and preparation method and application thereof

Info

Publication number: CN112266743B
Application number: CN202011164310.9A
Authority: CN
Inventors: 冯琼华; 冯伦武; 李胜杰; 王成; 肖俊平
Original assignee: HUBEI BLUESKY NEW MATERIALS Inc
Current assignee: HUBEI BLUESKY NEW MATERIALS Inc
Priority date: 2020-10-27
Filing date: 2020-10-27
Publication date: 2021-11-12
Anticipated expiration: 2040-10-27
Also published as: CN112266743A

Abstract

The invention discloses a modified silane end-capping reagent and a preparation method thereof, wherein the preparation method comprises the following steps: 1) adding 4-hydroxybutyl vinyl ether and a catalyst A into a reaction bottle, heating to 60-65 ℃, dropwise adding hydrosilane, and reacting for 2-6 hours at 60-100 ℃ after dropwise adding; 2) after the reaction is finished, performing negative pressure rectification to obtain hydroxyl-terminated silane; 3) adding the hydroxyl-terminated silane obtained in the step 2) and a catalyst B into a reaction bottle, heating to 50 ℃, then starting to dropwise add p-toluenesulfonyl isocyanate, and reacting at 50-80 ℃ for 1-3 hours after dropwise adding; 4) and 3) carrying out reduced pressure distillation on the reaction liquid obtained in the step 3) to remove impurities, thereby obtaining the modified silane. The modified silane end-capping agent has the advantages of simple preparation method, low cost, environmental friendliness and convenience in industrialization. The prepared modified silane end-capping agent can improve the storage stability, high and low temperature resistance, ultraviolet stability and cohesiveness of the sealant.

Description

Modified silane end-capping agent and preparation method and application thereof

Technical Field

The invention relates to the technical field of silane end-capping agents, in particular to a modified silane end-capping agent and a preparation method and application thereof.

Background

In recent years, because China puts forward stricter requirements on safety and environmental protection, the traditional polyurethane sealant is limited in many application fields because the traditional polyurethane sealant contains free isocyanate and is easy to form bubbles during curing, and the silicone sealant is low in tearing strength and poor in recoatability and is easy to pollute building materials, so that the application of the silicone sealant is quite popular with users. The silane modified polyurethane sealant has the advantages of both polyurethane sealant and silicone sealant, overcomes the defects of respective performances, has excellent mechanical strength, recoatability and stain resistance, does not contain isocyanate and solvent, and is the main direction of novel elastic sealants at home and abroad.

The silane modified polyurethane has various synthesis methods, and the silane modified polyurethane prepared by using secondary amino silane as an end-capping agent has many advantages, good storage stability and excellent heat resistance.

The invention patent with patent publication number CN110734733A describes a silane modified polyurethane sealant, the end capping agent of which uses anilinopropyltrimethoxysilane, the silane modified polyurethane sealant synthesized by the method has good high temperature and low temperature resistance effect, but poor ultraviolet resistance stability.

The patent name is silane modified polyurethane glass primer and a preparation method thereof, and the Chinese patent with the publication number of CN102516921A discloses a silane modified polyurethane glass primer, wherein a main material silane-terminated polyurethane prepolymer is prepared by performing end-capping modification on an end isocyanate-based polyurethane prepolymer by aminopropyltrimethoxysilane and gamma-mercaptopropyltrimethoxysilane; the prepared silane modified polyurethane primer has long operable time in the air, is simple to use and is convenient to construct; the method has the disadvantages that the silane modified polyurethane obtained by the method has higher viscosity, needs more thickening agents and has larger influence on the environment.

As is well known, the silane end-capping reagent plays an important role in the preparation process of silane end-capping polyurethane, and the selection of the silane end-capping reagent with moderate price and good end-capping effect is very critical in order to ensure that the application of the silane end-capping polyurethane is simpler and more extensive. Some of the preparation methods of the silane-terminated polyurethane firstly synthesize hydroxyl-terminated polyurethane prepolymer, and then use isocyanate silane coupling agent to terminate the polyurethane, however, the price of the existing isocyanate silane coupling agent is very expensive, the production and application in China are few, most of the isocyanate silane coupling agent is imported from foreign countries, and the preparation is complex. Some isocyanate-based polyurethane prepolymers are subjected to end-capping modification by using commercially available primary amine silane or mercaptosilane, however, the coupling agent has too high activity in the end-capping process, the reaction process is not easy to control, and the phenomenon of gelation is easy to occur.

In view of the above, there is a need to design a capping agent for silane-modified polyurethane, which can overcome the defects of use under severe conditions.

Disclosure of Invention

In order to achieve the purpose, the invention discloses a modified silane end-capping agent, which has a structure shown in a formula 1:

in formula 1, R is methyl or methoxy.

The invention adopts the molecular structure of the modified silane end-capping reagent, solves the technical difficulty of the structural defect of the traditional end-capping reagent for silane modified polyurethane, and has the core advantages that: firstly, a reasonable secondary amine group is designed in a molecular structure, and can better perform end-capping reaction with a polyurethane prepolymer; secondly, benzene rings are introduced into the molecular structure to endow the molecular structure with chemical resistance; thirdly, enough active reaction groups are constructed in the molecular structure, and the silane modified polyurethane can be endowed with cohesiveness after the reaction with the polyurethane prepolymer. After the prepolymer containing-NCO is blocked by the modified silane blocking agent synthesized by the invention, the obtained silanized resin can be subjected to moisture vulcanization at room temperature through hydrolysis and polycondensation of the end group (alkoxy silane), and the formed silica skeleton has stability to heat, solvent and ultraviolet radiation.

The modified silane end-capping agent designed by the invention adopts the molecular structure and has the following advantages: 1. the main chain is designed with benzenesulfonyloxy, so that the surface activity of the resin can be reduced, and the generation of bubbles can be reduced in application; 2. the compatibility of silane in the polyurethane prepolymer can be improved by long-chain alkyl and ether bonds on the main chain. 3. When the modified silane designed by the invention is used as an end-capping agent of a polyurethane prepolymer, the modified silane can be better compatible with the polyurethane prepolymer according to similar compatibility because a plurality of ether bonds and alkyl groups exist on the main chain of the polyurethane prepolymer, so that the end-capping effect of the modified silane is better.

The invention also discloses a preparation method of the modified silane end-capping reagent, which comprises the following steps:

1) adding 4-hydroxybutyl vinyl ether and a catalyst A into a reaction bottle, heating to 60-65 ℃, dropwise adding hydrosilane, and reacting for 2-6 hours at 60-100 ℃ after dropwise adding; the molar ratio of the added 4-hydroxybutyl vinyl ether to the hydrosilane is 1: 1.00 to 1.50;

2) after the reaction is finished, performing negative pressure rectification to obtain hydroxyl-terminated silane;

3) adding the hydroxyl-terminated silane obtained in the step 2) and a catalyst B into a reaction bottle, heating to 50 ℃, then starting to dropwise add p-toluenesulfonyl isocyanate, and reacting at 50-80 ℃ for 1-3 hours after dropwise adding; the molar ratio of the added hydroxyl-terminated silane to the p-toluenesulfonyl isocyanate is 1: 1.0-1.5;

4) and 3) distilling the reaction liquid obtained in the step 3) under reduced pressure to remove unreacted p-toluenesulfonyl isocyanate to obtain the modified silane.

Further, the catalyst A in the step 1) is a Speier catalyst-organic amine system, and the organic amine comprises one of the following: n-tributylamine, dimethylaniline, aniline, or n-butylamine.

Further, the catalyst B in the step 3) is one of the following: organotin, organobismuth, or organozinc.

Further, the hydrosilane in the step 1) comprises trimethoxyhydrosilane or methyldimethoxysilane.

Further, the input mass of the catalyst B in the step 3) is 1 per mill-1% of the total input mass in the step 3).

The invention also discloses application of the modified silane end-capping reagent, and the modified silane end-capping reagent is applied to an end-capping reagent for a polyurethane sealant.

Compared with the prior art, the invention has the following beneficial effects:

1. the preparation conditions of the active secondary amino silane are simple and easy to implement, the process of end-capping modification of polyurethane prepolymer by the active secondary amino silane is easy to control, the gel phenomenon can not be generated, and the product has good reproducibility during preparation.

2. The invention designs reasonable secondary amine groups in the molecular structure, and can better perform end-capping reaction with polyurethane prepolymer; meanwhile, a benzene ring is introduced into the molecular structure, so that the chemical resistance of the material is endowed; in addition, enough active reaction groups are constructed in the molecular structure, and can be reacted with the polyurethane prepolymer to endow the silane modified polyurethane with cohesiveness. After the prepolymer containing-NCO is blocked by the modified silane blocking agent synthesized by the invention, the obtained silanized resin can be subjected to moisture vulcanization at room temperature through hydrolysis and polycondensation of the end group (alkoxy silane), and the formed silica skeleton has stability to heat, solvent and ultraviolet radiation.

In a word, the modified silane end-capping agent disclosed by the invention is simple in preparation method, low in cost, environment-friendly and convenient for industrialization. The prepared modified silane end-capping agent can improve the storage stability, high and low temperature resistance, ultraviolet stability and cohesiveness of the sealant.

Detailed Description

In order to explain technical contents, structural features, and objects and effects of the technical means in detail, the following detailed description is given with reference to specific embodiments.

Example 1

First, 117 grams (1mol) of 4-hydroxybutyl vinyl ether was metered into a 500ml four-necked flask, and 0.0117g of Speier-n-tributylamine system catalyst (5% concentration of chloroplatinic acid solution in Speier catalyst) was added; heating and stirring, when the temperature is raised to 60 ℃, weighing 122 g (1mol) of trimethoxyhydrosilane, and starting to dropwise add. During the dropping, there is an exothermic phenomenon. After the trimethoxyhydrosilane was added dropwise over about two hours, the reaction was continued at 75 ℃ and stirred for 4 hours. Sampling and GC analysis show that the content of hydroxysilane in the intermediate end is 85 percent, and the content of isomer is 7 percent. And finally, rectifying the obtained crude product to obtain the hydroxyl-terminated silane with the content of 97%.

119.5g (0.5mol) of the hydroxyl-terminated silane synthesized in the previous step is added into a 500ml four-neck flask, and 0.218g of dibutyl tin dilaurate is added; heating and stirring, weighing 98.5g of p-toluenesulfonyl isocyanate when the temperature is raised to 50 ℃, starting dropwise adding, keeping the temperature at 65 ℃ for reaction and stirring for 2 hours after the dropwise adding is finished for about 1.5 hours. And after the reaction is finished, distilling the reaction liquid under reduced pressure to remove unreacted p-toluenesulfonyl isocyanate to obtain the p-toluenesulfonyl polyurethane-based butoxyethyl trimethoxysilane. Sampling and analyzing, wherein the content of the p-toluenesulfonylpolyurethane butoxyethyltrimethoxysilane is 90%;

example 2

Firstly, 117g (1mol) of 4-hydroxybutyl vinyl ether is metered into a 500ml four-neck flask, and 0.0117g of Speier-aniline system catalyst (the concentration of chloroplatinic acid solution in the Speier catalyst is 5%) is added; after the temperature was raised to 60 ℃ with stirring, 183 g (1.5mol) of trimethoxyhydrosilane were weighed out and added dropwise. During the dropping, there is an exothermic phenomenon. After the trimethoxyhydrosilane is added dropwise in about two hours, the temperature is kept at 60 ℃ and the reaction and stirring are carried out for 6 hours. Sampling GC analysis shows that the intermediate terminal hydroxyl silane content is 88 percent, and the isomer content is 6 percent. And finally, rectifying the obtained crude product to obtain the hydroxyl-terminated silane with the content of 97%.

119.5g (0.5mol) of the hydroxyl-terminated silane synthesized in the last step is added into a 500ml four-neck flask, and 0.218g of bismuth laurate is added; heating and stirring, when the temperature is raised to 50 ℃, weighing 147.5g (0.75mol) of p-toluenesulfonyl isocyanate, starting dropwise adding, after about 1.5 hours, continuously keeping the temperature at 50 ℃ for reaction and stirring for 3 hours. And after the reaction is finished, distilling the reaction liquid under reduced pressure to remove unreacted p-toluenesulfonyl isocyanate to obtain the p-toluenesulfonyl polyurethane-based butoxyethyl trimethoxysilane. Sampling and analyzing, wherein the content of the p-toluenesulfonylpolyurethane butoxyethyltrimethoxysilane is 90%;

example 3

First, 117g (1mol) of 4-hydroxybutyl vinyl ether was metered into a 500ml four-necked flask, and 0.117g of Speier-dimethylaniline system catalyst (5% concentration of chloroplatinic acid solution in Speier catalyst) was added; after stirring and heating to 65 ℃, 132 g (1.25mol) of methyldimethoxysilane was weighed out and added dropwise. During the dropping, there is an exothermic phenomenon. After the methyl dimethoxy hydrosilane is added dropwise for about two hours, the temperature is kept at 80 ℃ and the reaction is stirred for 4 hours. Sampling and GC analysis show that the content of hydroxysilane in the intermediate end is 87 percent, and the content of isomer is 6 percent. And finally, rectifying the obtained crude product to obtain the hydroxyl-terminated silane with the content of 97%.

119.5g (0.5mol) of the hydroxyl-terminated silane synthesized in the last step is added into a 500ml four-neck flask, and 2.42g of new bismuth decanoate is added; heating and stirring, when the temperature is raised to 50 ℃, weighing 123.5g (0.75mol) of p-toluenesulfonyl isocyanate, starting dropwise adding, after finishing dropwise adding about 1.5 hours, continuously keeping the temperature at 80 ℃ for reaction and stirring for 1 hour. And (3) after the reaction is finished, distilling the reaction liquid under reduced pressure to remove unreacted p-toluenesulfonyl isocyanate to obtain the p-toluenesulfonylpolyurethane butoxyethyl methyldimethoxysilane. Sampling and analyzing, wherein the content of the p-toluenesulfonylpolyurethane butoxyethylmethyldimethoxysilane is 85%;

example 4

First, 117g (1mol) of 4-hydroxybutyl vinyl ether was metered into a 500ml four-necked flask, and 0.0117g of Speier-n-butylamine system catalyst (concentration of chloroplatinic acid solution in Speier catalyst: 5%) was added; after the temperature was raised to 60 ℃ with stirring, 112 g (1.25mol) of dimethylmethoxyhydrosilane was weighed out and added dropwise. During the dropping, there is an exothermic phenomenon. After the dimethyl methoxy hydrosilane was added dropwise over about two hours, the reaction was continued at 75 ℃ with stirring for 4 hours. Sampling and GC analysis show that the content of hydroxysilane in the intermediate end is 90 percent, and the content of isomer is 5 percent. And finally, rectifying the obtained crude product to obtain the hydroxyl-terminated silane with the content of 96%.

119.5g (0.5mol) of the hydroxyl-terminated silane synthesized in the last step is added into a 500ml four-neck flask, and 2.42g of zinc neodecanoate is added; heating and stirring, when the temperature is raised to 50 ℃, weighing 123.5g (0.75mol) of p-toluenesulfonyl isocyanate, starting dropwise adding, after about 1.5 hours, continuously keeping the temperature at 70 ℃ for reaction and stirring for 2 hours. And (3) after the reaction is finished, distilling the reaction liquid under reduced pressure to remove unreacted p-toluenesulfonyl isocyanate to obtain the p-toluenesulfonylpolyurethane butoxyethyl methyldimethoxysilane. The sample was analyzed, and the p-toluenesulfonylpolyurethane butoxyethylmethyldimethoxysilane content was 87%;

example 5

First, 117g (1mol) of 4-hydroxybutyl vinyl ether was metered into a 500ml four-necked flask, and 0.0117g of Speier-n-butylamine system catalyst (concentration of chloroplatinic acid solution in Speier catalyst: 5%) was added; the temperature is increased and stirred, when the temperature is increased to 60 ℃, 152 g (1mol) of trimethoxyhydrosilane is weighed and dropwise added. During the dropping, there is an exothermic phenomenon. After the trimethoxyhydrosilane is added dropwise in about two hours, the temperature is kept at 90 ℃ and the reaction and stirring are carried out for 3 hours. Sampling GC analysis shows that the intermediate terminal hydroxyl silane content is 81 percent, and the isomer content is 12 percent. And finally, rectifying the obtained crude product to obtain the hydroxyl-terminated silane with the content of 97%.

119.5g (0.5mol) of the hydroxyl-terminated silane synthesized in the previous step is added into a 500ml four-neck flask, and 2.42g of dibutyl tin dilaurate is added; heating and stirring, when the temperature is raised to 50 ℃, weighing 98.5g (0.5mol) of p-toluenesulfonyl isocyanate, starting dropwise adding, after about 1.5 hours, continuously keeping the temperature at 65 ℃ for reaction and stirring for 2 hours. And after the reaction is finished, distilling the reaction liquid under reduced pressure to remove unreacted p-toluenesulfonyl isocyanate to obtain the p-toluenesulfonyl polyurethane-based butoxyethyl trimethoxysilane. The sampling analysis shows that the content of the p-toluenesulfonylpolyurethane butoxyethyltrimethoxysilane is 87 percent;

example 6

First, 117g (1mol) of 4-hydroxybutyl vinyl ether was metered into a 500ml four-necked flask, and 0.0117g of Speier-n-butylamine system catalyst (concentration of chloroplatinic acid solution in Speier catalyst: 5%) was added; the temperature is increased and stirred, when the temperature is increased to 60 ℃, 152 g (1.25mol) of trimethoxyhydrosilane is weighed and dropwise added. During the dropping, there is an exothermic phenomenon. After the trimethoxyhydrosilane is added dropwise in about two hours, the temperature is kept at 100 ℃ and the reaction and stirring are carried out for 2 hours. Sampling and GC analysis show that the content of hydroxysilane in the intermediate end is 80 percent, and the content of isomer is 11 percent. And finally, rectifying the obtained crude product to obtain the hydroxyl-terminated silane with the content of 97%.

119.5g (0.5mol) of the hydroxyl-terminated silane synthesized in the previous step is added into a 500ml four-neck flask, and 0.242g of dibutyl tin dilaurate is added; heating and stirring, when the temperature is raised to 50 ℃, weighing 123.5g (0.75mol) of p-toluenesulfonyl isocyanate, starting dropwise adding, after about 1.5 hours, continuously keeping the temperature at 65 ℃ for reaction and stirring for 2 hours. And after the reaction is finished, distilling the reaction liquid under reduced pressure to remove unreacted p-toluenesulfonyl isocyanate to obtain the p-toluenesulfonyl polyurethane-based butoxyethyl trimethoxysilane. The sampling analysis shows that the content of the p-toluenesulfonylpolyurethane butoxyethyltrimethoxysilane is 87 percent;

the silane-modified polyurethane resins were prepared by using p-toluenesulfonylpolyurethane butoxyethyltrimethoxysilane or p-toluenesulfonylpolyurethane butoxyethylmethyldimethoxysilane obtained in examples 1 to 6 as a terminal blocking agent, and compared with anilinopropyltrimethoxysilane and aminopropyltrimethoxysilane.

Application examples

Polyether (viscosity 12000mPa.s) is reacted with hexamethylene diisocyanate to obtain an isocyanate-terminated prepolymer.

Example 7

2 kg of isocyanate-terminated prepolymer was charged into a 5L planetary mixer, and 40g of p-toluenesulfonylpolyurethane butoxyethyltrimethoxysilane prepared in example 1 as a terminal-blocking agent were added, and the reaction temperature was controlled at 80 ℃ for 5 hours. And detecting the NCO content in a titration mode, wherein the reaction end point is obtained when the content is 0. Thus obtaining the silane modified polyurethane resin.

In the above example, dibutyl tin dilaurate, the catalyst added in step 2) of example 1, was also the catalyst for this reaction, and therefore, there was no need to isolate dibutyl tin dilaurate, the catalyst in example 1.

Examples 8 to 12

The procedure of example 7 was repeated except for replacing p-toluenesulfonylpolycarbamoylbutoxyethyltrimethoxysilane with the silane-modified terminal-blocking agent prepared in examples 2 to 6 to obtain silane-modified polyurethane resins of examples 8 to 12, respectively.

Example 13

The procedure of example 7 was repeated except for replacing p-toluenesulfonylpolyaminobutoxyethyltrimethoxysilane with anilinopropyltrimethoxysilane to obtain a silane-modified polyurethane resin of example 13.

Example 14

The same operation as in example 7 was carried out except for replacing p-toluenesulfonylpolyaminobutoxyethyltrimethoxysilane with aminopropyltrimethoxysilane in example 7 to obtain a silane-modified polyurethane resin of example 14.

Examples 13 and 14 are comparative examples of the present invention.

Sealants were prepared from the silane-modified polyurethane resins prepared in examples 7 to 14, respectively, according to the following formulations.

And vulcanizing the obtained sealant sample, wherein the specific vulcanization comprises the following steps: the mixture was allowed to stand at 23 ℃ in an environment of 50% relative humidity for 3 days, and then at 50 ℃ in an environment of 50% relative humidity for 4 days.

The performance of the cured samples of the sealants prepared from the silane-modified polyurethane resins of examples 7 to 14 was tested. Mechanical properties were tested using ASTM standard methods. The samples were tested for tensile strength, elongation, Shore A hardness (ASTM C-661). Specific test results are shown in table 1.

TABLE 1 test properties of sealants prepared in examples 7-14

As can be seen from the above table, the modified silane prepared by the invention can be used as an end-capping agent for preparing the silane modified polyurethane resin, and the sealant further prepared from the prepared silane modified polyurethane resin has better tensile strength and elongation than the sealant prepared from anilinopropyltrimethoxysilane or aminopropyltrimethoxysilane.

The sealants prepared in examples 7 to 14 were subjected to the adhesion performance test after the UV-transparent aging treatment, and the test results are shown in table 2.

TABLE 2 data for testing the adhesion of the sealants of examples 7-14 after UV through aging

As can be seen from Table 2, the modified silane prepared by the invention is used as the end-capping agent for preparing the silane modified polyurethane resin, the wet bonding strength of the prepared sealant is basically kept unchanged after the UV transmission aging treatment, and the anilino propyl trimethoxy silane or aminopropyl trimethoxy silane is used as the end-capping agent for preparing the silane modified polyurethane resin, so that the wet bonding strength of the prepared sealant is obviously reduced after the UV transmission aging treatment, and is reduced to 2.3MPa from 3.5 MPa. This is because the C-C bond in the polyether is weak and is broken by ultraviolet rays for a long time. After the modified silane is used for end capping, Si-C bonds are generated at two ends of polyether, the bond energy is strong, and ether bonds and carbon-carbon long chains exist in the molecular structure of the modified silane, so that the modified silane has better compatibility with the polyether, stronger acting force can be brought, and the anti-aging performance of resin is greatly enhanced.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or terminal that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or terminal. Without further limitation, an element defined by the phrases "comprising … …" or "comprising … …" does not exclude the presence of additional elements in a process, method, article, or terminal that comprises the element. Further, herein, "greater than," "less than," "more than," and the like are understood to exclude the present numbers; the terms "above", "below", "within" and the like are to be understood as including the number.

It should be noted that, although the above embodiments have been described herein, the invention is not limited thereto. Therefore, based on the innovative concepts of the present invention, the technical solutions of the present invention can be directly or indirectly applied to other related technical fields by making changes and modifications to the embodiments described herein or by using equivalent structures or equivalent processes performed in the present specification, and are included in the scope of the present invention.

Claims

1. A modified silane end-capping agent characterized by: the structure is shown as formula 1:

in formula 1, R is methyl or methoxy.

2. The method for producing the modified silane end-capping agent according to claim 1, wherein: which comprises the following steps:

1) adding 4-hydroxybutyl vinyl ether and a catalyst A into a reaction bottle, heating to 60-65 ℃, dropwise adding hydrosilane, and reacting for 2-6 hours at 60-100 ℃ after dropwise adding; the molar ratio of the charged 4-hydroxybutyl vinyl ether to the hydrosilane is 1: 1.00 to 1.50;

4) carrying out reduced pressure distillation on the reaction liquid obtained in the step 3) to remove unreacted p-toluenesulfonyl isocyanate, so as to obtain the modified silane;

the catalyst A in the step 1) is a Speier catalyst-organic amine system, and the organic amine comprises one of the following: n-tributylamine, dimethylaniline, aniline, or n-butylamine;

the catalyst B in the step 3) is one of the following: organotin, organobismuth, or organozinc.

3. The method for producing the modified silane end-capping agent according to claim 2, wherein: the hydrosilane in the step 1) comprises trimethoxyhydrosilane or methyldimethoxysilane.

4. The method for producing the modified silane end-capping agent according to claim 2, wherein: the input mass of the catalyst B in the step 3) is 1 per mill-1% of the total input mass of the step 3).

5. The use of the modified silane capping agent of claim 1, wherein: the modified silane end-capping agent is applied to an end-capping agent for a polyurethane sealant.