A high-temperature resistant, fire-retardant sealant, its preparation method and application

Abstract

This invention belongs to the field of fire-retardant sealant technology, specifically relating to a high-temperature resistant, fire-retardant sealant, its preparation method, and its application. By weight, it comprises the following components: 100 parts α,ω-dihydroxypolydimethylsiloxane, 5-15 parts crosslinking agent, 0.1-1 parts catalyst, 1-5 parts coupling agent, 30-40 parts flame retardant, 2-10 parts plasticizer, 50-80 parts ceramic filler, and 10-40 parts reinforcing filler fumed silica. This invention, through the combined use of modified recycled micro-powder and modified wollastonite / zinc borate composite particles, improves the thermal insulation effect of the sealant after ceramic formation while ensuring its ceramic strength.

Description

Technical Field

[0001] This invention belongs to the field of fire-retardant sealant technology, specifically relating to a high-temperature resistant, fire-retardant sealant, its preparation method, and its application. Background Technology

[0002] With the rapid development of my country's construction industry, metal panel curtain walls, stone curtain walls, point-supported glass curtain walls, and hybrid curtain walls composed of various new materials are widely used. Silicone sealants, used for bonding, sealing, and caulking, possess a main chain structure of silicon-oxygen links and exhibit excellent weather resistance. Through long-term practical application, silicone sealants have been recognized by the domestic and international construction industries as a reliable high-performance chemical building material for elastic structures, bonding, sealing, and caulking.

[0003] However, with the increasing requirements for building fire protection levels and the construction industry's emphasis on the fire resistance of curtain walls, the flame-retardant and fire-resistant properties of silicone sealants have become an inevitable development direction. A relatively effective method for achieving flame-retardant and fire-resistant properties in silicone sealants is to add flame-retardant fillers and fillers that can undergo ceramic transformation at high temperatures to the silicone resin matrix, thereby achieving highly efficient flame-retardant and fire-resistant performance.

[0004] Chinese Patent CN110003844B discloses a method for preparing a ceramicized fire-retardant silicone sealant. The sealant comprises: 80-100 parts of α,ω-dihydroxypolydimethylsiloxane, 1-50 parts of polydimethylsiloxane, 50-100 parts of functional filler, 2-24 parts of silane coupling agent, 2-15 parts of plasticizer, 0.5-3 parts of catalyst, and 5-20 parts of water glass. This sealant achieves flame retardancy and fireproofing by forming a dense ceramic body at high temperature. However, the ceramic body formed by this sealant at high temperature has a high density and poor thermal insulation performance, resulting in poor heat insulation effect after a fire. Summary of the Invention

[0005] The purpose of this invention is to provide a high-temperature resistant, fire-retardant sealant, its preparation method, and its application, in order to solve the above-mentioned technical problems.

[0006] To achieve the above-mentioned technical objectives, the technical solution of the present invention is as follows:

[0007] A high-temperature resistant, fire-retardant sealant, comprising the following components by weight: 100 parts of α,ω-dihydroxypolydimethylsiloxane, 5-15 parts of crosslinking agent, 0.1-1 parts of catalyst, 1-5 parts of coupling agent, 30-40 parts of flame retardant, 2-10 parts of plasticizer, 50-80 parts of ceramic filler, and 10-40 parts of reinforcing filler fumed silica;

[0008] The ceramic filler comprises, by weight, the following components: 100 parts of modified wollastonite / zinc borate composite particles, 5-10 parts of modified recycled micro powder, and 5-8 parts of kaolin.

[0009] The modified wollastonite / zinc borate composite particles are obtained by surface hydrophobic modification of wollastonite / zinc borate composite particles.

[0010] The modified recycled micro powder is obtained by high-temperature calcination modification of recycled micro powder.

[0011] As a further improvement, the crosslinking agent is methyl tributanone oxime or vinyl tributanone oxime; the catalyst is dibutyltin dicarboxylate or dibutyltin diacetate; the coupling agent is γ-aminopropyltriethoxysilane or γ-(2,3-epoxypropoxy)propyltrimethoxysilane; the flame retardant is one of melamine polyphosphate, ammonium polyphosphate or melamine; and the plasticizer is polydimethylsiloxane or polyethylene glycol.

[0012] This invention also provides a method for preparing a high-temperature resistant, fire-retardant sealant, comprising the following steps:

[0013] S1. Add wollastonite to deionized water to prepare a wollastonite suspension. Heat the suspension in a constant temperature water bath at 90-95℃ for 1 hour with stirring. Then, add 0.25 mol / L borax solution dropwise. After the addition is complete, continue stirring for 30-40 minutes. Then, slowly add 0.25 mol / L zinc sulfate solution dropwise. After the addition is complete, keep the temperature at 90-95℃ for 5-6 hours. During the reaction, control the pH of the reaction system to 7.5-8.0. After the reaction is complete, separate the solid, wash, dry, and pulverize to obtain wollastonite / zinc borate composite particles.

[0014] Surface hydrophobic modification of wollastonite / zinc borate composite particles yields modified wollastonite / zinc borate composite particles.

[0015] S2. Modified recycled micro powder is obtained by high-temperature calcination;

[0016] S3. Weigh and mix modified wollastonite / zinc borate composite particles, modified recycled micro powder and kaolin to obtain ceramic filler.

[0017] Weigh out the ceramic filler, flame retardant, plasticizer, crosslinking agent, coupling agent, catalyst, and fumed silica;

[0018] α,ω-dihydroxypolydimethylsiloxane was added to a kneader and kneaded continuously. Then, ceramic filler, flame retardant and plasticizer were added in three batches, with an interval of 5 minutes between each addition. After the addition was completed, the mixture was heated to 120~130℃ and kneaded under vacuum for 2.5~3 hours at 0.05~0.1MPa. The mixture was then allowed to cool naturally to room temperature while maintaining the vacuum condition to obtain the base material, which was then sealed and stored for later use.

[0019] S4. Take the base material and stir it under vacuum of 0.05~0.1MPa for 10 minutes. Add the crosslinking agent and stir under vacuum for 30 minutes. Then add the dried fumed silica in three parts. Then add the catalyst and coupling agent and stir under vacuum for 30 minutes. Seal to obtain a high-temperature resistant, fireproof and flame-retardant sealant.

[0020] As a further improvement, in step S1, the mass concentration of wollastonite in the wollastonite suspension is 6-8%, and the volume ratio of the wollastonite suspension, borax solution, and zinc sulfate solution is 1.7-1.8:1:1.

[0021] As a further improvement, in step S1, the surface modification of the wollastonite / zinc borate composite particles specifically involves: dissolving the modifier in anhydrous ethanol, adding the wollastonite / zinc borate composite particles while stirring, stirring and modifying at 60~80℃ for 30~60 min, filtering to obtain a solid, washing and drying to obtain the modified wollastonite / zinc borate composite particles.

[0022] As a further improvement, the mass of the modifier is 1.5 to 2% of the mass of the wollastonite / zinc borate composite particles.

[0023] As a further improvement, in step S3, the high-temperature modification of the regenerated micro powder is specifically carried out by: placing the regenerated micro powder in a crucible, heating it from room temperature (25°C) to 600°C at a heating rate of 4°C / min, holding it at the temperature for 5~5.5 hours, and then naturally cooling it to obtain the modified regenerated micro powder.

[0024] As a further improvement, the preparation method of the modifier is as follows: take ethylene glycol, slowly add phosphorus oxychloride dropwise to it under stirring conditions in an ice-water bath at 5~10℃. After the addition is completed, stir the reaction for 5~6 hours. Then, slowly add a mixed solution containing hexadecyl alcohol, tetrahydrofuran and triethylamine dropwise to it at room temperature. After the addition is completed, react for 2 hours, filter to remove the solid, and then mix the filtrate with deionized water and continue to react for 10~12 hours. After the reaction is completed, a white crude product is obtained, which is recrystallized, washed and dried to obtain the modifier.

[0025] As a further improvement, the molar ratio of ethylene glycol, phosphorus oxychloride and cetyl alcohol is 1:2:2~3.

[0026] This invention also provides the application of high-temperature resistant, fire-retardant sealant in the bonding of prefabricated building components, door and window materials, and fire protection facility materials.

[0027] Due to the adoption of the above technical solution, the beneficial effects of the present invention are as follows:

[0028] This invention provides a high-temperature resistant, fire-retardant sealant and its preparation method. By using modified recycled micro powder and modified wollastonite / zinc borate composite particles, the heat insulation effect of the sealant after ceramic formation is improved while ensuring its ceramic strength.

[0029] In this invention, the high-temperature calcination modification temperature of the recycled micro powder is selected as 600℃. Some calcium carbonate in the modified recycled micro powder is still undecomposed, which can decompose to produce carbon dioxide during the fire process. This forms a closed-cell structure inside the sealant after ceramic formation, which reduces the thermal conductivity of the sealant after ceramic formation and improves the heat insulation effect.

[0030] In this invention, during the high-temperature calcination modification of the recycled micro powder, the moisture in the recycled micro powder is evaporated, and at the same time, the calcium carbonate and CSH gel hydration products in the recycled micro powder are partially decomposed into calcium oxide. Calcium oxide can form calcium feldspar under the high temperature conditions during a fire, which further improves the thermal stability of the sealant after it is made into porcelain.

[0031] In this invention, the recycled micro powder is obtained from waste concrete, which is inexpensive and facilitates the recycling of waste concrete, making it more environmentally friendly.

[0032] Because recycled micropowder forms a closed-cell structure inside the sealant after ceramic formation during a fire, it can reduce the strength of the sealant. This invention deposits zinc borate on the surface of wollastonite to form composite particles with a coating structure. During a fire, under high temperature conditions, the zinc borate on the outside of wollastonite decomposes to form molten boron oxide, which coats the outside of wollastonite as a liquid phase. After the sealant is ceramicized, it can further improve the density of the ceramic. Combined with the porous structure formed by the recycled micropowder, it can prevent the porous ceramic from having insufficient strength after ceramic formation. Attached Figure Description

[0033] Figure 1 This is the FT-IR spectrum of the modifier in Example 1 of this invention;

[0034] Figure 2 These are the XRD patterns of the modified regenerated micro powders from Example 1 and Comparative Examples 1-2 of this invention;

[0035] Figure 3 These are the results of the three-point bending strength test of the ceramic body samples obtained in Example 1 and Comparative Examples 3-7;

[0036] Figure 4 This is a graph showing the highest temperature curve on the back side of the ceramic body sample obtained in Example 1 and Comparative Examples 3-7. Detailed Implementation

[0037] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0038] In this invention, the viscosity of α,ω-dihydroxypolydimethylsiloxane is 20 Pa·s, and the specific surface area of ​​fumed silica is 300 m². 2 / g, the viscosity of polydimethylsiloxane is 0.1 Pa·s, and the polyethylene glycol used is PG400.

[0039] Example 1 A high-temperature resistant, fire-retardant sealant, comprising the following components by weight: 100 parts of α,ω-dihydroxypolydimethylsiloxane, 5 parts of crosslinking agent methyl tributanone oxime, 0.1 parts of catalyst dibutyltin disilicate, 1 part of coupling agent γ-aminopropyltriethoxysilane, 30 parts of flame retardant melamine polyphosphate, 2 parts of plasticizer polydimethylsiloxane, 50 parts of ceramic filler, and 10 parts of reinforcing filler fumed silica;

[0040] The ceramic filler, by weight, includes the following components: 100 parts modified wollastonite / zinc borate composite particles, 5 parts modified recycled micro powder, and 5 parts kaolin.

[0041] This embodiment also provides a method for preparing the above-mentioned high-temperature resistant, fire-retardant sealant, specifically including the following steps:

[0042] S1. Take 6.2 g (0.1 mol) of ethylene glycol and slowly add 30.7 g (0.2 mol) of phosphorus oxychloride dropwise under stirring in an ice-water bath at 5 °C. After the addition is complete, stir the reaction for 5 h. Then, slowly add a mixed solution containing 48.5 g (0.2 mol) of hexadecyl alcohol, 20 mL of tetrahydrofuran and 1 mL of triethylamine dropwise at room temperature. After the addition is complete, react for 2 h, filter to remove the solid, and then mix the filtrate with 60 mL of deionized water and continue to react for 10 h. After the reaction is complete, a white crude product is obtained. After recrystallization with anhydrous ethanol, wash and dry at 50 °C to obtain the modifier. The modifier prepared in this step is mainly used for hydrophobic modification of wollastonite / zinc borate composite particles. The preparation method of the modifier can also adopt the existing preparation method.

[0043] The reaction equation is:

[0044] ;

[0045] ;

[0046] ;

[0047] S2. Dissolve 47.7g (0.125mol) of borax in 300mL of water, and make up the volume to 500mL to obtain a 0.25mol / L borax solution;

[0048] Dissolve 36g (0.125mol / L) zinc sulfate solid in 300mL of water, and make up the volume to 500mL to prepare a 0.25mol / L zinc sulfate solution;

[0049] A 6% wollastonite suspension was prepared by adding 170 mL of deionized water and heating it in a constant temperature water bath at 90 °C for 1 h with stirring. Then, 100 mL of 0.25 mol / L borax solution was added dropwise. After the addition was completed, stirring was continued for 30 min. Then, 100 mL of 0.25 mol / L zinc sulfate solution was slowly added dropwise. After the addition was completed, the reaction was kept at 90 °C for 6 h. During the reaction, the pH of the reaction system was controlled at 7.5 with 4 mol / L sodium hydroxide solution. After the reaction was completed, the solid was separated, washed three times with warm water and three times with ethanol, and finally dried at 80 °C to obtain wollastonite / zinc borate composite particles.

[0050] S3. Dissolve 1.5g of modifier in 50mL of anhydrous ethanol, add 100g of wollastonite / zinc borate composite particles while stirring, stir and modify at 60℃ for 60min, filter to obtain solid, wash with ethanol and dry to obtain modified wollastonite / zinc borate composite particles.

[0051] S4. Place the regenerated micro powder into a crucible and heat it from room temperature (25°C) to 600°C at a heating rate of 4°C / min. After holding the temperature for 5 hours, allow it to cool naturally to obtain the modified regenerated micro powder.

[0052] The preparation method of recycled micro powder is to crush waste concrete, grind it through a grinding mill, and then screen out powder with a thickness of less than 0.075mm, which is recycled micro powder. The specific preparation method is the existing technology.

[0053] S5. Weigh and mix modified wollastonite / zinc borate composite particles, modified recycled micro powder and kaolin to obtain ceramic filler.

[0054] Weigh out the ceramic filler, flame retardant, plasticizer, crosslinking agent, coupling agent, catalyst, and fumed silica;

[0055] α,ω-dihydroxypolydimethylsiloxane was added to a kneader and kneaded continuously. Then, ceramic filler, flame retardant and plasticizer were added in three batches, with a 5-minute interval between each addition. After the addition was completed, the temperature was raised to 120°C and vacuum kneaded at 0.05 MPa for 3 hours. The mixture was then kept under vacuum and allowed to cool naturally to room temperature to obtain the base material, which was then sealed and stored for later use.

[0056] S6. Take the base material and stir it under vacuum of 0.05MPa for 10 minutes. Add the crosslinking agent and stir under vacuum for 30 minutes. Then add the dried fumed silica in three parts. Then add the catalyst and coupling agent and stir under vacuum for 30 minutes. Seal to obtain a high-temperature resistant, fireproof and flame-retardant sealant.

[0057] The drying method for fumed silica is existing technology and will not be described in detail here.

[0058] In this embodiment, the FT-IR spectrum of the modifier is as follows: Figure 1 As shown, by Figure 1 It can be seen that 3462cm -1 The absorption peak at 2850 cm⁻¹ is the stretching vibration absorption peak of the hydroxyl group. -1 and 2918cm -1 The absorption peak at 1643 cm⁻¹ is the stretching vibration peak of CH₂ and CH₃. -1 The absorption peak at 1212 cm⁻¹ is the stretching vibration absorption peak of P-OH. -1 The absorption peak for the stretching vibration of PO is at 1049 cm⁻¹. -1 The peak at this location represents the stretching vibration absorption peak of POC.

[0059] In this embodiment, contact angle tests were performed on wollastonite, wollastonite / zinc borate composite particles, and modified wollastonite / zinc borate composite particles. The water contact angle of wollastonite was 23.22°, the contact angle of the wollastonite / zinc borate composite particles was close to 0°, and the contact angle of the surface-modified wollastonite / zinc borate composite particles increased to 153.2°, showing good oleophilicity. Therefore, it can be determined that in the prepared wollastonite / zinc borate composite particles, zinc borate is coated on the surface of wollastonite, making the surface of the wollastonite / zinc borate composite particles completely wetted and the contact angle close to 0°.

[0060] The high-temperature resistant, fire-retardant sealant prepared in this embodiment is mainly used for bonding prefabricated building components, door and window materials, and fire protection facility materials.

[0061] Example 2 A high-temperature resistant, fire-retardant sealant, comprising the following components by weight: 100 parts of α,ω-dihydroxypolydimethylsiloxane, 15 parts of crosslinking agent vinyltributanone oxime, 1 part of catalyst dibutyltin diacetate, 5 parts of coupling agent γ-(2,3-epoxypropoxy)propyltrimethoxysilane, 40 parts of flame retardant ammonium polyphosphate, 10 parts of plasticizer polyethylene glycol, 80 parts of ceramic filler, and 40 parts of reinforcing filler fumed silica;

[0062] The ceramic filler, by weight, includes the following components: 100 parts of modified wollastonite / zinc borate composite particles, 10 parts of modified recycled micro powder, and 8 parts of kaolin.

[0063] This embodiment also provides a method for preparing the above-mentioned high-temperature resistant, fire-retardant sealant, specifically including the following steps:

[0064] S1. Take 6.2 g (0.1 mol) of ethylene glycol and slowly add 30.7 g (0.2 mol) of phosphorus oxychloride dropwise under stirring in an ice-water bath at 10 °C. After the addition is complete, stir the reaction for 6 h. Then, slowly add a mixed solution containing 72.75 g (0.3 mol) of hexadecyl alcohol, 30 mL of tetrahydrofuran and 1 mL of triethylamine dropwise at room temperature. After the addition is complete, react for 2 h. Filter to remove the solid. Then mix the filtrate with 60 mL of deionized water and continue to react for 12 h. After the reaction is complete, a white crude product is obtained. After recrystallization with anhydrous ethanol, wash and dry at 50 °C to obtain the modifier.

[0065] S2. Dissolve 47.7g of borax in 300mL of water, and make up the volume to 500mL to obtain a 0.25mol / L borax solution;

[0066] Dissolve 36g of zinc sulfate solid in 300mL of water, and make up the volume to 500mL to prepare a 0.25mol / L zinc sulfate solution;

[0067] A wollastonite suspension with a mass concentration of 8% was prepared by adding 170 mL of deionized water and heating it in a constant temperature water bath at 95 °C for 1 h with stirring. Then, 100 mL of 0.25 mol / L borax solution was added dropwise. After the addition was completed, stirring was continued for 40 min. Then, 100 mL of 0.25 mol / L zinc sulfate solution was slowly added dropwise. After the addition was completed, the reaction was kept at 95 °C for 5 h. During the reaction, the pH of the reaction system was controlled at 8.0 with 4 mol / L sodium hydroxide solution. After the reaction was completed, the solid was separated, washed three times with warm water and three times with ethanol, and finally dried at 80 °C to obtain wollastonite / zinc borate composite particles.

[0068] S3. Dissolve 2g of modifier in 50mL of anhydrous ethanol, add 100g of wollastonite / zinc borate composite particles while stirring, stir and modify at 80℃ for 30min, filter to obtain solid, wash with ethanol and dry to obtain modified wollastonite / zinc borate composite particles.

[0069] S4. Place the regenerated micro powder into a crucible and heat it from room temperature (25°C) to 600°C at a heating rate of 4°C / min. Hold the temperature for 5.5 hours and then allow it to cool naturally to obtain the modified regenerated micro powder.

[0070] The preparation method of recycled micro powder is to crush waste concrete, grind it through a grinding mill, and then screen out powder with a thickness of less than 0.075mm, which is recycled micro powder. The specific preparation method is the existing technology.

[0071] S5. Weigh and mix modified wollastonite / zinc borate composite particles, modified recycled micro powder and kaolin to obtain ceramic filler.

[0072] Weigh out the ceramic filler, flame retardant, plasticizer, crosslinking agent, coupling agent, catalyst, and fumed silica;

[0073] α,ω-dihydroxypolydimethylsiloxane was added to a kneader and kneaded continuously. Then, ceramic filler, flame retardant and plasticizer were added in three batches, with a 5-minute interval between each addition. After the addition was completed, the temperature was raised to 130°C and vacuum kneaded at 0.1 MPa for 2.5 hours. The mixture was then kept under vacuum and allowed to cool naturally to room temperature to obtain the base material, which was then sealed and stored for later use.

[0074] S6. Take the base material and stir it under a vacuum of 0.1MPa for 10 minutes. Add the crosslinking agent and stir under vacuum for 30 minutes. Then add the dried fumed silica in three parts. Then add the catalyst and coupling agent and stir under vacuum for 30 minutes. Seal to obtain a high-temperature resistant, fireproof and flame-retardant sealant.

[0075] The drying method for fumed silica is existing technology and will not be described in detail here.

[0076] Example 3 A high-temperature resistant, fire-retardant sealant, comprising the following components by weight: 100 parts of α,ω-dihydroxypolydimethylsiloxane, 10 parts of crosslinking agent vinyltributanone oxime, 0.6 parts of catalyst dibutyltin diacetate, 2.5 parts of coupling agent γ-(2,3-epoxypropoxy)propyltrimethoxysilane, 35 parts of flame retardant melamine, 6 parts of plasticizer polyethylene glycol, 65 parts of ceramic filler, and 20 parts of reinforcing filler fumed silica;

[0077] The ceramic filler, by weight, includes the following components: 100 parts of modified wollastonite / zinc borate composite particles, 8 parts of modified recycled micro powder, and 6 parts of kaolin.

[0078] This embodiment also provides a method for preparing the above-mentioned high-temperature resistant, fire-retardant sealant, specifically including the following steps:

[0079] S1. Take 6.2 g (0.1 mol) of ethylene glycol and slowly add 30.7 g (0.2 mol) of phosphorus oxychloride dropwise under stirring in an ice-water bath at 5 °C. After the addition is complete, stir the reaction for 6 h. Then, slowly add a mixed solution containing 60.6 g (0.25 mol) of hexadecyl alcohol, 30 mL of tetrahydrofuran and 1 mL of triethylamine dropwise at room temperature. After the addition is complete, react for 2 h. Filter to remove the solid. Then mix the filtrate with 60 mL of deionized water and continue to react for 11 h. After the reaction is complete, a white crude product is obtained. After recrystallization with anhydrous ethanol, wash and dry at 50 °C to obtain the modifier.

[0080] S2. Dissolve 47.7g of borax in 300mL of water, and make up the volume to 500mL to obtain a 0.25mol / L borax solution;

[0081] Dissolve 36g of zinc sulfate solid in 300mL of water, and make up the volume to 500mL to prepare a 0.25mol / L zinc sulfate solution;

[0082] A 6% wollastonite suspension was prepared by adding wollastonite to 180 mL of deionized water and heating it in a constant temperature water bath at 93 °C for 1 h with stirring. Then, 100 mL of 0.25 mol / L borax solution was added dropwise. After the addition was completed, stirring was continued for 40 min. Then, 100 mL of 0.25 mol / L zinc sulfate solution was slowly added dropwise. After the addition was completed, the reaction was kept at 93 °C for 5.5 h. During the reaction, the pH of the reaction system was controlled at 7.8 with 4 mol / L sodium hydroxide solution. After the reaction was completed, the solid was separated, washed three times with warm water and three times with ethanol, and finally dried at 80 °C to obtain wollastonite / zinc borate composite particles.

[0083] S3. Dissolve 1.8g of modifier in 50mL of anhydrous ethanol, add 100g of wollastonite / zinc borate composite particles while stirring, stir and modify at 70℃ for 45min, filter to obtain solid, wash with ethanol and dry to obtain modified wollastonite / zinc borate composite particles.

[0084] S4. Place the regenerated micro powder into a crucible and heat it from room temperature (25°C) to 600°C at a heating rate of 4°C / min. Hold the temperature for 5.5 hours and then allow it to cool naturally to obtain the modified regenerated micro powder.

[0085] The preparation method of recycled micro powder is to crush waste concrete, grind it through a grinding mill, and then screen out powder with a thickness of less than 0.075mm, which is recycled micro powder. The specific preparation method is the existing technology.

[0086] S5. Weigh and mix modified wollastonite / zinc borate composite particles, modified recycled micro powder and kaolin to obtain ceramic filler.

[0087] Weigh out the ceramic filler, flame retardant, plasticizer, crosslinking agent, coupling agent, catalyst, and fumed silica;

[0088] α,ω-dihydroxypolydimethylsiloxane was added to a kneader and kneaded continuously. Then, ceramic filler, flame retardant and plasticizer were added in three batches, with an interval of 5 minutes between each addition. After the addition was completed, the temperature was raised to 125°C and vacuum kneaded at 0.08 MPa for 2.8 hours. The mixture was then kept under vacuum and allowed to cool naturally to room temperature to obtain the base material, which was then sealed and stored for later use.

[0089] S6. Take the base material and stir it under vacuum of 0.08MPa for 10 minutes. Add the crosslinking agent and stir under vacuum for 30 minutes. Then add the dried fumed silica in three parts. Then add the catalyst and coupling agent and stir under vacuum for 30 minutes. Seal to obtain a high-temperature resistant, fireproof and flame-retardant sealant.

[0090] The drying method for fumed silica is existing technology and will not be described in detail here.

[0091] Example 4 A high-temperature resistant, fire-retardant sealant, comprising the following components by weight: 100 parts of α,ω-dihydroxypolydimethylsiloxane, 8 parts of crosslinking agent vinyltributanone oxime, 0.4 parts of catalyst dibutyltin diacetate, 1.8 parts of coupling agent γ-(2,3-epoxypropoxy)propyltrimethoxysilane, 33 parts of flame retardant ammonium polyphosphate, 4 parts of plasticizer polyethylene glycol, 55 parts of ceramic filler, and 15 parts of reinforcing filler fumed silica;

[0092] The ceramic filler, by weight, includes the following components: 100 parts of modified wollastonite / zinc borate composite particles, 6 parts of modified recycled micro powder, and 5.5 parts of kaolin.

[0093] This embodiment also provides a method for preparing the above-mentioned high-temperature resistant, fire-retardant sealant, specifically including the following steps:

[0094] S1. Take 6.2 g (0.1 mol) of ethylene glycol and slowly add 30.7 g (0.2 mol) of phosphorus oxychloride dropwise under stirring in an ice-water bath at 5 °C. After the addition is complete, stir the reaction for 6 h. Then, slowly add a mixed solution containing 60.6 g (0.25 mol) of hexadecyl alcohol, 30 mL of tetrahydrofuran and 1 mL of triethylamine dropwise at room temperature. After the addition is complete, react for 2 h. Filter to remove the solid. Then mix the filtrate with 60 mL of deionized water and continue to react for 11 h. After the reaction is complete, a white crude product is obtained. After recrystallization with anhydrous ethanol, wash and dry at 50 °C to obtain the modifier.

[0095] S2. Dissolve 47.7g of borax in 300mL of water, and make up the volume to 500mL to obtain a 0.25mol / L borax solution;

[0096] Dissolve 36g of zinc sulfate solid in 300mL of water, and make up the volume to 500mL to prepare a 0.25mol / L zinc sulfate solution;

[0097] A wollastonite suspension with a mass concentration of 8% was prepared by adding 180 mL of deionized water and heating it in a constant temperature water bath at 93 °C for 1 h with stirring. Then, 100 mL of 0.25 mol / L borax solution was added dropwise. After the addition was completed, stirring was continued for 40 min. Then, 100 mL of 0.25 mol / L zinc sulfate solution was slowly added dropwise. After the addition was completed, the reaction was kept at 93 °C for 5.5 h. During the reaction, the pH of the reaction system was controlled at 7.8 with 4 mol / L sodium hydroxide solution. After the reaction was completed, the solid was separated, washed three times with warm water and three times with ethanol, and finally dried at 80 °C to obtain wollastonite / zinc borate composite particles.

[0098] S3. Dissolve 1.8g of modifier in 50mL of anhydrous ethanol, add 100g of wollastonite / zinc borate composite particles while stirring, stir and modify at 70℃ for 45min, filter to obtain solid, wash with ethanol and dry to obtain modified wollastonite / zinc borate composite particles.

[0099] S4. Place the regenerated micro powder into a crucible and heat it from room temperature (25°C) to 600°C at a heating rate of 4°C / min. Hold the temperature for 5.5 hours and then allow it to cool naturally to obtain the modified regenerated micro powder.

[0100] The preparation method of recycled micro powder is to crush waste concrete, grind it through a grinding mill, and then screen out powder with a thickness of less than 0.075mm, which is recycled micro powder. The specific preparation method is the existing technology.

[0101] S5. Weigh and mix modified wollastonite / zinc borate composite particles, modified recycled micro powder and kaolin to obtain ceramic filler.

[0102] Weigh out the ceramic filler, flame retardant, plasticizer, crosslinking agent, coupling agent, catalyst, and fumed silica;

[0103] α,ω-dihydroxypolydimethylsiloxane was added to a kneader and kneaded continuously. Then, ceramic filler, flame retardant and plasticizer were added in three batches, with an interval of 5 minutes between each addition. After the addition was completed, the temperature was raised to 125°C and vacuum kneaded at 0.08 MPa for 2.8 hours. The mixture was then kept under vacuum and allowed to cool naturally to room temperature to obtain the base material, which was then sealed and stored for later use.

[0104] S6. Take the base material and stir it under vacuum of 0.08MPa for 10 minutes. Add the crosslinking agent and stir under vacuum for 30 minutes. Then add the dried fumed silica in three parts. Then add the catalyst and coupling agent and stir under vacuum for 30 minutes. Seal to obtain a high-temperature resistant, fireproof and flame-retardant sealant.

[0105] The drying method for fumed silica is existing technology and will not be described in detail here.

[0106] Comparative Example 1 This comparative example provides a method for preparing modified regenerated micro powder. The specific steps are as follows: the regenerated micro powder is placed in a crucible, and the temperature is raised from room temperature (25°C) to 400°C at a heating rate of 4°C / min. After holding at the temperature for 5 hours, it is naturally cooled to obtain modified regenerated micro powder.

[0107] Comparative Example 2 This comparative example provides a method for preparing modified regenerated micro powder. The specific steps are as follows: the regenerated micro powder is placed in a crucible, and the temperature is raised from room temperature (25°C) to 800°C at a heating rate of 4°C / min. After holding at the temperature for 5 hours, it is naturally cooled to obtain modified regenerated micro powder.

[0108] The mass of the regenerated micro powder in Example 1 and Comparative Examples 1-2 before and after the high-temperature calcination modification process was measured, and the results are shown in Table 1.

[0109] Table 1. Results of mass changes of regenerated micro powder before and after high-temperature calcination modification.

[0110]

[0111] As shown in Table 1, after temperature intensification at 400℃, 600℃, and 800℃, the mass of the regenerated micro powder decreased by 8.42%, 9.74%, and 10.70%, respectively. This indicates that the higher the temperature, the greater the mass loss of the regenerated micro powder. There are two main reasons for this: firstly, the high temperature evaporates the free water in the regenerated micro powder; secondly, it causes the Ca(OH)2 and CaCO3 molecules in the regenerated micro powder to decompose into lighter CaO molecules.

[0112] The modified regenerated micropowders obtained in Example 1 and Comparative Examples 1-2 were subjected to X-ray diffraction to obtain XRD patterns, as follows: Figure 2 As shown.

[0113] Depend on Figure 2 It can be seen that when the regenerated micro powder was modified at 400℃, no calcium oxide peak appeared at 42° (2θ), but when it was modified at 600℃, a calcium oxide peak appeared at 42° (2θ). This indicates that after modification at 600℃, some of the hydrated components in the regenerated micro powder began to decompose to form calcium oxide, and the intensity of the calcium hydroxide peak in the unhydrated part decreased, indicating that calcium hydroxide also began to decompose gradually.

[0114] When the calcination temperature is increased to 800℃, the peak intensity of calcium oxide is further enhanced, indicating that the content of calcium oxide is relatively high. At the same time, there is basically no peak value of calcium carbonate, indicating that when the modification temperature is increased to 800℃, almost all of the calcium carbonate is decomposed. Therefore, the modified regenerated micro powder is used at 600℃ in this invention.

[0115] Comparative Example 3 This comparative example provides a high-temperature resistant, fire-retardant sealant. The specific formula and preparation method are the same as those in Example 1, except that the ceramic filler is different. The ceramic filler used in this comparative example includes the following components by weight: 100 parts of modified wollastonite / zinc borate composite particles, 5 parts of recycled micro powder, and 5 parts of kaolin.

[0116] Comparative Example 4 This comparative example provides a high-temperature resistant, fire-retardant sealant. The specific formula and preparation method are the same as those in Example 1. The difference lies in the different ceramic filler. The ceramic filler used in this comparative example includes the following components by weight: 100 parts of modified wollastonite / zinc borate composite particles and 5 parts of kaolin.

[0117] Comparative Example 5 This comparative example provides a high-temperature resistant, fire-retardant sealant. The specific formula and preparation method are the same as those in Example 1. The difference lies in the different ceramic filler. The ceramic filler used in this comparative example includes the following components by weight: 80 parts of wollastonite, 20 parts of zinc borate, and 5 parts of kaolin.

[0118] Comparative Example 6 This comparative example provides a high-temperature resistant, fire-retardant sealant. The specific formula and preparation method are the same as those in Example 1. The difference lies in the different ceramic fillers. The ceramic fillers used in this comparative example include the following components by weight: 80 parts modified wollastonite, 20 parts zinc borate, and 5 parts kaolin.

[0119] In this comparative example, the modified wollastonite was obtained by modifying it with silane coupling agent KH570. Specifically, 10g of wollastonite was added to a three-necked flask containing 50mL of 80vol% ethanol solution. The three-necked flask was placed in an 80℃ constant temperature water bath and stirred for 30min at a stirring speed of 500r / min. 0.3g of silane coupling agent KH570 was added to 50mL of 80vol% ethanol solution and stirred for 30min to hydrolyze the coupling agent, resulting in a hydrolyzed alcohol solution of the coupling agent. The hydrolyzed alcohol solution of the coupling agent was slowly added dropwise to the three-necked flask containing wollastonite. After the addition was complete, stirring was continued for 40min. The flask was then removed, ultrasonically dispersed, filtered, repeatedly washed, and dried in an 80℃ oven for 12h to obtain the modified wollastonite.

[0120] The specific methods for modifying KH570 wollastonite are not limited to the methods mentioned above, and modification can be carried out according to existing methods in the prior art.

[0121] Comparative Example 7 This comparative example provides a high-temperature resistant, fire-retardant sealant. The specific formula and preparation method are the same as those in Example 1, except that the ceramic filler is different. The ceramic filler used in this comparative example includes the following components by weight: 100 parts of wollastonite / zinc borate composite particles, 5 parts of modified recycled micro powder, and 5 parts of kaolin.

[0122] The sealants obtained in Example 1 and Comparative Examples 3-7 were subjected to surface drying time and mechanical property tests.

[0123] The surface drying time test was conducted according to GB / T 13477.5-2002, Method B, and the test results are shown in Table 2.

[0124] Table 2. Surface drying time results of the sealants obtained in Example 1 and Comparative Examples 3-7.

[0125]

[0126] As can be seen from Table 2, the different flame-retardant fillers do not have a significant impact on the surface drying time of the sealant. The changes in the surface drying time of the sealant in Comparative Example 5 and Comparative Example 7 may be due to the changes in the quality of wollastonite in the ceramic filler.

[0127] The tensile bond strength was tested according to the method in standard GB / T 13477.8-2017 "Test methods for building sealing materials - Part 8: Determination of tensile bond strength", and the test results are shown in Table 3.

[0128] Table 3. Tensile bond strength results of the sealants in Example 1 and Comparative Examples 3-7

[0129]

[0130] As can be seen from Table 3, compared with Example 1, the results of Comparative Example 3 or Comparative Example 4 show that the recycled micro powder and modified recycled micro powder have basically no effect on the tensile bond strength of the sealant. In Comparative Example 7, the addition of unmodified wollastonite / zinc borate composite particles led to a decrease in its tensile bond strength. This is because the unmodified wollastonite / zinc borate composite particles are prone to agglomeration in the sealant matrix, which affects the tensile bond strength of the sealant.

[0131] Compared with Example 1, the tensile bond strength of Comparative Example 6 was slightly lower than that of Example 1, possibly due to the uneven dispersion of zinc borate in the sealant matrix. The tensile bond strength of Comparative Example 5 was similar to that of Comparative Example 7, both showing a significant decrease, which is because unmodified wollastonite was used in Comparative Example 5, which also exhibited uneven dispersion.

[0132] The sealant obtained in Example 1 and Comparative Examples 3-7 was used to prepare ablation ceramic bodies. The specific method was as follows: the sealant was prepared into a sample of 200mm×200mm×4mm using the scraping method, and cured in air at room temperature for 10 days for vulcanization. The vulcanized sample was cut into strips of 10mm×8mm×4mm and placed in a programmable rapid heating box furnace. The temperature was increased at a rate of 10℃ / min, and after reaching 1000℃, it was held for 30min. Then it was naturally cooled to obtain ceramic body samples.

[0133] Three-point bending strength tests were performed on the ceramic samples obtained in Example 1 and Comparative Examples 3-7. The test method was in accordance with GB / T 1449-2005. The test results are as follows: Figure 3 As shown.

[0134] Depend on Figure 3 It can be seen that, compared with Comparative Example 4, the three-point bending strength of the ceramic body sample in Example 1 is about the same and is higher than that of other comparative examples. The three-point bending strength of the ceramic body sample in Comparative Example 3 is very low. This is because when the regenerated micro powder is not modified, it contains a large amount of calcium carbonate, which decomposes at high temperature to form a large number of large pores, which greatly reduces the three-point bending strength of the ceramic body sample.

[0135] Compared with Example 1, the three-point bending strength of the ceramic body samples in Comparative Examples 5 and 6 was also reduced to a certain extent. This is because the zinc borate had a better coating effect on wollastonite during the vitrification process of the wollastonite / zinc borate composite particles used in Example 1, resulting in a higher density of the ceramic body sample.

[0136] Compared with Example 1, the three-point bending strength of the ceramic body sample was reduced. This was because the unmodified wollastonite / zinc borate composite particles were poorly dispersed in the sealant matrix, resulting in a certain degree of reduction in the three-point bending strength of the ceramic body sample.

[0137] Fire resistance tests were conducted on the ceramic samples obtained in Example 1 and Comparative Examples 3-7, referring to the fire-resistant sealing material standard GB 23864-2023. Specifically, the fire source used in the test was a flame generated by a butane liquefied gas spray gun, with a flame temperature of approximately 1300℃. The flame length was fixed at 80mm before the test, and the distance between the flame root and the test sample was 30mm during the test. The sample dimensions were 200mm long × 170mm wide × 4mm thick. The test time was timed using a stopwatch, and the firing duration was 30 minutes. The temperature of the back side of the sample was detected using an infrared thermal imager. The change in temperature of the back side of the sample over time was monitored, and a curve of the highest temperature on the back side of the sample was obtained, as shown in the figure. Figure 4 As shown.

[0138] Depend on Figure 4It can be seen that the highest temperature of Comparative Example 3 is lower than that of Example 1. This is because the calcium carbonate content in the unmodified regenerated micro powder is higher, and there are more closed-pore structures inside the ceramic body sample after ceramic formation. The resulting ceramic body sample has better heat insulation effect. However, the strength of the ceramic body sample of Comparative Example 3 is low. Therefore, its overall performance is not as good as that of Example 1 of the present invention.

[0139] In Comparative Example 6, modified wollastonite and zinc borate were used, and the density of the resulting ceramic body sample was slightly lower than that of Example 1. Therefore, its maximum temperature was slightly higher than that of Example 1.

[0140] Comparative Example 7 used unmodified wollastonite / zinc borate composite particles, which were unevenly dispersed within the sealant matrix, resulting in a slightly worse thermal insulation effect compared to Example 1.

[0141] In Comparative Example 5, unmodified wollastonite and zinc borate were used. The resulting ceramic sample not only had a low density, but the unmodified wollastonite and zinc borate were also unevenly dispersed within the sealant matrix, which further reduced its thermal insulation effect.

[0142] Comparative Example 4 did not add modified recycled micro powder and used modified wollastonite / zinc borate composite particles. The resulting ceramic sample had the highest density among all comparative examples. However, it lacked the closed-cell structure left by the modified recycled micro powder when heated, resulting in the worst thermal insulation effect. Therefore, it can be seen that the modified recycled micro powder has a much greater impact on the thermal insulation effect of the ceramic sample than wollastonite and zinc borate.

[0143] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A high-temperature resistant, fire-retardant sealant, characterized in that, By weight, it includes the following components: 100 parts of α,ω-dihydroxypolydimethylsiloxane, 5-15 parts of crosslinking agent, 0.1-1 parts of catalyst, 1-5 parts of coupling agent, 30-40 parts of flame retardant, 2-10 parts of plasticizer, 50-80 parts of ceramic filler and 10-40 parts of reinforcing filler fumed silica. The ceramic filler comprises, by weight, the following components: 100 parts of modified wollastonite / zinc borate composite particles, 5-10 parts of modified recycled micro powder, and 5-8 parts of kaolin. The modified wollastonite / zinc borate composite particles are obtained by surface hydrophobic modification of wollastonite / zinc borate composite particles. The wollastonite / zinc borate composite particles are prepared by the following method: wollastonite is added to deionized water to form a wollastonite suspension, and the suspension is heated in a constant temperature water bath at 90-95℃ with stirring for 1 hour. Then, 0.25 mol / L borax solution is added dropwise. After the addition is completed, stirring is continued for 30-40 minutes. Then, 0.25 mol / L zinc sulfate solution is slowly added dropwise. After the addition is completed, the mixture is kept at 90-95℃ for 5-6 hours. During the reaction, the pH of the reaction system is controlled at 7.5-8.

0. After the reaction is completed, the solid is separated, washed, dried, and pulverized to obtain wollastonite / zinc borate composite particles. The modified wollastonite / zinc borate composite particles are prepared by the following method: the modifier is dissolved in anhydrous ethanol, and the wollastonite / zinc borate composite particles are added to it while stirring. The mixture is stirred and modified at 60~80℃ for 30~60 min, filtered, and the solid is obtained. After washing and drying, the modified wollastonite / zinc borate composite particles are obtained. The modifier is prepared by the following method: ethylene glycol is taken, and phosphorus oxychloride is slowly added dropwise to it under stirring in an ice-water bath at 5-10°C. After the addition is completed, the mixture is stirred for 5-6 hours. Then, a mixed solution containing hexadecyl alcohol, tetrahydrofuran and triethylamine is slowly added dropwise to it at room temperature. After the addition is completed, the mixture is reacted for 2 hours. The solid is removed by filtration, and the filtrate is mixed with deionized water and the reaction is continued for 10-12 hours. After the reaction is completed, a white crude product is obtained. The product is recrystallized, washed and dried to obtain the modifier. The modified recycled micro powder is obtained by high-temperature calcination modification of recycled micro powder.

2. The high-temperature resistant, fire-retardant sealant according to claim 1, characterized in that, The crosslinking agent is methyl tributanone oxime or vinyl tributanone oxime; the catalyst is dibutyltin dicarboxylate or dibutyltin diacetate; the coupling agent is γ-aminopropyltriethoxysilane or γ-(2,3-epoxypropoxy)propyltrimethoxysilane; the flame retardant is one of melamine polyphosphate, ammonium polyphosphate or melamine; and the plasticizer is polydimethylsiloxane or polyethylene glycol.

3. The method for preparing the high-temperature resistant, fire-retardant sealant according to claim 1, characterized in that, Includes the following steps: S1. Add wollastonite to deionized water to prepare a wollastonite suspension. Heat the suspension in a constant temperature water bath at 90-95℃ for 1 hour with stirring. Then, add 0.25 mol / L borax solution dropwise. After the addition is complete, continue stirring for 30-40 minutes. Then, slowly add 0.25 mol / L zinc sulfate solution dropwise. After the addition is complete, keep the temperature at 90-95℃ for 5-6 hours. During the reaction, control the pH of the reaction system to 7.5-8.

0. After the reaction is complete, separate the solid, wash, dry, and pulverize to obtain wollastonite / zinc borate composite particles. Surface hydrophobic modification of wollastonite / zinc borate composite particles yields modified wollastonite / zinc borate composite particles. S2. Modified recycled micro powder is obtained by high-temperature calcination; S3. Weigh and mix modified wollastonite / zinc borate composite particles, modified recycled micro powder and kaolin to obtain ceramic filler. Weigh out the ceramic filler, flame retardant, plasticizer, crosslinking agent, coupling agent, catalyst, and fumed silica; α,ω-dihydroxypolydimethylsiloxane was added to a kneader and kneaded continuously. Then, ceramic filler, flame retardant and plasticizer were added in three batches, with an interval of 5 minutes between each addition. After the addition was completed, the mixture was heated to 120~130℃ and kneaded under vacuum for 2.5~3 hours at 0.05~0.1MPa. The mixture was then allowed to cool naturally to room temperature while maintaining the vacuum condition to obtain the base material, which was then sealed and stored for later use. S4. Take the base material and stir it under vacuum conditions of 0.05~0.1MPa for 10 minutes. Add the crosslinking agent and stir under vacuum for 30 minutes. Then add the dried fumed silica in three batches. Then add the catalyst and coupling agent and stir under vacuum for 30 minutes. Seal to obtain a high-temperature resistant, fireproof and flame-retardant sealant.

4. The method for preparing the high-temperature resistant, fire-retardant sealant according to claim 3, characterized in that, In step S1, the mass concentration of wollastonite in the wollastonite suspension is 6-8%, and the volume ratio of the wollastonite suspension, borax solution, and zinc sulfate solution is 1.7-1.8:1:

1.

5. The method for preparing the high-temperature resistant, fire-retardant sealant according to claim 3, characterized in that, In step S1, the surface modification of the wollastonite / zinc borate composite particles specifically involves: dissolving the modifier in anhydrous ethanol, adding the wollastonite / zinc borate composite particles while stirring, stirring and modifying at 60-80°C for 30-60 minutes, filtering to obtain a solid, and washing and drying to obtain the modified wollastonite / zinc borate composite particles.

6. The method for preparing the high-temperature resistant, fire-retardant sealant according to claim 5, characterized in that, The mass of the modifier is 1.5 to 2% of the mass of the wollastonite / zinc borate composite particles.

7. The method for preparing the high-temperature resistant, fire-retardant sealant according to claim 3, characterized in that, In step S3, the high-temperature modification of the regenerated micro powder is specifically carried out by: placing the regenerated micro powder in a crucible, heating it from room temperature (25°C) to 600°C at a heating rate of 4°C / min, holding it at the temperature for 5~5.5 hours, and then naturally cooling it to obtain the modified regenerated micro powder.

8. The method for preparing the high-temperature resistant, fire-retardant sealant according to claim 5 or 6, characterized in that, The modifier is prepared as follows: ethylene glycol is taken and phosphorus oxychloride is slowly added dropwise to it under stirring conditions in an ice-water bath at 5-10°C. After the addition is completed, the mixture is stirred for 5-6 hours. Then, a mixed solution containing hexadecyl alcohol, tetrahydrofuran and triethylamine is slowly added dropwise to it at room temperature. After the addition is completed, the mixture is reacted for 2 hours. The solid is removed by filtration. The filtrate is then mixed with deionized water and the reaction continues for 10-12 hours. After the reaction is completed, a white crude product is obtained. The product is recrystallized, washed and dried to obtain the modifier.

9. The method for preparing the high-temperature resistant, fire-retardant sealant according to claim 8, characterized in that, The molar ratio of ethylene glycol, phosphorus oxychloride and cetyl alcohol is 1:2:2~3.

10. The application of the high-temperature resistant, fire-retardant sealant as described in claim 1 in the bonding of prefabricated building components, door and window materials, and fire-resistant facility materials.

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