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

Abstract

The present invention relates to the technical field of thermal insulation materials, and specifically to a low-density, high-elasticity glass fiber mat and a preparation method thereof. The glass fiber mat 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%. The density of the glass fiber mat of the present invention is significantly reduced to 5-10 kg / m³, which is 33-50% lower than that of the prior art, thereby significantly reducing the weight of the material and facilitating a reduction in the total weight of the entire thermal insulation system.

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 mat 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 weight of the material and helping to reduce the total weight of the entire insulation system;

[0027] (2) The coefficient of resilience of the glass fiber mat 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 in extremely low temperature environments, significantly improving the mechanical properties of the material;

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

[0029] (4) The present invention adopts a multi-level thermal insulation structure combining hollow glass microspheres and graphene aerogel, which reduces the thermal conductivity to 10-15mW / (m·K), which is 40-50% lower than the existing technology, significantly improving the thermal insulation performance of the material;

[0030] (5) The present invention introduces self-repairing microcapsule technology, which enables the material to self-repair when microcracks are generated during use, thereby 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 elliptical motion needling technology, which reduces damage to the fiber and improves the z-direction connection strength, making the material have better overall performance. DETAILED DESCRIPTION

[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, can make equivalent substitutions or equivalent modifications to the present invention without departing from the technical solution of the present invention, and all such technical solutions fall within the scope of protection of the present invention.

[0034] If no specific conditions are specified in the examples, the experiments were carried out under conventional conditions or those recommended by the manufacturer; unless otherwise specified, the experimental methods were 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, density 0.25g / cm³, diameter 40-60μm, compressive strength 180-220MPa;

[0036] (2) Graphene oxide: single-layer graphene oxide dispersion produced by Graphenea, Germany, with a concentration of 4 mg / mL;

[0037] (3) Glass microfiber: E-grade glass fiber produced by Owens Corning, USA, with an initial diameter of 6-8 μm;

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

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

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

[0041] (7) Urea and formaldehyde: analytical grade.

[0042] Preparation of surface-modified glass microfibers: Glass microfibers were treated in an Andritz atmospheric plasma treatment system using an argon-oxygen mixture (argon:oxygen ratio, 80:20, by volume) at 1000 W for 4 minutes. The treated fibers were then immersed in a 2-part 3-aminopropyltriethoxysilane solution (ethanol / water, 95:5, by volume) and hydrolyzed at pH 4.5 for 30 minutes. The fibers were then dried at 80°C for 2 hours to yield amino-functionalized glass microfibers.

[0043] Preparation of Graphene Aerogel-Coated Hollow Glass Microspheres: A graphene oxide suspension was diluted to a concentration of 5 mg / mL and mixed with hollow glass microspheres at a mass ratio of 1:20. After ultrasonic dispersion for 30 minutes, the mixture was hydrothermally reduced at 180°C for 12 hours. The mixture was then solvent-exchanged, washed three times with deionized water and three times with acetone, and finally transferred to a supercritical drying apparatus. The acetone was replaced with liquid CO2 (liquid CO2 was replaced three times daily for three consecutive days). The mixture was then supercritically dried at 31.1°C and 7.39 MPa for six hours. Finally, the pressure was slowly reduced to ambient pressure (at a rate of 0.1 MPa / hour) to yield a composite material of hollow glass microspheres coated with graphene aerogel.

[0044] Preparation of self-healing microcapsules: Urea-formaldehyde microcapsules containing cyanoacrylate were prepared by an in-situ polymerization method. First, 5.0 g of urea and 0.5 g of ammonium chloride were dissolved in 100 mL of deionized water. Then, 10 mL of cyanoacrylate was added and stirred to form a stable emulsion. The pH was adjusted to 3.5, and 12.7 g of formaldehyde solution (37 parts concentration) was added. The mixture was reacted at 60°C for 4 hours. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed with deionized water and ethanol, and dried in a vacuum at 40°C for 24 hours to obtain self-healing microcapsules with a diameter of 50-80 μm.

[0045] Example 1

[0046] This low-density, high-elasticity glass fiber mat comprises, by weight, 70 parts hollow glass microspheres, 10 parts graphene aerogel, 8 parts surface-modified glass microfibers, 5 parts phenol-modified silicone resin adhesive, and 1.5 parts graphene oxide. The hollow glass microspheres have a density of 0.25 g / cm³ and a diameter of 40 μm; the graphene aerogel has a density of 0.16 g / cm³; and the surface-modified glass microfibers have a diameter of 0.5 μm and a length of 2 cm.

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

[0048] (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 1000 W for 4 minutes to form surface active functional groups;

[0049] (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;

[0050] (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.

[0051] (4) A hybrid spinning system was used to prepare the fiber layer, in which the central electrospinning unit produced nanofibers (average diameter of 300 nm) at a voltage of 20 kV, and the eight peripheral centrifugal spinning units produced micron-sized 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.

[0052] (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 5 parts by weight;

[0053] (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;

[0054] (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.

[0055] The low-density, highly elastic glass fiber mat prepared in this example has a density of 8.5 kg / m³, a coefficient of resilience of 68, a thermal conductivity of 11.5 mW / (m·K) at -196°C, and a tensile strength of 9.2 kPa. The glass fiber mat has excellent self-healing capabilities and can recover approximately 55% of its strength after damage from external forces.

[0056] Example 2

[0057] This low-density, high-elasticity glass fiber mat comprises, by weight, 85 parts hollow glass microspheres, 5 parts graphene aerogel, 5 parts surface-modified glass microfibers, 2 parts phenol-modified silicone resin adhesive, and 0.5 parts graphene oxide. The hollow glass microspheres have a density of 0.30 g / cm³ and a diameter of 65 μm; the graphene aerogel has a density of 0.20 g / cm³; and the surface-modified glass microfibers have a diameter of 2.5 μm and a length of 8 cm.

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

[0059] (1) The glass microfibers were placed in an atmospheric plasma treatment system and treated with argon-oxygen mixed gas (argon to oxygen volume ratio of 80:20) at a power of 800 W for 3 minutes to form surface active functional groups;

[0060] (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 90:10), hydrolyzing at a pH of 4.5 for 30 minutes, and drying at 85°C for 2.5 hours to prepare amino-functionalized glass fibers;

[0061] (3) The graphene oxide suspension (concentration 4 mg / mL) was mixed with hollow glass microspheres and hydrothermally reduced at 175 °C for 10 h. The mixture was then solvent exchanged (water → acetone → liquid carbon dioxide) and supercritical dried at 31.1 °C and 7.39 MPa for 5 h to form a composite material of hollow glass microspheres coated with graphene aerogel.

[0062] (4) A hybrid spinning system was used to prepare the fiber layer, in which the central electrospinning unit produced nanofibers (average diameter of 450 nm) at a voltage of 18 kV, and the eight peripheral centrifugal spinning units produced micron-sized support fibers at a speed of 3500 rpm. A computer-controlled fiber orientation system was used to achieve a 0° / 60° laying pattern, and the fiber layer thickness was controlled at 150 mm.

[0063] (5) mixing a phenol-modified silicone resin with a carbon dioxide foaming agent, adding 10 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 8 parts by weight;

[0064] (6) placing the composite prepared in step (5) in a microwave curing system at a frequency of 915 MHz and a power of 1.5 kW for 6 minutes to form a porous foam adhesive 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 hybrid spinning system was used to prepare the fiber layer, in which the central electrospinning unit produced nanofibers (average diameter 350 nm) at a voltage of 20 kV, and the eight peripheral centrifugal spinning units produced micron-sized 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 120 mm.

[0074] (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 6.5 parts by weight;

[0075] (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;

[0076] (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 12 mm, and a needling frequency of 1000 times / min to form a composite structure with z-direction fiber bridging.

[0077] The low-density, highly elastic glass fiber mat prepared in this example has a density of 7.2 kg / m³, a coefficient of resilience of 62, a thermal conductivity of 12.8 mW / (m·K) at -196°C, and a tensile strength of 8.9 kPa. The glass fiber mat has excellent self-healing capabilities and can recover approximately 50% of its strength after damage from external forces.

[0078] Example 4

[0079] A low-density, highly elastic glass fiber mat comprising, by weight, 80 parts hollow glass microspheres, 7 parts graphene aerogel, 6 parts surface-modified glass microfibers, 4 parts phenol-modified silicone resin adhesive, and 1.0 part graphene oxide. The hollow glass microspheres have a density of 0.28 g / cm³ and a diameter of 55 μm; the graphene aerogel has a density of 0.18 g / cm³; and the surface-modified glass microfibers have a diameter of 2.0 μm and a length of 6 cm.

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

[0081] (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 85:15) at a power of 1100 W for 4.5 minutes 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] This low-density, high-elasticity glass fiber mat comprises, by weight, 78 parts hollow glass microspheres, 9 parts graphene aerogel, 7 parts surface-modified glass microfibers, 4 parts phenol-modified silicone resin adhesive, and 1.2 parts graphene oxide. The hollow glass microspheres have a density of 0.22 g / cm³ and a diameter of 45 μm; the graphene aerogel has a density of 0.14 g / cm³; and the surface-modified glass microfibers have a diameter of 1.2 μm and a length of 4 cm.

[0091] The preparation method of the glass fiber felt is basically the same as that of Example 3, except that: in step (3), the hydrothermal reduction temperature is 175° C. and the treatment 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; and in step (7), the needling density is 210 needles / cm².

[0092] The low-density, highly elastic glass fiber mat prepared in this example has a density of 6.9 kg / m³, a coefficient of resilience of 64, a thermal conductivity of 12.1 mW / (m·K) at -196°C, and a tensile strength of 9.3 kPa. The glass fiber mat exhibits excellent self-healing capabilities and can recover approximately 58% of its strength after damage from external forces.

[0093] Example 6

[0094] This low-density, high-elasticity glass fiber mat comprises, by weight, 82 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 0.25 g / cm³ and a diameter of 40-60 μm; the graphene aerogel has a density of 0.16 g / cm³; and the surface-modified glass microfibers have a diameter of 0.8-1.5 μm and a length of 3-5 cm.

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

[0096] (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 1000 W for 4 minutes to form surface active functional groups;

[0097] (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;

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

[0107] Comparative Example 2

[0108] This comparative example differs from Example 3 in that ordinary glass fiber is used instead of the surface-modified glass microfiber. The composition comprises, by weight, 75 parts of hollow glass microspheres, 8 parts of graphene aerogel, 6 parts of ordinary glass fiber, 3 parts of a phenol-modified silicone resin adhesive, and 1.0 part of graphene oxide. The preparation method is the same as that of Example 3, except that the surface treatment of the glass fiber in steps (1) and (2) is omitted.

[0109] The test results show that the glass fiber mat prepared in Comparative Example 2 has a density of 7.5 kg / m³, a rebound coefficient of 53 parts, a thermal conductivity of 14.1 mW / (m·K) at -196°C, and a tensile strength of 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 tensile strength and rebound coefficient, and a significant decrease in self-repair ability, indicating that surface modification plays an important role in enhancing the interfacial bonding strength between components.

[0110] Comparative Example 3

[0111] This comparative example differs from Example 4 in that conventional phenolic resin powder is used instead of the phenol-modified silicone resin adhesive, and no self-healing microcapsules are added. The comparative example comprises, 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, except that step (5) is modified to apply the phenolic resin powder to the fiber layer by electrostatic spraying, and no self-healing microcapsules are added.

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

[0113] Comparative Example 4

[0114] This comparative example prepared a glass fiber mat according to the method described in CN 116005359 A. The mat comprised, by weight, 80 parts of glass fiber and 20 parts of phenolic resin powder. The glass fiber had a diameter of 7-9 μm and a length of 5-15 cm. The phenolic resin powder contained 9.3 parts of methenamine, 1.49 parts of free phenol, a tumbling degree of 28 at 125°C, and a polymerization rate of 86.

[0115] The preparation method is carried out according to the method in CN 116005359 A, including the steps of fiber opening, cotton blending, cotton feeding, carding, powdering, web laying, drying in a drying tunnel, and slitting and winding.

[0116] Test results show that the glass fiber mat prepared in Comparative Example 4 has a density of 16.1 kg / m³, a coefficient of resilience of 46, a thermal conductivity of 24.5 mW / (m·K) at -196°C, and a tensile strength of 6.5 kPa. The material's coefficient of resilience drops to 25 at -196°C, and it lacks self-healing capabilities. Compared to the examples of the present invention, Comparative Example 4 has a density more than doubled, and its coefficient of resilience and thermal insulation performance are significantly inferior.

[0117] Performance testing method:

[0118] (1) Density test: The density was determined in accordance with GB / T 5480-2017. The sample size was 300 mm × 300 mm × 100 mm. The mass and volume of the sample were measured at 23 ± 2°C and relative humidity of 50 ± 5 %. The density was then calculated.

[0119] (2) Rebound coefficient test: The test is conducted in accordance with GB / T 6670-2008. The sample is compressed to 50 parts of its original thickness, held for 5 minutes, and then the pressure is released. The thickness recovery after 30 minutes is recorded. Rebound coefficient = recovered thickness / original thickness × 100 parts.

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

[0121] (4) Tensile strength test: measured in accordance with GB / T 17911-2018.

[0122] (5) Self-repair ability test: Cut the sample into test pieces of 100 mm × 100 mm × 50 mm, apply pressure to compress it 70 times, maintain the pressure for 2 hours, and then release the pressure. After standing at room temperature for 48 hours, measure the tensile strength of the sample. Self-repair ability = tensile strength after recovery / original tensile strength × 100 times.

[0123] Performance test results:

[0124] Table 1 Comparison of main performance parameters of various embodiments and comparative examples

[0125]

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

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

[0128]

[0129] Table 3 Comparison of the rebound coefficients of the examples and comparative examples at extremely low temperatures (-196°C) and room temperature (25°C)

[0130]

[0131] The test results in Tables 1-3 demonstrate that all examples of the present invention have significantly lower densities than Comparative Example 4 (prior art), generally ranging from 5-10 kg / m³, representing a reduction of over 33-50% compared to Comparative Example 4. Furthermore, the examples of the present invention exhibit significantly higher coefficients of resilience than the comparative example, particularly at extremely low temperatures (-196°C), where the coefficient of resilience retention is significantly higher than that of the comparative example. This demonstrates that the glass fiber mat of the present invention maintains good elasticity and does not become brittle even at extremely low temperatures. Furthermore, the thermal conductivity of the examples of the present invention is significantly lower than that of the comparative example, particularly at -196°C, demonstrating excellent thermal insulation performance.

[0132] Through comparative analysis, we can also find that:

[0133] (1) Comparative Example 1 (no graphene aerogel) shows an increase in thermal conductivity of approximately 62 parts and a decrease in resilience of approximately 28 parts compared to Example 1, indicating that graphene aerogel plays a key role in reducing thermal conductivity and improving resilience. This is because the graphene aerogel forms a three-dimensional network structure throughout the material, which not only blocks the heat conduction path but also provides additional elastic support, enabling the material to better recover after being compressed.

[0134] (2) Comparative Example 2 (no surface modification) shows significantly lower tensile strength and self-healing ability compared to Example 3, indicating that surface modification plays an important role in enhancing interfacial bonding between components and improving the overall performance of the material. The surface of the modified glass microfibers contains amino functional groups, which can form stronger chemical bonds with the graphene aerogel and adhesive, improving interfacial bonding strength and thus 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 glass fiber mat, characterized by: The glass fiber mat 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 density of the glass fiber mat is 5-10 kg / m³, and the coefficient of resilience is greater than 50%; 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; The surface-modified glass microfiber is treated with aminopropyltriethoxysilane, and has amino functional groups on its surface. The phenol-modified silicone resin adhesive contains 10-20% phenyl side chain structures, which maintains elasticity at low temperatures. The graphene oxide is used as a surface functionalizing agent to improve the interfacial bonding strength between components. The glass fiber mat has a three-level hierarchical structure: hollow glass microspheres constitute the basic matrix structure, graphene aerogel forms a network structure that penetrates 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-repairing microcapsules.

2. The low-density, high-elasticity glass fiber mat according to claim 1, characterized in that: The glass fiber felt has the following characteristics: 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.

3. The method for preparing a low-density, high-elasticity glass fiber mat according to claim 1 or 2, characterized in that: The following steps are involved: a) placing the glass microfiber in an atmospheric plasma treatment system and treating it with an argon-oxygen mixed gas at a power of 800-1200 W for 3-5 minutes, with an argon-to-oxygen volume ratio of 80:20, to form surface active functional groups; b) immersing the glass microfiber treated in step a) in a 2-part 3-aminopropyltriethoxysilane solution in an ethanol / water mixture at a pH of 4.5 for 30 minutes to prepare amino-functionalized glass fibers; c) mixing a graphene oxide suspension at a concentration of 5 mg / mL with hollow glass microspheres, subjecting the mixture to hydrothermal reduction at 180°C for 12 hours, followed by solvent exchange from water to acetone to liquid carbon dioxide, and 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) The fiber layer was prepared using a hybrid spinning system, in which the central electrospinning unit produced nanoscale fibers (100-500 nm) at a voltage of 20 kV, and the 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; 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 based on the total weight; 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; 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.

4. The method for preparing a low-density, high-elasticity glass fiber mat according to claim 3, characterized in that: In step c), the supercritical drying process uses carbon dioxide as a supercritical fluid. 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 and prevent collapse of the aerogel structure.

5. The method for preparing a low-density, high-elasticity glass fiber mat according to claim 3, characterized in that: 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, with the fiber layer thickness controlled at 80-150 mm.

6. The method for preparing a low-density, high-elasticity glass fiber mat according to claim 3, 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 phenol-modified silicone resin adhesive. The amount of the microcapsules added is 10-15 parts by weight of the adhesive.

7. The method for preparing a low-density, high-elasticity glass fiber mat according to claim 3, characterized in that: In step g), the three-dimensional reinforcement treatment uses DiloGroup Hyperpunch technology, with a needle plate using a 6000X needle type, a needling depth of 5-15 mm, and a needling frequency of 800-1200 times / minute. The elliptical motion trajectory of the needle reduces damage to the fiber and improves the z-direction connection strength.

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