Low-density and high-elasticity glass fiber felt and preparation method thereof

Abstract

The invention relates to the technical field of thermal insulation materials, in particular to a low-density and high-elasticity glass fiber felt and a preparation method thereof.The low-density and high-elasticity glass fiber felt is prepared from, by weight, 70-85 parts of hollow glass beads, 5-10 parts of graphene aerogel, 5-8 parts of surface modified glass microfibers, 2-5 parts of phenolic modified silicon resin adhesive and 0.5-1.5 parts of graphene oxide; the density of the glass fiber felt is 5-10 kg / m, the rebound coefficient is larger than 50%, the density of the glass fiber felt is obviously reduced to 5-10 kg / m and is reduced by 33-50% compared with the prior art, the material weight is greatly reduced, and reduction of the total weight of the whole heat insulation system is facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal insulation materials, and in particular to a low-density, high-elasticity glass fiber felt and a preparation method thereof, which is particularly suitable for use as a buffer layer material in thermal insulation systems of extremely low-temperature storage tanks and pipelines such as liquid natural gas. Background Art

[0002] In the fields of liquefied natural gas (LNG) and other cryogenic storage tanks, the buffer layer of the tank wall generally requires a low-density, highly elastic, and thick insulation material. Due to the extremely low operating temperature of cryogenic storage tanks (LNG is approximately -162°C), conventional insulation materials often cannot provide sufficient thermal and mechanical properties.

[0003] Prior art, Chinese invention patent application CN 116005359 A (A Low-Density, High-Elasticity Glass Fiber Mat and Its Preparation Method) discloses a glass fiber mat made primarily from glass fiber and phenolic resin powder. This technology comprises, by weight, 75-85% glass fiber and 15-25% phenolic resin powder. The glass fiber has a fiber diameter of 7-9 μm and a fiber length of 5-15 cm. The phenolic resin powder contains 8.5-9.5% hexamine, 1-2% free phenol, a tumbling angle of 22-30 at 125°C, and a polymerization rate of 65-90. This glass fiber mat has a density of 15.5-18.5 kg / m³, a tensile strength of >6.1 kPa, and a coefficient of resilience >44%.

[0004] However, this technology still has the following shortcomings: First, the density is relatively high, usually around 16kg / m³, which increases the total weight of the system when used in extremely low temperature environments; second, the rebound coefficient is only about 44%, the elastic recovery performance is limited, and permanent deformation is prone to occur in low temperature environments; third, traditional phenolic resin is used as an adhesive, which becomes brittle in low temperature environments and affects the overall elasticity of the material; fourth, the thermal conductivity is high, and the insulation performance is significantly reduced in extremely low temperature environments below -160°C; fifth, there is no self-repair function, and after microcracks are generated during use, the performance will continue to decline.

[0005] Therefore, there is an urgent need to develop a glass fiber felt material with lower density, higher elasticity and better thermal insulation performance to meet the application requirements in extremely low temperature environments. Summary of the Invention

[0006] The purpose of the present invention is to provide a low-density, high-elasticity glass fiber mat and a preparation method thereof. By innovatively introducing a three-level hierarchical structure of hollow glass microspheres, graphene aerogel and special surface-modified glass microfibers, combined with a phenol-modified silicone resin adhesive and a supercritical carbon dioxide processing technology, a new glass fiber mat material with significantly reduced density, greatly improved elasticity, excellent low-temperature insulation performance and self-repairing function is prepared.

[0007] To achieve the above objectives, the present invention provides the following technical solutions:

[0008] The present invention provides a low-density, high-elasticity glass fiber mat, which comprises, by weight, 70-85 parts of hollow glass microspheres, 5-10 parts of graphene aerogel, 5-8 parts of surface-modified glass microfibers, 2-5 parts of phenol-modified silicone resin adhesive, and 0.5-1.5 parts of graphene oxide; the glass fiber mat has a density of 5-10 kg / m³ and a coefficient of resilience greater than 50%.

[0009] Preferably, the hollow glass microspheres have a density of 0.20-0.30 g / cm³ and a diameter of 35-65 μm; the graphene aerogel has a density of 0.10-0.20 g / cm³, forming a three-dimensional interconnected network structure; the surface-modified glass microfibers have a diameter of 0.5-2.5 μm and a length of 2-8 cm.

[0010] Preferably, the surface-modified glass microfiber is treated with aminopropyltriethoxysilane, and its surface has amino functional groups; the phenol-modified silicone resin adhesive contains 10-20% phenyl side chain structure and maintains elasticity at low temperatures; the graphene oxide is used as a surface functionalizing agent to improve the interfacial bonding strength between components.

[0011] Preferably, the glass fiber felt has the following properties: thermal conductivity of 10-15 mW / (m·K) at -196°C, operating temperature range of -196°C to +200°C, tensile strength greater than 8.0 kPa, and self-repairing ability.

[0012] Preferably, the glass fiber mat has a three-level hierarchical structure: hollow glass microspheres constitute the basic matrix structure, graphene aerogel forms a network structure running through the gaps between the microspheres, and surface-modified glass microfibers form a connecting and reinforcing structure; the phenol-modified silicone resin adhesive forms a foam structure containing 1-2 parts of self-healing microcapsules.

[0013] The present invention also provides a method for preparing a low-density, high-elasticity glass fiber mat, comprising the following steps:

[0014] a) Placing the glass microfiber in an atmospheric plasma treatment system at 800-1200W power and using an argon-oxygen mixed gas (argon to oxygen volume ratio of 80:20) for 3-5 minutes to form surface active functional groups;

[0015] b) immersing the glass microfiber treated in step a) in a 3-aminopropyltriethoxysilane solution (2 parts, solvent: ethanol / water mixture), and hydrolyzing the solution at a pH of 4.5 for 30 minutes to prepare amino-functionalized glass fibers;

[0016] c) mixing a graphene oxide suspension (concentration 5 mg / mL) with hollow glass microspheres, hydrothermally reducing them at 180°C for 12 hours, followed by solvent exchange (water → acetone → liquid carbon dioxide), and supercritical drying at 31.1°C and 7.39 MPa for 6 hours to form a graphene aerogel-coated hollow glass microsphere composite material;

[0017] d) The fiber layer was prepared using a hybrid spinning system, in which a central electrospinning unit produced nanofibers (100-500 nm) at a voltage of 20 kV, and a peripheral centrifugal spinning unit produced micron-sized support fibers at a speed of 4000 rpm, which were simultaneously deposited to form a gradient fiber structure;

[0018] e) mixing a phenol-modified silicone resin with a carbon dioxide foaming agent and applying the mixture to the fiber layer formed in step d) by electrostatic spraying in an amount of 5-8 parts by weight;

[0019] f) placing the composite prepared in step e) in a microwave curing system at a frequency of 915 MHz and a power of 2 kW for 5 minutes to form a porous foam-like adhesive structure;

[0020] g) The material prepared in step f) is subjected to three-dimensional reinforcement by elliptical motion needling at a needling density of 200 needles / cm² to form a composite structure with z-direction fiber bridging.

[0021] Preferably, in step c), the supercritical drying process uses carbon dioxide as a supercritical fluid, and under the conditions of 31.1° C. and 7.39 MPa, the pressure is gradually reduced to normal pressure to achieve slow release of the supercritical fluid to prevent collapse of the aerogel structure.

[0022] Preferably, in step d), the hybrid spinning system consists of a central electrospinning unit and eight peripheral centrifugal spinning units, and a computer-controlled fiber orientation system is used to achieve a 0° / 45° / 90° laying pattern, and the fiber layer thickness is controlled at 80-150 mm.

[0023] Preferably, in step e), urea-formaldehyde microcapsules with a diameter of 50-80 μm containing a cyanoacrylate self-healing agent are added to the phenol-modified silicone resin adhesive, and the amount of microcapsules added is 10-15 parts by weight of the adhesive.

[0024] Preferably, in step g), the three-dimensional reinforcement treatment uses DiloGroup Hyperpunch technology, the needle plate adopts 6000X needle type, the needling depth is 5-15 mm, and the needling frequency is 800-1200 times / minute. The elliptical motion trajectory of the needle reduces damage to the fiber and improves the z-direction connection strength.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The density of the glass fiber felt of the present invention is significantly reduced to 5-10 kg / m³, which is 33-50% lower than that of the prior art, greatly reducing the material weight and being beneficial to reducing the total weight of the entire thermal insulation system;

[0027] (2) The rebound coefficient of the glass fiber felt of the present invention reaches 55-70 parts, which is 25-59 parts higher than that of the prior art. It can still maintain good elastic recovery at extremely low temperatures, significantly improving the mechanical properties of the material;

[0028] (3) The present invention uses phenolic-modified silicone resin as an adhesive, which still maintains good elasticity at an extremely low temperature of -196°C and does not embrittle, greatly improving the stability of the material in a low-temperature environment;

[0029] (4) The present invention adopts a multi-stage heat insulation structure combining hollow glass microspheres and graphene aerogel, and the thermal conductivity is reduced to 10-15 mW / (m·K), which is 40-50 parts lower than that of the prior art, significantly improving the heat insulation performance of the material;

[0030] (5) The present invention introduces a self-healing microcapsule technology, and when microcracks occur during the use of the material, it can be self-repaired, extending the service life of the material;

[0031] (6) The present invention adopts a supercritical carbon dioxide treatment process, which can effectively maintain the integrity of the aerogel network structure and prepare a more stable composite structure;

[0032] (7) The present invention adopts an elliptical motion needle punching technology, which reduces the damage to the fibers and at the same time improves the z-direction connection strength, making the material have better overall performance. Detailed Embodiments

[0033] The present invention will be further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto. Those skilled in the art, based on the given embodiments, without departing from the technical solution of the present invention, the technical solutions obtained by equivalent substitution or equivalent modification of the present invention all fall within the protection scope of the present invention.

[0034] For those not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer; if there is no special description for the experimental methods, they are all conventional methods. The main raw materials used in the present invention and their sources are as follows:

[0035] (1) Hollow glass microspheres: S42XHS grade produced by 3M Company of the United States, with a density of 0.25 g / cm³, a diameter of 40-60 μm, and a compressive strength of 180-220 MPa;

[0036] (2) Graphene Oxide: A monolayer graphene oxide dispersion produced by Graphenea in Germany, with a concentration of 4 mg / mL;

[0037] (3) Glass Microfiber: E-grade glass fiber produced by Owens Corning in the United States, with an initial diameter of 6 - 8 μm;

[0038] (4) Phenol-modified Silicone Resin: R3-2160 type silicone rubber produced by NuSil in the United States, modified with phenyl side chains; 50 g of the R3-2160 type silicone rubber base polymer produced by NuSil in the United States was placed in a three-necked flask, 120 mL of anhydrous toluene was added as a solvent, and it was stirred until completely dissolved under nitrogen protection. 12 g of diphenyldimethoxysilane and 6 g of phenol-formaldehyde prepolymer (phenol-to-formaldehyde molar ratio of 1:1.2) were slowly added dropwise to the reaction system, and 0.6 g of stannous acetate was added as a catalyst. The reaction temperature was raised to 80 - 85 °C and stirred for 10 hours to ensure that the phenyl side chains fully reacted with the Si-H groups on the silicone rubber main chain. During the reaction, samples were taken every 2 hours to monitor the change in infrared absorption peaks. When the intensity of the characteristic peak of the Si-H group (2150 cm⁻¹) decreased to less than 10% of the original, the reaction was considered basically complete. After the reaction was completed, the mixture was cooled to room temperature, 5 g of activated carbon was added, and stirring was continued for 2 hours to adsorb the residual catalyst, and then filtered. The toluene solvent was removed by rotary evaporation under reduced pressure to obtain a viscous modified silicone resin. The product was vacuum dried at 60 °C for 16 hours to ensure that the residual solvent content was less than 0.5%. The final product was determined by gel permeation chromatography (GPC) to have an average molecular weight of 28,000 - 32,000 Da, and infrared spectroscopy confirmed that the phenyl side chains were successfully grafted onto the silicone resin molecular chain, with a phenyl content of 15 - 18% (quantitative analysis by ¹H-NMR). The prepared phenol-modified silicone resin was light yellow and translucent, still maintained good elasticity at -196 °C, had a glass transition temperature (Tg) of -125 °C, a tensile strength of 3.8 MPa, and an elongation at break of 265%. The viscosity of this modified silicone resin was 8,500 - 9,200 mPa·s (25 °C), the Shore A hardness after curing was 38 - 42, the initial temperature of thermal weight loss was 380 °C, and it showed excellent flexibility and mechanical stability in extremely low temperature environments.

[0039] (5) 3-Aminopropyltriethoxysilane (APTES): Produced by Sigma-Aldrich in Germany, with a purity > 98%;

[0040] (6) Cyanoacrylate: 4860 type ultra-low viscosity glue produced by Loctite in the United States;

[0041] (7) Urea and Formaldehyde: Analytically pure.

[0042] Preparation of surface-modified glass microfibers: Place the glass microfibers in an Andritz atmospheric plasma treatment system and treat them with a mixed gas of argon and oxygen (volume ratio of argon to oxygen is 80:20) at a power of 1000 W for 4 minutes. Subsequently, immerse the treated fibers in 2 parts of 3-aminopropyltriethoxysilane solution (the solvent is a mixed solution of ethanol / water with a volume ratio of 95:5), hydrolyze for 30 minutes under the condition of pH value 4.5, and then dry at 80 °C for 2 hours to obtain amino-functionalized glass microfibers.

[0043] Preparation of graphene aerogel-coated hollow glass microspheres: Dilute the graphene oxide suspension to a concentration of 5 mg / mL, mix it with hollow glass microspheres according to a mass ratio of 1:20, ultrasonically disperse for 30 minutes, and then hydrothermally reduce at 180 °C for 12 hours. Subsequently, perform solvent exchange, wash with deionized water 3 times and acetone 3 times in sequence, and finally transfer to a supercritical drying device. Replace acetone with liquid carbon dioxide (replace liquid CO2 three times a day for 3 consecutive days), and then perform supercritical drying at 31.1 °C and 7.39 MPa for 6 hours. Finally, slowly depressurize to atmospheric pressure (the pressure reduction rate is controlled at 0.1 MPa / hour) to obtain a composite material of hollow glass microspheres coated with graphene aerogel.

[0044] Preparation of self-healing microcapsules: Prepare urea-formaldehyde microcapsules containing cyanoacrylate by in-situ polymerization method. First, dissolve 5.0 g of urea and 0.5 g of ammonium chloride in 100 mL of deionized water, then add 10 mL of cyanoacrylate and stir to form a stable emulsion. Adjust the pH value to 3.5, add 12.7 g of formaldehyde solution (37 parts concentration), and react at 60 °C for 4 hours. After the reaction is completed, cool to room temperature, filter, wash with deionized water and ethanol, and vacuum dry at 40 °C for 24 hours to obtain self-healing microcapsules with a diameter of 50 - 80 μm.

[0045] Example 1

[0046] The low-density, high-elastic glass fiber mat, by weight, includes: 70 parts of hollow glass microspheres, 10 parts of graphene aerogel, 8 parts of surface-modified glass microfibers, 5 parts of phenol-based modified silicone resin binder, and 1.5 parts of graphene oxide. Among them, the density of the hollow glass microspheres is 0.25 g / cm³, and the diameter is 40 μm; the density of the graphene aerogel is 0.16 g / cm³; the diameter of the surface-modified glass microfibers is 0.5 μm, and the length is 2 cm.

[0047] The preparation method of the glass fiber mat includes the following steps:

[0048] (1) Place the glass microfibers in an atmospheric plasma treatment system and treat them for 4 minutes at a power of 1000 W using a mixed gas of argon and oxygen (volume ratio of argon to oxygen is 80:20) to form surface active functional groups;

[0049] (2) Immerse the glass microfibers treated in step (1) in a 3-aminopropyltriethoxysilane solution with a concentration of 2 parts (the solvent is a mixed solution of ethanol / water with a volume ratio of 95:5), hydrolyze for 30 minutes under the condition of pH value 4.5, and dry at 80 °C for 2 hours to prepare amino-functionalized glass fibers;

[0050] (3) Mix the graphene oxide suspension (concentration 5 mg / mL) with hollow glass microspheres, hydrothermally reduce at 180 °C for 12 hours, then perform solvent exchange (water → acetone → liquid carbon dioxide), and carry out supercritical drying at 31.1 °C and 7.39 MPa for 6 hours to form a composite material of hollow glass microspheres coated with graphene aerogel;

[0051] (4) Use a hybrid spinning system to prepare a fiber layer. Among them, the central electrospinning unit generates nanofibers (average diameter 300 nm) at a voltage of 20 kV, and the 8 peripheral centrifugal spinning units generate microscale support fibers at a rotational speed of 4000 rpm. Use a computer-controlled fiber orientation system to achieve a layering pattern of 0° / 45° / 90°, and control the thickness of the fiber layer at 100 mm;

[0052] (5) Mix the phenol-modified silicone resin with a carbon dioxide foaming agent, and add self-healing microcapsules accounting for 12 parts by weight of the binder. Apply it to the fiber layer formed in step (4) by electrostatic spraying, and the dosage is 5 parts by total weight;

[0053] (6) Place the composite prepared in step (5) in a microwave curing system and treat it at a frequency of 915 MHz and a power of 2 kW for 5 minutes to form a porous foam-like binder structure;

[0054] (7) Perform three-dimensional reinforcement treatment on the material prepared in step (6) using the elliptical motion needling technique. Use a 6000X needle type, the needling density is 200 needles / cm², the needling depth is 10 mm, and the needling frequency is 1000 times / minute to form a composite structure with z-direction fiber bridging.

[0055] The density of the low-density and high-elastic glass fiber mat prepared in this example is 8.5 kg / m³, the resilience coefficient is 68 parts, the thermal conductivity is 11.5 mW / (m·K) at -196 °C, and the tensile strength is 9.2 kPa. This glass fiber mat has good self-healing ability and can recover about 55 parts of its strength after being damaged by external forces.

[0056] Example 2

[0057] A low-density, high-elasticity glass fiber mat, by weight, includes: 85 parts of hollow glass microspheres, 5 parts of graphene aerogel, 5 parts of surface-modified glass microfibers, 2 parts of phenol-based modified silicone resin binder, and 0.5 part of graphene oxide. Among them, the density of the hollow glass microspheres is 0.30 g / cm³, and the diameter is 65 μm; the density of the graphene aerogel is 0.20 g / cm³; the diameter of the surface-modified glass microfibers is 2.5 μm, and the length is 8 cm.

[0058] The preparation method of the glass fiber mat includes the following steps:

[0059] (1) Place the glass microfibers in an atmospheric plasma treatment system, and treat them for 3 minutes at a power of 800 W using an argon-oxygen mixed gas (volume ratio of argon to oxygen is 80:20) to form surface active functional groups;

[0060] (2) Immerse the glass microfibers treated in step (1) in a 2-part concentration of 3-aminopropyltriethoxysilane solution (the solvent is an ethanol / water mixed solution with a volume ratio of 90:10), hydrolyze for 30 minutes at a pH value of 4.5, and dry at 85 °C for 2.5 hours to prepare amino-functionalized glass fibers;

[0061] (3) Mix the graphene oxide suspension (concentration 4 mg / mL) with the hollow glass microspheres, hydrothermally reduce at 175 °C for 10 hours, then perform solvent exchange (water → acetone → liquid carbon dioxide), and perform supercritical drying at 31.1 °C and 7.39 MPa for 5 hours to form a hollow glass microsphere composite coated with graphene aerogel;

[0062] (4) Use a hybrid spinning system to prepare a fiber layer, where the central electrospinning unit generates nanofibers (average diameter of 450 nm) at a voltage of 18 kV, and the surrounding 8 centrifugal spinning units generate micron-scale support fibers at a rotational speed of 3500 rpm. Use a computer-controlled fiber orientation system to achieve a 0° / 60° layering pattern, and control the fiber layer thickness at 150 mm;

[0063] (5) Mix the phenol-based modified silicone resin with a carbon dioxide foaming agent, and add 10 parts of self-healing microcapsules based on the weight of the binder. Apply it to the fiber layer formed in step (4) by electrostatic spraying, and the dosage is 8 parts of the total weight;

[0064] (6) Place the composite prepared in step (5) in a microwave curing system, and treat it at a frequency of 915 MHz and a power of 1.5 kW for 6 minutes to form a porous foamed binder structure;

[0065] (7) The material prepared in step (6) was subjected to three-dimensional reinforcement treatment by elliptical motion needling technology, using a 6000X needle type, a needling density of 180 needles / cm², a needling depth of 15 mm, and a needling frequency of 800 times / min to form a composite structure with z-direction fiber bridging.

[0066] The low-density, highly elastic glass fiber mat prepared in this example has a density of 9.8 kg / m³, a coefficient of resilience of 58, a thermal conductivity of 14.2 mW / (m·K) at -196°C, and a tensile strength of 8.5 kPa. The glass fiber mat exhibits a certain degree of self-repair ability, recovering approximately 45% of its strength after damage from external forces.

[0067] Example 3

[0068] This low-density, high-elasticity glass fiber mat comprises, by weight, 75 parts hollow glass microspheres, 8 parts graphene aerogel, 6 parts surface-modified glass microfibers, 3 parts phenol-modified silicone resin adhesive, and 1.0 part graphene oxide. The hollow glass microspheres have a density of 0.23 g / cm³ and a diameter of 50 μm; the graphene aerogel has a density of 0.15 g / cm³; and the surface-modified glass microfibers have a diameter of 1.5 μm and a length of 5 cm.

[0069] The preparation method of the glass fiber mat comprises the following steps:

[0070] (1) The glass microfibers were placed in an atmospheric plasma treatment system and treated with an argon-oxygen mixed gas (argon to oxygen volume ratio of 80:20) at a power of 900 W for 4 minutes to form surface active functional groups;

[0071] (2) immersing the glass microfiber treated in step (1) in a 2-part 3-aminopropyltriethoxysilane solution (the solvent is an ethanol / water mixture, with a volume ratio of 92:8), hydrolyzing the solution at a pH of 4.5 for 30 minutes, and drying the solution at 82°C for 2.2 hours to prepare amino-functionalized glass fibers;

[0072] (3) The graphene oxide suspension (concentration 5 mg / mL) was mixed with hollow glass microspheres and hydrothermally reduced at 180 °C for 12 h. Subsequently, solvent exchange (water → acetone → liquid carbon dioxide) was performed and supercritical drying was performed at 31.1 °C and 7.39 MPa for 6 h to form a composite material of hollow glass microspheres coated with graphene aerogel.

[0073] (4) A fiber layer is prepared by using a hybrid spinning system, in which a central electrospinning unit generates nanofibers (with an average diameter of 350 nm) at a voltage of 20 kV, and 8 peripheral centrifugal spinning units generate micron-scale support fibers at a rotational speed of 4000 rpm. A computer-controlled fiber orientation system is used to achieve a layering pattern of 0° / 45° / 90°, and the thickness of the fiber layer is controlled at 120 mm;

[0074] (5) A phenolic-modified silicone resin is mixed with a carbon dioxide foaming agent, and self-healing microcapsules accounting for 12 parts by weight of the binder are added. It is applied to the fiber layer formed in step (4) by electrostatic spraying, and the dosage is 6.5 parts by total weight;

[0075] (6) The composite prepared in step (5) is placed in a microwave curing system and treated at a frequency of 915 MHz and a power of 2 kW for 5 minutes to form a porous foam-like binder structure;

[0076] (7) The material prepared in step (6) is subjected to three-dimensional reinforcement treatment by using elliptical motion needle punching technology. The 6000X needle type is used, the needle punching density is 200 needles / cm², the needle punching depth is 12 mm, and the needle punching frequency is 1000 times per minute to form a composite structure with z-direction fiber bridging.

[0077] The low-density and high-elasticity glass fiber mat prepared in this example has a density of 7.2 kg / m³, a resilience coefficient of 62 parts, a thermal conductivity of 12.8 mW / (m·K) under the condition of -196 °C, and a tensile strength of 8.9 kPa. This glass fiber mat has good self-healing ability and can recover about 50 parts of its strength after being damaged by external forces.

[0078] Example 4

[0079] A low-density and high-elasticity glass fiber mat, including by weight: 80 parts of hollow glass microspheres, 7 parts of graphene aerogel, 6 parts of surface-modified glass microfibers, 4 parts of phenolic-modified silicone resin binder, and 1.0 part of graphene oxide. Among them, the density of the hollow glass microspheres is 0.28 g / cm³, and the diameter is 55 μm; the density of the graphene aerogel is 0.18 g / cm³; the diameter of the surface-modified glass microfibers is 2.0 μm, and the length is 6 cm.

[0080] The preparation method of this glass fiber mat includes the following steps:

[0081] (1) The glass microfibers are placed in an atmospheric plasma treatment system and treated for 4.5 minutes at a power of 1100 W by using an argon-oxygen mixed gas (the volume ratio of argon to oxygen is 85:15) to form surface active functional groups;

[0082] (2) immersing the glass microfiber treated in step (1) in a 2-part 3-aminopropyltriethoxysilane solution (the solvent is an ethanol / water mixture, the volume ratio is 95:5), hydrolyzing at a pH of 4.5 for 30 minutes, and drying at 80°C for 2 hours to prepare amino-functionalized glass fibers;

[0083] (3) The graphene oxide suspension (concentration 4.5 mg / mL) was mixed with hollow glass microspheres and hydrothermally reduced at 180°C for 11 hours. The mixture was then solvent exchanged (water → acetone → liquid carbon dioxide) and supercritical dried at 31.1°C and 7.39 MPa for 6 hours to form a composite material of hollow glass microspheres coated with graphene aerogel.

[0084] (4) A hybrid spinning system was used to prepare the fiber layer. The central electrospinning unit produced nanofibers (average diameter 400 nm) at a voltage of 19 kV, and eight peripheral centrifugal spinning units produced micron-sized support fibers at a speed of 3800 rpm. A computer-controlled fiber orientation system was used to achieve a 0° / 30° / 60° / 90° laying pattern. The fiber layer thickness was controlled at 110 mm.

[0085] (5) mixing a phenol-modified silicone resin with a carbon dioxide foaming agent, adding 15 parts by weight of self-repairing microcapsules to the adhesive, and applying the mixture to the fiber layer formed in step (4) by electrostatic spraying in an amount of 7 parts by weight;

[0086] (6) placing the composite prepared in step (5) in a microwave curing system at a frequency of 915 MHz and a power of 2.2 kW for 4.5 minutes to form a porous foam adhesive structure;

[0087] (7) The material prepared in step (6) was subjected to three-dimensional reinforcement treatment by elliptical motion needling technology, using a 6000X needle type, a needling density of 220 needles / cm², a needling depth of 8 mm, and a needling frequency of 1100 times / min to form a composite structure with z-direction fiber bridging.

[0088] The low-density, highly elastic glass fiber mat prepared in this example has a density of 6.5 kg / m³, a coefficient of resilience of 65, a thermal conductivity of 11.8 mW / (m·K) at -196°C, and a tensile strength of 9.5 kPa. The glass fiber mat has excellent self-healing capabilities and can recover approximately 60% of its strength after damage from external forces.

[0089] Example 5

[0090] Low-density, high-elasticity glass fiber mat, comprising by weight: 78 parts of hollow glass microspheres, 9 parts of graphene aerogel, 7 parts of surface-modified glass microfibers, 4 parts of phenol-based modified silicone resin binder, and 1.2 parts of graphene oxide. Among them, the density of the hollow glass microspheres is 0.22 g / cm³ and the diameter is 45 μm; the density of the graphene aerogel is 0.14 g / cm³; the diameter of the surface-modified glass microfibers is 1.2 μm and the length is 4 cm.

[0091] The preparation method of this glass fiber mat is basically the same as that of Example 3, except that: in step (3), the hydrothermal reduction temperature is 175 °C and the time is 13 hours; in step (4), the fiber layer thickness is 130 mm; in step (6), the microwave power is 2.3 kW and the treatment time is 4.8 minutes; in step (7), the needling density is 210 needles / cm².

[0092] The density of the low-density, high-elasticity glass fiber mat prepared in this example is 6.9 kg / m³, the resilience coefficient is 64 parts, the thermal conductivity is 12.1 mW / (m·K) under the condition of -196 °C, and the tensile strength is 9.3 kPa. This glass fiber mat has excellent self-healing ability and can recover about 58 parts of strength after being damaged by external forces.

[0093] Example 6

[0094] Low-density, high-elasticity glass fiber mat, comprising by weight: 82 parts of hollow glass microspheres, 8 parts of graphene aerogel, 6 parts of surface-modified glass microfibers, 3 parts of phenol-based modified silicone resin binder, and 1.0 part of graphene oxide. Among them, the density of the hollow glass microspheres is 0.25 g / cm³ and the diameter is 40 - 60 μm; the density of the graphene aerogel is 0.16 g / cm³; the diameter of the surface-modified glass microfibers is 0.8 - 1.5 μm and the length is 3 - 5 cm.

[0095] The preparation method of this glass fiber mat includes the following steps:

[0096] (1) Place the glass microfibers in an atmospheric plasma treatment system, treat them for 4 minutes with a power of 1000 W using an argon-oxygen mixed gas (volume ratio of argon to oxygen is 80:20) to form surface active functional groups;

[0097] (2) Immerse the glass microfibers treated in step (1) in a 3-aminopropyltriethoxysilane solution with a concentration of 2 parts (the solvent is an ethanol / water mixed solution with a volume ratio of 95:5), hydrolyze for 30 minutes under the condition of pH value 4.5, and dry at 80 °C for 2 hours to prepare amino-functionalized glass fibers;

[0098] (3) The graphene oxide suspension (concentration 5 mg / mL) was mixed with hollow glass microspheres and hydrothermally reduced at 180 °C for 12 h. Subsequently, solvent exchange (water → acetone → liquid carbon dioxide) was performed and supercritical drying was performed at 31.1 °C and 7.39 MPa for 6 h to form a composite material of hollow glass microspheres coated with graphene aerogel.

[0099] (4) A hybrid spinning system was used to prepare the fiber layer, in which the central electrospinning unit produced nano-scale fibers at a voltage of 20 kV, and the eight peripheral centrifugal spinning units produced micron-scale support fibers at a speed of 4000 rpm. A computer-controlled fiber orientation system was used to achieve a 0° / 45° / 90° laying pattern, and the fiber layer thickness was controlled at 100 mm.

[0100] (5) mixing a phenol-modified silicone resin with a carbon dioxide foaming agent, adding 12 parts by weight of self-repairing microcapsules to the adhesive, and applying the mixture to the fiber layer formed in step (4) by electrostatic spraying in an amount of 6 parts by weight;

[0101] (6) placing the composite prepared in step (5) in a microwave curing system at a frequency of 915 MHz and a power of 2 kW for 5 minutes to form a porous foam adhesive structure;

[0102] (7) The material prepared in step (6) was subjected to three-dimensional reinforcement treatment by elliptical motion needling technology, using a 6000X needle type, a needling density of 200 needles / cm², a needling depth of 10 mm, and a needling frequency of 1000 times / min to form a composite structure with z-direction fiber bridging.

[0103] The low-density, high-elasticity glass fiber felt prepared in this embodiment has a density of 6.2 kg / m³, a rebound coefficient of 67, a thermal conductivity of 11.2 mW / (m·K) at -196°C, and a tensile strength of 9.6 kPa.

[0104] Comparative Example 1

[0105] This comparative example differs from Example 1 in that it does not contain graphene aerogel and instead comprises, by weight, 80 parts of hollow glass microspheres, 8 parts of surface-modified glass microfibers, 5 parts of a phenol-modified silicone resin adhesive, and 1.5 parts of graphene oxide. The preparation method is the same as that of Example 1, but the steps involved in preparing the graphene aerogel are omitted, i.e., the operations related to the graphene aerogel in step (3) are omitted.

[0106] The test results show that the density of the glass fiber mat prepared in Comparative Example 1 is 9.2 kg / m³, the resilience coefficient is 49 parts, the thermal conductivity is 18.6 mW / (m·K) at -196 °C, and the tensile strength is 7.8 kPa. After being damaged by external force, the recovery strength is only 35 parts. Compared with Example 1, the resilience coefficient and adiabatic performance of Comparative Example 1 decreased significantly, indicating that graphene aerogel plays a key role in improving the elasticity of the material and reducing the thermal conductivity.

[0107] Comparative Example 2

[0108] The difference between this comparative example and Example 3 is that ordinary glass fibers are used instead of surface-modified glass microfibers, and it includes, by weight: 75 parts of hollow glass microspheres, 8 parts of graphene aerogel, 6 parts of ordinary glass fibers, 3 parts of phenol-based modified silicone resin binder, and 1.0 part of graphene oxide. The preparation method is the same as that of Example 3, but the surface treatment of the glass fibers in steps (1) and (2) is omitted.

[0109] The test results show that the density of the glass fiber mat prepared in Comparative Example 2 is 7.5 kg / m³, the resilience coefficient is 53 parts, the thermal conductivity is 14.1 mW / (m·K) at -196 °C, and the tensile strength is 7.2 kPa. After being damaged by external force, the recovery strength is about 30 parts. Compared with Example 3, the interfacial bonding strength of Comparative Example 2 is poor, resulting in a significant decrease in the tensile strength and resilience coefficient, and the self-healing ability also decreases significantly, indicating that surface modification plays an important role in enhancing the interfacial bonding force between components.

[0110] Comparative Example 3

[0111] The difference between this comparative example and Example 4 is that traditional phenolic resin powder is used instead of phenol-based modified silicone resin binder, and it does not contain self-healing microcapsules. It includes, by weight: 80 parts of hollow glass microspheres, 7 parts of graphene aerogel, 6 parts of surface-modified glass microfibers, 4 parts of phenolic resin powder, and 1.0 part of graphene oxide. The preparation method is the same as that of Example 4, but step (5) is changed to apply the phenolic resin powder to the fiber layer by electrostatic spraying, and no self-healing microcapsules are added.

[0112] The test results show that the density of the glass fiber mat prepared in Comparative Example 3 is 6.8 kg / m³, the resilience coefficient is 51 parts, the thermal conductivity is 12.3 mW / (m·K) at -196 °C, and the tensile strength is 8.3 kPa. At -196 °C, due to the brittleness of traditional phenolic resin at low temperature, the resilience coefficient of the material drops to 32 parts, and the self-healing ability is completely lost. Compared with Example 4, the elasticity of Comparative Example 3 decreases significantly at extremely low temperatures, indicating that phenol-based modified silicone resin binder is crucial for maintaining the elasticity of the material in low-temperature environments.

[0113] Comparative Example 4

[0114] This comparative example prepared a glass fiber mat according to the method in CN 116005359 A, including, by weight: 80 parts of glass fiber and 20 parts of phenolic resin powder. Among them, the diameter of the glass fiber is 7-9 μm and the length is 5-15 cm; the content of hexamethylenetetramine in the phenolic resin powder is 9.3 parts, the content of free phenol is 1.49 parts, the rolling degree at 125 °C is 28, and the polymerization rate is 86.

[0115] The preparation method was carried out according to the method in CN 116005359 A, including steps such as fiber opening, cotton mixing, cotton feeding, carding, powder spreading, web laying, drying in a drying channel, and slitting and coiling.

[0116] The test results showed that the density of the glass fiber mat prepared in Comparative Example 4 was 16.1 kg / m³, the resilience coefficient was 46 parts, the thermal conductivity was 24.5 mW / (m·K) under the condition of -196 °C, and the tensile strength was 6.5 kPa. The resilience coefficient of this material decreased to 25 parts under the condition of -196 °C, and it had no self-healing ability. Compared with the examples of the present invention, the density of Comparative Example 4 was more than twice as high, and the resilience coefficient and adiabatic performance were significantly worse.

[0117] Performance test method:

[0118] (1) Density test: It was measured according to the standard of GB / T 5480-2017. The sample size was taken as 300 mm × 300 mm × 100 mm. Under the conditions of 23 ± 2 °C and relative humidity of 50 ± 5 parts, the mass and volume of the sample were measured, and the density value was calculated.

[0119] (2) Resilience coefficient test: It was measured according to the standard of GB / T 6670-2008. The sample was compressed to 50 parts of the original thickness, the pressure was released after maintaining for 5 minutes, and the thickness recovery after 30 minutes was recorded. Resilience coefficient = recovered thickness / original thickness × 100 parts.

[0120] (3) Thermal conductivity test: According to the ASTM C177-13 standard, it was measured respectively at -196 °C, -100 °C, -50 °C, 0 °C, 25 °C and 100 °C using the hot flow meter method.

[0121] (4) Tensile strength test: It was measured according to the standard of GB / T 17911-2018.

[0122] (5) Self-healing ability test: The sample was cut into test blocks of 100 mm × 100 mm × 50 mm, and pressure was applied to compress it by 70 parts. After maintaining for 2 hours, the pressure was released. After placing it at room temperature for 48 hours, the tensile strength of the sample was measured. Self-healing ability = tensile strength after recovery / original tensile strength × 100 parts.

[0123] Performance test results:

[0124] Table 1 Comparison of main performance parameters of each example and comparative example

[0125]

[0126] *Note: The resilience coefficient before the slash is at room temperature, and the resilience coefficient after the slash is at -196°C.

[0127] Table 2 Thermal conductivity (mW / (m·K)) of each example and comparative example at different temperatures

[0128]

[0129] Table 3 Comparison of resilience coefficients of each example and comparative example at extremely low temperature (-196°C) and normal temperature (25°C)

[0130]

[0131] It can be seen from the test results in Tables 1 - 3 that all examples of the present invention have a density significantly lower than that of Comparative Example 4 (the prior art), generally in the range of 5 - 10 kg / m³, which is more than 33 - 50% lower than that of Comparative Example 4. At the same time, the examples of the present invention have a resilience coefficient significantly higher than that of the comparative examples, especially in an extremely low temperature (-196°C) environment, and the resilience coefficient retention rate is significantly higher than that of the comparative examples. This indicates that the glass fiber mat of the present invention can still maintain good elasticity in an extremely low temperature environment and will not become brittle. In addition, the thermal conductivity of the examples of the present invention is significantly lower than that of the comparative examples, especially under the condition of -196°C, showing excellent heat insulation performance.

[0132] It can also be found through comparative analysis that:

[0133] (1) Compared with Example 1, the thermal conductivity of Comparative Example 1 (without graphene aerogel) increased by about 62 parts, and the resilience coefficient decreased by about 28 parts, indicating that graphene aerogel plays a key role in reducing thermal conductivity and improving elasticity. This is because the graphene aerogel forms a three-dimensional network structure throughout the material, which on the one hand blocks the heat conduction path, and on the other hand provides additional elastic support, enabling the material to better return to its original state after being compressed.

[0134] (2) Compared with Example 3, the tensile strength and self-healing ability of Comparative Example 2 (without surface modification treatment) were significantly reduced, indicating that surface modification plays an important role in enhancing the interfacial bonding force between components and improving the overall performance of the material. After surface modification, the surface of the glass microfiber contains amino functional groups, which can form stronger chemical bonds with graphene aerogel and adhesives, improving the interfacial bonding strength, thereby enhancing the overall performance of the material.

[0135] (3) Comparative Example 3 (using traditional phenolic resin) shows similar performance at room temperature compared to Example 4, but its rebound coefficient drops sharply at extremely low temperatures, and its self-healing ability is completely lost. This indicates that the phenol-modified silicone resin adhesive is crucial for maintaining the elasticity of the material in low-temperature environments. The main reason why the phenol-modified silicone resin maintains flexibility at extremely low temperatures is that its molecular structure contains flexible silicon-oxygen bonds and phenyl side chains, which make the molecular chain still have a certain degree of mobility at low temperatures.

[0136] (4) Comparative Example 4 (prior art) performs poorly in all key performance indicators, such as density, rebound coefficient, and thermal conductivity, compared to all the examples of the present invention. The performance degradation is particularly significant in extremely low-temperature environments. The present invention significantly reduces the material density by introducing hollow glass microspheres to replace some of the glass fibers. The introduction of graphene aerogel and surface modification technology significantly improves the material's elasticity and thermal insulation properties. The use of phenol-modified silicone resin and self-healing technology improves the material's performance stability and service life in extremely low-temperature environments.

[0137] In summary, the low-density, high-elasticity glass fiber felt provided by the present invention achieves the technical effects of significantly reduced density, greatly improved elasticity, excellent insulation performance and self-repair function through innovative material combination and preparation process. It is particularly suitable for use in extremely low temperature environments such as liquefied natural gas, and has important practical value.

[0138] The low-density, high-elasticity glass fiber mat of the present invention has excellent performance mainly based on the following mechanisms:

[0139] (1) Multi-level hierarchical structure design: This invention adopts a three-level hierarchical structure design. Hollow glass microspheres serve as the basic structure to provide low density. Graphene aerogel forms a network structure that penetrates the gaps between the microspheres to provide elastic support and thermal insulation. Surface-modified glass microfibers form a connecting reinforcement structure to improve overall strength. This multi-level structural design enables the material to maintain low density while having good mechanical properties and thermal insulation properties.

[0140] (2) Multiple thermal insulation mechanisms: The present invention uses multiple mechanisms to block heat transfer. First, the static gas inside the hollow glass microspheres provides a good thermal barrier; second, the porous structure of the graphene aerogel effectively blocks solid heat conduction; third, a large amount of interface scattering heat radiation within the material; and finally, the foam structure formed by the phenol-modified silicone resin further reduces heat conduction. These mechanisms work synergistically, giving the material excellent thermal insulation properties in extremely low temperature environments.

[0141] (3) Supercritical CO2 Processing: This invention uses a supercritical CO2 drying process to prepare graphene aerogels, avoiding the collapse of the aerogel structure caused by capillary forces during the traditional drying process, while maintaining the aerogel's high porosity and low density. Furthermore, supercritical CO2 can be used as an environmentally friendly solvent, replacing traditional organic solvents, reducing the environmental impact of the preparation process.

[0142] (4) Surface modification technology: Through plasma treatment and silanization, active functional groups are formed on the surface of glass microfibers, which enhances the interfacial bonding between the fibers and other components and improves the overall performance of the material. In addition, the surface-modified fibers can be more effectively dispersed in the material, preventing fiber agglomeration and ensuring the uniformity of material properties.

[0143] (5) Self-repair mechanism: This invention achieves the material's self-repairing function by introducing urea-formaldehyde microcapsules containing cyanoacrylate into the adhesive. When the material is subjected to external forces and microcracks are generated, the microcapsules rupture and release cyanoacrylate, which fills the cracks and rapidly solidifies, repairing the damaged area and extending the material's service life.

[0144] It's important to note that the components of the present invention exhibit significant synergistic effects; the absence of any key component can significantly reduce performance. For example, the synergistic effect of hollow glass microspheres and graphene aerogel significantly reduces the material's density and thermal conductivity; the synergistic effect of surface-modified glass microfibers and the adhesive enhances the material's mechanical strength and elasticity; and the synergistic effect of the phenol-modified silicone resin adhesive and the self-healing microcapsules ensures the material's performance stability and long-term performance in low-temperature environments.

[0145] The present invention is not limited to the above-mentioned specific embodiments. Those skilled in the art may make equivalent modifications or substitutions based on the technical solutions of the present invention, and these modifications or substitutions shall fall within the scope of protection claimed by the present invention.

Claims

1. Low-density, high-elasticity fiberglass mat, characterized in that: Comprising, by weight parts: 70 - 85 parts of hollow glass microspheres, 5 - 10 parts of graphene aerogel, 5 - 8 parts of surface - modified glass microfibers, 2 - 5 parts of phenol - modified silicone resin binder, and 0.5 - 1.5 parts of graphene oxide; the density of the glass fiber mat is 5 - 10 kg / m³, and the resilience coefficient is greater than 50%.

2. The low-density, high-elasticity glass fiber mat according to claim 1, wherein: The density of the hollow glass microspheres is 0.20 - 0.30 g / cm³, and the diameter is 35 - 65 μm; the density of the graphene aerogel is 0.10 - 0.20 g / cm³, forming a three - dimensional interconnected network structure; the diameter of the surface - modified glass microfibers is 0.5 - 2.5 μm, and the length is 2 - 8 cm.

3. The low-density, high-elasticity glass fiber mat according to claim 1, characterized in that: The surface - modified glass microfibers are treated with 3 - aminopropyltriethoxysilane, and their surface has amino functional groups; the phenol - modified silicone resin binder contains 10 - 20% phenyl side - chain structure and remains elastic at low temperatures; the graphene oxide is used as a surface functionalizing agent to improve the interfacial bonding force between components.

4. The low-density, high-elasticity glass fiber felt according to claim 1, wherein: The glass fiber mat has the following properties: the thermal conductivity is 10 - 15 mW / (m·K) at - 196°C, the service temperature range is from - 196°C to + 200°C, the tensile strength is greater than 8.0 kPa, and it has self - healing ability.

5. The low-density, high-elasticity glass fiber mat according to claim 1, characterized in that: The glass fiber mat has a three - level hierarchical structure: hollow glass microspheres form the basic matrix structure, graphene aerogel forms a network structure penetrating the gaps between microspheres, surface - modified glass microfibers form a connecting and strengthening structure; the phenol - modified silicone resin binder forms a foamy structure containing 1 - 2 parts of self - healing microcapsules.

6. A method for preparing a low-density, high-elasticity glass fiber mat, characterized in that, Including the following steps: a) Place the glass microfibers in an atmospheric plasma treatment system, treat them with an argon - oxygen mixed gas at a power of 800 - 1200 W for 3 - 5 minutes, with the volume ratio of argon to oxygen being 80:20, to form surface - active functional groups; b) Immerse the glass microfibers treated in step a) in a 3 - aminopropyltriethoxysilane solution with a concentration of 2 parts, using an ethanol / water mixed solution as the solvent, and hydrolyze for 30 minutes at a pH value of 4.5 to prepare amino - functionalized glass fibers; c) Mix the graphene oxide suspension with a concentration of 5 mg / mL with the hollow glass microspheres, perform hydrothermal reduction at 180°C for 12 hours, then carry out solvent exchange: water → acetone → liquid carbon dioxide, and perform supercritical drying at 31.1°C and 7.39 MPa for 6 hours to form a composite material of hollow glass microspheres coated with graphene aerogel; d) Use a hybrid spinning system to prepare a fiber layer, where the central electrospinning unit generates nanofibers with a diameter of 100 - 500 nm at a voltage of 20 kV, and the peripheral centrifugal spinning unit generates micro - scale support fibers at a rotational speed of 4000 rpm, and deposit them simultaneously to form a gradient fiber structure; e) Mix the phenol - modified silicone resin with a carbon dioxide foaming agent, and apply it to the fiber layer formed in step d) by electrostatic spraying, with a dosage of 5 - 8 parts by total weight; f) Place the composite prepared in step e) in a microwave curing system, and treat it at a frequency of 915 MHz and a power of 2 kW for 5 minutes to form a porous foamy binder structure; g) The three-dimensional enhancement treatment is carried out on the material prepared in step f) by using the elliptical motion needle punching technology, with a needle punching density of 200 needles / cm², to form a composite structure with z-direction fiber bridging.

7. The preparation method according to claim 6, characterized in that: In step c), carbon dioxide is used as the supercritical fluid in the supercritical drying process. Under the conditions of 31.1 °C and 7.39 MPa, the supercritical fluid is slowly released by gradually reducing the pressure to atmospheric pressure to prevent the collapse of the aerogel structure.

8. The preparation method according to claim 6, characterized in that: In step d), the hybrid spinning system consists of a central electrospinning unit and eight peripheral centrifugal spinning units. A computer-controlled fiber orientation system is used to achieve a 0° / 45° / 90° layering pattern, and the fiber layer thickness is controlled within 80 - 150 mm.

9. The preparation method according to claim 6, characterized in that: In step e), urea-formaldehyde microcapsules with a diameter of 50 - 80 μm containing a cyanoacrylate self-healing agent are added to the phenolic modified silicone resin adhesive, and the addition amount of the microcapsules is 10 - 15 parts by weight of the adhesive.

10. The preparation method according to claim 6, characterized in that: In step g), the three-dimensional enhancement treatment uses DiloGroup Hyperpunch technology. The needle plate adopts a 6000X needle type, the needle punching depth is 5 - 15 mm, and the needle punching frequency is 800 - 1200 times / minute. The elliptical motion trajectory of the needle reduces the damage to the fibers and improves the z-direction connection strength.

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