Single-component flame-retardant silicone sealant and preparation method thereof

Abstract

The invention discloses a single-component flame-retardant silicone sealant and a preparation method thereof, and aims to provide a sealing material with excellent flame retardance, good adhesive force and long weather resistance. Comprising the following raw materials: 30 to 50 parts of alpha, omega-dihydroxy polydimethylsiloxane, 30 to 50 parts of nano calcium carbonate, 1 to 5 parts of a flame retardant, 5 to 15 parts of a flame-retardant filler, 0.3 to 0.5 part of a cross-linking agent, 0.3 to 0.8 part of a coupling agent and 0.02 to 0.05 part of a catalyst. By optimizing the proportion of the components and introducing the specific phosphorus-based flame retardant and the flame-retardant inorganic filler, the sealant can effectively inhibit combustion and delay flame propagation when encountering fire. Meanwhile, the flame-retardant sealant disclosed by the invention also shows excellent mechanical properties and weather resistance, is easy for industrial production and has a wide market application prospect.

Description

Technical Field

[0001] The invention relates to the field of silicone sealants for photovoltaics, and in particular to a fire-resistant and flame-retardant single-component sealant. Background Art

[0002] With the rapid development of the solar photovoltaic industry in China, it has become an indispensable part of my country's energy structure. In the manufacturing and installation process of photovoltaic modules, silicone sealants ensure the long-term and stable operation of photovoltaic modules due to their weather resistance, flame retardancy, elasticity and electrical insulation, and meet the application requirements of photovoltaic systems under various extreme environmental conditions. However, traditional silicone sealants are usually composed of polydimethylsiloxane, nano-calcium carbonate and additives, and their flame retardant properties are relatively limited. The fire risk of components exposed to high temperature, strong ultraviolet rays and extreme weather for a long time cannot be ignored. Therefore, improving the flame retardant properties of silicone sealants is a necessary measure to deal with the safety risks of photovoltaic systems. At present, common flame retardant sealants have problems such as low mechanical properties, difficult processing and limited weather resistance.

[0003] Therefore, the present invention provides a fire-retardant silicone sealant and a preparation method thereof, which solves the technical problems of low mechanical properties, great processing difficulty and limited weather resistance of existing flame-retardant silicone sealants, and uses a flame retardant with strong flame retardancy and halogen-free elements to cooperate with the flame retardant filler, thereby reducing the amount of traditional flame retardant fillers added, and compensating for the problems of low mechanical properties, great processing difficulty and poor weather resistance of common flame retardant silicone sealants. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a fire-retardant silicone sealant and a preparation method thereof, which can achieve V-0 level flame retardancy while meeting the requirements of the photovoltaic industry for the initial mechanical properties and aging mechanical properties of silicone sealants.

[0005] The purpose of the present invention is to provide a flame retardant silicone sealant.

[0006] Another object of the present invention is to provide a method for preparing the flame retardant silicone sealant.

[0007] The flame retardant silicone sealant provided by the present invention comprises the following raw materials in parts by weight: α,ω-dihydroxypolydimethylsiloxane 30-50 parts, nano calcium carbonate 30-50 parts, flame retardant 1-5 parts, flame retardant filler 5-15 parts, cross-linking agent 0.3-0.5 parts, coupling agent 0.3-0.8 parts, catalyst 0.02-0.05 parts.

[0008] Furthermore, the viscosity of α,ω-dihydroxypolydimethylsiloxane is 18000-85000 mpa·s.

[0009] Furthermore, the nano calcium carbonate is nano calcium carbonate modified by a phosphonate surfactant, and the modification method is a surfactant modification method, wherein calcium oxide is mixed with a certain amount of distilled water for digestion, an alcohol solution of a phosphonate surfactant is added, and after mixing for 1-2 hours, a mixed solution of carbon dioxide and nitrogen is introduced until the pH is neutral, and then the nano calcium carbonate modified by a phosphonate surfactant is obtained by drying.

[0010] The mass of the phosphonate surfactant is 5-20% of the mass of the calcium oxide powder.

[0011] The phosphonate surfactant is a combination of one or more of octadecyl aminobutyl phosphate, didodecyl butane diphosphonate, and didodecyl aminobutyl phosphate; the alcohol solution is a C1-C5 alcohol solvent, and the mass concentration of the alcohol solution of the phosphonate surfactant is 1-3%.

[0012] In some embodiments, the nano-calcium carbonate is a phosphate surfactant-modified nano-calcium carbonate, and the preparation method is that the nano-calcium carbonate is a phosphonate surfactant-modified nano-calcium carbonate. The modification method is a surfactant modification method, wherein calcium oxide is mixed with a certain amount of distilled water for digestion, and an ethanol aqueous solution of a phosphonate surfactant with a concentration of 1-3% of the powder mass is added, and after mixing for 1-2 hours, a mixed solution of carbon dioxide and nitrogen with a volume ratio of 1:3-5 is introduced until the pH is 7.0-7.5, and then dried to obtain the phosphate surfactant-modified nano-calcium carbonate.

[0013] Furthermore, the flame retardant is one or more of UN-333, melamine, melamine polyphosphate and ammonium polyphosphate.

[0014] Furthermore, the flame retardant filler is aluminum hydroxide and / or magnesium hydroxide modified by a modifier. Preparation method: aluminum hydroxide and / or magnesium hydroxide are mixed with distilled water to form a slurry, and the modifier diluted with anhydrous ethanol is added and stirred for 20-60 minutes, and then placed in an oven at 110°C for drying to obtain a flame retardant filler modified by a composite coupling agent. The modifier is obtained by compounding 1-3 coupling agents among silane, titanate, and aluminate with stearic acid.

[0015] The silane is selected from any one of [3-(phenylamino)propyl]trimethoxysilane, N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane, aminopropyltrimethoxysilane, ureapropyltrimethoxysilane, methylaminopropyldimethoxysilane, and N-[3-(trimethoxysilyl)propyl]ethylenediamine; the phthalate is selected from any one of isopropyl tri(dioctyl pyrophosphate acyloxy) titanate, isopropyl trioleate acyloxy titanate, tetraisopropyl di(dioctyl phosphite acyloxy) titanate, and isopropyl tri(dioctyl phosphate acyloxy) titanate; and the aluminate is selected from any one of distearoyloxyisopropylaluminate, (ethyl acetoacetate) aluminate diisopropyl, (acetylacetone) aluminate diisopropyl, and isopropyl distearoyloxy aluminate. Furthermore, the crosslinking agent is any one or more of methyltributy!ketoximesilane, vinyltributyketoximesilane and phenyltributyketoximesilane.

[0016] Furthermore, the silane coupling agent is any one or more of γ-aminopropyltriethoxysilane and β-aminoethyl-γ-aminopropyltrimethoxysilane.

[0017] Furthermore, the catalyst is any one or more of isopropyl titanate, butyl titanate, dibutyl tin dilaurate and dibutyl tin diacetate.

[0018] A method for preparing a flame retardant silicone sealant, characterized in that it comprises the following steps: (1) α, ω-dihydroxy polydimethylsiloxane, calcium carbonate and flame retardant filler are uniformly stirred in a kneader under vacuum to remove moisture to obtain a base material; (2) After the base material is cooled to room temperature, a flame retardant is added to the base material obtained in step (1) under vacuum conditions, and the mixture is vacuum stirred to obtain a flame retardant base material.

[0019] (3) adding a crosslinking agent to the flame retardant base material obtained in step (2), stirring and mixing the mixture in a vacuum manner, then adding a coupling agent and a catalyst, stirring the mixture in a vacuum manner, and obtaining the flame retardant silicone sealant.

[0020] Furthermore, in step (1), the stirring temperature is 120-160° C., the reaction time is 150-300 min, and the stirring speed is 50 r / min.

[0021] Furthermore, in step (2), the vacuum degree of stirring is -0.1 Mpa, and the stirring rate is 80-120 r / min.

[0022] Furthermore, in step (3), the stirring vacuum degree is -0.1PMpa, the stirring time is 15-30min, and the stirring rate is 80-120r / min.

[0023] Compared with the existing flame retardant silicone sealant, the present invention has the following beneficial effects: 1. The use of phosphate surfactants to modify nano-calcium carbonate reduces the surface energy and polarity of nano-calcium carbonate, allowing nano-calcium carbonate to better knead with α, ω-dihydroxypolydimethylsiloxane and improve its aging performance. At the same time, the use of phosphate modifiers can be used as acid sources to cooperate with flame retardants to form intumescent flame retardants, thereby reducing the amount of flame retardant fillers added.

[0024] 2. Using a compound coupling agent to modify aluminum hydroxide and magnesium hydroxide can obtain a flame retardant filler with a better powder activation value, improve the interface between the flame retardant filler and α, ω-dihydroxypolydimethylsiloxane, and enhance the comprehensive performance of the sealant.

[0025] The invention has simple raw materials, scientific and reasonable design, and convenient preparation process. Although common flame retardant fillers (aluminum hydroxide and magnesium hydroxide) have the advantages of good flame retardancy, good smoke performance, good corrosion resistance, etc., when added in large quantities, the prepared sealant often shows poor weather resistance in the double 85 aging test, and it is difficult to meet the requirements of the photovoltaic industry for mechanical properties. The invention combines the expansive flame retardant formed by combining modified nano calcium carbonate and flame retardant with the flame retardant filler, thereby reducing the usage of the flame retardant filler. At the same time, only the aluminum hydroxide and magnesium hydroxide are modified with a complex cross-linking agent, thereby improving the compatibility of the flame retardant filler with α, ω-dihydroxy polydimethylsiloxane, so that the flame retardancy of the silicone sealant reaches V-0 level, and the mechanical strength after aging is basically consistent with that of the silicone sealant without adding the flame retardant filler. DETAILED DESCRIPTION

[0026] In view of this, the present invention provides a fire-retardant silicone sealant and a preparation method thereof, which can achieve V-0 level flame retardancy while meeting the requirements of the photovoltaic industry for the initial mechanical properties and aging mechanical properties of silicone sealants.

[0027] The raw materials used are as follows: α,ω-dihydroxypolydimethylsiloxane was purchased from Hubei Xingrui Silicon Materials Co., Ltd.

[0028] Nano calcium carbonate, homemade modified nano calcium carbonate.

[0029] The flame retardants are UN-333 and melamine phosphate. UN-333 is purchased from Shanghai Unai Silicone Materials Co., Ltd. on the market; melamine phosphate is purchased from Shanghai Huayuan Century Trading Co., Ltd. on the market.

[0030] The flame retardant fillers are aluminum hydroxide and magnesium hydroxide, and homemade modified aluminum hydroxide and modified magnesium hydroxide.

[0031] The crosslinking agents are methyltributy!ketoneoximesilane, vinyltributy!ketoneoximesilane and phenyltributy!ketoneoximesilane, purchased from Hubei Xinlantian Chemical Co., Ltd. The coupling agents are γ-aminopropyltriethoxysilane and β-aminoethyl-γ-aminopropyltrimethoxysilane, which are purchased from Hubei Xinlantian Chemical Co., Ltd.

[0032] The catalysts are isopropyl titanate, butyl titanate, dibutyl tin dilaurate and dibutyl tin diacetate, which are purchased from Hubei Xinlantian Chemical Co., Ltd.

[0033] The preparation method of nano-calcium carbonate modified by phosphate surfactant is as follows: calcium oxide is mixed with a certain amount of distilled water for digestion to obtain a calcium hydroxide solution, and an ethanol solution of octadecyl alcohol aminobutyl phosphate with a concentration of 1-3% of the powder mass and the same mass as the distilled water is added, and after mixing for 1-2 hours, a mixed solution of carbon dioxide and nitrogen with a volume ratio of 1:3 is introduced until the pH is 7, and then dried to obtain nano-calcium carbonate modified by phosphate surfactant. Different concentrations of phosphate surfactants can obtain modified nano-calcium carbonate with different modification degrees, wherein the phosphate surfactant is one of octadecyl alcohol aminobutyl phosphate, didodecyl alcohol butane diphosphonate, didodecyl alcohol aminobutyl phosphate, etc.

[0034] The preparation method of the flame retardant filler is as follows: aluminum hydroxide or magnesium hydroxide is mixed with distilled water to form a slurry, a modifier diluted with anhydrous ethanol is added, stirred for 20-60 minutes, and then placed in an oven at 110 degrees Celsius for drying to obtain a flame retardant filler modified by a composite modifier. The modifier is a compound of 1-3 coupling agents among silane, titanate, and aluminate and stearic acid. The silane is selected from any one of [3-(phenylamino)propyl]trimethoxysilane, N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane, aminopropyltrimethoxysilane, ureapropyltrimethoxysilane, methylaminopropyldimethoxysilane, and N-[3-(trimethoxysilyl)propyl]ethylenediamine; the phthalate is selected from any one of isopropyl tri(dioctyl pyrophosphate acyloxy) titanate, isopropyl trioleate acyloxy titanate, tetraisopropyl di(dioctyl phosphite acyloxy) titanate, and isopropyl tri(dioctyl phosphate acyloxy) titanate; the aluminate is selected from any one of distearoyloxy isopropyl aluminate, (ethyl acetoacetate) aluminate diisopropyl, (acetylacetone) aluminate diisopropyl, and isopropyl distearoyloxy aluminate. .

[0035] The embodiment provides a fire-retardant silicone sealant and a preparation method thereof, comprising the following steps: Example 1 A sealant base material, comprising the following raw materials in parts by weight:

[0036] The preparation method of phosphate surfactant modified nano calcium carbonate is as follows: calcium oxide is mixed with an excess of distilled water until the solution is cooled, and then an ethanol solution of octadecyl aminobutyl phosphate with a concentration of 2% of the powder mass and the same mass as the distilled water is added (the mass of the phosphonate surfactant is 5% of the mass of the calcium oxide powder), and after mixing and stirring for 1-2 hours, continue stirring and introduce a mixed gas of carbon dioxide and nitrogen with a volume ratio of 1:3 until the pH of the solution is 7.0, and then vacuum dry to obtain phosphate surfactant modified nano calcium carbonate 1.

[0037] The preparation method of the flame retardant filler is as follows: aluminum hydroxide is mixed with distilled water to form a slurry, a modifier diluted with anhydrous ethanol is added, stirred for 20-60 minutes, and then placed in an oven at 110°C for drying to obtain a flame retardant filler modified by a composite modifier. The modifier is a composite of [3-(phenylamino)propyl]trimethoxysilane and stearic acid in a mass ratio of 1:1 to obtain a flame retardant filler 1.

[0038] Preparation of fire-retardant silicone sealant: α,ω-dihydroxy polydimethylsiloxane with a viscosity of 20,000, modified nano calcium carbonate 1 and flame-retardant filler 1 are added to a kneader, vacuum heated to 130°C, and dehydrated at high temperature for 3 hours. After cooling to 25°C, melamine phosphate and UN-333 are added, and vacuum stirred in a planetary machine for 10 minutes. The above-mentioned cross-linking agent, coupling agent and catalyst are added twice every 15 minutes, and the material is discharged after vacuum stirring to obtain a fire-retardant silicone sealant.

[0039] Example 2

[0040] Preparation of modified nano-calcium carbonate: The preparation method of nano-calcium carbonate modified by phosphate surfactant is as follows: calcium oxide is mixed with a certain amount of distilled water for digestion to obtain a calcium hydroxide solution, and a di(dodecanol)butane diphosphonate ethanol solution with a concentration of 2% of the powder mass and the same mass as distilled water is added (the mass of the phosphonate surfactant is 5% of the mass of the calcium oxide powder). After mixing for 1-2 hours, a mixed solution of carbon dioxide and nitrogen with a volume ratio of 1:3 is introduced until the pH is 7.0, and then dried to obtain phosphate surfactant-modified nano-calcium carbonate 2.

[0041] Preparation of modified aluminum hydroxide: The modifier is a mixture of isopropyl trioleyl titanate and stearic acid in a ratio of 1:1. Aluminum hydroxide is mixed with distilled water to form a slurry. The modifier diluted with anhydrous ethanol (modifier mass fraction 2%) is added and stirred for 40 minutes. The mixture is then placed in an oven at 110 degrees Celsius for drying to obtain modified aluminum hydroxide, i.e., flame retardant filler 2-1.

[0042] Preparation of modified magnesium hydroxide: The modifier is a mixture of isopropyl trioleyl titanate and stearic acid in a ratio of 1:1. Magnesium hydroxide is mixed with distilled water to form a slurry. The modifier diluted with anhydrous ethanol (modifier mass fraction 2%) is added and stirred for 40 minutes. The mixture is then placed in an oven at 110 degrees Celsius for drying to obtain modified magnesium hydroxide, i.e., flame retardant filler 2-2.

[0043] Preparation of fire-retardant silicone sealant: 20,000 viscosity α, ω-dihydroxy polydimethylsiloxane, modified nano calcium carbonate 2, flame retardant filler 2-1, and flame retardant filler 2-2 are added to a kneader, vacuum heated to 130°C, and dehydrated at high temperature for 3 hours. After cooling to 25°C, melamine phosphate and UN-333 are added, and vacuum stirred in a planetary machine for 10 minutes. The above-mentioned cross-linking agent, coupling agent and catalyst are added twice every 15 minutes, and the material is discharged after vacuum stirring to obtain a fire-retardant silicone sealant.

[0044] Example 3

[0045] Preparation of modified nano-calcium carbonate: The preparation method of phosphate surfactant modified nano-calcium carbonate is as follows: calcium oxide is mixed with a certain amount of distilled water for digestion to obtain a calcium hydroxide solution, and a dioctadecyl aminobutyl phosphate ethanol solution with a concentration of 2% of the powder mass and the same mass as distilled water is added (the mass of the phosphonate surfactant is 5% of the mass of the calcium oxide powder). After mixing for 1-2 hours, a mixed solution of carbon dioxide and nitrogen with a volume ratio of 1:3 is introduced until the pH is 7.0, and then dried to obtain phosphate surfactant modified nano-calcium carbonate 3.

[0046] Preparation of modified aluminum hydroxide: The modifier is a mixture of N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane and stearic acid in a ratio of 1:1. Aluminum hydroxide is mixed with distilled water to form a slurry. The modifier diluted with anhydrous ethanol (modifier mass fraction 2%) is added and stirred for 40 minutes. The mixture is then dried in an oven at 110°C to obtain modified aluminum hydroxide, i.e., flame retardant filler 3-1.

[0047] Preparation of modified magnesium hydroxide: The modifier is a mixture of N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane and stearic acid in a ratio of 1:1. Magnesium hydroxide is mixed with distilled water to form a slurry. The modifier diluted with anhydrous ethanol (modifier mass fraction 2%) is added and stirred for 40 minutes. The mixture is then placed in an oven at 110°C for drying to obtain modified magnesium hydroxide, i.e., flame retardant filler 3-2.

[0048] Preparation of fire-retardant silicone sealant: 20,000 viscosity α, ω-dihydroxy polydimethylsiloxane, modified nano calcium carbonate 3, modified aluminum hydroxide 3-1, and modified magnesium hydroxide 3-2 are added to a kneader, vacuum heated to 130°C, and dehydrated at high temperature for 3 hours. After cooling to 25°C, melamine phosphate and UN-333 are added, and vacuum stirred in a planetary machine for 10 minutes. The above-mentioned cross-linking agent, coupling agent and catalyst are added twice every 15 minutes, and the material is discharged after vacuum stirring to obtain a fire-retardant silicone sealant.

[0049] Example 4

[0050] Preparation of modified nano-calcium carbonate: The preparation method of nano-calcium carbonate modified by phosphate surfactant is as follows: calcium oxide is mixed with a certain amount of distilled water for digestion to obtain a calcium hydroxide solution, and 1% octadecanol aminobutyl phosphate ethanol solution and 2% di(octadecanol) aminobutyl phosphate ethanol solution (the mass of phosphonate surfactant is 8% of the mass of calcium oxide powder) with the same mass as distilled water are added. After mixing for 1-2 hours, a mixed solution of carbon dioxide and nitrogen with a volume ratio of 1:3 is introduced until the pH is 7.0, and then dried to obtain phosphate surfactant-modified nano-calcium carbonate 4.

[0051] Preparation of modified aluminum hydroxide: The modifier is a mixture of distearoyloxyisopropylaluminate and stearic acid in a ratio of 1:1. Aluminum hydroxide is mixed with distilled water to form a slurry, and then the modifier diluted with anhydrous ethanol (modifier mass fraction 2%) is added and stirred for 40 minutes. The mixture is then placed in an oven at 110°C for drying to obtain modified aluminum hydroxide, i.e., flame retardant filler 4-1.

[0052] Preparation of modified magnesium hydroxide: The modifier is a mixture of distearoyloxyisopropylaluminate and stearic acid in a ratio of 1:1. Magnesium hydroxide is mixed with distilled water to form a slurry. The modifier diluted with anhydrous ethanol (modifier mass fraction 2%) is added and stirred for 40 minutes. The mixture is then placed in an oven at 110°C for drying to obtain modified magnesium hydroxide, i.e., flame retardant filler 4-2.

[0053] Preparation of fire-retardant silicone sealant: 80,000 viscosity α,ω-dihydroxy polydimethylsiloxane, modified nano calcium carbonate, modified aluminum hydroxide, and modified magnesium hydroxide are added to a kneader, vacuum heated to 130°C, and dehydrated at high temperature for 3 hours. After cooling to 25°C, melamine phosphate and UN-333 are added, and vacuum stirred in a planetary machine for 10 minutes. The above-mentioned cross-linking agent, coupling agent and catalyst are added twice every 15 minutes, and the material is discharged after vacuum stirring to obtain a fire-retardant silicone sealant.

[0054] Comparative Example 1 A common flame retardant silicone sealant component and composition by mass are 40 parts of α,ω-dihydroxy polydimethylsiloxane, 25 parts of nano calcium carbonate, 25 parts of distearyloxyisopropylaluminate modified aluminum hydroxide, 0.5 parts of a crosslinking agent, 0.4 parts of a coupling agent and 0.02 parts of a catalyst. The crosslinking agent is vinyl tributyl ketoxime silane, the coupling agent is γ-aminopropyl triethoxysilane, and the catalyst is dibutyltin diacetate.

[0055] Preparation method: Heat and knead α,ω-dihydroxypolydimethylsiloxane and distearoyloxyisopropylaluminate in a vacuum kneader until uniform, then pour into a double planetary mixer, add a crosslinking agent, a coupling agent and a catalyst according to a proportion, mix uniformly and then discharge and package.

[0056] Comparative Example 2 The invention discloses a common flame retardant silicone sealant whose components and weight parts are 40 parts of α,ω-dihydroxypolydimethylsiloxane, 30 parts of nano calcium carbonate, 10 parts of distearoyloxyisopropylaluminate modified aluminum hydroxide, 10 parts of distearoyloxyisopropylaluminate modified magnesium hydroxide, 0.5 parts of a crosslinking agent, 0.3 parts of a coupling agent and 0.02 parts of a catalyst.

[0057] Preparation method: Heat and knead α,ω-dihydroxypolydimethylsiloxane and aluminum salt flame retardant in a vacuum kneader, pour them into a double planetary mixer, add crosslinking agent, coupling agent and catalyst according to the proportion, mix them evenly and then discharge and package them.

[0058] Comparative Example 3 A common flame retardant silicone sealant component and its mass composition are 40 parts of 107 silicone rubber, 45 parts of nano calcium carbonate, 8 parts of distearoyloxyisopropylaluminate modified aluminum hydroxide, 2 parts of distearoyloxyisopropylaluminate modified aluminum hydroxide, 2 parts of melamine phosphate, 3 parts of UN-333, 0.5 parts of a crosslinking agent, 0.5 parts of a coupling agent and 0.03 parts of a catalyst.

[0059] Preparation method: Heat and knead α,ω-dihydroxypolydimethylsiloxane and aluminum salt flame retardant in a vacuum kneader, pour into a double planetary mixer, add crosslinking agent, coupling agent and catalyst according to the proportion, mix evenly in vacuum, and then discharge and package.

[0060] The performance test data of the sealants prepared in the examples and comparative examples under standard conditions are as follows:

[0061] It can be seen from the table that the flame retardant sealant of the present invention has excellent initial mechanical properties, aging mechanical properties and flame retardant properties. By comparing Examples 1 and 2, it can be seen that when aluminum hydroxide and magnesium hydroxide cooperate with each other, less flame retardant filler is required to achieve V-0 grade flame retardancy, and the aging performance is also better. By comparing Examples 2, 3, and 4, the flame retardant filler modified by compounding phthalate coupling agents and stearic acid has the best aging resistance. By comparing Examples 1, 2, 3, and 4 with the comparative example, it can be found that the sealant prepared by the modified filler has V-0 grade flame retardant effect and excellent aging performance.

Claims

1. A one-component flame retardant silicone sealant, characterized in that: The invention comprises the following raw materials in parts by weight: α,ω-dihydroxypolydimethylsiloxane 30-50 parts, nano calcium carbonate 30-50 parts, flame retardant 1-5 parts, flame retardant filler 5-15 parts, cross-linking agent 0.3-0.5 parts, coupling agent 0.3-0.8 parts, catalyst 0.02-0.05 parts.

2. A one-component flame retardant silicone sealant according to claim 1, characterized in that: The viscosity of the α,ω-dihydroxy polydimethylsiloxane is 18000-85000 mpa·s; the flame retardant is one or more of UN-333, melamine, polyphosphate melamine and ammonium polyphosphate.

3. The one-component flame retardant silicone sealant according to claim 1, characterized in that: The nano calcium carbonate is nano calcium carbonate modified by a phosphonate surfactant, and the modification method is a surfactant modification method, wherein calcium oxide is mixed with a certain amount of distilled water for digestion, an alcohol solution of a phosphonate surfactant is added, and after mixing for 1-2 hours, a mixed solution of carbon dioxide and nitrogen is introduced until the pH value is neutral, and then the nano calcium carbonate modified by a phosphonate surfactant is obtained by drying.

4. The one-component flame retardant silicone sealant according to claim 1, characterized in that: The mass of the phosphonate surfactant is 5-20% of the mass of the calcium oxide powder.

5. The one-component flame retardant silicone sealant according to claim 1, characterized in that: The phosphonate surfactant is one or more of octadecyl aminobutyl phosphate, didodecyl butane diphosphonate, and didodecyl aminobutyl phosphate; the alcohol solution is a C1-C5 alcohol solvent, and the mass concentration of the alcohol solution of the phosphonate surfactant is 1-3%.

6. The one-component flame retardant silicone sealant according to claim 1, characterized in that: The flame retardant filler is modified aluminum hydroxide and / or magnesium hydroxide, and the modification method is to mix aluminum hydroxide and / or magnesium hydroxide with distilled water to form a slurry, add a modifier diluted with anhydrous ethanol, stir for 20-60 minutes, and then put it into an oven at 110°C for drying to obtain a flame retardant filler modified by a composite modifier; wherein the modifier is a composite of 1-3 coupling agents selected from silane, titanate, and aluminate and stearic acid; the silane is selected from [3-(phenylamino)propyl]trimethoxysilane, N-(β-aminoethyl-γ-aminopropyl)methyldimethoxysilane, aminopropyltrimethoxysilane, ureapropyl The phthalate is selected from any one of isopropyl tri(dioctyl pyrophosphate acyloxy) titanate, isopropyl trioleate acyloxy titanate, tetraisopropyl di(dioctyl phosphite acyloxy) titanate and isopropyl tri(dioctyl phosphate acyloxy) titanate; the aluminate is selected from any one of distearoyloxy isopropyl aluminate, (ethyl acetoacetate) aluminate diisopropyl ester, (acetylacetone) aluminate diisopropyl ester and isopropyl distearoyloxy aluminate.

7. The one-component flame retardant silicone sealant according to claim 1, characterized in that: The crosslinking agent is any one or more of methyltributyketoximesilane, vinyltributyketoximesilane and phenyltributyketoximesilane; the silane coupling agent is any one or more of γ-aminopropyltriethoxysilane and β-aminoethyl-γ-aminopropyltrimethoxysilane; the catalyst is any one or more of isopropyl titanate, butyl titanate, dibutyltin dilaurate and dibutyltin diacetate.

8. A method for preparing a one-component flame-retardant silicone sealant according to any one of claims 1 to 7, characterized in that: The following steps are involved: (1) α, ω-dihydroxy polydimethylsiloxane, calcium carbonate and flame retardant filler are uniformly stirred in a kneader under vacuum to remove moisture, thereby obtaining a base material; (2) After the base material is cooled to room temperature, a flame retardant is added to the base material obtained in step (1) under vacuum conditions and the mixture is stirred evenly in a vacuum to obtain a flame retardant base material; (3) Add 0.3-0.5 parts of a cross-linking agent to the flame-retardant base material obtained in step (2), stir and mix them evenly under vacuum, then add 0.3-0.8 parts of a coupling agent and 0.02-0.05 parts of a catalyst, stir and mix them evenly under vacuum to obtain the flame-retardant silicone sealant.

9. The method for preparing the one-component flame-retardant silicone sealant according to claim 8, characterized in that: In step (1), the stirring reaction temperature is 120-160° C., the reaction time is 150-300 min, and the stirring speed is 50 r / min.

10. The method for preparing a one-component flame-retardant silicone sealant according to claim 8, characterized in that: In step (2), the stirring vacuum degree is -0.1Mpa, and the stirring rate is 80-120r / min. In step (3), the stirring vacuum degree is -0.1PMpa, the stirring time is 15-30min, and the stirring rate is 80-120r / min.

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