Aerogel / spacer fabric composite material, preparation method and application

Abstract

The invention discloses an aerogel / spacer fabric composite material as well as a preparation method and application thereof, and belongs to the technical field of thermal insulation materials. A three-dimensional spacer fabric with the upper surface layer being a hexagonal mesh structure and the lower surface layer being a chaining and weft insertion structure is selected as a substrate, the lower surface layer of the fabric is firstly filled with an aerogel coating in a coating mode, and then the fabric is completely filled with the coating on the upper surface layer; and drying to obtain the aerogel / three-dimensional spacer fabric composite material with better heat preservation effect and flexibility. The two-phase composite structure thermal insulation material obtained by the method has the characteristics of light weight, high strength and low thermal conductivity. Meanwhile, by adding the three-dimensional spacer fabric, the mechanical property of the material is effectively improved. The thermal insulation material can be used as a thermal insulation material for buildings, engineering, vehicles and the like, and is wide in application range and good in market prospect. The preparation process is simple, short in flow, mild in reaction condition and suitable for industrial production.

Description

Technical Field

[0001] This invention relates to an aerogel / spacer fabric composite material, its preparation method and application, belonging to the field of thermal insulation technology. Background Technology

[0002] Aerogels possess a unique nanoporous structure, exhibiting characteristics such as light weight, low density, high specific surface area, and low thermal conductivity, demonstrating excellent thermal insulation performance and lightweight properties. They show great application potential in aerospace, building insulation, and new energy battery insulation. However, the inherent brittleness of their three-dimensional nanoframework structure makes the material prone to structural collapse under shear or bending stress, manifesting as macroscopic brittle fracture, surface powdering, and internal particle shedding, severely limiting their engineering applications on curved surfaces or under dynamic loads.

[0003] To improve the mechanical properties of aerogels, existing technologies attempt to use three-dimensional spacer fabrics as a reinforcing skeleton. Three-dimensional spacer fabrics are sandwich-structured three-dimensional fabrics composed of upper and lower surface layers connected by vertical spacer filaments in the middle. They possess advantages such as high resilience, compression resistance, and strong design flexibility, and their combination can significantly improve material properties. However, existing composite technologies have significant limitations in terms of interfacial bonding, preparation processes, and functional compatibility. For example, patent CN108221365A discloses an aerogel-filled three-dimensional woven spacer fabric, which is a composite material prepared by impregnation with alcohol sol and then drying under normal pressure. Although the composite material has good tensile strength and certain thermal insulation properties, the aerogel is prone to shrinkage stress due to solvent evaporation during the drying process, which leads to microcracks in the interior and reduces the stability of the structure. In addition, the spacer fabric used does not distinguish the porosity of the upper and lower surface layers, and the aerogel is prone to excessive overflow from the surface mesh, affecting the composite efficiency. Furthermore, the preparation process requires steps such as sol hydrolysis (6-10 hours), gel aging (6-8 hours), surface modification (24 hours), and gradient drying (36 hours), with a total time of over 72 hours. It also requires the use of toxic reagents such as trimethylchlorosilane, resulting in high environmental costs. Patent CN113833140B discloses a thermal insulation material based on a three-phase composite structure of three-dimensional spacer fabric, polyurethane, and silica aerogel. Specifically, the three-dimensional spacer fabric is first foamed in a polyurethane precursor solution to obtain a three-dimensional spacer fabric-polyurethane composite. Then, the three-dimensional spacer fabric-polyurethane composite is immersed in a silica precursor solution, gelled, washed, and dried to obtain the three-phase composite thermal insulation material. While this method produces a three-phase composite thermal insulation material with excellent thermal insulation capabilities and a micro-perforated structure that can also block noise, it suffers from several drawbacks. Firstly, the bonding strength between the aerogel and the spacer fabric is weak, and the aerogel itself has low mechanical strength, making the surface of the resulting three-phase composite thermal insulation material prone to cracking. Furthermore, its low flexibility limits its application in dynamic load scenarios (such as vehicle interiors). Secondly, this three-phase composite process requires prior polyurethane foaming, followed by immersion in an aerogel precursor solution and vacuum freeze-drying (-100℃, 36-48 hours) for molding, which demands sophisticated equipment and hinders large-scale production. Summary of the Invention

[0004] [Technical Issues]

[0005] Existing methods for preparing aerogel / spacer fabric composites are prone to aging and cracking, and the composites lack flexibility. They also suffer from problems such as complex preparation methods and long processes.

[0006] [Technical Solution]

[0007] To address the aforementioned problems, the present invention aims to provide a method for preparing an aerogel / spacer fabric composite material. This method utilizes a three-dimensional spacer fabric with a hexagonal mesh upper layer and a braided and weft-lined lower layer as a carrier. A silica aerogel coating with specific rheological properties is filled into the three-dimensional spacer fabric using a scraping method. After drying, a thermal insulation material is obtained, thus solving the problems of easy cracking, aging, and insufficient flexibility in existing aerogel / spacer fabric composite materials. The thermal insulation material prepared using the method of this invention exhibits good thermal insulation performance and flexibility, with a thermal conductivity as low as 0.027 W / (m·K). Furthermore, the method of this invention is simple and can prepare the thermal insulation material within 3–5 hours, significantly shortening the preparation time.

[0008] To achieve the above objectives, the present invention first provides a method for preparing an aerogel / spacer fabric composite material, comprising the following steps:

[0009] (1) Select a three-dimensional spacer fabric and lay it on a polytetrafluoroethylene board;

[0010] (2) Apply an aerogel coating to the lower layer of the three-dimensional spacer fabric using a scraper;

[0011] (3) Place the three-dimensional spaced fabric obtained in step (2) into an oven for drying;

[0012] (4) Apply aerogel coating to the upper layer of the three-dimensional spacer fabric obtained in step (3) with a scraper to ensure that the aerogel coating completely fills the interior of the three-dimensional spacer fabric.

[0013] (5) The fabric obtained in step (4) is dried to obtain a two-phase composite thermal insulation material;

[0014] The aerogel coating comprises, by mass percentage, 4.7-16% aerogel powder, 80-93% aqueous acrylic resin emulsion, 0.9-1.6% aqueous polymeric dispersant, 0.5-0.8% aqueous defoamer, and 0.5-1.6% aqueous rheology modifier, wherein the solid content of the aqueous acrylic resin emulsion is 40%.

[0015] In one embodiment of the present invention, the upper layer of the three-dimensional spacer fabric described in step (1) is a knitted fabric formed by a hexagonal mesh structure, and the lower layer is a knitted fabric formed by a combination of chain knitting and weft weft weaving.

[0016] In one embodiment of the present invention, the thickness of the three-dimensional spacer fabric is 1.5 mm to 1 cm, and the areal density is 300 g / m³. 2 ~600g / m 3 .

[0017] In one embodiment of the present invention, the braided yarns of the upper layer, lower layer and spacer yarns of the three-dimensional spacer fabric include any one of polyester, nylon, polypropylene, glass yarn, carbon yarn, aramid yarn, ultra-high molecular weight polyethylene yarn and quartz yarn.

[0018] In one embodiment of the present invention, the upper layer, lower layer and spacer yarn of the three-dimensional spacer fabric are all made of polyester.

[0019] In one embodiment of the present invention, the aerogel coating is a silica aerogel coating.

[0020] In one embodiment of the present invention, the silica aerogel coating comprises, by mass percentage, 4.7-16% silica aerogel powder, 80-93% aqueous acrylic resin emulsion, 0.9-1.6% aqueous polymeric dispersant, 0.5-0.8% aqueous defoamer, and 0.5-1.6% aqueous rheology modifier, wherein the solid content of the aqueous acrylic resin emulsion is 40%.

[0021] Silica aerogel coating is a thermal insulation material prepared primarily from a novel, highly efficient, energy-saving, and environmentally friendly nanomaterial. Silica aerogel, as a solid material with a nanoporous network structure, has extremely low density and a very low thermal conductivity. Filling it into three-dimensional spacer fabrics holds promise for producing thermal insulation materials with excellent heat retention properties.

[0022] In one embodiment of the present invention, the preparation steps of the silica aerogel coating include: weighing waterborne acrylic resin emulsion (40% solid content), waterborne polymeric dispersant, and waterborne defoamer, mixing them, and then mixing them evenly with medium-speed mechanical stirring for 60 minutes. Then, aerogel powder and waterborne rheology modifier are added, and the mixture is stirred at high speed for 30-60 minutes until it is evenly mixed to obtain silica aerogel slurry.

[0023] In one embodiment of the present invention, the aqueous polymeric dispersant may be at least one selected from cellulose ether, polyvinyl alcohol, methylcellulose, hydroxypropyl cellulose, gelatin, etc.; the aqueous defoamer may be at least one selected from polyoxypropylene glycerol ether, polyoxyethylene polyoxypropylene ether, palmitic acid, lauryl alcohol, octanol, isopropyl ester, octanoic acid ester, etc.; and the aqueous rheology modifier may be at least one selected from acrylic copolymer solution, acrylate copolymer solution, fluorinated polyacrylate solution, etc.

[0024] In one embodiment of the present invention, in step (2), the speed of the doctor blade coating is 60 cm / min, the doctor blade pressure is 50 to 100 N / cm, the doctor blade angle is 40° to 60°, and the coating thickness is 20 to 30 μm.

[0025] In one embodiment of the present invention, in step (3), the drying is atmospheric pressure drying, the drying temperature is 60-80°C, and the drying time is 30 min.

[0026] In one embodiment of the present invention, in step (4), the scraper filling speed is 40 cm / min, the scraper pressure is 150 N to 250 N / cm, and the scraper angle is 30° to 50°.

[0027] In one embodiment of the present invention, in step (4), the drying is atmospheric pressure drying, the drying temperature is 60℃~80℃, and the drying time is 3~5h.

[0028] In one embodiment of the present invention, the drying in step (4) is to first pre-dry at 40°C to 60°C for 1 to 3 hours, and then dry at 60°C to 100°C under normal pressure for 2 to 4 hours.

[0029] In one embodiment of the present invention, before step (2) or step (4), the three-dimensional spacer fabric is subjected to surface pretreatment, the surface pretreatment comprising coating with a silane coupling agent solution with a concentration of 0.5wt% to 2wt%.

[0030] The present invention also discloses an aerogel / spacer fabric composite material prepared according to the above method.

[0031] In one embodiment of the present invention, the aerogel / spacer fabric composite material includes a three-dimensional spacer fabric and an aerogel coating matrix; the aerogel coating matrix is ​​composite-filled in the upper and lower layers of the three-dimensional spacer fabric, so that the interior of the three-dimensional spacer fabric is completely filled with aerogel coating, with a filling coefficient of 100%.

[0032] In one embodiment of the present invention, the density of the aerogel / spacer fabric composite material is 0.1–0.5 g / cm³. 3 The preferred concentration is 0.1–0.3 g / cm³. 3 The thermal conductivity is 0.02 to 0.05 W / (m·K), preferably 0.02 to 0.03 W / (m·K), and the compressive modulus (measured at 20% strain) is 0.1 to 10 MPa, preferably 0.1 to 8 MPa, and more preferably 1 to 5 MPa.

[0033] The present invention also discloses the application of the above-mentioned aerogel / spacer fabric composite material in the fields of construction, industry, transportation, cold chain, and home appliances.

[0034] In one embodiment of the present invention, the applications include those in the fields of wall insulation, roof insulation, floor insulation, industrial equipment insulation, industrial pipeline insulation, automotive insulation, ship insulation, aerospace insulation, and lithium battery thermal management.

[0035] Beneficial effects:

[0036] (1) The aerogel / spacer fabric composite material provided by this invention is a thermal insulation material with a certain structure based on a two-phase composite of three-dimensional spacer fabric and aerogel coating. Ultra-low density silica aerogel coating is applied to the three-dimensional spacer fabric using a scraping method to form a composite structure. On the one hand, the introduction of silica aerogel can reduce the thermal conductivity of the spacer fabric to as low as 0.027 W / (m·K), and can achieve lightweighting while maintaining excellent thermal insulation performance. On the other hand, by selecting three-dimensional spacer fabric as the matrix for reinforcing the aerogel coating, this invention can enhance the stress of the matrix. Filling the matrix with silica aerogel through scraping can also improve its mechanical strength, giving it certain buffering properties and effectively preventing the generation of microcracks.

[0037] (2) The present invention selects a three-dimensional spacer fabric with a hexagonal mesh structure on the upper layer and a braided and weft-lined structure on the lower layer as a carrier for aerogel, so that the aerogel coating can easily enter the interior of the spacer fabric and the coating is not easy to overflow from the bottom after it is filled in.

[0038] (3) The present invention uses water-based acrylic resin emulsion, silica aerogel, rheology modifier, polymeric dispersant and water-based defoamer to prepare silica aerogel coating. The coating has certain viscosity and rheological properties, which can adapt to the fabric of the present invention. That is, it can ensure that it is not easy to overflow from the bottom. At the same time, when it is filled into the fabric from the top layer, it is easy to enter the fabric, effectively preventing problems such as uneven filling or incomplete filling.

[0039] (4) By first coating a silane coupling agent solution onto a three-dimensional spacer fabric and then coating it with a silica aerogel coating, the silane coupling agent can act as a bonding material to increase the bonding strength between the coating and the fabric. Furthermore, the Si-O-Si network structure formed by the silane coupling agent on the fiber surface (containing a large number of nanopores (1-10nm)) can effectively block air convection and solid heat conduction, thereby reducing the thermal conductivity of the fabric and improving its heat preservation performance. In addition, the silane coupling agent forms a molecular lubricating layer between the fibers, reducing frictional resistance, replacing rigid hydrogen bonds, and making the fabric more deformable.

[0040] (5) The aerogel / spacer fabric composite material disclosed in this invention can be used in building insulation materials, pipeline insulation materials, automotive transportation insulation materials, special clothing thermal insulation, lithium battery pack thermal management and other fields. It has a wide range of applications and great engineering application potential.

[0041] (6) The preparation process of the above-mentioned two-phase composite thermal insulation material disclosed in this invention is short, the process is simple, the reaction conditions are mild, and it is suitable for industrial production. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the structure of an aerogel / spacer fabric composite material; 1 in the figure is a three-dimensional spacer fabric, 2 is silica aerogel, and 3 is the aerogel / spacer fabric composite material. Detailed Implementation

[0043] The technical solutions in the embodiments of the present invention will be described in full and clearly below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0044] The raw materials involved in the embodiments and comparative examples of this invention are all commercially available raw materials.

[0045] Example 1

[0046] A method for preparing an aerogel / spacer fabric composite material includes the following steps:

[0047] Step 1: The three-dimensional spacer fabric is woven on a double-needle bed Raschel warp knitting machine with six guide bars (GB1 to GB6). The upper layer of the fabric is a hexagonal mesh structure, and the lower layer is a warp-knitted spacer fabric composed of chain stitch and weft insertion structure. The yarns on GB2 and GB5 are 300D / 96F polyester multifilament, those on GB1 and GB6 are 300D / 96F polyester multifilament, and those on GB3 and GB4 are 0.08mm diameter polyester monofilament. Guide bars CB1 and GB2 knit the upper surface of the 3D spacer fabric on the front needle bed, while guide bars GB5 and GB6 knit the lower surface of the fabric on the back needle bed. Guide bars GB3 and GB4 carry spacer yarns, which are knitted alternately on the front and back needle beds to connect the upper and lower surfaces of the spacer fabric with spacer yarns, forming a three-dimensional spacer fabric. The resulting fabric has a thickness of 3.5mm and a surface density of 300g / m³. 2 After the fabric comes off the machine, the three-dimensional spaced fabric is cut to the required size.

[0048] Step 2: Place the three-dimensional spacer fabric on the polytetrafluoroethylene plate;

[0049] Step 3: Apply a layer of silica aerogel coating to the lower layer of the three-dimensional spacer fabric using a scraper. The scraper speed is 60 cm / min, the scraper pressure is 50 N / cm, the scraper angle is 40°, and the coating thickness is 20 μm.

[0050] Step 4: Place the spacer fabric obtained in Step 3 into an oven for drying at 60°C for 30 minutes.

[0051] Step 5: Using a scraper or similar tool, fill the silica aerogel coating from the top layer's mesh structure into the three-dimensional spacer fabric. After filling, allow it to dry. The scraper filling speed is 40 cm / min, the scraper pressure is 200 N / cm, and the scraper angle is 45°.

[0052] Step 6: The product obtained in Step 5 is placed in an oven for drying at a temperature of 60°C for 4 hours to obtain an aerogel / spacer fabric composite material.

[0053] The silica aerogel coating, calculated by mass percentage, comprises 80% waterborne acrylic resin (40% solid content) emulsion, 16% silica aerogel powder, 1.6% dispersant (cellulose ether), 0.8% defoamer (polyoxypropylene glycerol ether), and 1.6% rheology modifier (acrylic copolymer).

[0054] Example 2

[0055] A method for preparing a two-phase composite thermal insulation material includes the following steps:

[0056] Step 1: The three-dimensional spacer fabric is woven on a double-needle bed Raschel warp knitting machine with six guide bars (GB1 to GB6). The upper layer of the fabric is a hexagonal mesh structure, and the lower layer is a warp-knitted spacer fabric composed of chain stitch and weft insertion structure. The yarns on GB2 and GB5 are 300D / 96F polyester multifilament, those on GB1 and GB6 are 300D / 96F polyester multifilament, and those on GB3 and GB4 are 0.08mm diameter polyester monofilament. Guide bars CB1 and GB2 knit the upper surface of the 3D spacer fabric on the front needle bed, while guide bars GB5 and GB6 knit the lower surface of the fabric on the back needle bed. Guide bars GB3 and GB4 carry spacer yarns, which are knitted alternately on the front and back needle beds to connect the upper and lower surfaces of the spacer fabric with spacer yarns, forming a three-dimensional spacer fabric. The resulting fabric has a thickness of 4mm and a surface density of 350g / m³. 2 After the fabric comes off the machine, the three-dimensional spaced fabric is cut to the required size.

[0057] Step 2: Place the three-dimensional spacer fabric on the polytetrafluoroethylene plate;

[0058] Step 3: Apply a layer of silica aerogel coating to the lower layer of the three-dimensional spacer fabric using a doctor blade; the doctor blade application speed is 60 cm / min, the doctor blade pressure is 100 N / cm, the doctor blade angle is 60°, and the coating thickness is 30 μm.

[0059] Step 4: Place the spacer fabric obtained in Step 3 into an oven for drying at 60°C for 30 minutes.

[0060] Step 5: Using a scraper or similar tool, fill the silica aerogel coating from the top layer's mesh structure into the three-dimensional spacer fabric. After filling, allow it to dry. The scraper filling speed is 40 cm / min, the scraper pressure is 200 N / cm, and the scraper angle is 45°.

[0061] Step 6: The product obtained in Step 5 is placed in an oven for drying at a temperature of 80°C for 3 hours to obtain an aerogel / spacer fabric composite material.

[0062] The silica aerogel coating, calculated by mass percentage, comprises 93% waterborne acrylic resin (40% solid content) emulsion, 5% silica aerogel powder, 0.9% dispersant, 0.5% defoamer, and 0.6% rheology modifier.

[0063] Example 3

[0064] A method for preparing an aerogel / spacer fabric composite material includes the following steps:

[0065] Step 1: The three-dimensional spacer fabric is woven on a double-needle bed Raschel warp knitting machine with six guide bars (GB1 to GB6). The upper layer of the fabric is a hexagonal mesh structure, and the lower layer is a warp-knitted spacer fabric composed of chain stitch and weft insertion structure. The yarns on GB2 and GB5 are 300D / 96F polyester multifilament, those on GB1 and GB6 are 300D / 96F polyester multifilament, and those on GB3 and GB4 are 0.08mm diameter polyester monofilament. Guide bars CB1 and GB2 knit the upper surface of the 3D spacer fabric on the front needle bed, while guide bars GB5 and GB6 knit the lower surface of the fabric on the back needle bed. Guide bars GB3 and GB4 carry spacer yarns, which are knitted alternately on the front and back needle beds to connect the upper and lower surfaces of the spacer fabric with spacer yarns, forming a three-dimensional spacer fabric. The resulting fabric has a thickness of 3.5mm and a surface density of 300g / m³. 2 After the fabric comes off the machine, the three-dimensional spaced fabric is cut to the required size.

[0066] Step 2: Immerse the three-dimensional spacer fabric in a 1.5wt% silane coupling agent solution, remove it after 10 minutes, hang it at room temperature to drain for 10 minutes, remove excess solution, and then dry it in a 60℃ oven for 15 minutes.

[0067] Step 3: Apply another layer of silica aerogel coating to the underside of the three-dimensional spacer fabric using a scraper; the scraper speed is 60 cm / min, the scraper pressure is 75 N / cm, the scraper angle is 50°, and the coating thickness is 25 μm.

[0068] Step 4: Place the spacer fabric obtained in Step 3 into an oven for drying at 60°C for 30 minutes.

[0069] Step 5: Use a scraper to fill the silica aerogel coating from the mesh structure of the upper layer into the interior of the three-dimensional spacer fabric. After filling, allow it to dry. The scraper filling speed is 40 cm / min, the scraper pressure is 200 N / cm, and the scraper angle is 45°.

[0070] Step 6: The product obtained in Step 5 is placed in an oven for drying at a temperature of 60°C for 4 hours to obtain an aerogel / spacer fabric composite material.

[0071] The composition and proportion of the silica aerogel coating are the same as in Example 1.

[0072] Comparative Example 1

[0073] The difference between Comparative Example 1 and Example 1 is that steps 2, 3, 4 and 5 are not included. Instead, silica aerogel is filled into the three-dimensional spacer fabric by impregnation to prepare the aerogel / spacer fabric composite material.

[0074] The specific preparation method includes the following steps:

[0075] Step 1 is the same as in Example 1;

[0076] Step 2: Preparation of silica aerogel precursor solution: Tetraethyl orthosilicate, ethanol and water are mixed in a mass ratio of 1:1:2 and magnetically stirred in a 40°C water bath for 5 minutes. 0.05M hydrochloric acid is added dropwise to adjust the pH to 2. The mixture is reacted for 30 minutes until the solution becomes transparent. Then, methoxytrimethylsilane is added in a mass ratio of 1:5 to tetraethyl orthosilicate. The mixture is stirred at 60°C for 1 hour to obtain the silica aerogel precursor solution. The three-dimensional spacer fabric is impregnated in the silica aerogel precursor solution. Ammonia is added dropwise to adjust the pH to 6 to form a gel. The mixture is allowed to stand and age in a 40°C water bath for 24 hours. After drying under normal pressure, the spacer fabric-impregnated silica aerogel composite material is obtained.

[0077] Comparative Example 2

[0078] The difference between Comparative Example 2 and Example 1 is that the silica aerogel coating in steps 3 and 5 is replaced with a commercially available silica aerogel coating. By weight, the coating formulation is 20 parts silica aerogel powder, 120 parts water-based acrylic emulsion (40%), 10 parts methoxytrimethylsilane, 2 parts hexadecyltrimethylammonium bromide, and 1 part organosilicon.

[0079] Comparative Example 3

[0080] The difference between Comparative Example 3 and Example 1 is that the mass fraction of aerogel powder in the prepared silica aerogel coating was adjusted to 35%.

[0081] Comparative Example 4

[0082] The difference between Comparative Example 4 and Example 1 is that the upper and lower layers of the spacer fabric in step 1 are both chain-knitted + weft-inserted weave structures, with an areal density of 650 g / m². 2 .

[0083] Comparative Example 5

[0084] The difference between Comparative Example 5 and Example 1 is that the content of the rheology modifier component in the prepared silica aerogel coating was adjusted to 0.01%.

[0085] Comparative Example 6

[0086] The difference between Comparative Example 6 and Example 1 is that the mass fraction of the aqueous acrylic resin emulsion in the prepared silica aerogel coating was adjusted to 50%.

[0087] Table 1. Thermal conductivity of the composite materials in Examples 1-3 and Comparative Examples 1-6

[0088]

[0089] The aerogel / spacer fabric composite material prepared by the method of this invention exhibits excellent thermal insulation performance, with a thermal conductivity as low as 0.027 W / (m·K). The silica aerogel coating adheres well to the spacer fabric interface; after being rubbed, folded, and rolled, no coating detachment, cracking, or powdering occurred. This indicates that the two-phase composite thermal insulation material prepared by the method of this invention has good thermal insulation effect and strong design flexibility.

[0090] Comparative Example 1, which composites silica aerogel with spacer fabric using a conventional method, yields a thermal insulation composite material with a thermal conductivity of 0.140 W / (m·K), exhibiting lower thermal insulation performance than the composite material prepared by the method of this invention. Furthermore, during activities such as rubbing, folding, and rolling, the filled silica aerogel cracks and detaches from the spacer fabric mesh, indicating that the conventional method of combining silica aerogel and spacer fabric results in weak interfacial adhesion, leading to reduced thermal insulation performance. The silica aerogel insulation layer formed within the spacer fabric through impregnation increases the fabric's compressive modulus, reducing its flexibility.

[0091] Comparative Example 2 used commercially available conventional silica aerogel coating to fill the spacer fabric, resulting in a thermal conductivity of 0.085 W / (m·K). Conventional silica aerogel coating filling of the spacer fabric easily leads to particle agglomeration within the fabric, causing uneven filling and poor thermal insulation performance. Under actions such as rubbing, folding, and bending, coating clumps fall off, and powder is shed during rubbing. Furthermore, the compressive modulus and radius of curvature are higher than in Example 1, indicating that ordinary silica aerogel coating reduces the flexibility of the composite fabric.

[0092] In Comparative Example 3, the mass fraction of aerogel powder in the silica aerogel coating of Example 1 was adjusted to 35%, while other conditions remained the same. The resulting thermal insulation material did not show an increase in thermal conductivity; in fact, it decreased. This is because excessive aerogel powder cannot be completely dispersed in the coating, forming large aggregates. After drying, these aggregates, when filled into the spacer fabric, form large lumps, leading to a decrease in thermal conductivity. The increased proportion of aerogel powder increases the solid content in the coating, thereby increasing the compressive modulus of the composite fabric and weakening its flexibility. Under actions such as rubbing, folding, and bending, coating lumps will also detach, and powder will fall off when rubbed.

[0093] The difference between Comparative Example 4 and Example 1 is that the spacer fabric used has a chain-link + weft-insertion weave structure on both the upper and lower layers, with an areal density of 650 g / m². 2 The thermal conductivity of the aerogel / spacer fabric composite material obtained by coating the spacer fabric with a doctor blade is much higher than that of the aerogel / spacer fabric composite material prepared by the method of this invention. This is because the upper layer uses a braided + weft-inserted structure, which makes it difficult for the silica aerogel coating to be coated into the interior of the spacer fabric under the action of the doctor blade, resulting in less silica aerogel coating filling the interior of the spacer fabric, thus resulting in a higher thermal conductivity. On the other hand, the reduction in the amount of coating also makes the composite fabric of Comparative Example 4 more flexible than the composite fabrics of other comparative examples.

[0094] The difference between Comparative Example 5 and Example 1 is that the rheology modifier content in the prepared silica aerogel coating was adjusted to 0.01%. The resulting aerogel / spacer fabric composite material has a much higher thermal conductivity than the spacer fabric composite material prepared by the method of this invention. This is because the rheology modifier content in the silica aerogel coating is lower than the range of this invention, resulting in reduced fluidity of the silica aerogel coating. This makes it difficult to coat into the spacer fabric under the action of a doctor blade, resulting in less silica aerogel coating filling the spacer fabric, thus leading to a higher thermal conductivity. In addition, the reduced fluidity of the coating causes it to harden after drying, leading to an increase in compressive modulus and a decrease in flexibility.

[0095] The difference between Comparative Example 6 and Example 1 lies in the fact that the mass fraction of the aqueous acrylic resin emulsion in the prepared silica aerogel coating was adjusted to 50%. The resulting aerogel / spacer fabric composite material did not show a significant improvement in thermal conductivity. This is because the reduced mass fraction of the aqueous acrylic resin emulsion leads to poor dispersion of the aerogel powder, resulting in uneven distribution of silica aerogel in the coating filled into the spacer fabric. This, in turn, increases the thermal conductivity and deteriorates the insulation performance. The uneven dispersion of aerogel in the coating leads to a decrease in the overall performance of the coating; compared to the composite fabric filled with the coating prepared in Example 1, the flexibility is not improved but rather worse.

[0096] The thermal insulation material provided by this invention has a reasonable structural design and can be widely used in building thermal insulation, pipeline thermal insulation, lithium battery thermal management and other fields, and has good application prospects.

[0097] The embodiments provided above are not intended to limit the scope of the invention, nor are the described steps intended to limit the order of execution. Any obvious modifications made to the invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined by the claims.

Claims

1. A method for preparing an aerogel / spacer fabric composite material, characterized in that, Includes the following steps: (1) Select a three-dimensional spacer fabric and lay it on a polytetrafluoroethylene board; (2) Apply an aerogel coating to the lower layer of the three-dimensional spacer fabric using a scraper; (3) Place the three-dimensional spaced fabric obtained in step (2) into an oven for drying; (4) Apply aerogel coating to the upper layer of the three-dimensional spacer fabric obtained in step (3) with a scraper to ensure that the aerogel coating completely fills the interior of the three-dimensional spacer fabric. (5) The fabric obtained in step (4) is dried to obtain a two-phase composite thermal insulation material; The aerogel coating comprises, by mass percentage, 4.7-16% aerogel powder, 80-93% aqueous acrylic resin emulsion, 0.9-1.6% aqueous polymeric dispersant, 0.5-0.8% aqueous defoamer, and 0.5-1.6% aqueous rheology modifier, wherein the solid content of the aqueous acrylic resin emulsion is 40%.

2. The preparation method according to claim 1, characterized in that, The upper layer of the three-dimensional spacer fabric described in step (1) is a knitted fabric formed by a hexagonal mesh structure, and the lower layer is a knitted fabric formed by a combination of chain knitting and weft weft weaving.

3. The preparation method according to claim 1, characterized in that, The thickness of the three-dimensional spacer fabric is 1.5 mm to 1 cm, and the areal density is 300 g / m³. 2 ~600g / m 3 The upper layer, lower layer and spacer yarn of the three-dimensional spacer fabric include any one of polyester, nylon, polypropylene, glass yarn, carbon yarn, aramid yarn, ultra-high molecular weight polyethylene yarn and quartz yarn.

4. The preparation method according to claim 1, characterized in that, The aerogel coating is a silica aerogel coating. The preparation steps of the silica aerogel coating include: weighing water-based acrylic resin emulsion (40% solid content), water-based polymeric dispersant, and water-based defoamer, mixing them, and then mixing them evenly with medium-speed mechanical stirring for 60 minutes. Then, aerogel powder and water-based rheology modifier are added, and the mixture is stirred at high speed for 30-60 minutes until it is evenly mixed to obtain silica aerogel slurry.

5. The preparation method according to claim 1, characterized in that, In step (2), the speed of the doctor blade coating is 60 cm / min, the doctor blade pressure is 50 to 100 N / cm, the doctor blade angle is 40° to 60°, and the coating thickness is 20 to 30 μm.

6. The preparation method according to claim 1, characterized in that, In step (4), the scraper filling speed is 40 cm / min, the scraper pressure is 150 N to 250 N / cm, and the scraper angle is 30° to 50°. In steps (3) and (4), the drying is atmospheric pressure drying, the drying temperature is 60° to 80°, and the drying time is 3 to 5 hours.

7. The preparation method according to claim 1, characterized in that, Before step (2) or step (4), the three-dimensional spacer fabric is subjected to surface pretreatment, which includes coating with a silane coupling agent solution with a concentration of 0.5wt% to 2wt%.

8. The aerogel / spacer fabric composite material prepared by the preparation method according to any one of claims 1 to 7, wherein the aerogel / spacer fabric composite material comprises a three-dimensional spacer fabric and an aerogel coating matrix; the aerogel coating matrix is ​​composite-filled in the upper and lower layers of the three-dimensional spacer fabric, so that the interior of the three-dimensional spacer fabric is completely filled with aerogel coating, and the filling coefficient is 100%.

9. The aerogel / spacer fabric composite material according to claim 8, characterized in that, The density of the aerogel / spacer fabric composite material is 0.1–0.3 g / cm³. 3 It has a thermal conductivity of 0.02–0.05 W / (m·K) and a compressive modulus of 0.1–10 MPa.

10. The application of the aerogel / spacer fabric composite material according to claim 8 or 9 in the fields of construction, industry, transportation, cold chain, and home appliances.

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