Multi-layer flexible heat insulation pad embedded with composite heat preservation filler and preparation method of multi-layer flexible heat insulation pad

Abstract

The invention discloses a multi-layer flexible heat insulation pad embedded with composite heat preservation filler and a preparation method of the multi-layer flexible heat insulation pad, belongs to the technical field of heat insulation pad preparation, and aims to solve the technical problem that the heat insulation performance and the mechanical property of a heat insulation pad in the prior art need to be further improved. The aluminum foil glass fabric is attached to the two sides of the heat insulation fiber felt. According to the invention, the pretreated fiber felt is soaked in the ternary sol, the heat insulation fiber felt core layer is obtained after drying and heat treatment, the aluminum foil glass fiber cloth is used as a double-sided skin and is bonded with the heat insulation core layer by adopting the high-temperature-resistant silicone adhesive, and a sandwich structure of a hard surface layer and a flexible core layer is constructed, so that the heat insulation performance of the multi-layer flexible heat insulation cushion is improved; the mechanical property is also improved.

Description

Technical Field

[0001] This invention relates to the field of thermal insulation pad preparation technology, specifically to a multi-layer flexible thermal insulation pad with embedded composite thermal insulation filler and its preparation method. Background Technology

[0002] With the continuous improvement of energy efficiency and the demand for lightweight industrial equipment, multi-layer flexible thermal insulation pads have been widely used in aviation, rail transportation, vehicle thermal management and industrial pipeline insulation. At present, flexible thermal insulation materials mainly include aluminum silicate fiber felt, glass fiber cloth, aerogel composite felt, silica / alumina ceramic fiber pads and flexible thermal insulation materials with foamed rubber and plastic as the base material.

[0003] To improve its high-temperature resistance, inhibit high-temperature shrinkage, enhance mechanical properties, and reduce thermal conductivity, the following methods are often used: coating the fibers with silica through sol-gel; using nano-silica or nano-alumina for reinforcement; introducing glass fiber cloth or aramid cloth as a reinforcing layer; utilizing infrared reflective metal films or metal coatings to enhance radiation insulation capabilities; cross-linking and curing with organic resins, inorganic binders, or heat-resistant adhesives to improve overall strength; or using foaming agents and aerogel powder to construct a microporous structure to reduce thermal conductivity.

[0004] Currently, flexible thermal insulation materials often use nanofillers or inorganic coatings to improve thermal insulation performance. This often leads to partial blockage of the pores between fibers, making the material structure prone to collapse at high temperatures, resulting in a high dry heat shrinkage rate. Furthermore, organic resin-based reinforcement systems are prone to carbonization or decomposition during high-temperature use, leading to a rapid decline in mechanical strength. Although metal reflective films or metal coatings can improve radiation thermal insulation performance, they have poor flexibility, are prone to cracking and delamination, and are not suitable for complex curved surfaces or dynamic bending conditions. Thermal insulation pads with single or few layers have uneven stress and insufficient bending rigidity, making them prone to wrinkles and tears during installation. When using aerogel powder or foam materials to construct microporous structures, the pore structure has poor stability and is prone to pulverization or shrinkage at long-term high temperatures, leading to an increase in thermal conductivity.

[0005] To address this technical deficiency, a solution is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a multi-layer flexible thermal insulation pad with embedded composite thermal insulation filler and its preparation method, in order to solve the technical problem that the thermal insulation performance and mechanical properties of thermal insulation pads in the prior art need to be further improved.

[0007] The objective of this invention can be achieved through the following technical solution: a multi-layer flexible thermal insulation pad with embedded composite thermal insulation filler, comprising thermal insulation fiber felt and aluminum foil fiberglass cloth attached to both sides of the thermal insulation fiber felt;

[0008] The heat-insulating fiber felt has a thickness of 15-20 mm, and the aluminum foil fiberglass cloth is a fiberglass fabric with a thin aluminum foil and a thickness of 0.1-0.2 mm.

[0009] The heat-insulating fiber felt is prepared by the following steps:

[0010] A1. Place tetraethyl orthosilicate, aluminum chloride hexahydrate, yttrium chloride hexahydrate, deionized water and ethanol in a reaction vessel, stir at room temperature for 30-60 min, cool the reaction vessel to 0-5℃ in an ice bath, add 1,2-epoxypropane, keep warm and stir for 1-3 min to obtain a ternary composite sol.

[0011] A2. Place the pretreated basalt fiber felt in a mold, add ternary composite sol, let it stand at room temperature for 20-24 hours for aging, and then dry it with ethanol via supercritical drying to obtain the heat insulation fiber felt.

[0012] The reaction principle for preparing thermal insulation fiber felt is as follows:

[0013] During the reaction, tetraethyl orthosilicate reacts with Al 3+ Y 3+ Hydrolysis and preliminary condensation occur in the ethanol-water system. After the addition of 1,2-epoxypropane, the epoxy groups open the ring under acidic conditions and rapidly consume some of the acidic substances in the system, causing the pH of the solution to rise slowly. This triggers the co-hydrolysis of tetraethyl orthosilicate, aluminum salt, and yttrium salt to form a ternary composite sol containing Si-O-Al and Si-OY bonds. In step A2, the ternary composite sol is impregnated into the pretreated basalt fiber felt and aged at room temperature for 20-24 hours. The sol undergoes continuous condensation and structural rearrangement, gradually forming a three-dimensional inorganic network and solidifying between the fibers to obtain fiber-reinforced thermal insulation fiber felt.

[0014] Furthermore, in step A1, the ratio of tetraethyl orthosilicate, aluminum chloride hexahydrate, yttrium chloride hexahydrate, deionized water, ethanol and 1,2-epoxypropane is 2-4g:1-2g:6-8g:10-12mL:80-120mL:0.5-1g.

[0015] Furthermore, in step A2, the impregnation ratio of the ternary composite sol and the pretreated basalt fiber felt is 2-4:1, the relative humidity of the static aging environment is 30-50%, and the supercritical ethanol drying step includes: after static aging, the product is transferred to an ethanol solution for soaking for 48 hours, the solvent is replaced every 24 hours, the product is transferred to a closed high-pressure autoclave, and kept at 270-280℃ and 9-9.5MPa for 2-4 hours to obtain the heat-insulating fiber felt.

[0016] Furthermore, the pretreated basalt fiber felt is prepared by the following steps:

[0017] B1. Place the alkaline solution in a reaction vessel and stir. Add basalt fiber felt for impregnation. Heat the reaction vessel to 50-60℃ and keep it at that temperature for 1-2 hours. Post-treatment yields activated basalt fiber felt.

[0018] B2. Modified hollow microspheres, activated basalt fiber felt, deionized water, γ-glycidyl etheroxypropyltrimethoxysilane and ethanol are placed in a reaction vessel, and dilute acetic acid aqueous solution is added. The reaction vessel is heated to 45-55℃ and kept at this temperature for 2-4 hours. The post-treatment yields pretreated basalt fiber felt.

[0019] The reaction principle for preparing pretreated basalt fiber felt is as follows:

[0020] During the reaction, the basalt fiber felt is impregnated in an alkaline solution. The alkaline solution can undergo saponification, dissolution, or ion exchange reactions with the carbonates, metal oxides, and organic impurities remaining on the fiber surface. At the same time, it slightly etches the surface of the basalt fiber, exposing more hydroxyl groups and micro-nano rough structures on the fiber surface. In step B2, the modified hollow microspheres, activated basalt fiber felt, and γ-glycidoxypropyltrimethoxysilane are dispersed together in an ethanol and water system. Dilute acetic acid breaks the silicon-oxygen bonds of the silane to generate silanol, which further combines with the hydroxyl groups on the surface of the basalt fiber and the hollow microsphere through a condensation reaction to form a stable Si-O-Si, thus obtaining the pretreated basalt fiber felt.

[0021] Further, in step B1, the impregnation ratio of basalt fiber felt to alkaline solution is 1:12-15, and the alkaline solution is a 1-5 wt% sodium hydroxide aqueous solution. The post-treatment steps include: after the reaction is completed, the reaction system is cooled to room temperature, filtered, the product is washed with deionized water 2-4 times, transferred to an oven at 50-60℃, and dried to constant weight to obtain activated basalt fiber felt.

[0022] Further, in step B2, the ratio of the modified hollow microspheres, activated basalt fiber felt, deionized water, γ-glycidyl etheroxypropyltrimethoxysilane, ethanol, and dilute acetic acid aqueous solution is 1-2g:8-10g:10-12mL:0.5-1.0g:150-200mL:4-6mL, and the concentration of the dilute acetic acid aqueous solution is 3-5wt%. The post-treatment steps include: after the reaction is completed, the reaction system is cooled to room temperature, filtered, the product is washed 2-4 times with deionized water and ethanol, transferred to an oven at 50-60℃, and dried to constant weight to obtain pretreated basalt fiber felt.

[0023] Furthermore, the modified hollow microspheres are prepared by the following steps:

[0024] C1. Place zirconium propoxide, methyltriethoxysilane, n-propanol, acetylacetone and deionized water in a reaction vessel and stir. Heat the reaction vessel to 70-80℃ and keep it at that temperature for 6-8 hours. After post-treatment, obtain the Zr-Si polymerization precursor.

[0025] The reaction principle for preparing Zr-Si polymerization precursors is as follows:

[0026] During the reaction, zirconium propoxide undergoes alcoholysis-hydrolysis-condensation reaction with methyltriethoxysilane under the coordination stabilization of acetylacetone, gradually forming an organic-inorganic hybrid polymer network containing Zr-O-Si bonds. The Zr-Si polymerization precursor is obtained after post-treatment.

[0027] C2. Place polyacrylonitrile, polyvinylpyrrolidone and N,N-dimethylformamide in a reaction vessel and stir. Heat the reaction vessel to 60-70℃ and stir for 0.5-1h. Add Zr-Si polymerization precursor and stir for 0.5-1h. Post-treatment yields spray precursor liquid.

[0028] C3. The spray precursor liquid is loaded into a syringe, ultrasonically sprayed and granulated, and then solidified to obtain modified hollow microspheres.

[0029] Further, in step C1, the ratio of zirconium propoxide, methyltriethoxysilane, n-propanol, acetylacetone and deionized water is 7-9g:2-4g:40-60mL:1-2g:0.5-1mL. The post-processing step includes: after the reaction is completed, the reaction vessel is heated to 90-100℃ and distilled under reduced pressure until no liquid is collected, to obtain the Zr-Si polymerization precursor.

[0030] Further, in step C2, the ratio of polyacrylonitrile, polyvinylpyrrolidone, N,N-dimethylformamide and Zr-Si polymerization precursor is 6-8g:2-4g:100-120mL:4-6g. The post-treatment step includes: after the reaction is completed, wait for the reaction system to cool to 20-30℃, add 8-12mL of chloroform, stir for 15-30min, and obtain the spray precursor liquid.

[0031] Furthermore, the preparation method of the modified hollow microspheres is as follows: the spray precursor liquid is loaded into a syringe and sprayed out through an ultrasonic atomizing nozzle at a propulsion speed of 0.3-0.8 mL / min. After the droplets are sprayed into the stirred ethanol for sizing, they are filtered out with a filter cloth and transferred to ammonia water with a pH of 8-9. The solution is cured at a temperature of 75-85℃ for 1-2 hours, filtered, and the filter cake is heat-cured in an oven at 240-260℃ for 0.5-1 hours. Then, it is transferred to a tube furnace under nitrogen atmosphere protection and calcined at high temperature to obtain the modified hollow microspheres.

[0032] The preparation reaction principle of modified hollow microspheres is as follows:

[0033] During the reaction, the spray precursor liquid is ultrasonically atomized to form microdroplets. The droplets rapidly separate and solidify in ethanol due to solvent exchange. Subsequently, the Zr-Si precursor undergoes condensation and cross-linking in weakly alkaline ammonia water, causing the droplets to gel and form a core-shell structure. After being cured in an oven to remove some organic components, the mixture is calcined at high temperature under an inert atmosphere. The polyacrylonitrile and polyvinylpyrrolidone are completely decomposed and release gas. At the same time, the Zr-Si network undergoes a ceramic transformation, retaining the original morphology of the droplets and forming cavities inside, ultimately yielding modified hollow microspheres.

[0034] Furthermore, the high-temperature calcination operation steps include: heating the reactants to 600°C at 5°C / min, holding at that temperature for 2-4 hours, then heating them to 1000°C at 0.5°C / min, holding at that temperature for 1-2 hours, and then cooling them through a 200-mesh sieve to obtain modified hollow microspheres.

[0035] The present invention also proposes a method for preparing a multi-layer flexible heat insulation pad with embedded composite heat insulation filler. After fixing the heat insulation fiber felt on the operating table, adhesive is applied to both sides of the heat insulation fiber felt. Then, two layers of aluminum foil fiberglass cloth are laid on both sides of the heat insulation fiber felt, with the aluminum foil side facing outward. After heat curing, a multi-layer flexible heat insulation pad is obtained.

[0036] Furthermore, the adhesive is a silicone adhesive, and the thermosetting temperature is 180-200℃.

[0037] The present invention has the following beneficial effects:

[0038] 1. The modified hollow microspheres prepared by this invention have a typical shell-cavity structure, which encapsulates a large amount of static gas inside, effectively blocking solid heat conduction. Its micron-level wall layer is formed by high-temperature sintering of Zr-Si composite inorganic phase to form a dense and high-temperature resistant ceramic structure, which can maintain the integrity of the shell under high-temperature conditions and will not collapse or crack due to thermal shock, ensuring long-term stability of thermal insulation performance. Secondly, the surface of the hollow microspheres forms abundant active sites during precursor polymerization, ethanol shaping and high-temperature sintering, which form chemical bonds with the γ-glycidyl etheroxypropyltrimethoxysilane graft layer, significantly improving the adhesion between it and basalt fiber, avoiding peeling or pulverization under bending, vibration and compression conditions, thereby improving the overall mechanical toughness of the flexible thermal insulation pad. In addition, the modified hollow microspheres are uniformly dispersed in the fiber felt, and the fiber felt is densified by ternary composite sol. The hollow microspheres play a dual role in skeleton reinforcement and pore control in the composite network, so that the thermal insulation layer still has high stability and thermal shock resistance at high temperatures.

[0039] 2. After alkaline activation treatment, the pretreated basalt fiber felt prepared by this invention forms a large number of rough structures and active groups such as hydroxyl groups on the fiber surface, which greatly improves the wettability and reactivity of the fiber surface. This makes it easier for the subsequently modified hollow microspheres and silane coupling agents to be anchored in situ on the fiber surface, thereby significantly improving the chemical bonding strength between the fiber and the functional filler. In addition, the pretreatment process improves the bonding state between fibers, so that the fiber felt can still maintain good structural integrity and dimensional stability after high temperature and high pressure gel curing. It will not cause pore collapse or increase in thermal conductivity due to fiber slippage or interface loosening. Finally, the pretreated basalt fiber felt is embedded as an intermediate heat insulation layer in a multi-layer flexible heat insulation pad, which can improve the flexibility and mechanical durability of the material, as well as more stable high temperature heat insulation performance.

[0040] 3. The thermal insulation fiber felt prepared by this invention uses pretreated basalt fiber as a skeleton. It is impregnated with a ternary composite sol, aged and supercritically dried to form a continuous inorganic oxide gel network. This network is composed of SiO2-Al2O3-Y2O3 and can maintain excellent structural stability under high temperature conditions, thereby ensuring that the thermal insulation pad has long-term reliable thermal insulation performance. Secondly, a large number of multi-scale pores of nanoscale and microscale coexist in the interior of the thermal insulation fiber felt. The porosity is high but the structure is uniform, which enables the material to block solid heat conduction while significantly inhibiting gas convection heat transfer and reducing radiative heat transfer through multiple scattering, thereby achieving a triple thermal insulation effect. In addition, the ternary composite sol forms a strong interfacial bond with the surface of basalt fiber during aging and high temperature curing, which improves the overall mechanical strength, tear resistance and flexibility of the fiber felt. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a schematic diagram of the overall structure of the present invention after being cut open.

[0043] In the picture: 1. Insulating fiber felt; 2. Aluminum foil fiberglass cloth. Detailed Implementation

[0044] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0045] The silicone adhesive used in this invention is purchased from a silicone adhesive supplier, model KN-300B, product name: plastic adhesive.

[0046] The basalt fiber felt used in this invention was purchased from Hebei Nuanzheng Energy Saving Technology Co., Ltd., brand name Nuanzheng, with a breaking elongation of 1.3% and an operating temperature of 0-600℃;

[0047] The polyacrylonitrile used in this invention was purchased from Hubei GREAT Biomedical Technology Co., Ltd., with the model number GREAT5777, a molecular weight of 30,000, and the brand name GREAT.

[0048] Example 1

[0049] This embodiment provides a method for preparing modified hollow microspheres, including the following steps:

[0050] Step I: Preparation of Zr-Si polymerization precursor

[0051] Weigh out 70g of zirconium n-propoxide, 20g of methyltriethoxysilane, 400mL of n-propanol, 10g of acetylacetone and 5mL of deionized water and place them in a reaction vessel and stir. Heat the reaction vessel to 70℃ and keep it at that temperature for 6 hours. After the reaction is complete, heat the reaction vessel to 90℃ and distill under reduced pressure until no liquid is collected to obtain the Zr-Si polymerization precursor.

[0052] Step II: Preparation of spray precursor solution

[0053] Weigh out 60g of polyacrylonitrile, 20g of polyvinylpyrrolidone and 1000mL of N,N-dimethylformamide and place them in a reaction vessel and stir. Heat the reaction vessel to 60℃ and stir for 0.5h. Add 40g of Zr-Si polymerization precursor and stir for 0.5h. After the reaction is complete, wait for the reaction system to cool to 20℃, add 80mL of chloroform and stir for 15min to obtain the spray precursor liquid.

[0054] Step III: Preparation of modified hollow microspheres

[0055] The spray precursor liquid was loaded into a syringe and sprayed through an ultrasonic atomizing nozzle at a speed of 0.3 mL / min. After the droplets were sprayed into the stirred ethanol for sizing, they were filtered through a filter cloth and transferred to ammonia water with a pH of 8. The solution was cured at 75°C for 1 hour, filtered, and the filter cake was heat-cured in an oven at 240°C for 0.5 hours. Then, it was transferred to a tube furnace under nitrogen atmosphere protection. The reactants were heated to 600°C at 5°C / min and held for 2 hours. Then, the temperature was increased to 1000°C at 0.5°C / min and held for 1 hour. After cooling, the solution was passed through a 200-mesh sieve to obtain modified hollow microspheres.

[0056] Example 2

[0057] This embodiment provides a method for preparing modified hollow microspheres, including the following steps:

[0058] Step I: Preparation of Zr-Si polymerization precursor

[0059] Weigh out 80g of zirconium n-propoxide, 30g of methyltriethoxysilane, 500mL of n-propanol, 15g of acetylacetone and 7mL of deionized water and place them in a reaction vessel and stir. Heat the reaction vessel to 75℃ and keep it at that temperature for 7h. After the reaction is complete, heat the reaction vessel to 95℃ and distill under reduced pressure until no liquid is collected to obtain the Zr-Si polymerization precursor.

[0060] Step II: Preparation of spray precursor solution

[0061] Weigh out 70g of polyacrylonitrile, 30g of polyvinylpyrrolidone and 1100mL of N,N-dimethylformamide and place them in a reaction vessel and stir. Heat the reaction vessel to 65℃ and stir for 1h. Add 50g of Zr-Si polymerization precursor and stir for 1h. After the reaction is complete, wait for the reaction system to cool to 25℃, add 100mL of chloroform and stir for 22min to obtain the spray precursor liquid.

[0062] Step III: Preparation of modified hollow microspheres

[0063] The spray precursor liquid was loaded into a syringe and sprayed through an ultrasonic atomizing nozzle at a speed of 0.5 mL / min. After the droplets were sprayed into the stirred ethanol for sizing, they were filtered through a filter cloth and transferred to ammonia water with a pH of 8.5. The solution was cured at 80°C for 1.5 h, filtered, and the filter cake was heat-cured in an oven at 250°C for 1 h. Then, it was transferred to a tube furnace under nitrogen atmosphere protection. The reactants were heated to 600°C at 5°C / min and held for 3 h. Then, the temperature was increased to 1000°C at 0.5°C / min and held for 1.5 h. After cooling, the solution was passed through a 200-mesh sieve to obtain modified hollow microspheres.

[0064] Example 3

[0065] This embodiment provides a method for preparing modified hollow microspheres, including the following steps:

[0066] Step I: Preparation of Zr-Si polymerization precursor

[0067] Weigh out 90g of zirconium n-propoxide, 40g of methyltriethoxysilane, 600mL of n-propanol, 20g of acetylacetone and 10mL of deionized water and place them in a reaction vessel and stir. Heat the reaction vessel to 80℃ and keep it at that temperature for 8h. After the reaction is complete, heat the reaction vessel to 100℃ and distill under reduced pressure until no liquid is collected, to obtain the Zr-Si polymerization precursor.

[0068] Step II: Preparation of spray precursor solution

[0069] Weigh out 80g of polyacrylonitrile, 40g of polyvinylpyrrolidone and 1200mL of N,N-dimethylformamide and place them in a reaction vessel and stir. Heat the reaction vessel to 70℃ and stir for 1h. Add 60g of Zr-Si polymerization precursor and stir for 1h. After the reaction is complete, wait for the reaction system to cool to 30℃, add 120mL of chloroform and stir for 30min to obtain the spray precursor liquid.

[0070] Step III: Preparation of modified hollow microspheres

[0071] The spray precursor liquid was loaded into a syringe and sprayed through an ultrasonic atomizing nozzle at a propulsion speed of 0.8 mL / min. After the droplets were sprayed into the stirred ethanol for sizing, they were filtered through a filter cloth and transferred to ammonia water with a pH of 9. The solution was cured at 85°C for 2 hours, filtered, and the filter cake was heat-cured in an oven at 260°C for 1 hour. Then, it was transferred to a tube furnace under nitrogen atmosphere protection. The reactants were heated to 600°C at 5°C / min and held for 4 hours. Then, the temperature was increased to 1000°C at 0.5°C / min and held for 2 hours. After cooling, the solution was passed through a 200-mesh sieve to obtain modified hollow microspheres.

[0072] Example 4

[0073] This embodiment provides a method for preparing pretreated basalt fiber felt, including the following steps:

[0074] Step ①: Preparation of activated basalt fiber felt

[0075] Weigh out 1 wt% sodium hydroxide aqueous solution and place it in a reaction vessel and stir. Add basalt fiber felt at an impregnation ratio of 1:12 for impregnation. Heat the reaction vessel to 50°C and keep it at that temperature for 1 hour. After the reaction is complete, wait for the reaction system to cool to room temperature, filter it, wash the product twice with deionized water, transfer it to an oven at 50°C, and dry it to constant weight to obtain activated basalt fiber felt.

[0076] Step ②: Preparation of pretreated basalt fiber felt

[0077] Weigh out 10g of the modified hollow microspheres prepared in Example 1, 80g of activated basalt fiber felt, 100mL of deionized water, 5g of γ-glycidyl etheroxypropyltrimethoxysilane, and 1500mL of ethanol and place them in a reaction vessel. Add 40mL of 3wt% dilute acetic acid aqueous solution, heat the reaction vessel to 45℃, and keep it at that temperature for 2h. After the reaction is completed, wait for the reaction system to cool to room temperature, filter it, wash the product twice with deionized water and ethanol, transfer it to an oven at 50℃, and dry it to constant weight to obtain pretreated basalt fiber felt.

[0078] Example 5

[0079] This embodiment provides a method for preparing pretreated basalt fiber felt, including the following steps:

[0080] Step ①: Preparation of activated basalt fiber felt

[0081] Weigh out 3 wt% sodium hydroxide aqueous solution and place it in a reaction vessel and stir. Add basalt fiber felt at an impregnation ratio of 1:13.5 for impregnation. Heat the reaction vessel to 55°C and keep it at that temperature for 1.5 hours. After the reaction is complete, wait for the reaction system to cool to room temperature, filter it, wash the product three times with deionized water, transfer it to an oven at 55°C, and dry it to constant weight to obtain activated basalt fiber felt.

[0082] Step ②: Preparation of pretreated basalt fiber felt

[0083] Weigh out 15g of the modified hollow microspheres prepared in Example 2, 90g of activated basalt fiber felt, 110mL of deionized water, 7.5g of γ-glycidyl etheroxypropyltrimethoxysilane, and 1750mL of ethanol and place them in a reaction vessel. Add 50mL of 4wt% dilute acetic acid aqueous solution, heat the reaction vessel to 50℃, and keep it at that temperature for 3h. After the reaction is complete, wait for the reaction system to cool to room temperature, filter it, wash the product three times with deionized water and ethanol, transfer it to an oven at 55℃, and dry it to constant weight to obtain pretreated basalt fiber felt.

[0084] Example 6

[0085] This embodiment provides a method for preparing pretreated basalt fiber felt, including the following steps:

[0086] Step ①: Preparation of activated basalt fiber felt

[0087] Weigh out 5 wt% sodium hydroxide aqueous solution and place it in a reaction vessel and stir. Add basalt fiber felt at an impregnation ratio of 1:15 for impregnation. Heat the reaction vessel to 60°C and keep it at that temperature for 2 hours. After the reaction is complete, wait for the reaction system to cool to room temperature, filter it, wash the product with deionized water 4 times, transfer it to an oven at 60°C, and dry it to constant weight to obtain activated basalt fiber felt.

[0088] Step ②: Preparation of pretreated basalt fiber felt

[0089] Weigh out 20g of the modified hollow microspheres prepared in Example 3, 100g of activated basalt fiber felt, 120mL of deionized water, 10g of γ-glycidyl etheroxypropyltrimethoxysilane, and 2000mL of ethanol and place them in a reaction vessel. Add 60mL of 5wt% dilute acetic acid aqueous solution, heat the reaction vessel to 55℃, and keep it at that temperature for 4h. After the reaction is complete, wait for the reaction system to cool to room temperature, filter it, wash the product 4 times with deionized water and ethanol, transfer it to an oven at 60℃, and dry it to constant weight to obtain pretreated basalt fiber felt.

[0090] Example 7

[0091] This embodiment provides a method for preparing a heat-insulating fiber felt, including the following steps:

[0092] Step (1): Preparation of ternary composite sol

[0093] Weigh out 20g of tetraethyl orthosilicate, 10g of aluminum chloride hexahydrate, 60g of yttrium chloride hexahydrate, 100mL of deionized water and 800mL of ethanol and place them in a reaction vessel. Stir at room temperature for 30min, then cool the reaction vessel to 0℃ in an ice bath. Add 5g of 1,2-epoxypropane and stir for 1min to obtain a ternary composite sol.

[0094] Step 2: Preparation of heat-insulating fiber felt

[0095] The pretreated basalt fiber felt was placed in a mold, and a ternary composite sol was added at an impregnation ratio of 2:1. The mixture was allowed to stand for 20 hours at room temperature with a relative humidity of 30%. After the standing aging was completed, the product was transferred to an ethanol solution and soaked for 48 hours. The solvent was changed every 24 hours. The product was then transferred to a closed autoclave and kept at 270℃ and 9MPa for 2 hours to obtain the heat insulation fiber felt.

[0096] Example 8

[0097] This embodiment provides a method for preparing a heat-insulating fiber felt, including the following steps:

[0098] Step (1): Preparation of ternary composite sol

[0099] Weigh out 30g of tetraethyl orthosilicate, 15g of aluminum chloride hexahydrate, 70g of yttrium chloride hexahydrate, 110mL of deionized water and 1000mL of ethanol and place them in a reaction vessel. Stir at room temperature for 45min, then heat the reaction vessel to 3℃ in an ice bath. Add 7.5g of 1,2-epoxypropane and stir for 2min to obtain a ternary composite sol.

[0100] Step 2: Preparation of heat-insulating fiber felt

[0101] The pretreated basalt fiber felt was placed in a mold, and a ternary composite sol was added at an impregnation ratio of 3:1. The mixture was allowed to stand for 22 hours at room temperature with a relative humidity of 40%. After the standing aging was completed, the product was transferred to an ethanol solution and soaked for 48 hours. The solvent was changed every 24 hours. The product was then transferred to a closed autoclave and kept at 275℃ and 9.3MPa for 3 hours to obtain the heat-insulating fiber felt.

[0102] Example 9

[0103] This embodiment provides a method for preparing a heat-insulating fiber felt, including the following steps:

[0104] Step (1): Preparation of ternary composite sol

[0105] Weigh out 40g of tetraethyl orthosilicate, 20g of aluminum chloride hexahydrate, 80g of yttrium chloride hexahydrate, 120mL of deionized water and 1200mL of ethanol and place them in a reaction vessel. Stir at room temperature for 60min, then heat the reaction vessel to 5℃ in an ice bath. Add 10g of 1,2-epoxypropane and stir for 3min to obtain a ternary composite sol.

[0106] Step 2: Preparation of heat-insulating fiber felt

[0107] The pretreated basalt fiber felt was placed in a mold, and a ternary composite sol was added at an impregnation ratio of 4:1. The mixture was allowed to stand for 24 hours at room temperature with a relative humidity of 50%. After the standing aging was completed, the product was transferred to an ethanol solution and soaked for 48 hours. The solvent was changed every 24 hours. The product was then transferred to a sealed autoclave and kept at 280℃ and 9.5MPa for 4 hours to obtain the heat-insulating fiber felt.

[0108] Example 10

[0109] This embodiment provides a method for preparing a multilayer flexible thermal insulation pad with embedded composite thermal insulation filler, including the following steps:

[0110] After fixing the heat insulation fiber felt 1 on the operating table, apply silicone adhesive to both sides of the heat insulation fiber felt 1, and then lay two layers of aluminum foil fiberglass cloth 2 on both sides of the heat insulation fiber felt 1, with the aluminum foil side facing outwards. After heat curing at a temperature of 180°C, a multi-layer flexible heat insulation pad is obtained.

[0111] Example 11

[0112] This embodiment provides a method for preparing a multilayer flexible thermal insulation pad with embedded composite thermal insulation filler, including the following steps:

[0113] After fixing the heat insulation fiber felt 1 on the operating table, apply silicone adhesive to both sides of the heat insulation fiber felt 1, and then lay two layers of aluminum foil fiberglass cloth 2 on both sides of the heat insulation fiber felt 1, with the aluminum foil side facing outwards. After heat curing at a temperature of 190°C, a multi-layer flexible heat insulation pad is obtained.

[0114] Example 12

[0115] This embodiment provides a method for preparing a multilayer flexible thermal insulation pad with embedded composite thermal insulation filler, including the following steps:

[0116] After fixing the heat insulation fiber felt 1 on the operating table, apply silicone adhesive to both sides of the heat insulation fiber felt 1, and then lay two layers of aluminum foil fiberglass cloth 2 on both sides of the heat insulation fiber felt 1, with the aluminum foil side facing outwards. After heat curing at a temperature of 200°C, a multi-layer flexible heat insulation pad is obtained.

[0117] Comparative Example 1

[0118] The difference between this comparative example and Example 12 is that the modified hollow microspheres were omitted in step ② when preparing the pretreated basalt fiber felt.

[0119] Comparative Example 2

[0120] The difference between this comparative example and Example 12 is that, in step (2) when preparing the heat-insulating fiber felt, basalt fiber felt is used in an equal amount to replace the pretreated basalt fiber felt.

[0121] Comparative Example 3

[0122] The difference between this comparative example and Example 12 is that aluminum foil fiberglass cloth is omitted in the case of multi-layer flexible thermal insulation pads.

[0123] Performance testing:

[0124] The longitudinal tensile strength, dry heat shrinkage rate (100℃×100h) and thermal conductivity (room temperature) of the multilayer flexible heat insulation pads prepared in Examples 10-12 and Comparative Examples 1-3 were tested in accordance with the standard FZ / T 64058-2016 "Reprocessed fiber felt for automotive sound insulation and heat insulation pads".

[0125] The bending properties of the multilayer flexible thermal insulation pads prepared in Examples 10-12 and Comparative Examples 1-3 were tested according to the standard GB / T 18318.1-2009 "Determination of bending properties of textiles - Part 1: Inclined plane method". The specific data are shown in Table 1.

[0126] Table 1 - Performance Test Data for Each Sample

[0127] Project Group Example 10 Example 11 Example 12 Comparative Example 1 Comparative Example 2 Comparative Example 3 Longitudinal fracture strength / N 574 576 575 559 513 544 Dry heat shrinkage rate / % 1.28 1.26 1.27 1.32 1.41 1.35 <![CDATA[Thermal conductivity / W·(m·k) -1 > 0.032 0.030 0.032 0.038 0.043 0.036 Flexural strength / mN·cm <![CDATA[2.3×10 4 ]]> <![CDATA[2.2×10 4 ]]> <![CDATA[2.2×10 4 ]]> <![CDATA[2.0×10 4 ]]> <![CDATA[2.1×10 4 ]]> <![CDATA[2.0×10 4 ]]>

[0128] Data Analysis:

[0129] Comparative analysis of the data in Table 1 shows that the multilayer flexible thermal insulation pad prepared by this invention has a tensile strength of 576 N, a dry heat shrinkage rate of 1.26%, and a thermal conductivity of 0.030 W·(m·K). -1 At the same time, the flexural strength is 2.2×10. 4 mN·cm;

[0130] Therefore, the present invention obtains a heat-insulating fiber felt core layer by impregnating pretreated fiber felt with ternary sol, followed by drying and heat treatment. Aluminum foil fiberglass cloth is used as the double-sided skin and bonded to the heat-insulating core layer with high-temperature resistant silicone adhesive to construct a sandwich structure of hard surface layer-flexible core layer. This not only improves the heat insulation performance of multi-layer flexible heat insulation pads, but also improves their mechanical properties.

[0131] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A multi-layer flexible thermal insulation pad with embedded composite thermal insulation filler, characterized in that, It includes heat insulation fiber felt (1) and aluminum foil fiberglass cloth (2) attached to both sides of the heat insulation fiber felt (1); The heat insulation fiber felt (1) has a thickness of 15-20 mm, and the aluminum foil fiberglass cloth (2) is a fiberglass fabric with a thin aluminum foil and a thickness of 0.1-0.2 mm. The heat-insulating fiber felt is prepared by the following steps: A1. Place tetraethyl orthosilicate, aluminum chloride hexahydrate, yttrium chloride hexahydrate, deionized water and ethanol in a reaction vessel, stir at room temperature for 30-60 min, cool the reaction vessel to 0-5℃ in an ice bath, add 1,2-epoxypropane, keep warm and stir for 1-3 min to obtain a ternary composite sol. A2. Place the pretreated basalt fiber felt in a mold, add ternary composite sol, let it stand at room temperature for 20-24 hours for aging, and then dry it with ethanol via supercritical drying to obtain the heat insulation fiber felt.

2. The multi-layer flexible thermal insulation pad with embedded composite thermal insulation filler according to claim 1, characterized in that, In step A1, the ratio of tetraethyl orthosilicate, aluminum chloride hexahydrate, yttrium chloride hexahydrate, deionized water, ethanol, and 1,2-epoxypropane is 2-4g:1-2g:6-8g:10-12mL:80-120mL:0.5-1g; in step A2, the volume ratio of the ternary composite sol to the pretreated basalt fiber felt is 2-4:1, and the relative humidity of the static aging environment is 30-50%.

3. The multi-layer flexible thermal insulation pad with embedded composite thermal insulation filler according to claim 1, characterized in that, The pretreated basalt fiber felt is prepared by the following steps: B1. Place the alkaline solution in a reaction vessel and stir. Add basalt fiber felt for impregnation. Heat the reaction vessel to 50-60℃ and keep it at that temperature for 1-2 hours. Post-treatment yields activated basalt fiber felt. B2. Modified hollow microspheres, activated basalt fiber felt, deionized water, γ-glycidyl etheroxypropyltrimethoxysilane and ethanol are placed in a reaction vessel, and dilute acetic acid aqueous solution is added. The reaction vessel is heated to 45-55℃ and kept at this temperature for 2-4 hours. The post-treatment yields pretreated basalt fiber felt.

4. The multi-layer flexible thermal insulation pad with embedded composite thermal insulation filler according to claim 3, characterized in that, In step B1, the impregnation ratio of basalt fiber felt to alkaline solution is 1:12-15, and the alkaline solution is a 1-5 wt% sodium hydroxide aqueous solution; in step B2, the ratio of the amount of modified hollow microspheres, activated basalt fiber felt, deionized water, γ-glycidoxypropyltrimethoxysilane, ethanol and dilute acetic acid aqueous solution is 1-2 g: 8-10 g: 10-12 mL: 0.5-1.0 g: 150-200 mL: 4-6 mL, and the concentration of dilute acetic acid aqueous solution is 3-5 wt%.

5. A multi-layer flexible thermal insulation pad with embedded composite thermal insulation filler according to claim 3, characterized in that, The modified hollow microspheres were prepared by the following steps: C1. Place zirconium propoxide, methyltriethoxysilane, n-propanol, acetylacetone and deionized water in a reaction vessel and stir. Heat the reaction vessel to 70-80℃ and keep it at that temperature for 6-8 hours. After post-treatment, obtain the Zr-Si polymerization precursor. C2. Place polyacrylonitrile, polyvinylpyrrolidone and N,N-dimethylformamide in a reaction vessel and stir. Heat the reaction vessel to 60-70℃ and stir for 0.5-1h. Add Zr-Si polymerization precursor and stir for 0.5-1h. Post-treatment yields spray precursor liquid. C3. The spray precursor liquid is loaded into a syringe, ultrasonically sprayed and granulated, and then solidified to obtain modified hollow microspheres.

6. A multi-layer flexible thermal insulation pad with embedded composite thermal insulation filler according to claim 5, characterized in that, In step C1, the ratio of zirconium propoxide, methyltriethoxysilane, n-propanol, acetylacetone, and deionized water is 7-9 g: 2-4 g: 40-60 mL: 1-2 g: 0.5-1 mL; in step C2, the ratio of polyacrylonitrile, polyvinylpyrrolidone, N,N-dimethylformamide, and Zr-Si polymerization precursor is 6-8 g: 2-4 g: 100-120 mL: 4-6 g.

7. A multi-layer flexible thermal insulation pad with embedded composite thermal insulation filler according to claim 5, characterized in that, The modified hollow microspheres are prepared as follows: the spray precursor liquid is loaded into a syringe and sprayed out through an ultrasonic atomizing nozzle at a propulsion speed of 0.3-0.8 mL / min. After the droplets are sprayed into the stirred ethanol for sizing, they are filtered out with a filter cloth and transferred to ammonia water with a pH of 8-9. The solution is cured at a temperature of 75-85℃ for 1-2 hours, filtered, and the filter cake is heat-cured in an oven at 240-260℃ for 0.5-1 hours. The solution is then transferred to a tube furnace under nitrogen atmosphere protection and calcined at high temperature to obtain the modified hollow microspheres.

8. A method for preparing a multilayer flexible thermal insulation pad with embedded composite thermal insulation filler as described in any one of claims 1-7, characterized in that, After fixing the heat insulation fiber felt (1) on the operating table, apply adhesive to both sides of the heat insulation fiber felt (1), and then lay two layers of aluminum foil fiberglass cloth (2) on both sides of the heat insulation fiber felt (1) with the aluminum foil side facing outward. After heat curing, a multi-layer flexible heat insulation pad is obtained.

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