High-strength thermal shock resistant composite fiber board and preparation method thereof

Abstract

The invention relates to the technical field of fiber boards, and discloses a high-strength thermal-shock-resistant composite fiber board and a preparation method thereof.The high-strength thermal-shock-resistant composite fiber board is prepared from, by weight, 100 parts of inorganic fiber felt and 35-42 parts of composite adhesive; the composite adhesive is composed of 25-38 parts by weight of a KH590-silica sol adhesive and 4-10 parts by weight of a modified phenolic resin adhesive; in the high-temperature thermocuring process, phenolic resin molecular chains are bonded on the surface of the silica sol, meanwhile, the modified phenolic resin contains a large number of carboxyl groups, the adhesive force and the adhesive property between the silica sol and the inorganic fiber felt are improved, the modified phenolic resin and the silica sol serve as organic-inorganic composite adhesives, the better bonding effect on the inorganic fiber felt is achieved, and the inorganic fiber felt can be well bonded. The bending strength of the fiber board is improved, and the fiber board still has very high bending strength after thermal shock and is excellent in thermal shock resistance.

Description

Technical Field

[0001] This invention relates to the field of fiberboard technology, specifically to a high-strength, thermally shock resistant composite fiberboard and its preparation method. Background Technology

[0002] Inorganic fiber composite boards, mainly including glass fiber boards and basalt fiber boards, possess excellent thermal insulation and mechanical strength properties, and have been widely used in high-temperature insulation industries such as building materials, metallurgy, power, and chemicals in recent years. With social and economic development, industrial kilns and equipment place higher demands on the thermal insulation and thermal shock resistance of high-strength inorganic fiber composite boards. Existing inorganic fiber materials are no longer sufficient to meet the requirements of industrial kilns and equipment. Therefore, the preparation of high-strength, thermally shock resistant insulation materials is an important development direction for fiber composite materials.

[0003] High-performance adhesives are used to bond the fibers, resulting in fiberboards with improved mechanical and other properties. Patent CN116180483B discloses a formula and process for ultrafine glass fiber insulation blankets. Using polyurethane epoxy resin, epoxy resin, toughening curing agent, and siloxane-modified mesoporous silica microspheres as raw materials, the prepared adhesive and ultrafine glass fiber insulation blanket exhibit good temperature resistance and insulation properties. However, this patent does not improve the bending resistance and thermal shock resistance of glass fiber materials. Summary of the Invention

[0004] (a) Technical problem solved: The present invention solves the problem of poor bonding performance of existing silica sol adhesives to inorganic fiber felt, and at the same time improves the bending resistance, thermal shock resistance and other properties of inorganic fiber boards.

[0005] (II) Technical solution: A high-strength thermal shock resistant composite fiberboard and its preparation method, wherein the composite fiberboard comprises 100 parts by weight of inorganic fiber felt and 35-42 parts by weight of composite adhesive; The composite adhesive consists of 25-38 parts by weight of KH590-silica sol adhesive and 4-10 parts by weight of modified phenolic resin adhesive.

[0006] Preparation method of high-strength thermal shock resistant composite fiberboard: (1) Solvent and phenolic resin were added to a flask equipped with a reflux condenser. After stirring, 2-chloro-4,6-di(aminopentenoic acid)-1,3,5-triazine was added. After stirring, an aqueous solution of an inorganic base was added to carry out the reaction. The mixture was diluted with saturated sodium chloride solution, extracted with dichloromethane, and the organic layer was collected. The product was then subjected to vacuum distillation, washed with petroleum ether, and dried to obtain the modified phenolic resin adhesive. The reaction formula is as follows: (2) Mix KH590-silica sol adhesive and modified phenolic resin adhesive to obtain composite adhesive.

[0007] .

[0008] (3) Lay the inorganic fiber felt flat in the tray under the molding machine, and apply the composite adhesive evenly to the inorganic fiber felt to form the first layer of fiber felt; then lay another layer of inorganic fiber felt, and then apply the composite adhesive evenly to the inorganic fiber felt to form the second layer of fiber felt; repeat this operation until the specified number of layers is reached, use the molding machine to mold, and then place it in a heating box for heat curing, cooling, edge cutting, and sanding to obtain a high-strength thermal shock resistant composite fiber board.

[0009] Preferably, the inorganic fiber felt is aluminum silicate fiber felt, quartz fiber felt, basalt fiber felt or glass fiber felt.

[0010] Preferably, the solvent in (1) is acetone or 1,4-dioxane.

[0011] Preferably, the reaction temperature in (1) is 70-90℃ and the reaction time is 5-8h.

[0012] Preferably, the ratio of phenolic resin, 2-chloro-4,6-di(aminopentenoic acid)-1,3,5-triazine, and inorganic base in (1) is 100g:(6-25):(0.7-3).

[0013] Preferably, the inorganic base in (1) is sodium hydroxide or potassium hydroxide.

[0014] Preferably, (3) has 5-200 layers.

[0015] Preferably, the pressure during molding in (3) is 10-20 MPa.

[0016] Preferably, the heat curing process in (3) is as follows: first, cure at 100-120℃ for 1-2 hours, then cure at 150-180℃ for 4-7 hours, and finally cure at 240-260℃ for 2-3 hours.

[0017] A preferred method for preparing 2-chloro-4,6-di(aminopentenoic acid)-1,3,5-triazine includes: adding acetone, cyanuric chloride in a ratio of 1 mol: 2 mol: (4-4.4) mol, 2-aminopent-4-enoic acid, sodium carbonate, and water to a flask under an ice-water bath; stirring the reaction at 15-25°C for 12-18 h; adjusting the pH to 3-4 with hydrochloric acid solution; precipitating a large amount of precipitate; filtering; washing the product with acetone; and drying to obtain 2-chloro-4,6-di(aminopentenoic acid)-1,3,5-triazine. The reaction formula is: .

[0018] Preferably, the preparation method of KH590-silica sol adhesive includes: adding ethanol and 100 parts by weight of tetraethyl orthosilicate to a flask equipped with a reflux condenser, stirring, adding water, adding concentrated ammonia dropwise, heating to 50-60℃, adding 3-8 parts by weight of KH590 dropwise, stirring and reacting for 4-7 hours to obtain KH590-silica sol adhesive.

[0019] (III) Beneficial Technical Effects of the Invention: Using glass fiber mat, aluminum silicate fiber mat, and other substrates, KH590-silica sol and modified phenolic resin as composite adhesives, a high-strength, thermally shock resistant composite fiberboard is obtained through adhesive thermosetting. The modified phenolic resin contains alkenyl groups. During high-temperature thermosetting, the alkenyl groups undergo an addition reaction with the mercapto groups of KH590-silica sol, thereby bonding phenolic resin molecular chains to the silica sol surface. Simultaneously, the modified phenolic resin contains a large number of carboxyl groups, which form hydrogen bonds and other interactions with the surface of inorganic fibers such as glass fibers, thereby improving the adhesion and bonding performance between the silica sol and the inorganic fiber mat, which is beneficial for enhancing the mechanical strength of the bonded fiberboard.

[0020] The phenolic resin of this invention also has good bonding properties. When used with silica sol as an organic-inorganic composite adhesive, it provides better bonding to inorganic fiber felt, significantly improving the bending strength of the fiberboard. Furthermore, the fiberboard still has high bending strength after thermal shock, demonstrating excellent thermal shock resistance. Detailed Implementation

[0021] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. Example 1

[0022] (1) Add 200 mL of ethanol and 200 g of tetraethyl orthosilicate to a flask equipped with a reflux condenser. After stirring, add 75 mL of water and 13 mL of concentrated ammonia solution with a mass fraction of 28%. Heat to 50 °C and add 6 g of 3-mercaptopropyltriethoxysilane KH590. Stir and react for 4 h to obtain KH590-silica sol binder.

[0023] (2) Under an ice-water bath, add 350 mL of acetone, 0.3 mol of cyanuric chloride, 0.6 mol of 2-aminopent-4-enoic acid, 1.2 mol of sodium carbonate, and 450 mL of water to a flask. Stir the reaction at 15 °C for 18 h. Add 20% hydrochloric acid solution dropwise until the pH reaches 3. A large amount of precipitate is precipitated. After filtration, wash the product with acetone and dry to obtain 2-chloro-4,6-di(aminopentenoic acid)-1,3,5-triazine.

[0024] (3) Add 2L of acetone and 400g of phenolic resin to a flask equipped with a reflux condenser. After stirring, add 24g of 2-chloro-4,6-di(aminopentenoic acid)-1,3,5-triazine. After stirring, add 200mL of an aqueous solution containing 2.8g of sodium hydroxide. Heat to 75℃ and stir for 5h. Dilute with saturated sodium chloride solution, extract with dichloromethane, collect the organic layer, distill under reduced pressure, wash the product with petroleum ether, and dry to obtain the modified phenolic resin adhesive.

[0025] (4) Mix 380g of KH590-silica sol adhesive and 40g of modified phenolic resin adhesive to make a composite adhesive.

[0026] (5) Lay the glass fiber mat flat in the tray under the molding machine, and apply the composite adhesive evenly to the glass fiber mat with a mass ratio of 42:100 to form the first layer of fiber mat; then lay another layer of glass fiber mat, and apply the composite adhesive evenly to the glass fiber mat with a mass ratio of 42:100 to form the second layer of fiber mat; repeat this operation until 20 layers are reached, and use the molding machine to mold the mat at a pressure of 15MPa. Then place it in a heating box, heat cure at 100℃ for 2 hours, then heat cure at 160℃ for 7 hours, and finally heat cure at 240℃ for 3 hours. Cool, cut the edges, and sand to obtain a high-strength thermal shock resistant composite fiber board.

[0027] Comparative Example 1 (1) Lay the glass fiber mat flat in the tray under the molding machine, and uniformly coat the glass fiber mat with KH590-silica sol adhesive (prepared by Example 1) at a mass ratio of 42:100 to form the first layer of fiber mat; then lay another layer of glass fiber mat, and uniformly coat the glass fiber mat with composite adhesive at a mass ratio of 42:100 to form the second layer of fiber mat; repeat this operation until 20 layers are reached, and use the molding machine to mold the mat at a pressure of 15 MPa. Then place it in a heating box, heat cure at 100°C for 2 hours, then heat cure at 160°C for 7 hours, and finally heat cure at 240°C for 3 hours. Cool, cut the edges, and sand to obtain the composite fiber board.

[0028] Comparative Example 2 (1) Mix 380g of KH590-silica sol adhesive (prepared from Example 1) and 40g of phenolic resin to form a composite adhesive.

[0029] (2) Lay the glass fiber mat flat in the tray under the molding machine, and apply the composite adhesive evenly to the glass fiber mat with a mass ratio of 42:100 to form the first layer of fiber mat; then lay another layer of glass fiber mat, and apply the composite adhesive evenly to the glass fiber mat with a mass ratio of 42:100 to form the second layer of fiber mat; repeat this operation until 20 layers are reached, and use the molding machine to mold the mat at a pressure of 15MPa. Then place it in a heating box, heat cure at 100℃ for 2 hours, then heat cure at 160℃ for 7 hours, and finally heat cure at 240℃ for 3 hours. Cool, cut the edges, and sand to obtain the composite fiber board.

[0030] Comparative Example 3 (1) Under ice-water bath conditions, 350 mL of acetone, 0.3 mol of cyanuric chloride, 0.6 mol of glycine, 1.2 mol of sodium carbonate, and 450 mL of water were added to a flask. The mixture was stirred at 15 °C for 18 h. A 20% hydrochloric acid solution was added dropwise until the pH reached 3, resulting in the precipitation of a large amount of precipitate. The product was filtered, washed with acetone, and dried to obtain 2-chloro-4,6-diglycine-1,3,5-triazine. The structural formula is... .

[0031] (2) Add 2L of acetone and 400g of phenolic resin to a flask equipped with a reflux condenser. After stirring, add 24g of 2-chloro-4,6-diglycine-1,3,5-triazine. After stirring, add 200mL of an aqueous solution containing 2.8g of sodium hydroxide. Heat to 75℃ and stir for 5h. Dilute with saturated sodium chloride solution, extract with dichloromethane, collect the organic layer, distill under reduced pressure, wash the product with petroleum ether, and dry to obtain the modified phenolic resin adhesive.

[0032] (3) Mix 380g of KH590-silica sol adhesive (prepared from Example 1) and 40g of modified phenolic resin adhesive to form a composite adhesive.

[0033] (4) Lay the glass fiber mat flat in the tray under the molding machine, and apply the composite adhesive evenly to the glass fiber mat with a mass ratio of 42:100 to form the first layer of fiber mat; then lay another layer of glass fiber mat, and apply the composite adhesive evenly to the glass fiber mat with a mass ratio of 42:100 to form the second layer of fiber mat; repeat this operation until 20 layers are reached, and use the molding machine to mold the mat at a pressure of 15MPa. Then place it in a heating box, heat cure at 100℃ for 2 hours, then heat cure at 160℃ for 7 hours, and finally heat cure at 240℃ for 3 hours. Cool, cut the edges, and sand to obtain the composite fiber board.

[0034] Comparative Example 4 (1) Under ice-water bath conditions, 350 mL of acetone, 0.3 mol of cyanuric chloride, 0.6 mol of allylamine hydrochloride, 1.8 mol of sodium carbonate, and 450 mL of water were added to a flask. The mixture was stirred at 15 °C for 18 h. A 20% hydrochloric acid solution was added dropwise until the pH reached 3, resulting in the precipitation of a large amount of precipitate. The product was filtered, washed with acetone, and dried to obtain 2-chloro-4,6-diallylamine-1,3,5-triazine. The structural formula is... .

[0035] (2) Add 2L of acetone and 400g of phenolic resin to a flask equipped with a reflux condenser. After stirring, add 24g of 2-chloro-4,6-diglycine-1,3,5-triazine. After stirring, add 200mL of an aqueous solution containing 2.8g of sodium hydroxide. Heat to 75℃ and stir for 5h. Dilute with saturated sodium chloride solution, extract with dichloromethane, collect the organic layer, distill under reduced pressure, wash the product with petroleum ether, and dry to obtain the modified phenolic resin adhesive.

[0036] (3) Mix 380g of KH590-silica sol adhesive (prepared from Example 1) and 40g of modified phenolic resin adhesive to form a composite adhesive.

[0037] (4) Lay the glass fiber mat flat in the tray under the molding machine, and apply the composite adhesive evenly to the glass fiber mat with a mass ratio of 42:100 to form the first layer of fiber mat; then lay another layer of glass fiber mat, and apply the composite adhesive evenly to the glass fiber mat with a mass ratio of 42:100 to form the second layer of fiber mat; repeat this operation until 20 layers are reached, and use the molding machine to mold the mat at a pressure of 15MPa. Then place it in a heating box, heat cure at 100℃ for 2 hours, then heat cure at 160℃ for 7 hours, and finally heat cure at 240℃ for 3 hours. Cool, cut the edges, and sand to obtain the composite fiber board. Example 2

[0038] (1) Add 240 mL of ethanol and 200 g of tetraethyl orthosilicate to a flask equipped with a reflux condenser. After stirring, add 70 mL of water and 13 mL of concentrated ammonia solution with a mass fraction of 28%. Heat to 55 °C and add 16 g of 3-mercaptopropyltriethoxysilane KH590. Stir the reaction for 7 h to obtain KH590-silica sol binder.

[0039] (2) Under ice-water bath conditions, add 400 mL of acetone, 0.3 mol of cyanuric chloride, 0.6 mol of 2-aminopent-4-enoic acid, 1.32 mol of sodium carbonate, and 450 mL of water to a flask. Stir the reaction at 25 °C for 12 h. Add 20% hydrochloric acid solution dropwise until the pH reaches 4. A large amount of precipitate is precipitated. After filtration, wash the product with acetone and dry to obtain 2-chloro-4,6-di(aminopentenoic acid)-1,3,5-triazine.

[0040] (3) Add 3L of acetone and 400g of phenolic resin to a flask equipped with a reflux condenser. After stirring, add 100g of 2-chloro-4,6-di(aminopentenoic acid)-1,3,5-triazine (prepared from Example 1). After stirring, add 500mL of an aqueous solution containing 12g of sodium hydroxide. Heat to 70°C and stir for 8h. Dilute with saturated sodium chloride solution, extract with dichloromethane, collect the organic layer, distill under reduced pressure, wash the product with petroleum ether, and dry to obtain the modified phenolic resin adhesive.

[0041] (4) Mix 330g of KH590-silica sol adhesive and 60g of modified phenolic resin adhesive to make a composite adhesive.

[0042] (5) Lay the quartz fiber felt flat in the tray under the molding machine, and apply the composite adhesive evenly to the quartz fiber felt with a mass ratio of 39:100 to form the first layer of fiber felt; then lay another layer of quartz fiber felt, and apply the composite adhesive evenly to the quartz fiber felt with a mass ratio of 39:100 to form the second layer of fiber felt; repeat this operation until 20 layers are reached, and use the molding machine to mold it with a pressure of 10MPa. Then place it in a heating box, heat cure it at 120℃ for 1h, then heat cure it at 150℃ for 7h, and finally heat cure it at 250℃ for 3h. Cool, cut the edges, and sand to obtain a high-strength thermal shock resistant composite fiber board. Example 3

[0043] (1) Add 240 mL of ethanol and 200 g of tetraethyl orthosilicate to a flask equipped with a reflux condenser. After stirring, add 70 mL of water and 12 mL of concentrated ammonia solution with a mass fraction of 28%. Heat to 60 °C and add 12 g of 3-mercaptopropyltriethoxysilane KH590. Stir the reaction for 4 h to obtain KH590-silica sol binder.

[0044] (2) Add 3L of acetone and 400g of phenolic resin to a flask equipped with a reflux condenser. After stirring, add 75g of 2-chloro-4,6-di(aminopentenoic acid)-1,3,5-triazine (prepared from Example 1). After stirring, add 500mL of an aqueous solution containing 8.2g of sodium hydroxide. Heat to 70°C and stir for 8h. Dilute with saturated sodium chloride solution, extract with dichloromethane, collect the organic layer, distill under reduced pressure, wash the product with petroleum ether, and dry to obtain the modified phenolic resin adhesive.

[0045] (3) Mix 290g of KH590-silica sol adhesive and 80g of modified phenolic resin adhesive to make a composite adhesive.

[0046] (4) Lay the aluminum silicate fiber felt flat in the tray under the molding machine, and apply the composite adhesive evenly to the aluminum silicate fiber felt with a mass ratio of 37:100 to form the first layer of fiber felt; then lay another layer of aluminum silicate fiber felt, and apply the composite adhesive evenly to the aluminum silicate fiber felt with a mass ratio of 37:100 to form the second layer of fiber felt; repeat this operation until 20 layers are reached, use the molding machine to mold, the pressure is 20MPa, and then place it in a heating box, first heat cure at 100℃ for 2h, then heat cure at 180℃ for 4h, and finally heat cure at 260℃ for 2h, cool, cut the edges, and sand to obtain a high-strength thermal shock resistant composite fiber board. Example 4

[0047] (1) Add 240 mL of ethanol and 200 g of tetraethyl orthosilicate to a flask equipped with a reflux condenser. After stirring, add 80 mL of water and 10 mL of concentrated ammonia solution with a mass fraction of 28%. Heat to 50 °C and add 9 g of 3-mercaptopropyltriethoxysilane KH590. Stir the reaction for 6 h to obtain KH590-silica sol binder.

[0048] (2) Add 2.5L of 1,4-dioxane and 400g of phenolic resin to a flask equipped with a reflux condenser. After stirring, add 50g of 2-chloro-4,6-di(aminopentenoic acid)-1,3,5-triazine. After stirring, add 300mL of an aqueous solution containing 6.3g of potassium hydroxide. Heat to 90℃ and stir for 7h. Dilute with saturated sodium chloride solution, extract with dichloromethane, collect the organic layer, distill under reduced pressure, wash the product with petroleum ether, and dry to obtain the modified phenolic resin adhesive.

[0049] (3) Mix 250g of KH590-silica sol adhesive and 100g of modified phenolic resin adhesive to make a composite adhesive.

[0050] (4) Lay the basalt fiber felt flat in the tray under the molding machine, and apply the composite adhesive evenly to the basalt fiber felt with a mass ratio of 35:100 to form the first layer of fiber felt; then lay another layer of basalt fiber felt, and apply the composite adhesive evenly to the basalt fiber felt with a mass ratio of 35:100 to form the second layer of fiber felt; repeat this operation until 20 layers are reached, use the molding machine to mold, the pressure is 10MPa, and then place it in a heating box, first heat cure at 110℃ for 1h, then heat cure at 160℃ for 6h, and finally heat cure at 250℃ for 3h, cool, cut the edges, and sand to obtain a high-strength thermal shock resistant composite fiber board.

[0051] The bending strength of composite fiberboard was tested using the three-point bending test method and an electronic universal testing machine.

[0052] Bending strength W = 3P × L / (2b × h) 2 P is the maximum load when the specimen breaks, L is the distance between the specimen supports, b is the specimen width, and h is the specimen height.

[0053] Thermal shock resistance test: The composite fiberboard was placed in a heating chamber and kept at 250℃ for 10 minutes, and then immersed in water at 25℃ for 10 minutes to cool. The heat preservation-cooling procedure was repeated 19 times, and the bending strength was tested. The bending strength retention rate before and after thermal shock was calculated.

[0054] Table 1 Performance Tests of Composite Fiberboard

[0055] Compared with Comparative Example 1, Example 1 uses KH590-silica sol and modified phenolic resin as composite adhesives. The modified phenolic resin contains alkenyl groups, which undergo an addition reaction with the mercapto groups of KH590-silica sol during high-temperature thermosetting, thereby bonding the phenolic resin to the silica sol surface. At the same time, the modified phenolic resin contains a large number of carboxyl groups, which form hydrogen bonds and other interactions with the surface of inorganic fibers such as glass fibers, thereby improving the adhesion and bonding performance between silica sol and inorganic fiber felt, which is beneficial to enhancing the mechanical strength of the bonded fiberboard. Furthermore, the phenolic resin itself also has good bonding performance. Together with silica sol as an organic-inorganic composite adhesive, it plays a better bonding role to inorganic fiber felt, significantly improving the bending strength of the fiberboard. Moreover, the fiberboard still has high bending strength after thermal shock, and has excellent thermal shock resistance.

[0056] Comparative Example 2 used ordinary phenolic resin and KH590-silica sol as composite adhesives. Phenolic resin does not contain alkenyl groups and cannot react with KH590-silica sol. It also does not contain carboxyl groups, so it does not improve the adhesion and bonding performance between phenolic resin and silica sol and inorganic fiber felt, which is not conducive to improving the bending strength and thermal shock resistance of fiberboard.

[0057] The modified phenolic resin of Comparative Example 3 does not contain alkenyl groups, and the modified phenolic resin of Comparative Example 4 does not contain carboxyl groups. The flexural strength and thermal shock resistance of the fiberboard prepared by both examples are lower than those of Example 1.

[0058] Examples 2-4 use quartz fiber felt, aluminum silicate fiber felt, and basalt fiber felt as substrates, respectively, and KH590-silica sol and modified phenolic resin as composite adhesives. The resulting fiberboards also have good flexural strength and thermal shock resistance.

[0059] 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-strength, thermally shock resistant composite fiberboard, characterized in that, The high-strength thermal shock resistant composite fiberboard comprises 100 parts by weight of inorganic fiber felt and 35-42 parts by weight of composite adhesive. The composite adhesive is composed of 25-38 parts by weight of KH590-silica sol adhesive and 4-10 parts by weight of modified phenolic resin adhesive; The modified phenolic resin adhesive is prepared by adding solvent and phenolic resin to a flask equipped with a reflux condenser, stirring, adding 2-chloro-4,6-di(aminopentenoic acid)-1,3,5-triazine, stirring, adding an aqueous solution of inorganic base, reacting, extracting, washing the product, and drying to obtain the modified phenolic resin adhesive.

2. The high-strength, thermally shock resistant composite fiberboard according to claim 1, characterized in that, The inorganic fiber felt is aluminum silicate fiber felt, quartz fiber felt, basalt fiber felt or glass fiber felt.

3. The high-strength, thermally shock resistant composite fiberboard according to claim 1, characterized in that, The solvent is acetone or 1,4-dioxane.

4. The high-strength, thermally shock resistant composite fiberboard according to claim 1, characterized in that, The reaction temperature is 70-90℃, and the reaction time is 5-8h.

5. The high-strength, thermally shock resistant composite fiberboard according to claim 1, characterized in that, The ratio of the phenolic resin, 2-chloro-4,6-di(aminopentenoic acid)-1,3,5-triazine, and inorganic base is 100g:(6-25):(0.7-3).

6. The high-strength, thermally shock resistant composite fiberboard according to claim 5, characterized in that, The inorganic base is sodium hydroxide or potassium hydroxide.

7. The high-strength, thermally shock resistant composite fiberboard according to claim 1, characterized in that, The preparation method of the 2-chloro-4,6-di(aminopentenoic acid)-1,3,5-triazine includes: adding acetone, cyanuric chloride in a ratio of 1 mol: 2 mol: (4-4.4) mol, 2-aminopent-4-enoic acid, sodium carbonate, and water to a flask under an ice-water bath; stirring the reaction at 15-25℃ for 12-18 h; adding hydrochloric acid solution dropwise; precipitating the precipitate; filtering and washing the product; and drying to obtain 2-chloro-4,6-di(aminopentenoic acid)-1,3,5-triazine.

8. The high-strength, thermally shock resistant composite fiberboard according to claim 1, characterized in that, The preparation method of the KH590-silica sol adhesive includes: adding ethanol and 100 parts by weight of tetraethyl orthosilicate to a flask equipped with a reflux condenser, stirring, adding water, adding concentrated ammonia dropwise, heating to 50-60℃, adding 3-8 parts by weight of KH590 dropwise, stirring and reacting for 4-7 hours to obtain the KH590-silica sol adhesive.

9. A method for preparing a high-strength, thermally shock resistant composite fiberboard as described in any one of claims 1-8, characterized in that, The preparation method includes: (1) KH590-silica sol adhesive and modified phenolic resin adhesive are stirred and mixed to obtain composite adhesive; (2) Lay the inorganic fiber felt flat in the tray under the molding machine, and apply the composite adhesive evenly to the inorganic fiber felt to form the first layer of fiber felt; then lay another layer of inorganic fiber felt, and then apply the composite adhesive evenly to the inorganic fiber felt to form the second layer of fiber felt; repeat this operation until the specified number of layers is reached, use the molding machine to mold, and then place it in a heating box for heat curing, cooling, edge cutting, and sanding to obtain a high-strength thermal shock resistant composite fiber board.

10. The method for preparing the high-strength, thermally shock resistant composite fiberboard according to claim 9, characterized in that, The thermosetting process is as follows: first, cure at 100-120℃ for 1-2 hours, then cure at 150-180℃ for 4-7 hours, and finally cure at 240-260℃ for 2-3 hours.

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