High-temperature-resistant silicone sealant and preparation method thereof

Abstract

The invention discloses a high-temperature-resistant silicone sealant and a preparation method thereof. The silicone sealant is prepared from 100 parts of 107 base glue, 20 to 30 parts of hydroxyl-terminated phenyl silicone oil, 70 to 110 parts of modified filler, 10 to 20 parts of plasticizer, 3 to 8 parts of cross-linking agent, 1 to 3 parts of adhesion promoter and 0.01 to 0.05 part of catalyst, the modified filler comprises a filler and silicone rubber coating the surface of the filler, and the silicone rubber comprises the following raw materials: 5-20 parts of vinyl-terminated silicone oil, 10-15 parts of vinyl polysilazane, 3-10 parts of crosslinked hydrogen silicone oil, 100-500ppm of an inhibitor and 5-20ppm of a platinum catalyst. The contradiction between the displacement capability and the silicone oil precipitation resistance of the silicone sealant can be relieved, and the silicone sealant with high displacement capability and low silicone oil precipitation pollution at high temperature can be prepared.

Description

Technical Field

[0001] This application relates to the field of silicone sealants, and in particular to a high-temperature resistant silicone sealant and its preparation method. Background Technology

[0002] Silicone sealants are widely used in construction, automotive, and electronics industries due to their excellent weather resistance, elasticity, and adhesion. Especially in building curtain wall projects, sealants need to be exposed to complex environments for extended periods, withstanding extreme temperature changes, ultraviolet radiation, and structural displacement. Modern high-rise buildings, due to the significant difference in thermal expansion coefficients between metal and glass, face challenges where joints can reach temperatures above 80°C in summer and below -30°C in winter. They must also adapt to the periodic deformation of joints caused by wind loads and thermal expansion and contraction, with displacement capabilities often requiring ±25% to ±50%.

[0003] To meet the requirements of high displacement capacity, existing technologies generally require the addition of small-molecule plasticizers (such as methyl silicone oil) to reduce modulus and improve flexibility. However, these plasticizers have limited compatibility with the silicone rubber matrix and are prone to migrating and precipitating onto the surface under long-term high-temperature environments, forming oily exudates. This phenomenon not only causes polluting oil stains on substrates such as curtain wall stone and glass, seriously affecting aesthetics, but also attracts environmental dust, forming stains that are difficult to remove. More seriously, the precipitated silicone oil forms a weak boundary layer at the interface between the colloid and the substrate, leading to weakened adhesion and ultimately causing seal failure or even complete detachment of the sealant joint. Summary of the Invention

[0004] This application provides a high-temperature resistant silicone sealant and its preparation method, which can effectively solve the contradiction between the displacement capability and the anti-silicone oil precipitation performance of current silicone sealants, and obtain a silicone sealant with both high displacement capability and (high temperature) low silicone oil precipitation risk.

[0005] In a first aspect, this application provides a high-temperature resistant silicone sealant, comprising the following raw materials in parts by weight: 100 parts of 107 base adhesive, 20-30 parts of hydroxyl-terminated phenyl silicone oil, 70-110 parts of modified filler, 10-20 parts of plasticizer, 3-8 parts of crosslinking agent, 1-3 parts of adhesion promoter, and 0.01-0.05 parts of catalyst; wherein the modified filler comprises a filler and silicone rubber coated on the surface of the filler, and the raw materials of the silicone rubber include 5-20 parts of vinyl-terminated silicone oil, 10-15 parts of vinyl polysilazane, 3-10 parts of crosslinked hydrogen silicone oil, 100-500 ppm of inhibitor, and 5-20 ppm of platinum catalyst.

[0006] In any of the above technical solutions, under standard test conditions (25°C), the viscosity of the 107-based adhesive is 20,000 to 80,000 mPa·s.

[0007] This application achieves a high displacement capability of ±50% for silicone sealant through the synergistic combination of multiple components, while effectively suppressing silicone oil precipitation. The key point is that the tensile properties, cohesive strength and interfacial adhesion strength of the sealant are optimized simultaneously.

[0008] First, the addition of a plasticizer (methyl silicone oil) enhances the tensile properties of the sealant and reduces its modulus, providing the necessary physical basis for achieving high displacement capacity. Second, the application of modified fillers significantly enhances the cohesive strength of the sealant, ensuring that failure does not occur initially within the sealant when the displacement limit of ±50% is reached (i.e., cohesive failure is avoided), thus guaranteeing the integrity of the sealing layer. Furthermore, the use of an adhesion promoter ensures a synergistic improvement in interfacial strength and cohesive strength, further optimizing overall performance.

[0009] It should be noted that the prerequisite for modified fillers to enhance cohesive strength is to solve the problem of agglomeration and sedimentation caused by poor compatibility between the filler and the matrix. This application significantly enhances the compatibility between the filler and the matrix by coating the filler surface with a layer of silicone rubber, thereby improving the interfacial strength between the two phases. This coating silicone rubber is made from vinyl polysilazane and high-crosslinking-density hydrogen silicone oil (hydrogen content ≥3 mol in 1 mol of silicone oil), forming a highly branched three-dimensional network structure through a hydrosilylation reaction. This structure utilizes its molecular cavities to adsorb silicone oil plasticizers, and the steric hindrance effect of the branched structure greatly extends the migration path of the silicone oil. Simultaneously, the Si-N bonds contained in vinyl polysilazane exhibit excellent high-temperature stability (withstanding prolonged sunlight irradiation), which helps to suppress the diffusion and precipitation of silicone oil under high-temperature conditions.

[0010] On the other hand, by introducing hydroxyl-terminated phenyl silicone oil (hydroxyl-terminated diphenyl polysiloxane), a rigid benzene ring structure is introduced into the sealant molecular chain. The introduction of the benzene ring can effectively suppress the movement of molecular chain segments at high temperatures, reduce the molecular vacancies that can be migrated by silicone oil due to chain segment movement, and thus reduce the tendency of silicone oil precipitation at the matrix level.

[0011] Ultimately, the introduction of the phenyl segment and polysilazane, based on their different heat resistance mechanisms, together endow the system with excellent heat resistance, inhibiting performance degradation and silicone oil precipitation caused by long-term high-temperature aging. The synergistic effect of the three enables the sealant to maintain high elasticity, strong cohesion, and durable and reliable adhesion even under conditions of low silicone oil content, ultimately achieving a high displacement capability of ±50%.

[0012] In any of the above technical solutions, the catalyst is selected from any one or more of dibutyltin dilaurate, dibutyltin diacetate, dioctyltin dilaurate, or stannous octoate.

[0013] In any of the above technical solutions, the mass ratio of the silicone rubber to the filler is 0.5 to 1.2:10.

[0014] In any of the above technical solutions, the raw material of the silicone rubber further includes 1 to 5 parts of phenyl hydrogen silicone oil.

[0015] In any of the above technical solutions, under standard test conditions (25°C), the viscosity of the phenyl hydrogen-containing silicone oil is 1–200 mPa·s.

[0016] Phenyl hydrogen-containing silicone oil is added to silicone rubber raw materials, and its phenyl groups are introduced into the silicone rubber coating layer network through hydrosilylation. This phenyl group interacts strongly with the phenyl groups introduced by the hydroxyl-terminated phenyl silicone oil in the base rubber, forming dynamic physical crosslinking points at the filler-matrix interface. This interaction not only enhances the compatibility between the filler and the base rubber and improves cohesive strength, but also constructs a denser three-dimensional shielding network, further hindering the migration of silicone oil plasticizers to the surface, significantly reducing the risk of silicone oil exudation, and suppressing the problem of contamination in curtain wall substrates.

[0017] In any of the above technical solutions, under standard test conditions (25°C), the viscosity of the vinyl-terminated silicone oil in the silicone rubber raw material is 100–500 mPa·s.

[0018] In any of the above technical solutions, the filler is one or more of calcium carbonate, heavy calcium carbonate powder, and fumed silica.

[0019] In any of the above technical solutions, the modified filler is prepared by processes such as spraying, soaking, or rolling granulation.

[0020] In any of the above technical solutions, the platinum catalyst is selected from any one or more of the following: an alcoholic solution of chloroplatinic acid, a platinum catalyst coordinated with tetrahydrofuran, and a platinum catalyst coordinated with divinyltetramethylsiloxane.

[0021] In any of the above technical solutions, the inhibitor is selected from one or more of 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane, 1,1,3,3-tetramethyl-1,3-divinylsiloxane, 3-methyl-1-butyn-3-ol, 1-ethynylcyclohexanol, 3-phenyl-1-butyn-3-ol, 3-propyl-1-butyn-3-ol, and 3-octyl-1-butyn-3-ol.

[0022] In any of the above technical solutions, the adhesion promoter is prepared by the following method: an epoxy-based alkenyl monomer and a perhydropolysilazane undergo hydrosilylation under a platinum catalyst to obtain an epoxy-modified polysilazane; a polycondensation reaction is carried out using a diacid and a diamine in a molar ratio of 1:1.1 to 1.3 as raw materials to obtain a polyamide; the epoxy-modified polysilazane and the polyamide are reacted in a solvent, and the solvent is removed to obtain the final product.

[0023] In any of the above technical solutions, the epoxy-alkenyl monomer is allyl alcohol glycidyl ether and / or glycidyl methacrylate.

[0024] In any of the above technical solutions, the mass ratio of the epoxy-based alkenyl monomer to the perhydropolysilazane is 8-12:100.

[0025] At a mass ratio of 8 to 12:100, the amount of silane groups in the perhydropolysilazane is significantly excessive, resulting in a large number of reactive silane groups remaining in the reaction product.

[0026] In any of the above technical solutions, the dicarboxylic acid and diamine are reacted at 130-170°C for 6-8 hours to obtain polyamide.

[0027] In any of the above technical solutions, the mass ratio of the epoxy-modified polysilazane to the polyamide is 10:1.0 to 1.8, and the reaction temperature is 80 to 100°C.

[0028] Epoxy-modified polysilazane and polyamide undergo a ring-opening reaction. The epoxy-modified polysilazane and polyamide oligomers are mixed at a mass ratio of 10:1.0 to 1.8. The system contains excess epoxy groups, which are grafted onto the polysilazane backbone. The steric hindrance of the silazane skeleton, combined with the regulation of reaction conditions, results in reactive epoxy groups in the reaction product. A small amount of amino groups are retained in the polyamide oligomers.

[0029] In any of the above technical solutions, the dicarboxylic acid is selected from any one or more of iodic acid, octanoic acid, sebacic acid, and terephthalic acid.

[0030] In any of the above technical solutions, the diamine is selected from bis(diamine) and / or decanediamine.

[0031] This adhesive accelerator is synthesized in three steps. First, an epoxy-based alkenyl monomer undergoes hydrosilylation with a perhydropolysilazane, introducing epoxy groups into the polysilazane. Second, a diacid (adipic acid / sebacic acid, etc.) undergoes condensation polymerization with an excess diamine (hexamethylenediamine / decanediamine) to prepare an amine-terminated polyamide. Finally, the epoxy-modified polysilazane reacts with the polyamide to form a polymer containing epoxy groups, amine groups, and residual Si-H bonds. The epoxy groups react with the hydroxyl groups on the substrate surface, the amine groups participate in the curing network, and the Si-H bonds of the polysilazane condense with the silicone adhesive matrix, achieving strong interfacial adhesion.

[0032] Compared to traditional silane coupling agents, the polar amide groups in the polyamide segment of this adhesion promoter promote the enrichment of molecules at the bonding interface (such as ceramic / concrete), overcoming the weakness of traditional silane coupling agents in terms of weak interfacial adhesion under low addition and high adhesive layer thickness conditions. It ensures interfacial adhesion stability under ±50% displacement and avoids interfacial peeling failure caused by high displacement.

[0033] In any of the above technical solutions, the crosslinking agent is selected from any one or more of methyl vinyl dibutyl ketone oxime silane, dimethyl dibutyl ketone oxime silane, methyl vinyl di(methyl isobutyl ketone oxime) silane, methyl vinyl diacetone oxime silane, methyl tributanone oxime silane, vinyl tributanone oxime silane, and phenyl tributanone oxime silane.

[0034] In any of the above technical solutions, the silane coupling agent is selected from any one or more of epoxy silane coupling agents, amino silane coupling agents, and acryloyloxy silane coupling agents.

[0035] In any of the above technical solutions, the plasticizer is methyl silicone oil.

[0036] Secondly, this application provides a method for preparing a high-temperature resistant silicone sealant, comprising the following steps: According to the raw material ratio of any of the silicone sealants described in the first aspect, 107 base adhesive, hydroxyl-terminated phenyl silicone oil, plasticizer, and modified filler are mixed evenly, heated to 120-150°C, and dehydrated under vacuum; the temperature is controlled to <40°C, and crosslinking agent, adhesion promoter and catalyst are added, and mixed evenly under vacuum to obtain the sealant.

[0037] In summary, this application has the following beneficial effects: This application presents a high-temperature resistant silicone sealant that achieves high displacement capability and low silicone oil exudation risk through an overall design. Specifically, a silicone oil plasticizer is used to enhance the flexibility of the sealant, while a filler coated with silicone rubber on the surface enhances the cohesive strength and constructs a three-dimensional adsorption network to inhibit silicone oil exudation. An adhesion promoter strengthens interfacial bonding. Furthermore, hydroxyl-terminated phenyl silicone oil is used to introduce a benzene ring structure into the base sealant, disrupting the formation of silicone oil migration pathways and reducing the tendency for silicone oil exudation at the matrix level. In addition, the introduction of phenyl segments and polysilazane significantly improves heat resistance, allowing it to withstand performance degradation caused by high temperatures of 80°C. Ultimately, while achieving a high displacement capability of ±50%, it effectively solves the problems of silicone oil exudation contamination and adhesion attenuation in traditional products, meeting the long-term sealing requirements of high-rise building curtain walls. Detailed Implementation

[0038] Preparation Example

[0039] Preparation Example 1-1 The modified filler is prepared by following these steps: 13g of vinyl-terminated silicone oil (RH-Vi1323, viscosity 285-315 mPa·s), 12.5g of vinyl polysilazane (MDH25410), 6.5g of crosslinked hydrogen silicone oil (side-containing hydrogen silicone oil, hydrogen content 0.75%-0.79%), 3g of phenyl hydrogen silicone oil (IOTA 231), 300ppm of 1-ethynylcyclohexanol, and 15ppm of Karstedt catalyst were mixed and stirred at 800 rpm for 30 min under nitrogen protection to form a homogeneous silicone rubber premix. Under stirring conditions, the silicone rubber premix was uniformly sprayed into a fluidized bed through a pressure spray device (nozzle diameter 0.5 mm) onto 100g of fumed silica (specific surface area 200 m²) being stirred at high speed (1200 rpm). 2 / g) surface. The spray rate was controlled at 10 mL / min, and the atomization pressure at 0.3 MPa. After spraying, the material was transferred to a reactor, heated to 90°C under a nitrogen atmosphere, and held for 2 hours to ensure complete hydrosilylation. After the reaction, the product was ground using an air jet mill to ensure uniform dispersion, and then sieved to obtain the modified filler.

[0040] Preparation Examples 1-2 The modified filler is prepared by following these steps: 5g of vinyl-terminated silicone oil (RH-Vi311, viscosity 475-525 mPa·s), 10g of vinyl polysilazane (SYLG-113), 3g of crosslinked hydrogen silicone oil (end-side hydrogen-containing silicone oil, hydrogen content 0.78%-0.82%), 1g of phenyl hydrogen-containing silicone oil (KM220), 100ppm of 1-ethynylcyclohexanol, and 10ppm of Karstedt catalyst were mixed and stirred at 500rpm for 30min under nitrogen protection to form a homogeneous silicone rubber premix. Under stirring conditions, the silicone rubber premix was uniformly sprayed into a fluidized bed through a pressure spray device (nozzle diameter 0.5mm) onto 100g of fumed silica (specific surface area 180m²) being stirred at high speed (1000rpm). 2 / g) surface. The spray rate was controlled at 10 mL / min, and the atomization pressure at 0.3 MPa. After spraying, the material was transferred to a reactor, heated to 80°C under a nitrogen atmosphere, and held for 3 hours to ensure complete hydrosilylation. After the reaction, the product was ground using an air jet mill to ensure uniform dispersion, and then sieved to obtain the modified filler.

[0041] Preparation Examples 1-3 The modified filler is prepared by following these steps: 20g of vinyl-terminated silicone oil (RH-Vi322, viscosity 190-230 mPa·s), 15g of vinyl polysilazane (KMK-1157), 10g of crosslinked hydrogen silicone oil (side-containing hydrogen silicone oil, hydrogen content 0.53%-0.57%), 5g of phenyl hydrogen silicone oil (IOTA 231), 500ppm of 1-ethynylcyclohexanol, and 20ppm of Karstedt catalyst were mixed and stirred at 1200rpm for 40min under nitrogen protection to form a homogeneous silicone rubber premix. Under stirring conditions, the silicone rubber premix was uniformly sprayed into a fluidized bed through a pressure spray device (nozzle diameter 0.5mm) onto 100g of fumed silica (specific surface area 300 m²) being stirred at high speed (1200rpm). 2 / g) surface. The spray rate was controlled at 10 mL / min, and the atomization pressure at 0.3 MPa. After spraying, the material was transferred to a reactor, heated to 95°C under a nitrogen atmosphere, and held for 2.5 h to ensure complete hydrosilylation. After the reaction, the product was ground using an air jet mill to ensure uniform dispersion, and then sieved to obtain the modified filler.

[0042] Preparation Examples 1-4 The modified filler differs from that in Preparation Example 1-1 in that it does not contain phenyl hydrogen silicone oil (IOTA 231).

[0043] Preparation Examples 1-5 The modified filler differs from Preparation Example 1-1 in that an equal amount of crosslinked hydrogen silicone oil (side-containing hydrogen silicone oil with a hydrogen content of 0.75-0.79%) is used to replace the phenyl hydrogen silicone oil (IOTA 231).

[0044] Preparation Examples 1-6 The modified filler differs from that in Preparation Example 1-1 in that it replaces the crosslinked hydrogen silicone oil (side-side hydrogen silicone oil with a hydrogen content of 0.75-0.79%) with an equal amount of phenyl hydrogen silicone oil (IOTA 231).

[0045] Preparation Examples 1-7 The modified filler differs from Preparation Example 1-1 in that it replaces vinyl polysilazane (SYLG-113) with an equal amount of end-vinyl silicone oil (viscosity 300±15 mPa·s).

[0046] Preparation Examples 1-8 The modified filler differs from Preparation Example 1-1 in that it replaces the end vinyl silicone oil (viscosity 300±15 mPa·s) with an equal amount of vinyl polysilazane (SYLG-113).

[0047] Preparation Examples 1-9 The modified filler is prepared by following these steps: Mix 200 mL of anhydrous ethanol, 20 mL of deionized water, and 10 g of octadecyltrimethoxysilane, and stir until homogeneous to obtain a mixed solution; add 100 g of dried fumed silica (specific surface area 200 m² / g). 2 (g) is slowly added to the mixed solution and stirred until homogeneous, ensuring full contact between the fumed silica and the modified solution. The mixture is then placed in a water bath at 65°C and reacted for 3 hours under nitrogen protection. The mixture is stirred continuously during the reaction. After the reaction is complete, the mixture is filtered and washed three times with anhydrous ethanol to remove unreacted silicon coupling agent and other impurities. The filter cake is then placed in a drying oven and dried at 80°C to constant weight.

[0048] Preparation Example 2-1 The adhesion promoter was prepared according to the following method: Step 1: Add 100g of perhydropolysilazane (IOTA-PHPS), 10g of allyl alcohol glycidyl ether, and 0.05g of Karstedt platinum catalyst (Pt content 2000ppm) to a reactor. Under nitrogen protection, add 150g of anhydrous toluene. Heat to 80℃ and stir at 500rpm for 3h. Remove toluene by vacuum distillation (-0.095MPa, 80℃) to obtain epoxy-modified polysilazane.

[0049] Step 2: Add 146g adipic acid (1mol) and 139g hexamethylenediamine (1.2mol) to the reaction vessel, heat to 150℃ under nitrogen protection, and stir for 6h to obtain polyamide.

[0050] Step 3: Add 100g of epoxy-modified polysilazane and 14.5g of polyamide to 200g of toluene, and heat to 90℃ under nitrogen protection. React for 4h, and remove the solvent by vacuum distillation (-0.098MPa, 90℃) to obtain the adhesion promoter.

[0051] Preparation Example 2-2 The adhesion promoter was prepared according to the following method: Step 1: Add 100g of perhydropolysilazane (IOTA-PHPS), 8g of allyl alcohol glycidyl ether, and 0.05g of Karstedt platinum catalyst (Pt content 2000ppm) to a reactor. Under nitrogen protection, add 120g of anhydrous toluene. Heat to 70℃ and stir at 500rpm for 4h. Remove toluene by vacuum distillation (-0.095MPa, 80℃) to obtain epoxy-modified polysilazane.

[0052] Step 2: Add 202g sebacic acid (1mol) and 127.8g hexamethylenediamine (1.1mol) to the reaction vessel, heat to 130℃ under nitrogen protection, and stir for 8 hours to obtain polyamide.

[0053] Step 3: Add 100g of epoxy-modified polysilazane and 10.5g of polyamide to 150g of toluene, and heat to 80℃ under nitrogen protection. React for 5h, then remove the solvent by vacuum distillation (-0.098MPa, 90℃) to obtain the adhesion promoter.

[0054] Preparation Examples 2-3 The adhesion promoter was prepared according to the following method: Step 1: Add 100g of perhydropolysilazane (IOTA-PHPS), 10g of glycidyl methacrylate, and 0.2g of Karstedt platinum catalyst (Pt content 2000ppm) to a reactor. Under nitrogen protection, add 180g of anhydrous toluene. Heat to 90℃ and stir at 800rpm for 2.5h. Remove toluene by vacuum distillation (-0.095MPa, 80℃) to obtain epoxy-modified polysilazane.

[0055] Step 2: Add 146g adipic acid (1mol) and 151g hexamethylenediamine (1.3mol) to the reaction vessel, heat to 170℃ under nitrogen protection, and stir for 6h to obtain polyamide.

[0056] Step 3: Add 100g of epoxy-modified polysilazane and 18g of polyamide to 230g of toluene, and heat to 100℃ under nitrogen protection. React for 3 hours, and remove the solvent by vacuum distillation (-0.098MPa, 90℃) to obtain the adhesion promoter.

[0057] Preparation Examples 2-4 The adhesion promoter differs from that in Preparation Example 2-1 in that the amount of hexamethylenediamine used in step 2 is 116 g (1.0 mol).

[0058] Preparation Examples 2-5 The adhesion promoter was prepared according to the following method: Step 1: Add 100g of perhydropolysilazane (IOTA-PHPS), 10g of allyl alcohol glycidyl ether, and 0.05g of Karstedt platinum catalyst (Pt content 2000ppm) to a reactor. Under nitrogen protection, add 150g of anhydrous toluene. Heat to 80℃ and stir at 500rpm for 3h. Remove toluene by vacuum distillation (-0.095MPa, 80℃) to obtain epoxy-modified polysilazane.

[0059] Step 2: Add 100g of epoxy-modified polysilazane and 14.5g of N-β-aminoethyl-γ-aminopropylmethyldimethoxysilane to 500g of N-methylpyrrolidone, and heat to 90℃ under nitrogen protection. React for 6 hours, remove the solvent by vacuum distillation (-0.098MPa, 100℃), then precipitate with n-hexane to remove unreacted N-β-aminoethyl-γ-aminopropylmethyldimethoxysilane, and dry to obtain the adhesion promoter.

[0060] Example

[0061] In the following examples and comparative examples, the 107-based adhesive was obtained from Xin'an Chemical, with the brand name XHG-107; the hydroxyl-terminated phenyl silicone oil was obtained from Kemike, with the model name L182706; and the plasticizer was methyl silicone oil obtained from Blue Star Spark, with the brand name Starsil™ PDMS 47V300.

[0062] Example 1: A high-temperature resistant silicone sealant was prepared as follows: 1000g of 107-based adhesive (107-C2, viscosity 50000mPa·s), 250g of hydroxyl-terminated phenyl silicone oil, 165g of methyl silicone oil, and 900g of the modified filler from Preparation Example 1-1 were added to a planetary disperser and stirred at 100rpm for 3 hours. The temperature was raised to 130℃, and water and low-boiling substances were removed under vacuum (-0.09MPa). The temperature was controlled to <40℃, and 30g of dimethyl dibutyl ketone oxime silane, 20g of phenyl tributanone oxime silane, 20g of the adhesion promoter from Preparation Example 2-1, and 0.3g of dibutyltin dilaurate were added. The mixture was stirred under vacuum (-0.1MPa) for 30 minutes to obtain the sealant.

[0063] Example 2: A high-temperature resistant silicone sealant was prepared as follows: 1000g of 107-based silicone (107-C1, viscosity 20000mPa·s), 200g of hydroxyl-terminated phenyl silicone oil, 200g of methyl silicone oil, and 700g of the modified filler from Preparation Examples 1-2 were added to a planetary disperser and stirred at 100rpm for 3 hours. The temperature was raised to 120℃, and water and low-boiling substances were removed under vacuum (-0.09MPa). The temperature was controlled to <40℃, and 15g of dimethyl dibutyl ketone oxime silane, 20g of methyl tributanone oxime silane, 10g of the adhesion promoter from Preparation Example 2-2, and 0.1g of dibutyltin dilaurate were added. The mixture was stirred under vacuum (-0.1MPa) for 30 minutes to obtain the sealant.

[0064] Example 3: A high-temperature resistant silicone sealant was prepared as follows: 1000g of 107-based adhesive (107-C3, viscosity 80000mPa·s), 300g of hydroxyl-terminated phenyl silicone oil, 100g of methyl silicone oil, and 1100g of the modified filler from Examples 1-3 were added to a planetary disperser and stirred at 100rpm for 4 hours. The temperature was raised to 140℃, and water and low-boiling substances were removed under vacuum (-0.09MPa). The temperature was controlled to <40℃, and 40g of methylvinyl di(methyl isobutyl ketone oxime)silane, 40g of vinyl tributanone oxime silane, 30g of the adhesion promoter from Examples 2-3, and 0.5g of dibutyltin dilaurate were added. The mixture was stirred under vacuum (-0.1MPa) for 30 minutes to obtain the sealant.

[0065] Example 4, a high-temperature resistant silicone sealant, differs from Example 1 in that the modified filler of Preparation Example 1-1 is replaced with the modified filler of Preparation Example 1-1 by means of the modified filler of Preparation Example 1-4 in equal mass.

[0066] Example 5, a high-temperature resistant silicone sealant, differs from Example 1 in that the modified filler of Preparation Example 1-1 is replaced with the modified filler of Preparation Example 1-1 by means of the modified filler of Preparation Example 1-5 in equal mass.

[0067] Example 6, a high-temperature resistant silicone sealant, differs from Example 1 in that the adhesive accelerator of Preparation Example 2-4 is replaced with the adhesive accelerator of Preparation Example 2-1 in equal mass.

[0068] Example 7, a high-temperature resistant silicone sealant, differs from Example 1 in that the adhesive accelerator of Preparation Example 2-5 is replaced with the adhesive accelerator of Preparation Example 2-1 in equal mass.

[0069] Example 8, a high-temperature resistant silicone sealant, differs from Example 1 in that the adhesive accelerator in Preparation Example 2-1 is replaced by a composition of equal masses of aminopropyltrimethoxysilane and γ-(2,3-epoxypropoxy)propyltrimethoxysilane (mass ratio 1:1).

[0070] Comparative Example

[0071] Comparative Example 1, a high-temperature resistant silicone sealant, differs from Example 5 in that an equal mass of 107-based adhesive (107-C2, viscosity 50000 mPa·s) replaces the hydroxyl-terminated phenyl silicone oil.

[0072] Comparative Example 2, a high-temperature resistant silicone sealant, differs from Example 1 in that an equal mass of plasticizer (methyl silicone oil) is used instead of hydroxyl-terminated phenyl silicone oil.

[0073] Comparative Example 3, a high-temperature resistant silicone sealant, differs from Example 1 in that the modified filler of Preparation Example 1-1 is replaced with the modified filler of Preparation Example 1-1 by means of the modified filler of Preparation Example 1-6 in equal mass.

[0074] Comparative Example 4, a high-temperature resistant silicone sealant, differs from Example 1 in that the modified filler of Preparation Example 1-1 is replaced with the modified filler of Preparation Example 1-7 in equal mass.

[0075] Comparative Example 5, a high-temperature resistant silicone sealant, differs from Example 1 in that the modified filler of Preparation Example 1-1 is replaced with the modified filler of Preparation Example 1-8 in equal mass.

[0076] Comparative Example 6, a high-temperature resistant silicone sealant, differs from Example 1 in that the modified filler of Preparation Example 1-1 is replaced with the modified filler of Preparation Example 1-9 by the same mass.

[0077] Performance testing

[0078] Experiment 1: Physical and chemical properties test of silicone sealant Test methods: The tensile strength, maximum elongation and displacement capacity were tested in accordance with the provisions of GB / T 14683-2017 "Silicone and Modified Silicone Building Sealants". The test results are shown in Table 1.

[0079] Experiment 2: Test on the anti-exudation performance of silicone sealant Test method: The test was conducted according to Appendix B (Thermogravimetric method) of GB / T 14683-2017 "Silicone and Modified Silicone Building Sealants". The test specimens were circular discs with a diameter of 50 mm and a thickness of 2 mm, with 3 discs per group; the initial mass (m0) of the specimens was accurately weighed (accurate to 0.1 mg); the specimens were placed upright in an 80℃ oven for 168 h, then removed and cooled to 23℃, and the weight (m) was recorded. n ; Calculate the mass loss rate = (m0 - m n The higher the mass loss rate (%) / m0×100%, the higher the silicone oil precipitation rate. Simultaneously, surface precipitation is rated according to the following criteria (observed under a 100× microscope): Grade 0: No oily substances; Level 1: Localized tiny oil droplets; Level 2: Continuous oil film (area ≤10%); Level 3: Large area oil film (area > 10%); Experiment 3: Test of the bonding strength of silicone sealant Test method: The interfacial bond strength between the sealant and the substrate (aluminum alloy plate) was tested according to GB / T 13477.18—2017 "Test methods for building sealing materials - Part 18: Determination of peel adhesion". The tensile speed was 50 mm / min, the test temperature was 23±2℃, and the humidity was 50±5%.

[0080] Table 1. Performance Test Results

[0081] Analysis of experimental results: Examples 1-3 demonstrate that by using an appropriate amount of dihydroxy-terminated phenyl silicone oil, this application can effectively reduce silicone oil precipitation without degrading the tensile and adhesive properties of the silicone sealant. This may be because the phenyl structure of the dihydroxy-terminated phenyl silicone oil can inhibit the movement of sealant molecular chain segments at high temperatures, reducing molecular vacancies that can be created for silicone oil migration due to chain segment movement.

[0082] The mass loss (silicone oil precipitation) in Examples 1-3 was lower than that in Comparative Examples 4-6, indicating that the silicone rubber layer prepared on the filler surface using terminal vinyl silicone oil, vinyl polysilazane, and crosslinked hydrogen silicone oil as the main raw materials can effectively suppress silicone oil precipitation, and the optimal effect cannot be achieved without any of the components. This may be because the combination of the three components can form a silicone rubber layer with a highly branched three-dimensional network, which contains abundant molecular cavities that can adsorb silicone oil plasticizers, and the steric hindrance effect of its branched structure can significantly extend the silicone oil migration path. In particular, vinyl polysilazane can also improve the silicone oil adsorption stability of the silicone rubber under high-temperature conditions, thereby improving the stability of the silicone rubber under long-term solar irradiation.

[0083] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A high-temperature resistant silicone sealant, characterized in that, The raw materials include the following parts by weight: 100 parts of 107 base rubber, 20-30 parts of hydroxyl-terminated phenyl silicone oil, 70-110 parts of modified filler, 10-20 parts of plasticizer, 3-8 parts of crosslinking agent, 1-3 parts of adhesion promoter, and 0.01-0.05 parts of catalyst; the modified filler includes filler and silicone rubber coated on the surface of filler, and the raw materials of the silicone rubber include 5-20 parts of vinyl-terminated silicone oil, 10-15 parts of vinyl polysilazane, 3-10 parts of crosslinked hydrogen silicone oil, 100-500 ppm of inhibitor, and 5-20 ppm of platinum catalyst.

2. The high-temperature resistant silicone sealant according to claim 1, characterized in that, The modified filler is obtained by applying silicone rubber raw material to the surface of the filler and then cross-linking and curing it. The mass ratio of silicone rubber raw material to filler is 0.5 to 1.2:

10.

3. The high-temperature resistant silicone sealant according to claim 1, characterized in that, The raw materials for the silicone rubber also include 1 to 5 parts of phenyl hydrogen silicone oil.

4. The high-temperature resistant silicone sealant according to claim 1, characterized in that, The adhesion promoter is prepared by the following method: epoxy-based alkenyl monomers and perhydropolysilazane undergo hydrosilylation under a platinum catalyst to obtain epoxy-modified polysilazane; polycondensation reaction is carried out using diacid and diamine in a molar ratio of 1:1.1-1.3 as raw materials to obtain polyamide; epoxy-modified polysilazane and polyamide are reacted in a solvent, and the solvent is removed to obtain the final product.

5. The high-temperature resistant silicone sealant according to claim 4, characterized in that, The epoxy-alkenyl monomer is allyl alcohol glycidyl ether and / or glycidyl methacrylate.

6. The high-temperature resistant silicone sealant according to claim 4, characterized in that, The mass ratio of the epoxy-based alkenyl monomer to the perhydropolysilazane is 8–12:

100.

7. The high-temperature resistant silicone sealant according to claim 4, characterized in that, The dicarboxylic acid and diamine are reacted at 130–170°C for 6–8 hours to obtain polyamide.

8. The high-temperature resistant silicone sealant according to claim 4, characterized in that, The mass ratio of the epoxy-modified polysilazane to the polyamide is 10:1.0 to 1.8, and the reaction temperature is 80 to 100°C.

9. The high-temperature resistant silicone sealant according to claim 1, characterized in that, The crosslinking agent is selected from any one or more of methyl vinyl dibutyl ketone oxime silane, dimethyl dibutyl ketone oxime silane, methyl vinyl di(methyl isobutyl ketone oxime) silane, methyl vinyl diacetone oxime silane, methyl tributanone oxime silane, vinyl tributanone oxime silane, and phenyl tributanone oxime silane.

10. A method for preparing a high-temperature resistant silicone sealant, characterized in that, Includes the following steps: According to the raw material ratio of any one of claims 1 to 9, 107 base adhesive, hydroxyl-terminated phenyl silicone oil, plasticizer, and modified filler are mixed evenly, heated to 120-150°C, and dehydrated under vacuum; the temperature is controlled to <40°C, and crosslinking agent, adhesion promoter, and catalyst are added, and mixed evenly under vacuum to obtain the final product.

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