Modified cross-linking agent, dealcoholized silicone sealant with high curing speed and good heat resistance and preparation method of dealcoholized silicone sealant

Abstract

The invention provides a modified cross-linking agent, a dealcoholized silicone sealant with high curing speed and good heat resistance and a preparation method of the dealcoholized silicone sealant. According to the preparation method, a compound substrate containing a triaminobenzene structure and isocyanate trimethoxy silane are taken as raw materials, and the modified alkoxy cross-linking agent containing three ureido groups is synthesized. The dealcoholized silicone sealant is prepared from the cross-linking agent, alpha, omega-dihydroxy polydimethylsiloxane, an inorganic filler, a cross-linking agent, a catalyst, a coupling agent and the like in an alcohol system. Compared with an original system, the curing depth and the heat resistance of the silicone sealant prepared by adopting the preparation method are improved, meanwhile, good mechanical properties are kept, the mechanical strength is partially improved, and the improvement of the requirements on the heat resistance and the curing speed of the silicone sealant in the fields of the industry and the building industry is overcome to a certain extent; the use scene of the dealcoholized silicone sealant is expanded, and the method has great significance in improving the construction performance and prolonging the service life of the silicone sealant in a high-temperature environment.

Description

Technical Field

[0001] The invention relates to the field of silicone sealant materials, and in particular to a modified cross-linking agent, a dealcoholized silicone sealant with fast curing speed and good heat resistance, and a preparation method thereof. Background Art

[0002] Dealcoholized room temperature vulcanized silicone rubber can absorb water molecules in the air to undergo cross-linking reactions and remove small alcohol molecules to form an elastomer. Due to its stable chemical properties and strong weather resistance, this silicone rubber is often used in the construction industry, aerospace industry, and electronic communications. However, with the development of the industrial and construction industries, there is a higher demand for the curing speed and heat resistance of dealcoholized silicone sealants.

[0003] In order to make the dealcohol silicone sealant meet the above needs, the industry provides many solutions. For example, CN115975591B improves the crosslinking activity of the modified crosslinking agent through the electron-donating ability of the highly active group, so that the sealant can still be cured more quickly under the condition of less water vapor. However, the design of the crosslinking agent adopts a low-polymerization scheme in order to increase the crosslinking site, which causes the activity of the crosslinking agent to fluctuate due to the low controllability of the degree of polymerization, and the activity of the crosslinking agent is too high due to the high degree of polymerization and too many active groups, resulting in a shelf life problem. CN116239991A uses an organoaluminum compound as the first catalyst and a phthalate compound as the second catalyst to accelerate the curing depth of the silicone sealant obtained, and the effect is obvious. However, this method introduces an additional aluminum atom metal catalyst, which has certain pollution to the environment, and the instability of the metal catalyst is also difficult to distinguish in the short term.

[0004] In addition, in order to improve heat resistance, many solutions have proposed adding high temperature degradation inhibitors, metal oxides and other methods. For example, CN116376512B adds modified basalt fiber and magnesium copper oxide to the sealant system, and the mechanical properties, fire resistance and heat resistance of the prepared silicone sealant are improved. However, due to the introduction of new substances by physical addition, it may increase the difficulty of powder separation in the actual production process, resulting in problems such as poor appearance.

[0005] Based on this, the present invention designs a modified cross-linking agent, a dealcoholized silicone sealant with fast curing speed and good heat resistance, and a preparation method thereof. Summary of the invention

[0006] The present invention provides a modified cross-linking agent, a dealcoholized silicone sealant with fast curing speed and good heat resistance and a preparation method thereof, the purpose of which is to solve the above-mentioned problems existing in the background technology.

[0007] In order to achieve the above-mentioned purpose, the embodiments of the present invention provide a modified cross-linking agent and a dealcoholized silicone sealant with fast curing speed and good heat resistance and a preparation method thereof. The present invention develops a new cross-linking agent that can improve the heat resistance and curing depth of the dealcoholized silicone sealant, and obtains a dealcoholized silicone sealant based on this. The present invention uses a triaminobenzene structure compound substrate and isocyanate trimethoxysilane as raw materials to synthesize a modified alkoxy cross-linking agent containing three urea groups. The dealcoholized silicone sealant is prepared by reacting the cross-linking agent with α, ω-dihydroxy polydimethylsiloxane, inorganic filler, catalyst, coupling agent, etc. in an alcohol system. Compared with the original system, the curing depth and heat resistance of the silicone sealant prepared by this invention are improved, while maintaining good mechanical properties, and the mechanical strength is partially improved. To a certain extent, it overcomes the increased requirements for heat resistance and curing speed of silicone sealants in the industrial and construction industries, expands the use scenarios of dealcoholized silicone sealants, and is of great significance to improving construction performance and extending the service life of silicone sealants in high temperature environments.

[0008] In one aspect, an embodiment of the present invention provides a modified crosslinking agent for a dealcoholized silicone sealant, wherein the modified crosslinking agent is a triuretylphenyl-modified alkoxysilane having the following structural formula:

[0009]

[0010] The embodiments of the present invention further provide a method for preparing the modified crosslinking agent for dealcoholized silicone sealant, comprising the following steps:

[0011] Under the protection of inert gas, 1,3,5-triaminobenzene and isocyanatepropyltrimethoxysilane are subjected to addition reaction in the presence of solvent acetone and an organic tin catalyst, and the reaction is performed under reduced pressure distillation and column chromatography to prepare the modified crosslinking agent.

[0012] Wherein, the structure of the 1,3,5-triaminobenzene is as follows:

[0013]

[0014] The structure of the isocyanate propyl trimethoxy silane is as follows:

[0015]

[0016] Preferably, the molar ratio of the 1,3,5-triaminobenzene to isocyanatepropyltrimethoxysilane is 1:3.

[0017] Preferably, the addition reaction temperature is 60° C. and the addition reaction time is 5 h.

[0018] Preferably, the organotin catalyst is at least one of dibutyltin dilaurate, dibutyltin diacetate or triethylamine; the molar ratio of the organotin catalyst to isocyanatepropyltrimethoxysilane is 10 -6 :1.

[0019] Another aspect of the embodiment of the present invention provides a dealcoholized silicone sealant having fast curing speed and good heat resistance, wherein, by weight, 2 to 12 parts of the modified crosslinking agent as claimed in claim 1;

[0020] Also includes the following components:

[0021]

[0022] Preferably, the viscosity of the α,ω-dihydroxypolydimethylsiloxane at 25° C. is 5000 mPa.s to 150000 mPa.s.

[0023] Preferably, the viscosity of the dimethyl silicone oil at 25° C. is 100 mPa.s to 10000 mPa.s.

[0024] Preferably, the filler is active nano-calcium carbonate with a particle size of 20nm to 200nm.

[0025] Preferably, the crosslinking agent is at least one of methyltrimethoxysilane, vinyltrimethoxysilane, and phenyltrimethoxysilane; and the mass ratio of the crosslinking agent to triureidophenyl-modified alkoxysilane is 0.3 to 10:2.

[0026] Preferably, the coupling agent is at least one of γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, glycidyltriethoxysilane and glycidyltrimethoxysilane.

[0027] Preferably, the catalyst is diisopropyl bis(ethyl acetoacetate) titanate.

[0028] Based on a general concept of the invention, an embodiment of the present invention provides a method for preparing the above-mentioned dealcoholized silicone sealant, comprising the following steps:

[0029] S1: Add α,ω-dihydroxy polydimethylsiloxane, dimethyl silicone oil and filler into a kneader, control the temperature at 60-160°C, the vacuum degree at -0.06MPa--0.09MPa, dehydrate and blend for 45-300 minutes, and cool to obtain a base material;

[0030] S2: The base material is put into a planetary machine and dispersed and stirred for 5 to 10 minutes, the vacuum degree is -0.06MPa to -0.09MPa, and the rotation speed is 600 to 720rpm. Then, triuretylphenyl-modified alkoxysilane, coupling agent and catalyst are added to the planetary machine, and stirring is continued for 10 to 45 minutes. The vacuum degree is controlled at -0.045MPa to -0.09MPa, and the rotation speed is 600 to 720rpm to prepare the dealcoholized silicone sealant.

[0031] The above scheme of the present invention has the following beneficial effects:

[0032] (1) The present invention uses a triaminobenzene structure-containing compound substrate and isocyanate trimethoxysilane as raw materials to synthesize a modified alkoxy crosslinking agent containing three urea groups, introduces a rigid structure of the benzene ring by chemical modification, and the three amino groups on the benzene ring also provide a large number of methoxysilane crosslinking sites. The rigid structure of the benzene ring can improve the heat resistance of the silicone sealant. A large number of crosslinking sites strengthen the crosslinking density of the sealant, thereby improving the mechanical strength and curing depth of the sealant.

[0033] (2) The dealcoholization sealant of the present invention has a fast curing speed. Compared with the traditional low-polymerization degree cross-linking agent and the introduction of active groups, the present invention connects multiple main chain structures through the three amino groups of the phenyl group, and the cross-linking sites are concentrated on the rigid benzene ring, so the cross-linking density is high and the curing speed is fast.

[0034] (3) The dealcohol-free sealant of the present invention is environmentally friendly. It releases small alcohol molecules during the curing process, has little odor, and is non-corrosive to building substrates such as metal, concrete, and glass, minimizing the harm to the environment and human body.

[0035] (4) The dealcoholized sealant of the present invention maintains good mechanical properties. The higher cross-linking density enables the silicone sealant prepared by the present invention to maintain excellent mechanical strength, while the adhesion is also improved due to the presence of urea groups.

[0036] (5) The dealcoholized sealant of the present invention also has excellent heat resistance. DETAILED DESCRIPTION

[0037] In order to make the technical problems to be solved, technical solutions and advantages of the present invention more clear, they are described in detail below in conjunction with specific embodiments.

[0038] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0039] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0040] The curing speed of existing silicone sealants is not only affected by environmental factors, but also by the activity of the crosslinker and catalyst in the formula. Among them, the application of catalysts in silicone sealant systems is already very mature, while there is still a lot of room for optimization of crosslinkers. Although the common method of introducing active groups can improve the crosslinking activity of crosslinkers, due to the high electron donating ability of active groups, the crosslinker itself hydrolyzes too quickly, releasing small alcohol molecules, which is not conducive to taking into account both performance improvement and shelf life assurance. Although the crosslinking density can be increased simply by controlling the degree of polymerization through the use of oligomer crosslinkers, it is difficult to concentrate the crosslinking sites, resulting in difficulty in ensuring mechanical strength and mechanical properties.

[0041] In one aspect, an embodiment of the present invention provides a modified crosslinking agent for a dealcoholized silicone sealant, wherein the modified crosslinking agent is a triuretylphenyl-modified alkoxysilane having the following structural formula:

[0042]

[0043] The embodiments of the present invention further provide a method for preparing the modified crosslinking agent for dealcoholized silicone sealant, comprising the following steps:

[0044] Under the protection of inert gas, 1,3,5-triaminobenzene and isocyanatepropyltrimethoxysilane are subjected to addition reaction in the presence of solvent acetone and an organic tin catalyst, and the reaction is performed under reduced pressure distillation and column chromatography to prepare the modified crosslinking agent.

[0045] Wherein, the structure of the 1,3,5-triaminobenzene is as follows:

[0046]

[0047] The structure of the isocyanate propyl trimethoxy silane is as follows:

[0048]

[0049] Preferably, the molar ratio of the 1,3,5-triaminobenzene to isocyanatepropyltrimethoxysilane is 1:3.

[0050] Preferably, the addition reaction temperature is 60° C. and the addition reaction time is 5 h.

[0051] Preferably, the organotin catalyst is at least one of dibutyltin dilaurate, dibutyltin diacetate or triethylamine; the molar ratio of the organotin catalyst to isocyanatepropyltrimethoxysilane is 10 -6:1.

[0052] Another aspect of the embodiment of the present invention provides a dealcoholized silicone sealant having fast curing speed and good heat resistance, wherein, by weight, 2 to 12 parts of the modified crosslinking agent as claimed in claim 1;

[0053] Also includes the following components:

[0054]

[0055] Preferably, the viscosity of the α,ω-dihydroxypolydimethylsiloxane at 25° C. is 5000 mPa.s to 150000 mPa.s.

[0056] Preferably, the viscosity of the dimethyl silicone oil at 25° C. is 100 mPa.s to 10000 mPa.s.

[0057] Preferably, the filler is active nano-calcium carbonate with a particle size of 20nm to 200nm.

[0058] Preferably, the crosslinking agent is at least one of methyltrimethoxysilane, vinyltrimethoxysilane, and phenyltrimethoxysilane; and the mass ratio of the crosslinking agent to triureidophenyl-modified alkoxysilane is 0.3 to 10:2.

[0059] Preferably, the coupling agent is at least one of γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, glycidyltriethoxysilane and glycidyltrimethoxysilane.

[0060] Preferably, the catalyst is diisopropyl bis(ethyl acetoacetate) titanate.

[0061] Based on a general concept of the invention, an embodiment of the present invention provides a method for preparing the above-mentioned dealcoholized silicone sealant, comprising the following steps:

[0062] S1: Add α,ω-dihydroxy polydimethylsiloxane, dimethyl silicone oil and filler into a kneader, control the temperature at 60-160°C, the vacuum degree at -0.06MPa--0.09MPa, dehydrate and blend for 45-300 minutes, and cool to obtain a base material;

[0063] S2: The base material is put into a planetary machine and dispersed and stirred for 5 to 10 minutes, the vacuum degree is -0.06MPa to -0.09MPa, and the rotation speed is 600 to 720rpm. Then, triuretylphenyl-modified alkoxysilane, coupling agent and catalyst are added to the planetary machine, and stirring is continued for 10 to 45 minutes. The vacuum degree is controlled at -0.045MPa to -0.09MPa, and the rotation speed is 600 to 720rpm to prepare the dealcoholized silicone sealant.

[0064] The following is a detailed description through specific embodiments.

[0065] Example 1

[0066] This embodiment provides a method for preparing a dealcoholized silicone sealant with fast curing speed and good heat resistance.

[0067] The method of this embodiment specifically includes the following steps:

[0068] Step 1: Take 100 parts of α,ω-dihydroxy polydimethylsiloxane with a viscosity of 50000 mPa·s, 120 parts of active nano calcium carbonate with an average particle size of 50 nm, and 5 parts of dimethyl silicone oil with a viscosity of 500 mPa·s, add them into a kneader, dehydrate and blend for 120 minutes at a temperature of 120°C and a vacuum degree of -0.09 MPa, and cool to obtain a base material for standby use;

[0069] Step 2: Add the above base material to a planetary mixer, and then add 5 parts of methyltrimethoxysilane, 2 parts of triuretphenyl modified methoxysilane crosslinker, 2 parts of γ-aminopropyltrimethoxysilane, and 4 parts of diisopropyl bis(ethyl acetoacetate) titanate catalyst, and carry out chemical reaction for 45 minutes under the conditions of vacuum degree of -0.09 MPa and rotation speed of 600 rpm to prepare the dealcoholized silicone sealant.

[0070] Example 2

[0071] This embodiment provides a method for preparing a dealcoholized silicone sealant with fast curing speed and good heat resistance.

[0072] The method of this embodiment specifically includes the following steps:

[0073] Step 1: Take 100 parts of α,ω-dihydroxy polydimethylsiloxane with a viscosity of 50000 mPa·s, 120 parts of active nano calcium carbonate with an average particle size of 50 nm, and 5 parts of dimethyl silicone oil with a viscosity of 500 mPa·s, add them into a kneader, dehydrate and blend for 120 minutes at a temperature of 120°C and a vacuum degree of -0.09 MPa, and cool to obtain a base material for standby use;

[0074] Step 2: Add the above base material to a planetary mixer, and then add 3 parts of methyltrimethoxysilane, 6 parts of triureaphenyl modified methoxysilane crosslinker, 2 parts of γ-aminopropyltrimethoxysilane, and 4 parts of diisopropyl bis(ethyl acetoacetate) titanate catalyst, and carry out chemical reaction for 45 minutes under the conditions of vacuum degree of -0.09 MPa and rotation speed of 600 rpm to prepare the dealcoholized silicone sealant.

[0075] Example 3

[0076] This embodiment provides a method for preparing a dealcoholized silicone sealant with fast curing speed and good heat resistance.

[0077] The method of this embodiment specifically includes the following steps:

[0078] Step 1: Take 100 parts of α,ω-dihydroxy polydimethylsiloxane with a viscosity of 50000 mPa·s, 120 parts of active nano calcium carbonate with an average particle size of 50 nm, and 5 parts of dimethyl silicone oil with a viscosity of 500 mPa·s, add them into a kneader, dehydrate and blend for 120 minutes at a temperature of 120°C and a vacuum degree of -0.09 MPa to obtain a base material, and then cool it for use;

[0079] Step 2: Add the above base material to a planetary mixer, and then add 2 parts of methyltrimethoxysilane, 8 parts of triuretphenyl modified methoxysilane crosslinker, 2 parts of γ-aminopropyltrimethoxysilane, and 4 parts of diisopropyl bis(ethyl acetoacetate) titanate catalyst, and carry out chemical reaction for 45 minutes under the conditions of vacuum degree of -0.09 MPa and rotation speed of 600 rpm to prepare the dealcoholized silicone sealant.

[0080] Example 4

[0081] This embodiment provides a method for preparing a dealcoholized silicone sealant with fast curing speed and good heat resistance.

[0082] The method of this embodiment specifically includes the following steps:

[0083] Step 1: Take 100 parts of α,ω-dihydroxy polydimethylsiloxane with a viscosity of 50000 mPa·s, 120 parts of active nano calcium carbonate with an average particle size of 50 nm, and 5 parts of dimethyl silicone oil with a viscosity of 500 mPa·s, add them into a kneader, dehydrate and blend for 120 minutes at a temperature of 120°C and a vacuum degree of -0.09 MPa to obtain a base material, and then cool it for use;

[0084] Step 2: Add the above base material to a planetary mixer, and then add 4 parts of vinyltrimethoxysilane, 4 parts of triureaphenyl modified methoxysilane crosslinker, 2 parts of γ-aminopropyltrimethoxysilane, and 4 parts of diisopropyl bis(ethyl acetoacetate) titanate catalyst, and carry out a chemical reaction for 45 minutes under the conditions of a vacuum degree of -0.09 MPa and a rotation speed of 600 rpm to prepare the dealcoholized silicone sealant.

[0085] Example 5

[0086] This embodiment provides a method for preparing a dealcoholized silicone sealant with fast curing speed and good heat resistance.

[0087] The method of this embodiment specifically includes the following steps:

[0088] Step 1: Take 100 parts of α,ω-dihydroxy polydimethylsiloxane with a viscosity of 50000 mPa·s, 120 parts of active nano calcium carbonate with an average particle size of 50 nm, and 5 parts of dimethyl silicone oil with a viscosity of 500 mPa·s, add them into a kneader, dehydrate and blend for 120 minutes at a temperature of 120°C and a vacuum degree of -0.09 MPa to obtain a base material, and then cool it for use;

[0089] Step 2: Add the above base material to a planetary mixer, and then add 4.5 parts of phenyltrimethoxysilane, 3 parts of triureaphenyl modified methoxysilane crosslinker, 2 parts of γ-aminopropyltrimethoxysilane, and 4 parts of diisopropyl bis(ethyl acetoacetate) titanate catalyst, and carry out a chemical reaction for 45 minutes under the conditions of a vacuum degree of -0.09 MPa and a rotation speed of 600 rpm to prepare the dealcoholized silicone sealant.

[0090] This comparative example provides a silicone sealant, which is different from the embodiment in that the proportion of the added composite cross-linking agent is changed.

[0091] Comparative Example 1

[0092] This comparative example provides a silicone sealant, which is different from the embodiment in that a cross-linking agent is completely added without adding triureidophenyl-modified alkoxysilane, and specifically comprises the following steps:

[0093] Step 1: Take 100 parts of α,ω-dihydroxy polydimethylsiloxane with a viscosity of 50000 mPa·s, 120 parts of active nano calcium carbonate with an average particle size of 50 nm, and 5 parts of dimethyl silicone oil with a viscosity of 500 mPa·s, add them into a kneader, dehydrate and blend for 120 minutes at a temperature of 120°C and a vacuum degree of -0.09 MPa to obtain a base material, and then cool it for use;

[0094] Step 2: Add the above base material to a planetary mixer, then add 6 parts of methyltrimethoxysilane crosslinker, 2 parts of γ-aminopropyltrimethoxysilane, and 4 parts of diisopropyl bis(ethyl acetoacetate) titanate catalyst, and carry out chemical reaction for 45 minutes under the conditions of vacuum degree of -0.09 MPa and rotation speed of 600 rpm to prepare the silicone sealant.

[0095] Comparative Example 2

[0096] This comparative example provides a silicone sealant, which is different from the embodiment in that triuretylphenyl-modified alkoxysilane is used completely without adding a crosslinking agent, and specifically comprises the following steps:

[0097] Step 1: Take 100 parts of α,ω-dihydroxy polydimethylsiloxane with a viscosity of 50000 mPa·s, 120 parts of active nano calcium carbonate with an average particle size of 50 nm, and 5 parts of dimethyl silicone oil with a viscosity of 500 mPa·s, add them into a kneader, dehydrate and blend for 120 minutes at a temperature of 120°C and a vacuum degree of -0.09 MPa to obtain a base material, and then cool it for use;

[0098] Step 2: Add the above base material to a planetary mixer, and then add 12 parts of triuretphenyl modified methoxysilane crosslinker, 2 parts of γ-aminopropyltrimethoxysilane, and 4 parts of diisopropyl bis(ethyl acetoacetate) titanate catalyst, and carry out chemical reaction for 45 minutes under the conditions of vacuum degree of -0.09 MPa and rotation speed of 600 rpm to prepare the silicone sealant.

[0099] Comparative Example 3

[0100] This comparative example provides a silicone sealant, which is different from the embodiment in that the mass ratio of the crosslinking agent to the triuretylphenyl modified alkoxysilane crosslinking agent is 1:10, and specifically comprises the following steps:

[0101] Step 1: Take 100 parts of α,ω-dihydroxy polydimethylsiloxane with a viscosity of 50000 mPa·s, 120 parts of active nano calcium carbonate with an average particle size of 50 nm, and 5 parts of dimethyl silicone oil with a viscosity of 500 mPa·s, add them into a kneader, dehydrate and blend for 120 minutes at a temperature of 120°C and a vacuum degree of -0.09 MPa to obtain a base material, and then cool it for use;

[0102] Step 2: Add the above base material to a planetary mixer, and then add 1 part of methyltrimethoxysilane, 10 parts of triuretphenyl modified methoxysilane crosslinker, 2 parts of γ-aminopropyltrimethoxysilane, and 4 parts of diisopropyl bis(ethyl acetoacetate) titanate catalyst, and carry out chemical reaction for 45 minutes under the conditions of vacuum degree of -0.09 MPa and rotation speed of 600 rpm to prepare the silicone sealant.

[0103] Comparative Example 4

[0104] This comparative example provides a silicone sealant, which is different from the embodiment in that the mass ratio of the crosslinking agent to the triuretylphenyl modified alkoxysilane crosslinking agent is 5.5:1, and specifically comprises the following steps:

[0105] Step 1: Take 100 parts of α,ω-dihydroxy polydimethylsiloxane with a viscosity of 50000 mPa·s, 120 parts of active nano calcium carbonate with an average particle size of 50 nm, and 5 parts of dimethyl silicone oil with a viscosity of 500 mPa·s, add them into a kneader, dehydrate and blend for 120 minutes at a temperature of 120°C and a vacuum degree of -0.09 MPa to obtain a base material, and then cool it for use;

[0106] Step 2: Add the above base material to a planetary mixer, and then add 5.5 parts of methyltrimethoxysilane, 1 part of triureaphenyl modified methoxysilane crosslinker, 2 parts of γ-aminopropyltrimethoxysilane, and 4 parts of diisopropyl bis(ethyl acetoacetate) titanate catalyst, and carry out a chemical reaction for 45 minutes under the conditions of a vacuum degree of -0.09 MPa and a rotation speed of 600 rpm to prepare the silicone sealant.

[0107] The silicone sealants in the above examples and comparative examples were made into H-type specimens according to GB / T 13477.8-2017 Test Methods for Building Sealing Materials Part 8: Determination of Tensile Adhesion, and cured for 28 days under standard conditions of temperature 23 (± 2) ° C and relative humidity 50 (± 10)%. The specimens were then stretched to failure at a speed of (5.5 ± 0.7) mm / min on a tensile testing machine at (23 ± 2) ° C, and the maximum tensile strength and maximum strength elongation were recorded. According to the "GB / T2941-2006 Rubber Physical Test Methods Sample Preparation and Conditioning General Procedure", the specified temperature and aging time were selected for aging. The prepared H-type test piece was placed in a (275±2)℃ oven for aging for 7 days, and according to the method of "GB 16776-2005 Silicone Structural Sealant for Buildings", the test piece was stretched to failure at a speed of (5.5±0.7)mm / min at (90±2)℃, and the maximum tensile strength and maximum strength elongation were recorded. According to the second method in "GB / T32369-2015 Determination of the degree of curing of sealants", the prepared test piece was cured for 24 hours under the standard conditions of 23(±2)℃ and 50(±5)% relative humidity, and the thickness of the cured layer was recorded. The detailed experimental results are shown in Table 1 below:

[0108] Table 1

[0109]

[0110]

[0111] As shown in Table 1 above, Examples 1, 2, 3, 4, 5 and Comparative Example 1 show that when a composite crosslinking agent within a specific ratio is added, the maximum tensile strength decay after aging is less than the decay without adding a composite crosslinking agent, and the maximum strength elongation decay after aging is less than the decay without adding a composite crosslinking agent, which can indicate that the high temperature resistance after adding a composite crosslinking agent is improved. It can be learned from Examples 1, 2, and 3 that as the proportion of triureaphenyl-modified methoxysilane crosslinking agent in the composite crosslinking agent increases, the tensile strength and curing depth of the prepared dealcoholized silicone sealant can be improved, and when the composite crosslinking agent mass fraction ratio is 2:8 parts, the comprehensive improvement effect is the best. Comparative Examples 2 and 3 show that when triureaphenyl-modified methoxysilane crosslinking agent is fully used in the system without being compounded with other methoxysilane crosslinking agents or the proportion of triureaphenyl-modified methoxysilane crosslinking agent in the composite crosslinking agent is too large, it exceeds a specific ratio range, and semi-crosslinking phenomenon will occur during the preparation of the glue, resulting in the failure of the preparation of the glue. Comparative Example 4 shows that if the compounding ratio of the composite crosslinking agent exceeds a specific ratio range, the performance will not be improved. Therefore, the triureidophenyl modified methoxysilane crosslinking agent of the present invention needs to be compounded with other methoxysilane crosslinking agents, and the best effect is achieved when the mass ratio of the crosslinking agent to the triureidophenyl modified alkoxysilane is 0.3 to 10:2.

[0112] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A modified crosslinking agent for dealcoholized silicone sealant, characterized in that: The modified crosslinking agent is triureaphenyl modified alkoxysilane, having the following structural formula:

2. The method for preparing a modified crosslinking agent for dealcoholized silicone sealant according to claim 1, characterized in that: The steps include: Under the protection of inert gas, 1,3,5-triaminobenzene and isocyanatepropyltrimethoxysilane are subjected to addition reaction in the presence of solvent acetone and an organic tin catalyst, and the reaction is performed under reduced pressure distillation and column chromatography to prepare the modified crosslinking agent.

3. The method for preparing a modified crosslinking agent according to claim 2, characterized in that: The molar ratio of 1,3,5-triaminobenzene to isocyanate propyl trimethoxysilane is 1:3; the organotin catalyst is at least one of dibutyltin dilaurate, dibutyltin diacetate or triethylamine; the molar ratio of the organotin catalyst to isocyanate propyl trimethoxysilane is 10 -6 :

1.

4. The method for preparing a modified crosslinking agent according to claim 2, characterized in that: The addition reaction temperature is 60° C., and the addition reaction time is 5 h.

5. A dealcoholized silicone sealant with fast curing speed and good heat resistance, characterized in that: According to the weight of the parts, including 2 to 12 parts The modified cross-linking agent according to claim 1 or the modified cross-linking agent prepared by the preparation method of the modified cross-linking agent according to any one of claims 2 to 4; Also includes the following components:

6. The dealcoholized silicone sealant according to claim 5, characterized in that: The viscosity of the α,ω-dihydroxy polydimethylsiloxane at 25°C is 5000mPa.s to 150000mPa.s; the viscosity of the dimethyl silicone oil at 25°C is 100mPa.s to 10000mPa.s; the filler is active nano calcium carbonate with a particle size of 20nm to 200nm.

7. The dealcoholized silicone sealant according to claim 5, characterized in that: The crosslinking agent is at least one of methyltrimethoxysilane, vinyltrimethoxysilane, and phenyltrimethoxysilane; the mass ratio of the crosslinking agent to triureidophenyl-modified alkoxysilane is 0.3-10:

2.

8. The dealcoholized silicone sealant according to claim 5, characterized in that: The coupling agent is at least one of γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, glycidyltriethoxysilane and glycidyltrimethoxysilane.

9. The dealcoholized silicone sealant according to claim 5, characterized in that: The catalyst is diisopropyl bis(ethyl acetoacetate) titanate.

10. The method for preparing the dealcoholized silicone sealant according to any one of claims 5 to 9, characterized in that: The steps include: S1: Add α,ω-dihydroxy polydimethylsiloxane, dimethyl silicone oil and filler into a kneader, control the temperature at 60-160°C, the vacuum degree at -0.06MPa--0.09MPa, dehydrate and blend for 45-300 minutes, and cool to obtain a base material; S2: The base material is put into a planetary machine and dispersed and stirred for 5 to 10 minutes, the vacuum degree is -0.06MPa to -0.09MPa, and the rotation speed is 600 to 720rpm. Then, triuretylphenyl-modified alkoxysilane, coupling agent and catalyst are added to the planetary machine, and stirring is continued for 10 to 45 minutes. The vacuum degree is controlled at -0.045MPa to -0.09MPa, and the rotation speed is 600 to 720rpm to prepare the dealcoholized silicone sealant.

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