A modified crosslinking agent and a fast-curing, heat-resistant, alcohol-free silicone sealant, and their preparation method.

Abstract

This invention provides a modified crosslinking agent and a fast-curing, heat-resistant, alcohol-free silicone sealant, along with its preparation method. The invention uses a triaminobenzene-containing compound substrate and isocyanate-based trimethoxysilane as raw materials to synthesize a modified alkoxy crosslinking agent containing three urea groups. This crosslinking agent is then combined with α,ω-dihydroxypolydimethylsiloxane, inorganic fillers, a crosslinking agent, a catalyst, and a coupling agent in an alcohol-based system to prepare an alcohol-free silicone sealant. Compared to existing systems, the silicone sealant prepared using this invention exhibits improved curing depth and heat resistance while maintaining good mechanical properties, with a partial increase in mechanical strength. This addresses, to some extent, the increasing demands for heat resistance and curing speed in industrial and construction sectors for silicone sealants, expanding the application scenarios of alcohol-free silicone sealants and significantly improving their application performance and service life in high-temperature environments.

Description

Technical Field

[0001] This invention relates to the field of silicone sealant materials, and particularly to a modified crosslinking agent and a de-alcoholized silicone sealant with fast curing speed and good heat resistance, as well as its preparation method. Background Technology

[0002] De-alcoholized room temperature vulcanizing silicone rubber absorbs water molecules from the air, undergoes a cross-linking reaction, and releases small alcohol molecules to form an elastomer. Due to its stable chemical properties and excellent weather resistance, this silicone rubber is commonly used in the construction, aerospace, and electronics and communications industries. However, with the development of the industrial and construction sectors, there is a greater demand for faster curing speeds and higher heat resistance in de-alcoholized silicone sealants.

[0003] To meet the aforementioned requirements, the industry has offered many solutions for dealcohol-based silicone sealants. For example, CN115975591B enhances the crosslinking activity of the modified crosslinking agent by leveraging the electron-donating ability of highly active groups, allowing the sealant to cure relatively quickly even under conditions with low moisture content. However, this crosslinking agent is designed with a low polymerization rate to increase crosslinking sites, resulting in fluctuations in its activity due to the low controllability of the degree of polymerization. Furthermore, a high degree of polymerization and excessive active groups can lead to overly high activity in the crosslinking agent, causing storage problems. CN116239991A utilizes an organoaluminum compound as the first catalyst and a phthalate ester compound as the second catalyst, resulting in a significantly faster and more effective curing depth for the silicone sealant. However, this method introduces an additional aluminum atom metal catalyst, which causes some environmental pollution, and the instability of the metal catalyst is difficult to discern in the short term.

[0004] Furthermore, many solutions for improving heat resistance propose adding high-temperature degradation inhibitors and metal oxides. For example, CN116376512B adds modified basalt fiber and magnesium copper oxide to the sealant system, resulting in silicone sealant with improved mechanical properties, fire resistance, and heat resistance. However, the introduction of new substances through physical addition may increase the difficulty of powder separation during actual production, leading to problems such as poor appearance.

[0005] Based on this, the present invention designs a modified crosslinking agent and a de-alcoholized silicone sealant with fast curing speed and good heat resistance, as well as a method for preparing the same. Summary of the Invention

[0006] This invention provides a modified crosslinking agent and a de-alcoholized silicone sealant with fast curing speed and good heat resistance, as well as a method for preparing the same, in order to solve the aforementioned problems existing in the background art.

[0007] To achieve the above objectives, embodiments of the present invention provide a modified crosslinking agent and a de-alcoholized silicone sealant with fast curing speed and good heat resistance, as well as a method for preparing the same. The present invention develops a novel crosslinking agent that can improve the heat resistance and curing depth of de-alcoholized silicone sealants, and based on this, a de-alcoholized silicone sealant is obtained. The present invention uses a triaminobenzene-containing compound substrate and isocyanate-based trimethoxysilane as raw materials to synthesize a modified alkoxy crosslinking agent containing three urea groups. The de-alcoholized silicone sealant is then prepared by reacting this crosslinking agent with α,ω-dihydroxypolydimethylsiloxane, inorganic fillers, catalysts, coupling agents, etc., in an alcohol-based system. Compared to the original system, the silicone sealant prepared using this invention has improved curing depth and heat resistance, while maintaining good mechanical properties and partially improving mechanical strength. To a certain extent, it overcomes the increasing requirements for heat resistance and curing speed of silicone sealants in the industrial and construction sectors, expands the application scenarios of de-alcoholized silicone sealants, and is of great significance for improving construction performance and extending the service life of silicone sealants in high-temperature environments.

[0008] One embodiment of the present invention provides a modified crosslinking agent for de-alcoholized silicone sealants, wherein the modified crosslinking agent is a triuretylphenyl-modified alkoxysilane having the following structural formula:

[0009]

[0010] One aspect of the present invention also provides a method for preparing the above-mentioned modified crosslinking agent for de-alcoholized silicone sealant, comprising the following steps:

[0011] Under the protection of an inert gas, 1,3,5-triaminobenzene and isocyanate propyltrimethoxysilane were subjected to an addition reaction in the presence of acetone solvent and an organotin catalyst. The reaction was followed by vacuum distillation and column chromatography to prepare the modified crosslinking agent.

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

[0013]

[0014] The structure of the isocyanate propyltrimethoxysilane is as follows:

[0015]

[0016] Preferably, the molar ratio of 1,3,5-triaminobenzene and isocyanate propyltrimethoxysilane is 1:3.

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

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

[0019] Another embodiment of the present invention provides a de-alcoholized silicone sealant with fast curing speed and good heat resistance, comprising 2 to 12 parts by weight of the modified crosslinking agent as described in claim 1;

[0020] It 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; the mass ratio of the crosslinking agent to the triuret-phenyl-modified alkoxysilane is 0.3 to 10:2.

[0026] Preferably, the coupling agent is at least one selected from 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 inventive concept, embodiments of the present invention provide a method for preparing the above-mentioned alcohol-free 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℃, the vacuum degree at -0.06MPa--0.09MPa, dehydrate and blend for 45-300 minutes, and then cool to obtain the base material;

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

[0031] The above-described solution of the present invention has the following beneficial effects:

[0032] (1) This invention uses a triaminobenzene-containing compound substrate and isocyanate-based trimethoxysilane as raw materials to synthesize a modified alkoxy crosslinking agent containing three urea groups. A rigid benzene ring structure is introduced through chemical modification, and the three amino groups on the benzene ring also provide numerous crosslinking sites for the methoxysilane. The rigid structure of the benzene ring can improve the heat resistance of silicone sealants. The numerous crosslinking sites enhance the crosslinking density of the sealant, thereby improving its mechanical strength and curing depth.

[0033] (2) The de-alcoholized sealant of the present invention has a fast curing speed. Compared with traditional low-polymerization degree crosslinking agents and the introduction of active groups, the present invention uses the three amino groups of the phenyl group to connect multiple main chain structures, and the crosslinking sites are concentrated on the rigid benzene ring. Therefore, the crosslinking density is high and the curing speed is fast.

[0034] (3) The de-alcoholized sealant of the present invention is environmentally friendly. It releases small alcohol molecules during the curing process, has little odor, does not corrode building substrates such as metals, concrete, and glass, and minimizes the harm to the environment and human body.

[0035] (4) The de-alcoholized sealant of the present invention maintains good mechanical properties. The high crosslinking 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 de-alcoholized sealant of the present invention also has excellent heat resistance. Detailed Implementation

[0037] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with specific embodiments.

[0038] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

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

[0040] The curing speed of existing silicone sealants is affected not only by environmental factors but also by the activity of crosslinking agents and catalysts in the formulation. While the application of catalysts in silicone sealant systems is well-established, there is still significant room for optimization in crosslinking agents. Common methods of introducing active groups can improve the crosslinking activity of crosslinking agents, but the high electron-donating ability of these groups leads to excessively rapid hydrolysis of the crosslinking agent itself, releasing small alcohol molecules, which is not conducive to balancing performance improvement and shelf-life assurance. Using oligomer crosslinking agents, although it is easy to increase the crosslinking density by controlling the degree of polymerization, makes it difficult to concentrate the crosslinking sites, resulting in difficulties in ensuring mechanical strength and other properties.

[0041] One embodiment of the present invention provides a modified crosslinking agent for de-alcoholized silicone sealants, wherein the modified crosslinking agent is a triuretylphenyl-modified alkoxysilane having the following structural formula:

[0042]

[0043] One aspect of the present invention also provides a method for preparing the above-mentioned modified crosslinking agent for de-alcoholized silicone sealant, comprising the following steps:

[0044] Under the protection of an inert gas, 1,3,5-triaminobenzene and isocyanate propyltrimethoxysilane were subjected to an addition reaction in the presence of acetone solvent and an organotin catalyst. The reaction was followed by vacuum distillation and column chromatography to prepare the modified crosslinking agent.

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

[0046]

[0047] The structure of the isocyanate propyltrimethoxysilane is as follows:

[0048]

[0049] Preferably, the molar ratio of 1,3,5-triaminobenzene and isocyanate propyltrimethoxysilane is 1:3.

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

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

[0052] Another embodiment of the present invention provides a de-alcoholized silicone sealant with fast curing speed and good heat resistance, comprising 2 to 12 parts by weight of the modified crosslinking agent as described in claim 1;

[0053] It 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; the mass ratio of the crosslinking agent to the triuret-phenyl-modified alkoxysilane is 0.3 to 10:2.

[0059] Preferably, the coupling agent is at least one selected from 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 inventive concept, embodiments of the present invention provide a method for preparing the above-mentioned alcohol-free 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℃, the vacuum degree at -0.06MPa--0.09MPa, dehydrate and blend for 45-300 minutes, and then cool to obtain the base material;

[0063] S2: The base material is added to a planetary mixer and dispersed and stirred for 5-10 minutes at a vacuum of -0.06MPa to -0.09MPa and a rotation speed of 600-720rpm. Then, triuretylphenyl modified alkoxysilane, coupling agent and catalyst are added to the planetary mixer and stirred continuously for 10-45 minutes, controlling the vacuum at -0.045MPa to -0.09MPa and the rotation speed at 600-720rpm, 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 de-alcoholized silicone sealant with fast curing speed and good heat resistance.

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

[0068] Step 1: Take 100 parts of α,ω-dihydroxypolydimethylsiloxane 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 to a kneader, and dehydrate and blend them at a temperature of 120℃ and a vacuum degree of -0.09 MPa for 120 min. After obtaining the base material, cool it for later use.

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

[0070] Example 2

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

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

[0073] Step 1: Take 100 parts of α,ω-dihydroxypolydimethylsiloxane 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 to a kneader, and dehydrate and blend them at a temperature of 120℃ and a vacuum degree of -0.09 MPa for 120 min. After obtaining the base material, cool it for later use.

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

[0075] Example 3

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

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

[0078] Step 1: Take 100 parts of α,ω-dihydroxypolydimethylsiloxane 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 to a kneader, and dehydrate and blend them at a temperature of 120℃ and a vacuum degree of -0.09 MPa for 120 min. After obtaining the base material, cool it for later use.

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

[0080] Example 4

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

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

[0083] Step 1: Take 100 parts of α,ω-dihydroxypolydimethylsiloxane 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 to a kneader, and dehydrate and blend them at a temperature of 120℃ and a vacuum degree of -0.09 MPa for 120 min. After obtaining the base material, cool it for later use.

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

[0085] Example 5

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

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

[0088] Step 1: Take 100 parts of α,ω-dihydroxypolydimethylsiloxane 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 to a kneader, and dehydrate and blend them at a temperature of 120℃ and a vacuum degree of -0.09 MPa for 120 min. After obtaining the base material, cool it for later use.

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

[0090] This comparative example provides a silicone sealant, which differs from the example in that the proportion of the added composite crosslinking agent is changed.

[0091] Comparative Example 1

[0092] This comparative example provides a silicone sealant, which differs from the examples in that it completely adds a crosslinking agent without adding triuret-phenyl-modified alkoxysilane. Specifically, it includes the following steps:

[0093] Step 1: Take 100 parts of α,ω-dihydroxypolydimethylsiloxane 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 to a kneader, and dehydrate and blend them at a temperature of 120℃ and a vacuum degree of -0.09 MPa for 120 min. After obtaining the base material, cool it for later use.

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

[0095] Comparative Example 2

[0096] This comparative example provides a silicone sealant that differs from the examples in that it uses only triuret-phenyl-modified alkoxysilane without adding a crosslinking agent. Specifically, it includes the following steps:

[0097] Step 1: Take 100 parts of α,ω-dihydroxypolydimethylsiloxane 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 to a kneader, and dehydrate and blend them at a temperature of 120℃ and a vacuum degree of -0.09 MPa for 120 min. After obtaining the base material, cool it for later use.

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

[0099] Comparative Example 3

[0100] This comparative example provides a silicone sealant, which differs from the examples in that the mass ratio of the crosslinking agent to the triuret-phenyl-modified alkoxysilane crosslinking agent is 1:10, and specifically includes the following steps:

[0101] Step 1: Take 100 parts of α,ω-dihydroxypolydimethylsiloxane 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 to a kneader, and dehydrate and blend them at a temperature of 120℃ and a vacuum degree of -0.09 MPa for 120 min. After obtaining the base material, cool it for later use.

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

[0103] Comparative Example 4

[0104] This comparative example provides a silicone sealant, which differs from the examples in that the mass ratio of the crosslinking agent to the triuret-phenyl-modified alkoxysilane crosslinking agent is 5.5:1, and specifically includes the following steps:

[0105] Step 1: Take 100 parts of α,ω-dihydroxypolydimethylsiloxane 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 to a kneader, and dehydrate and blend them at a temperature of 120℃ and a vacuum degree of -0.09 MPa for 120 min. After obtaining the base material, cool it for later use.

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

[0107] The silicone sealants used in the above examples and comparative examples were prepared 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 23 (±2)℃ and 50 (±10)% relative humidity. Subsequently, the specimens were stretched to failure on a tensile testing machine at (23±2)℃ and a speed of (5.5±0.7) mm / min, and the maximum tensile strength and maximum elongation at strength were recorded. Following the prescribed temperature and aging time in GB / T2941-2006 "General Procedures for Specimen Preparation and Conditioning in Physical Tests of Rubber", the prepared H-type specimens were aged in an oven at (275±2)℃ for 7 days. Then, following the method in GB 16776-2005 "Silicone Structural Sealants for Building Construction", the specimens were stretched to failure at (90±2)℃ at a speed of (5.5±0.7) mm / min, and the maximum tensile strength and maximum elongation at strength were recorded. Following Method 2 in GB / T32369-2015 "Determination of Curing Degree of Sealants", the prepared specimens were cured for 24 hours under standard conditions of 23(±2)℃ and 50(±5)% relative humidity, and the thickness of the cured layer was recorded. 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 demonstrate that adding a composite crosslinking agent within a specific ratio range results in less attenuation of maximum tensile strength after aging compared to the case without the composite crosslinking agent, and also less attenuation of maximum elongation at aging. This indicates that the high-temperature resistance is improved after adding the composite crosslinking agent. Examples 1, 2, and 3 show that the higher the proportion of triuret-phenyl-modified methoxysilane crosslinking agent in the composite crosslinking agent, the better the tensile strength and curing depth of the prepared de-alcoholized silicone sealant. The best overall improvement effect is achieved when the mass fraction ratio of the composite crosslinking agent is 2:8. Comparative Examples 2 and 3 show that when the system uses only triuret-phenyl-modified methoxysilane crosslinking agent without combining it with other methoxysilane crosslinking agents, or when the proportion of triuret-phenyl-modified methoxysilane crosslinking agent in the composite crosslinking agent is too high, exceeding a specific ratio range, semi-crosslinking will occur during the mixing process, leading to mixing failure. Comparative Example 4 shows that if the ratio of the composite crosslinking agent exceeds a specific range, the performance will not be improved. Therefore, the triuret-phenyl modified methoxysilane crosslinking agent of the present invention needs to be used in combination with other methoxysilane crosslinking agents, and the effect is best when the mass ratio of the crosslinking agent to the triuret-phenyl modified alkoxysilane is 0.3 to 10:2.

[0112] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A de-alcoholized silicone sealant with fast curing speed and good heat resistance, characterized in that, By weight, it includes 2 to 12 parts of modified crosslinking agent; The preparation method of the modified crosslinking agent includes the following steps: Under inert gas protection, 1,3,5-triaminobenzene and isocyanate propyltrimethoxysilane were subjected to an addition reaction in the presence of acetone solvent and an organotin catalyst. The reaction was followed by vacuum distillation and column chromatography to obtain the final product. The molar ratio of 1,3,5-triaminobenzene to isocyanate propyltrimethoxysilane was 1:3, and the molar ratio of the organotin catalyst to isocyanate propyltrimethoxysilane was 10. -6 :1; The addition reaction temperature is 60 ℃, and the addition reaction time is 5 h; The modified crosslinking agent is triuretylphenyl modified alkoxysilane, having the following structural formula: ； The de-alcoholized silicone sealant also includes the following components: 100 parts of α,ω-dihydroxypolydimethylsiloxane 5-10 parts of dimethyl silicone oil 80-130 parts of filler 2-6 parts of crosslinking agent 1-3 parts of coupling agent Catalyst 2-6 parts.

2. The de-alcoholized silicone sealant according to claim 1, characterized in that, The organotin catalyst is at least one of dibutyltin dilaurate, dibutyltin diacetate, or triethylamine.

3. The de-alcoholized silicone sealant according to claim 1, characterized in that, The viscosity of the α,ω-dihydroxypolydimethylsiloxane at 25 °C is 5000 mPa·s to 150000 mPa·s; the viscosity of the dimethyl silicone oil at 25 °C is 100 mPa·s to 10000 mPa·s; and the filler is active nano-calcium carbonate with a particle size of 20 nm to 200 nm.

4. The de-alcoholized silicone sealant according to claim 1, characterized in that, The crosslinking agent is at least one of methyltrimethoxysilane, vinyltrimethoxysilane, and phenyltrimethoxysilane; the mass ratio of the crosslinking agent to the triuret-phenyl-modified alkoxysilane is 0.3 to 10:

2.

5. The de-alcoholized silicone sealant according to claim 1, 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.

6. The de-alcoholized silicone sealant according to claim 1, characterized in that, The catalyst is diisopropyl bis(ethyl acetoacetate) titanate.

7. The method for preparing the dealcoholized silicone sealant according to any one of claims 1 to 6, characterized in that, Includes the following steps: S1: Add α,ω-dihydroxy polydimethylsiloxane, dimethyl silicone oil and filler into a kneader, control the temperature at 60~160 ℃, the vacuum degree at -0.06 MPa~-0.09 MPa, dehydrate and blend for 45~300 minutes, and then cool to obtain the base material; S2: The base material is added to a planetary mixer and dispersed and stirred for 5-10 minutes at a vacuum of -0.06 MPa to -0.09 MPa and a rotation speed of 600-720 rpm. Then, triuretylphenyl modified alkoxysilane, coupling agent and catalyst are added to the planetary mixer and stirred continuously for 10-45 minutes, controlling the vacuum at -0.045 MPa to -0.09 MPa and the rotation speed at 600-720 rpm to prepare the dealcoholized silicone sealant.

Images