High-temperature-resistant silicone sealant and preparation method thereof

Abstract

The application discloses a high-temperature-resistant silicone sealant and a preparation method thereof. The silicone sealant comprises 100 parts of 107 base glue, 20-30 parts of hydroxyl-terminated phenyl silicone oil, 70-110 parts of modified filler, 10-20 parts of plasticizer, 3-8 parts of cross-linking agent, 1-3 parts of adhesion promoter and 0.01-0.05 parts of catalyst. The modified filler comprises filler and silicone rubber coated on the surface of the filler. Raw materials of the silicone rubber comprise 5-20 parts of end-vinyl silicone oil, 10-15 parts of vinyl polysilazane, 3-10 parts of cross-linking hydrogen silicone oil, 100-500 ppm of inhibitor and 5-20 ppm of platinum catalyst. The application can relieve the contradiction between displacement capacity and anti-silicone oil precipitation performance of the silicone sealant, and prepare the silicone sealant with high displacement capacity and low silicone oil precipitation pollution at high temperature.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of silicone sealant, in particular to a high-temperature-resistant silicone sealant and a preparation method thereof. BACKGROUND

[0002] As a key sealing material in the fields of building, automobile, electronics, etc., silicone sealant is widely used due to its excellent weather resistance, elasticity and bonding performance. Especially in building curtain wall engineering, the sealant needs to be exposed to complex environments for a long time, and withstands extreme temperature changes, ultraviolet radiation and structural displacement. Due to the significant difference in the thermal expansion coefficients of metal and glass materials, the joint part of modern high-rise buildings can be heated to above 80℃ in summer, and faces the challenge of low temperature below-30℃ in winter. At the same time, it also needs to adapt to the periodic deformation of the joint caused by wind load and thermal expansion and contraction, and the displacement capacity often needs to reach the level of ±25% to ±50%.

[0003] To meet the high displacement capacity requirement, the existing technology generally needs to add small molecule plasticizers (such as methyl silicone oil) to reduce the modulus and improve the flexibility. However, the compatibility of such plasticizers with the silicone rubber matrix is limited, and they are prone to migrate and precipitate to the surface in a long-term high-temperature environment, forming oil-like exudates. This phenomenon not only causes pollution of the base materials such as curtain wall stones and glass, seriously affecting the appearance, but also adsorbs environmental dust to form stubborn stains. More seriously, the precipitated silicone oil forms a weak boundary layer at the interface between the glue and the base material, leading to a decrease in adhesion, and eventually causing sealing failure or even the whole joint to fall off. SUMMARY

[0004] The present application provides a high-temperature-resistant silicone sealant and a preparation method thereof, which can effectively solve the contradiction between the displacement capacity and the anti-silicone oil precipitation performance of the current silicone sealant, and obtain a silicone glue with high displacement capacity and low silicone oil precipitation risk.

[0005] In a first aspect, the present application provides a high-temperature-resistant silicone sealant, which comprises the following raw materials by mass: 100 parts of 107 base glue, 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 comprises a filler and a silicone rubber coated on the surface of the filler, and the raw materials of the silicone rubber comprise 5-20 parts of vinyl-terminated silicone oil, 10-15 parts of vinyl polysilazane, 3-10 parts of crosslinking hydrogen silicone oil, 100-500 ppm of inhibitor, and 5-20 ppm of platinum catalyst.

[0006] In any of the above technical solutions, the viscosity of the 107 base glue is 20000-80000 mPa·s under standard test conditions (25℃).

[0007] The application realizes ±50% high displacement capacity of silicone sealant while effectively inhibiting the appearance of silicone oil by multi-component synergistic cooperation. The key point is to simultaneously optimize the tensile properties, cohesive strength and interfacial bonding strength of the sealant.

[0008] Firstly, the tensile properties of the sealant are improved and the modulus is reduced by adding a plasticizer (methyl silicone oil), which provides the necessary physical basis for realizing high displacement capacity. Secondly, the application of modified fillers significantly enhances the cohesive strength of the sealant, ensuring that the failure does not occur first in the interior of the sealant (i.e. avoiding cohesive failure) when reaching the displacement limit of ±50%, thereby ensuring the integrity of the sealing layer. In addition, the use of adhesion promoters ensures the synergistic improvement of interfacial strength and cohesive strength, further optimizing the overall performance.

[0009] It should be noted that the premise of strengthening the cohesive strength of the modified filler is to solve the problem of agglomeration and sedimentation caused by poor compatibility of the filler and the matrix. The application significantly enhances the compatibility of the filler and the matrix by coating a layer of silicone rubber on the surface of the filler, thereby improving the interfacial strength between the two phases. The coating layer silicone rubber is made of vinyl polysilazane and high cross-linking density hydrogen silicone oil (hydrogen content ≥3 mol in 1 mol of silicone oil) as raw materials, and forms a highly branched three-dimensional network structure through silicon-hydrogen addition reaction. This structure, on the one hand, uses its molecular cavity to adsorb silicone plasticizer, and on the other hand, greatly extends the migration path of silicone through the steric effect of branched structure. At the same time, the Si-N bond contained in the vinyl polysilazane has excellent high temperature stability (can withstand long-term sunlight irradiation), which helps to inhibit the diffusion and precipitation of silicone oil under high temperature environment.

[0010] On the other hand, by introducing hydroxyl-terminated phenyl silicone oil (hydroxyl-terminated diphenyl polysiloxane), rigid benzene ring structure is introduced into the molecular chain of the sealant. The introduction of benzene ring can effectively inhibit the movement of molecular chain segments at high temperature, reducing the molecular cavities available for silicone migration due to chain segment movement, thereby reducing the tendency of silicone precipitation from the matrix level.

[0011] Finally, the introduction of phenyl segments and polysilazane based on their different heat resistance mechanisms together gives the system excellent heat resistance, inhibiting the performance degradation and silicone precipitation caused by long-term high temperature aging. The synergistic effect of the three enables the sealant to have high elasticity, strong cohesion and durable bonding performance even under the condition of low silicone oil content, ultimately realizing the high displacement capacity of ±50%.

[0012] In any of the above technical solutions, the catalyst is selected from any one or several 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 0.5-1.2:10.

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

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

[0016] The phenyl-containing hydrogen silicone oil is added to the raw material of the silicone rubber, and the phenyl groups thereof are introduced into the network of the silicone rubber coating layer through hydrosilylation. The phenyl groups form strong π-π conjugation interaction with the phenyl groups introduced by the hydroxyl-terminated phenyl silicone oil in the base glue, forming dynamic physical crosslinking points at the filler-matrix interface. This force not only enhances the compatibility of the filler and the base glue and improves the cohesive strength, but also constructs a more compact three-dimensional shielding network, further hinders the migration of the silicone oil plasticizer to the surface, significantly reduces the risk of silicone oil precipitation, and inhibits the pollution problem of the curtain wall substrate.

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

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

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

[0020] In any of the above technical solutions, the platinum catalyst is selected from any one or more of an alcohol 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-butyne-3-ol, 1-ethynylcyclohexanol, 3-phenyl-1-butyne-3-ol, 3-propyl-1-butyne-3-ol, and 3-octyl-1-butyne-3-ol.

[0022] In any of the above technical solutions, the adhesion promoter is prepared by the following method: hydrosilylation of an epoxy group alkenyl monomer and perhydrogenated polysilazane under a platinum catalyst to obtain an epoxy-modified polysilazane; condensation polymerization of a dibasic acid and a dibasic amine with a molar ratio of 1:1.1-1.3 to obtain a polyamide; and reaction of the epoxy-modified polysilazane and the polyamide in a solvent, and removal of the solvent to obtain the adhesion promoter.

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

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

[0025] At the mass ratio of 8-12:100, the silicon hydrogen group in the perhydropolysilazane is greatly excessive, so that the reaction product remains more reactive silicon hydrogen groups.

[0026] In any of the above technical solutions, the binary acid and the binary amine are reacted at 130-170℃ for 6-8h to prepare the polyamide.

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

[0028] The epoxy-modified polysilazane and the polyamide are subjected to ring-opening reaction, and the epoxy-modified polysilazane and the polyamide oligomer are mixed at a mass ratio of 10:1.0-1.8. In the system, the epoxy groups are excessive, and the epoxy groups are grafted to the polysilazane main chain. The steric hindrance of the silazane skeleton and the control of the reaction conditions make the reaction product have reactive epoxy groups, and a small amount of amino groups are retained in the polyamide oligomer.

[0029] In any of the above technical solutions, the binary acid is any one or several of adipic acid, suberic acid, sebacic acid, and terephthalic acid.

[0030] In any of the above technical solutions, the binary amine is selected from hexamethylene diamine and / or decamethylene diamine.

[0031] The adhesion promoter of the present application is synthesized through three steps. Firstly, the epoxy group-containing alkenyl monomer is added to the perhydropolysilazane through silicon hydrogen addition to introduce epoxy groups into the polysilazane. Secondly, the binary acid (adipic acid / sebacic acid, etc.) is polycondensed with excessive binary amine (hexamethylene diamine / decamethylene diamine) to prepare an amine-terminated polyamide. Finally, the epoxy-modified polysilazane is reacted with the polyamide to form a polymer containing epoxy groups, amine groups, and residual Si-H bonds. Among them, the epoxy groups react with the hydroxyl groups on the surface of the substrate, the amine groups participate in the curing network, and the Si-H bonds of the polysilazane condense with the silicone matrix to realize strong interfacial adhesion.

[0032] Compared with the traditional silane coupling agent, the polar amide groups of the polyamide segment of the adhesion promoter promote the enrichment of the molecules at the bonding interface (such as ceramic / concrete), overcome the defect that the interfacial adhesion ability of the traditional silane coupling agent is weak under the conditions of low addition amount and high glue layer thickness, guarantee the interfacial adhesion stability under ±50% displacement, and avoid the interfacial peeling failure caused by high displacement.

[0033] In any of the above technical solutions, the cross-linking agent is selected from any one or more of methyl vinyl dibutanone oxime silane, dimethyl dibutanone oxime silane, methyl vinyl di(methyl isobutanone oxime) silane, methyl vinyl dipropanone 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 an epoxy silane coupling agent, an amino silane coupling agent, and an acryloxy silane coupling agent.

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

[0036] In a second aspect, the present application provides a preparation method of a high-temperature-resistant silicone sealant, comprising the following steps:

[0037] According to the raw material ratio of the silicone sealant of any of the first aspect, the 107 base glue, the hydroxyl-terminated phenyl silicone oil, the plasticizer, and the modified filler are uniformly mixed, and then heated to 120-150°C for vacuum dehydration; the temperature is controlled to be less than 40°C, the cross-linking agent, the adhesion promoter, and the catalyst are added, and then uniformly mixed under vacuum to obtain the product.

[0038] In summary, the present application has the following beneficial effects:

[0039] The high-temperature-resistant silicone sealant of the present application realizes high displacement capacity and low silicone oil precipitation risk through overall design. Specifically, the silicone oil plasticizer is used to improve the flexibility of the body, the filler coated with silicone rubber is used to improve the cohesive strength of the body, and the adsorption network is constructed to inhibit the precipitation of silicone oil, and the adhesion promoter is used to strengthen the interface bonding. Further, the hydroxyl-terminated phenyl silicone oil is used to introduce benzene ring structure in the base glue, which destroys the formation of silicone oil migration path and reduces the tendency of silicone oil precipitation from the base layer. In addition, the introduction of phenyl segment and polysilazane significantly improves the heat resistance and tolerates the performance degradation caused by 80°C high temperature. Finally, while achieving ±50% high displacement capacity, the problems of silicone oil precipitation pollution and adhesion decay of traditional products are effectively solved, and the long-term sealing demand of high-rise building curtain wall is met. DETAILED DESCRIPTION

[0040] Preparation Example

[0041] Preparation Example 1-1

[0042] The modified filler is prepared by the following steps:

[0043] 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.

[0044] Preparation Examples 1-2

[0045] The modified filler is prepared by following these steps:

[0046] 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.

[0047] Preparation Examples 1-3

[0048] The modified filler is prepared by following these steps:

[0049] 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.

[0050] Preparation Examples 1-4

[0051] The modified filler differs from that in Preparation Example 1-1 in that it does not contain phenyl hydrogen silicone oil (IOTA 231).

[0052] Preparation Examples 1-5

[0053] 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).

[0054] Preparation Examples 1-6

[0055] The modified filler differs from that in Preparation Example 1-1 in that it replaces the crosslinked hydrogen silicone oil (side-containing hydrogen silicone oil with a hydrogen content of 0.75-0.79%) with an equal amount of phenyl hydrogen silicone oil (IOTA 231).

[0056] Preparation Examples 1-7

[0057] 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).

[0058] Preparation Examples 1-8

[0059] 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).

[0060] Preparation Examples 1-9

[0061] The modified filler is prepared by following these steps:

[0062] 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.

[0063] Preparation Example 2-1

[0064] The adhesion promoter was prepared according to the following method:

[0065] 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.

[0066] 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.

[0067] 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.

[0068] Preparation Example 2-2

[0069] The adhesion promoter was prepared according to the following method:

[0070] 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.

[0071] 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.

[0072] 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.

[0073] Preparation Examples 2-3

[0074] The adhesion promoter was prepared according to the following method:

[0075] 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.

[0076] 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.

[0077] 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.

[0078] Preparation Examples 2-4

[0079] 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).

[0080] Preparation Examples 2-5

[0081] The adhesion promoter was prepared according to the following method:

[0082] 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.

[0083] 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.

[0084] Example

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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).

[0094] Comparative Example

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] Performance testing

[0102] Experiment 1: Physical and chemical properties test of silicone sealant

[0103] 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.

[0104] Experiment 2: Test on the anti-exudation performance of silicone sealant

[0105] 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):

[0106] Grade 0: No oily substances;

[0107] Level 1: Localized tiny oil droplets;

[0108] Level 2: Continuous oil film (area ≤10%);

[0109] Level 3: Large area oil film (area > 10%);

[0110] Experiment 3: Test of the bonding strength of silicone sealant

[0111] 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%.

[0112] Table 1. Performance Test Results

[0113]

[0114] Analysis of experimental results:

[0115] 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.

[0116] 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.

[0117] 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 a filler and silicone rubber coated on the surface of the filler. The modified filler is obtained by applying silicone rubber raw material to the surface of the filler and then crosslinking and curing it. The mass ratio of silicone rubber raw material to filler is 0.5-1.2:

10. The silicone rubber raw material contains 5-20 parts of vinyl-terminated silicone oil, 10-15 parts of vinyl polysilazane, 3-10 parts of crosslinked hydrogen silicone oil, 1-5 parts of phenyl hydrogen silicone oil, 100-500 ppm of inhibitor, and 5-20 ppm of platinum catalyst. The adhesion promoter is prepared by the following method: epoxy-modified polysilazane is prepared by hydrosilylation of epoxy-based alkenyl monomers and perhydropolysilazane in a mass ratio of 8-12:100 under a platinum catalyst; polyamide is prepared by polycondensation of diacid and diamine in a molar ratio of 1:1.1-1.3; and polyamide is prepared by reacting epoxy-modified polysilazane and polyamide in a solvent in a mass ratio of 10:1.0-1.8, and the solvent is removed to obtain the final product.

2. The high-temperature resistant silicone sealant according to claim 1, characterized in that, The epoxy-alkenyl monomer is allyl alcohol glycidyl ether and / or glycidyl methacrylate.

3. The high-temperature resistant silicone sealant according to claim 1, characterized in that, The dicarboxylic acid and diamine are reacted at 130–170°C for 6–8 hours to obtain polyamide.

4. The high-temperature resistant silicone sealant according to claim 1, characterized in that, The reaction temperature of the epoxy-modified polysilazane with the polyamide is 80–100 °C.

5. 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.

6. 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 5, 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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