WO2023040966A1 - Thermal insulation material, and preparation method therefor and use thereof - Google Patents

Abstract

A thermal insulation material, and a preparation method therefor and the use thereof. The thermal insulation material is a film-like material or felt-like material, and is a flexible material. The thermal insulation material comprises a three-dimensional interpenetrating network structure composed of SiO2 ceramic nanofibers having an average diameter of 200-350 nm. The preparation method of the present invention has a simple process, a short preparation period and good formability, comprises a three-dimensional interpenetrating network structure composed of ceramic fibers, has a low thermal conductivity coefficient, good mechanical properties, a light weight and good hydrophobic properties, and is expected to be applied to the aerospace field and a high-temperature humid environment, thereby achieving efficient thermal insulation.

Description

A kind of thermal insulation material and its preparation method and application

This application claims the priority of the earlier application filed with the State Intellectual Property Office of China on September 17, 2021 with the patent application number 202111091769.5 and the title of the invention "a method for preparing a flexible high-temperature-resistant _SiO2 ceramic nanofiber membrane". The entirety of this prior application is incorporated by reference into the present application.

This application claims the priority of the previous application with the patent application number 202111091766.1 and the title of the invention "a preparation method of rare earth doped silica airgel" submitted to the State Intellectual Property Office of China on September 17, 2021. The entirety of this prior application is incorporated by reference into the present application.

This application claims the priority of the earlier application filed with the State Intellectual Property Office of China on April 22, 2022 with the PCT application number PCT/CN2022/088412 and the title of the invention "A high-temperature-resistant and smoke-proof air duct and its manufacturing method" right. The entirety of this prior application is incorporated by reference into the present application.

This application claims the priority of the earlier application with the PCT application number PCT/CN2022/088414 and the invention title "A high-temperature-resistant and smoke-proof air duct" filed with the State Intellectual Property Office of China on April 22, 2022. The entirety of this prior application is incorporated by reference into the present application.

technical field

The invention belongs to the field of thermal insulation materials, and relates to a thermal insulation material and a preparation method and application thereof.

Background technique

In recent years, with the increasing speed of aircraft in the aerospace field, the research and development of thermal insulation materials with good mechanical flexibility, light weight and high efficiency have attracted wide attention from various industries. At the same time, the high-temperature mechanical stability of thermal insulation materials Performance, mechanical properties, etc. have higher requirements. Inorganic materials, especially ceramic materials, have the advantages of high temperature resistance, corrosion resistance, and good insulation. They have certain application advantages as high-temperature heat insulation materials on hypervelocity aircraft. Silica _SiO2 is a non-toxic, odorless and non-polluting inorganic non-metallic material widely distributed in nature. It has good temperature resistance, excellent corrosion resistance, good thermal conductivity, good insulation and stable chemical properties. Features, are widely used in many fields.

However, compared with metals and polymer materials, most ceramic materials directly undergo brittle fracture under the action of external loads. The defects of this inorganic material such as high brittleness, poor mechanical properties, and difficulty in bending seriously limit its practical application. use. In order not to make the brittleness of ceramic materials affect the performance of materials and the depth and breadth of material applications, how to improve the brittleness of ceramic materials and even develop flexible, bendable and non-brittle ceramics has always been one of the research focuses of ceramic material researchers. one.

Contents of the invention

The purpose of the present invention is to provide a thermal insulation material and its preparation method and application that can solve the defects of the existing ceramic-based thermal insulation materials in the aerospace field, such as high brittleness, difficult installation and maintenance, and unsuitability for high working temperature. In the thermal insulation material of the present invention, the diameter of the fiber is nanoscale, which endows the material with flexibility, and the unique large porosity and large specific surface area in the material make the material have a lower thermal conductivity. At the same time, the invention also provides a hydrophobically modified thermal insulation material, which has the prospect of being applied to high-temperature and humid environments. The invention also provides a preparation method of the thermal insulation material. The method has the advantages of simple process, easy-to-obtain raw materials, can reduce production costs, and has the prospect of mass production.

Specifically, the present invention provides the following technical solutions:

A kind of thermal insulation material, described thermal insulation material is a kind of membrane material or felt-like material, is a kind of flexible material; In the described thermal insulation material, comprise SiO ₂ three-dimensional interpenetrating network that ceramic nanofiber forms structure, the average diameter of the fibers is 200nm-350nm.

According to the present invention, the thermal insulation material has at least one of the following properties:

1) High temperature resistance, can be used at 800 ~ 1200 ℃;

2) The density (g/cm) is between 0.08 and 0.20;

3) The thermal conductivity is 0.04～0.08W/mK;

4) The tensile mechanical strength is 0.5-4.5MPa;

According to the present invention, the thermal insulation material further includes a sunscreen.

According to the present invention, the fiber is a nano hollow fiber having a hollow structure.

The present invention also provides a method for preparing the thermal insulation material, the method comprising the following steps:

1) preparation of spinning aids: template polymer and water to prepare high molecular polymer solution as spinning aids;

2) prepare SiO ₂ precursor spinnable sol: mix high molecular polymer solution and silica sol in step 1), obtain SiO ₂ precursor spinnable sol; The weight ratio of described high molecular polymer solution and silica sol is 1: (1~6);

3) Preparation of thermal insulation material: The SiO ₂ precursor spinnable sol in step 2) is prepared by electrospinning to obtain a film-like material or felt material, and after removing static electricity, it is calcined to obtain the thermal insulation material.

According to the present invention, described method also comprises the following steps:

4) Preparation of thermal insulation material with hydrophobic properties: use hydrophobic modifier to carry out hydrophobic modification treatment on the thermal insulation material in step 3), and dry to obtain the thermal insulation material with hydrophobic properties.

The present invention also provides a thermal insulation composite material, which is a composite of the thermal insulation material and silica airgel or rare earth doped silica airgel.

According to the present invention, the composite material is a composite of the above thermal insulation material and silica airgel, the composite includes a skeleton and a filler, the thermal insulation material serves as a skeleton, and the silica airgel serves as filler.

According to the present invention, the composite material is a composite of the above thermal insulation material and rare earth doped silica airgel, the composite includes a skeleton and a filler, the thermal insulation material serves as a skeleton, and the rare earth doped with two Silica airgel as filler.

According to the present invention, the aerogel further includes silicon micropowder.

According to the present invention, the airgel further includes an opacifying agent.

The present invention also provides a method for preparing the thermal insulation composite material, the method comprising the following steps:

S1. Prepare silica sol: prepare silica sol by mixing silicon source, water, and alcohol solvent;

S2. Prepare rare earth silica sol: configure a rare earth compound solution, and mix the rare earth compound solution with the above silica sol to obtain a rare earth silica sol;

S3. preparing a fiber preform, comprising the following steps:

S3-1. Preparation of spinning aids: template polymer and water to prepare polymer solution as spinning aids;

S3-2. Prepare SiO ₂ precursor spinnable sol: mix the polymer solution and silica sol in step S3-1 to obtain SiO ₂ precursor spinnable sol;

S3-3. Preparing fiber preforms: preparing the _SiO2 precursor spinnable sol in step S3-2 by electrospinning to obtain film-like materials or felt-like materials, after removing static electricity, calcining to obtain fiber preforms;

S4. Modification of the fiber preform: using a hydrophobic modifier to perform hydrophobic modification treatment on the fiber preform in step S3, and drying to obtain a fiber preform with hydrophobic properties;

S5. Preparation of gel: After adding a gel catalyst to the silica sol in step S1 or the rare earth silica sol in step S2, pour it into the fiber preform in step S3 or the modified fiber preform with hydrophobic properties in step S4 , stand still, obtain gel;

S6. Drying: drying the gel in step S5 to obtain the thermal insulation composite material.

The present invention also provides the application of the thermal insulation material or the thermal insulation composite material for thermal insulation in a high temperature and humid environment.

The present invention also provides a smoke prevention and exhaust air duct, the smoke prevention and exhaust air duct includes a metal pipe, the inner wall and/or outer wall of the metal pipe is provided with a heat shielding layer, the heat shielding layer includes a heat insulating layer, and the heat insulating layer It includes the thermal insulation material or the thermal insulation composite material.

Compared with the prior art, the present invention has the following significant advantages:

1. The present invention uses PVA as an auxiliary agent, mixes a polymer solvent and silica sol as a precursor sol, and prepares a thermal insulation material with a special porosity through a sol-gel electrospinning method. The preparation process is simple and the raw materials are easy to obtain , Can reduce production cost, has the prospect of mass production;

2. The thermal insulation material prepared by the present invention has the advantages of thin and controllable thickness, and good mechanical strength, can be folded and bent at will, and it also has good tensile strength (for example, the tensile strength can be as high as 4.145MPa) ;

3. The thermal insulation material prepared by the present invention can be applied at 800-1200°C without changing its fiber morphology and structure, and has low thermal conductivity, so it can be used as a high-temperature-resistant thermal insulation material in high-temperature fields;

4. The hydrophobically modified thermal insulation material prepared by the present invention has hydrophobic properties, combined with its high temperature resistance performance, it has potential applications in high temperature and humid environments.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiment technology of the present invention, the accompanying drawings that need to be used in the technical description of the embodiment will be briefly introduced below. The accompanying drawings are only used to provide a further understanding of the present invention and serve as constituent A part of the description is used to explain the present invention together with the following specific embodiments, but it does not constitute a limitation to the present invention. For those skilled in the art, they can also use these appended Figures for additional drawings.

Figure 1 is a flow chart of the preparation of _SiO2 ceramic nanofiber membrane.

FIG. 2 is a SEM image of the _SiO2 ceramic nanofiber membrane prepared in Example 1.

Fig. 3 is the TG curve of the SiO ₂ ceramic nanofiber membrane prepared in Example 1.

Figure 4 is the hydrophobically modified _SiO2 ceramic nanofiber membrane prepared in Example 1.

Fig. 5 is an electron microscope image of the nano hollow fiber of the present invention.

Fig. 6 is a schematic diagram of the coaxial trocar head of the present invention.

Fig. 7 is a schematic diagram of the smoke prevention and exhaust duct of the present invention.

Fig. 8 is a schematic diagram of the quick disassembly and assembly air duct of the present invention.

Fig. 9 is a schematic diagram of the heat shielding layer of the present invention.

Fig. 10 is a schematic diagram of the heat-insulating layer wrapping the high-temperature-resistant protective layer of the present invention.

Fig. 11 is a schematic diagram of the morphology of the high-temperature expansion layer of the present invention at different temperatures.

Fig. 12 is a schematic structural view of the smoke exhaust duct of the present invention.

In the figure: 100-metal pipe; 101-antibacterial metal pipe; 110-angle steel flange; 120-surrounding fixing hoop; 121-bolt; 122-nut; 220-heat conduction layer; 230-heat reflective layer; 250-high temperature resistant protective layer; 260-high temperature expansion layer; 810-inner needle; 820-outer needle; 830-receiving device; 880-nanometer hollow fiber.

Detailed ways

[thermal insulation material]

As mentioned above, the present invention provides a thermal insulation material, which is a film material or a felt material, and is a flexible material; the thermal insulation material includes a three-dimensional structure composed of _SiO2 ceramic nanofibers. The interpenetrating network structure, the average diameter of the fiber is 200nm-350nm.

According to one embodiment of the present invention, the average diameter of the fibers is, for example, 200nm, 205nm, 240nm, 245nm, 280nm, 281nm, 282nm, 283nm, 284nm, 285nm, 286nm, 287nm, 288nm, 289nm, 290nm, 300nm, 310nm , 320nm, 330nm, 340nm or 350nm. The standard deviation of the average diameter of the fibers is 30nm-70nm, such as 30nm, 35nm, 40nm, 45nm, 50nm, 55nm, 60nm, 65nm or 70nm.

According to an embodiment of the present invention, the surface of the thermal insulation material has hydrophobic functional groups.

According to one embodiment of the present invention, when the thermal insulation material is a film-like material, its thickness is 0.5 mm to 5.0 mm, specifically 0.5 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.3 mm, 1.5mm, 1.8mm, 2.0mm, 2.2mm, 2.5mm, 2.8mm, 3.0mm, 3.4mm, 3.5mm, 3.8mm, 4.0mm, 4.2mm, 4.5mm or 5.0mm; when the thermal insulation material is In the case of a felt material, its thickness is 0.5 cm to 5 cm, specifically 0.5 cm, 1 cm, 1.5 cm, 2.0 cm, 2.5 cm, 3 cm, 3.5 cm, 4 cm, 4.5 cm or 5 cm.

According to an embodiment of the present invention, the thermal insulation material is resistant to high temperature, specifically, it can be used at 800-1200°C.

According to one embodiment of the present invention, the density (g/cm) of the thermal insulation material is between 0.08 and 0.20, such as 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19 or 0.20.

According to an embodiment of the present invention, the thermal insulation material has a low thermal conductivity, specifically, its thermal conductivity is 0.04-0.08W/mK, for example, 0.04, 0.041, 0.04141, 0.042, 0.044, 0.05 , 0.06, 0.07, 0.072, 0.074, 0.07416, 0.076, 0.078, 0.08W/mK.

According to an embodiment of the present invention, the tensile mechanical strength of the thermal insulation material is 0.5-4.5 MPa, specifically, it can be 0.5, 0.51, 0.55, 0.6, 0.8, 1.0, 2.0, 3.0, 3.5, 4.0 , 4.1, 4.145, 4.2, 4.3, 4.4 or 4.5MPa.

According to an embodiment of the present invention, the thermal insulation material further includes an opacifying agent, in order to enhance the thermal insulation performance under high temperature conditions. Specifically, the opacifying agent may include at least one of titanium dioxide, carbon black, SiC, potassium hexatitanate, ZrO ₂ and the like. Further, titanium dioxide may be anatase titanium dioxide. Further, titanium dioxide can be fluorine-doped or nitrogen-doped titanium dioxide nanoparticles.

According to one embodiment of the present invention, the fiber is a hollow nanofiber with a hollow structure.

[Preparation method of thermal insulation material]

The present invention also provides a method for preparing the above-mentioned thermal insulation material, the method comprising the following steps:

1) preparation of spinning aids: template polymer and water to prepare high molecular polymer solution as spinning aids;

2) prepare SiO ₂ precursor spinnable sol: mix high molecular polymer solution and silica sol in step 1), obtain SiO ₂ precursor spinnable sol; The weight ratio of described high molecular polymer solution and silica sol is 1: (1~6);

3) Preparation of thermal insulation material: The SiO ₂ precursor spinnable sol in step 2) is prepared by electrospinning to obtain a film-like material or felt material, and after removing static electricity, it is calcined to obtain the thermal insulation material.

According to one embodiment of the present invention, described method also comprises the following steps:

4) Preparation of thermal insulation material with hydrophobic properties: the thermal insulation material in step 3) is subjected to hydrophobic modification treatment with a hydrophobic modifier, and dried to obtain the thermal insulation material with hydrophobic properties.

According to one embodiment of the present invention, in step 1), the template polymer is, for example, selected from PVA powder; specifically, the PVA powder can be 1788 type.

According to one embodiment of the present invention, in step 1), the mass fraction of the high molecular polymer solution may be 10%-12%.

According to one embodiment of the present invention, in step 1), the water can be ultrapure water.

According to one embodiment of the present invention, in step 1), the prepared polymer solution can be stirred for 6h-8h to completely dissolve the PVA powder in water.

According to one embodiment of the present invention, in step 2), the pH value of the silica sol is 8.5-9.0, the concentration is 2-4mol/L, the mass fraction is 15-25%, and the density is 0.957g/cm ³ .

According to one embodiment of the present invention, in step 2), the mass ratio of the polymer solution to the silica sol can be, for example, 1:1, 1:2, 1:3, 1:4, 1:5 or 1:6.

According to one embodiment of the present invention, in step 2), the SiO ₂ precursor spinnable sol is obtained by stirring after mixing; specifically, the stirring time may be 0.5h-3h.

According to an embodiment of the present invention, in step 3), the inner diameter of the electrospinning needle is 0.50 mm to 0.60 mm; specifically, the parameters of the electrospinning can be: relative humidity 25% to 45% , the extrusion speed is 0.9~1.5ml/h, the voltage is 12~16kv, the distance between the receiving device and the spinneret is 8~10cm, the spinning time is 1h~4h, the metal drum is used as the receiving device, and the drum speed is 40～70r/min.

According to one embodiment of the present invention, in step 3), place in an oven to remove static electricity, specifically, place in an oven at 40-50° C. for 30 minutes to 1 hour to remove static electricity.

According to an embodiment of the present invention, in step 3), the calcination procedure may be: heating from room temperature to 800°C at a heating rate of 5°C/min, and holding at 800°C for 1 hour.

According to one embodiment of the present invention, in step 3), it can be calcined at 900-1300°C, and the calcining program is controlled as follows: from room temperature to 900-1300°C, the heating rate is 5°C/min, and at the highest Keep the temperature for 1h.

According to one embodiment of the present invention, in step 4), the hydrophobic modifier is prepared by the following method: the silane coupling agent and ethanol are mixed according to the mass ratio of 3: (8 ~ 12), and 0.5 ~ 2wt % dilute nitric acid to adjust the pH value of the mixed solution to about 3, stir for 1h to 2h to hydrolyze it to obtain a hydrophobic modifier; specifically, the silane coupling agent can be selected from KH-570, KH-550, KH-560, Chlorotrimethylsilane, Tridecafluorooctyltriethoxysilane, Heptadecafluorodecyltriethoxysilane, Tridecylfluorooctyltrimethoxysilane, Heptadecafluorodecyltrimethoxysilane, Acetoxy Benzyltrimethylsilane, benzyldimethylchlorosilane, benzyltrichlorosilane, benzyltriethoxysilane, tert-butyltrimethylchlorosilane, dichloroisobutylmethylsilane, n-butyltrichlorosilane , cycloethyltrichlorosilane, 3-chlorocyclopentylsilane or dibutyl silicon dichloride at least one.

According to one embodiment of the present invention, in step 4), the hydrophobic modification is carried out in a vacuum drying oven; specifically, the temperature of the drying oven may be 40-80°C, and the treatment time is 4h-8h.

According to one embodiment of the present invention, in step 4), the drying is performed in an oven; specifically, it is performed under an air atmosphere. The purpose of drying is to remove residual solvent. Specifically, the drying temperature is 50-70°C, and the drying time is 6h-10h.

According to one embodiment of the present invention, the preparation method of the above-mentioned thermal insulation material specifically includes the following steps:

Step 1: preparing a polymer solution, which is prepared from a template polymer and water;

Step 2: Prepare SiO ₂ precursor spinnable sol, mix and stir the above polymer solution with silica sol to obtain SiO ₂ precursor spinnable sol;

Step 3: Electrospinning the _SiO2 precursor spinnable sol obtained above to obtain a template polymer/ _SiO2 composite ceramic nanofiber membrane, and place it in an oven to remove residual static electricity;

Step 4: placing the prepared PVA/ _SiO2 composite ceramic nanofiber membrane in a box furnace for calcining to remove organic matter, and obtaining a flexible _SiO2 ceramic nanofiber membrane;

Step 5: Mix the silane coupling agent and ethanol according to a certain mass ratio, and add dilute nitric acid to make it hydrolyze to prepare a hydrophobic modifier;

Step 6: Soak the _SiO2 ceramic nanofiber membrane in the hydrophobic modifier;

Step 7: Take out the wetted _SiO2 ceramic nanofibers in step 6 and put them into a vacuum oven for vacuum drying to remove the solvent.

According to one embodiment of the present invention, in step 1, the template polymer is selected from PVA powder.

According to one embodiment of the present invention, in step 1, the water is ultrapure water.

According to one embodiment of the present invention, in step 2, the silica sol is alkaline silica sol, neutral silica sol or acidic silica sol.

According to one embodiment of the present invention, in step 2, the polymer solution and silica sol are mixed according to a mass ratio of 1:(1-6), and stirred for 0.5h-3h to obtain a precursor sol.

According to one embodiment of the present invention, in step 2, an opacifying agent may be added to the silica sol for the purpose of enhancing the temperature insulation performance under high temperature conditions. Specifically, the opacifying agent may include at least one of titanium dioxide, carbon black, SiC, potassium hexatitanate, ZrO ₂ and the like. Further, titanium dioxide may be anatase titanium dioxide. Further, the titanium dioxide may be fluorine-doped or nitrogen-doped titanium dioxide nanoparticles, and the purpose of adding such titanium dioxide is to enhance the shading effect of infrared radiation.

According to one embodiment of the present invention, in step 2, rare earth compounds can be added to the silica sol, and the rare earth compounds are rare earth metal salts or rare earth metal oxides, such as yttrium metal salts, scandium metal salts, and La series metal salts. (specifically neodymium metal salt, ytterbium metal salt), yttrium metal oxide, scandium metal oxide, La-based metal oxide (specifically neodymium metal oxide, ytterbium metal oxide) and the like. Also for example, the rare earth compound is a combination of two or more, specifically, a combination of yttrium metal salt and scandium metal salt.

According to one embodiment of the present invention, in step 2, the rare earth compound is at least one of rare earth metal nitrate, rare earth metal oxalate, and rare earth metal carbonate. Specifically, it is rare earth metal nitrate hydrate, for example, the rare earth compound is Y(NO ₃ ) ₃ ·4H ₂ O, Sc(NO ₃ ) ₃ ·6H ₂ O, Nd(NO ₃ ) ₃ ·6H ₂ O, Yb( At least one of NO ₃ ) ₃ ·5H ₂ O and the like. Nitrates, oxalates or carbonates are used in the present invention.

According to one embodiment of the present invention, in step 3, a 10ml syringe is used in the electrospinning, the inner diameter of the electrospinning needle is 0.50 mm to 0.60 mm, the electrospinning parameters are: relative humidity 25% to 45%, extrusion The speed is 0.9~1.2ml/h, the voltage is 12~16kv, the distance between the receiving device and the spinneret is 8~10cm, the spinning time is 1h~4h, the metal drum is used as the receiving device, and the drum speed is 40~70r /min.

According to one embodiment of the present invention, in step 3, the needle used for electrospinning is a coaxial sleeve needle, the coaxial sleeve needle includes an inner layer needle and an outer layer needle, and the inner layer needle sleeve is inside the outer layer needle, and remain coaxial. Specifically, the high molecular polymer solution flows through the needles of the inner layer, and the SiO ₂ precursor spinnable sol flows between the needles of the inner layer and the outer layer of needles. Nano hollow fiber with hollow structure can be obtained through the coaxial sleeve needle. Specifically, the coaxial trocar head is shown in FIG. 6 .

According to one embodiment of the present invention, in step 3, the prepared PVA/SiO ₂ ceramic nanofiber membrane is placed in an oven at 40-50°C for 0.5h-2h to remove static electricity.

According to one embodiment of the present invention, the calcination procedure for removing organic matter in step 4 is: heating from room temperature to 800° C. at a heating rate of 5° C./min, and holding at 800° C. for 1 hour. In addition, the SiO2 ceramic nanofiber membrane was calcined at 900-1300°C, and the calcination program was controlled as follows: from room temperature to 900-1300°C, the heating rate was 5°C/min, and the temperature was kept at the highest temperature for 1h.

According to one embodiment of the present invention, the silane coupling agent in the step 5 is selected from KH-550, KH-560, KH-570, chlorotrimethylsilane, tridecafluorooctyltriethoxysilane, Heptafluorodecyltriethoxysilane, Tridecafluorooctyltrimethoxysilane, Heptadecafluorodecyltrimethoxysilane, Acetoxytrimethylsilane, Benzyldimethylchlorosilane, Benzyltrichlorosilane Silane, benzyltriethoxysilane, tert-butyltrimethylchlorosilane, dichloroisobutylmethylsilane, n-butyltrichlorosilane, cycloethyltrichlorosilane, 3-chlorocyclopentylsilane or dibutyl One of the base silicon dichlorides.

According to one embodiment of the present invention, in step 5, the silane coupling agent and the solvent are mixed according to a mass ratio of 1:(1-5), and the pH value of the mixed solution is adjusted to about 3 with 1 wt% dilute nitric acid, and stirred for 2 hours to make it hydrolysis to obtain a hydrophobic modifier; specifically, the solvent can be selected from n-hexane, ethanol, tetrahydrofuran, N,N-dimethylformamide, N,N-dimethylacetamide, chloroform, dichloromethane, methanol, At least one of carbon tetrachloride, pyrimidine, xylene, cyclohexane, methyl ethyl ketone or methyl acetate.

According to an embodiment of the present invention, in step 6, the modification is performed in an oven, specifically, the temperature of the oven is 60° C., and the treatment time is 6 hours to 8 hours.

According to one embodiment of the present invention, in step 7, the drying temperature is 50-70°C, and the drying time is 6h-10h.

[Heat insulation composite material]

The present invention also provides a thermal insulation composite material, which is a composite of the above thermal insulation material and silica aerogel or rare earth doped silica aerogel.

According to one embodiment of the present invention, the composite material is a composite of the above thermal insulation material and silica airgel; specifically, the composite includes a skeleton and a filler, and the thermal insulation material serves as a skeleton, so The above-mentioned silica airgel is used as filler.

According to one embodiment of the present invention, the composite material is a composite of the above-mentioned thermal insulation material and rare earth doped silica airgel; specifically, the composite includes a skeleton and a filler, and the thermal insulation material serves as framework, the rare earth-doped silica airgel acts as a filler.

According to one embodiment of the present invention, the aerogel further includes silicon micropowder.

Specifically, the particle size of the silicon micropowder ranges from 600 mesh to 1500 mesh.

Specifically, the silicon micropowder may be crystalline silica powder, or amorphous (amorphous) silica powder.

Studies have found that the use of silicon micropowder, especially the volume change caused by the crystal phase change of amorphous silica powder particles at high temperatures, can adjust and suppress the shrinkage of thermal insulation materials at high temperatures, and amorphous silicon micropowder can also improve The temperature resistance of thermal insulation materials. Amorphous silicon powder is a silicon dioxide material, and there will be a phenomenon of volume change caused by the transformation of crystal form under temperature change. The volume expansion of amorphous silicon micropowder will suppress and reduce the internal stress when the heat insulation material experiences high temperature, thereby reducing the structural change inside the heat insulation material and stabilizing its heat insulation performance under high temperature conditions. Microsilica powder will react and transform to mullite at high temperature and contain aluminum elements. Mullite is an excellent refractory material, so the addition of microsilica powder further improves the high temperature resistance of thermal insulation materials.

Further, the particle size of amorphous silicon micropowder is 800-8000 mesh, 1000-2000 mesh, 2000-3000 mesh, 3000-4000 mesh, 4000-5000 mesh, 5000-6000 mesh, 6000-7000 mesh, 7000-8000 mesh Mesh, 1000-1500 mesh, 1500-3000 mesh, or 10-800nm, 10-100nm, 50-200nm, 100-400nm, 300-800nm. The preferred particle size is 800-1000 mesh, 1000-1200 mesh, 1000-3000 mesh.

Further, the addition amount of silicon micropowder is 3-25wt%, 1-10wt%, 3-15wt%, 5-20wt%, 5-25wt%, 10-25wt%, the preferred addition amount is 2-10wt%, 3- 8wt%, 3-6wt%. The addition amount of the amorphous silicon micropowder is 1-20wt%, 1-15wt%, 2-10wt%, 3-8wt%. The preferred particle size can better promote the combination of silicon, aluminum and oxygen bonds, making the structure more stable. The optimal amount of addition can better improve the ability of the material to resist shrinkage at high temperatures while maintaining high thermal insulation performance and mechanical strength.

According to one embodiment of the present invention, the aerogel further includes a sunscreen agent. Specifically, the opacifying agent may include at least one of titanium dioxide, carbon black, SiC, potassium hexatitanate, ZrO ₂ and the like. Further, titanium dioxide may be anatase titanium dioxide. Further, titanium dioxide can be fluorine-doped or nitrogen-doped titanium dioxide nanoparticles.

[Preparation method of thermal insulation composite material]

The present invention also provides a method for preparing the above thermal insulation composite material, the method comprising the following steps:

S1. Prepare silica sol: prepare silica sol by mixing silicon source, water, and alcohol solvent;

S2. Prepare rare earth silica sol: configure rare earth compound solution, and mix rare earth compound solution with above-mentioned silica sol, obtain rare earth silica sol;

S3. preparing a fiber preform, comprising the following steps:

S3-1. Preparation of spinning aids: template polymer and water to prepare polymer solution as spinning aids;

S3-2. Prepare SiO ₂ precursor spinnable sol: mix the polymer solution and silica sol in step S3-1 to obtain SiO ₂ precursor spinnable sol;

S3-3. Preparing fiber preforms: preparing the _SiO2 precursor spinnable sol in step S3-2 by electrospinning to obtain film-like materials or felt-like materials, after removing static electricity, calcining to obtain fiber preforms;

S4. Modification of the fiber preform: using a hydrophobic modifier to perform hydrophobic modification treatment on the fiber preform in step S3, and drying to obtain a fiber preform with hydrophobic properties;

S5. Preparation of gel: After adding a gel catalyst to the silica sol in step S1 or the rare earth silica sol in step S2, pour it into the fiber preform in step S3 or the modified fiber preform with hydrophobic properties in step S4 , stand still, obtain gel;

S6. Drying: drying the gel in step S5 to obtain the thermal insulation composite material.

According to one embodiment of the present invention, step S1 specifically includes: preparing silica sol by mixing silicon source, water, alcohol solvent, and silicon micropowder. Specifically, a hydrolysis catalyst can be added to the silica sol to accelerate the hydrolysis of the silicon source and obtain the silica sol faster. Specifically, the silicon source can be selected from sodium silicate, ethyl orthosilicate, methyl orthosilicate, tetrapropoxysilane, tetrabutoxysilane, dimethyldimethoxysilane or dimethyldimethoxysilane Ethoxysilanes or combinations thereof. Specifically, the microsilica powder has the above-mentioned definition. Specifically, the hydrolysis catalyst can be selected from hydrochloric acid, oxalic acid, nitric acid, sulfuric acid, phosphoric acid or a combination thereof. Specifically, the alcohol solvent may be methanol, ethanol or a combination thereof.

According to an embodiment of the present invention, an opacifying agent may also be added to the silica sol in step S1, in order to enhance the temperature insulation performance under high temperature conditions. Specifically, the opacifying agent includes at least one of titanium dioxide, carbon black, SiC, potassium hexatitanate, ZrO ₂ and the like. Further, titanium dioxide may be anatase titanium dioxide. Further, the titanium dioxide may be fluorine-doped or nitrogen-doped titanium dioxide nanoparticles, and the purpose of selecting such titanium dioxide is to enhance the shading effect of infrared radiation.

According to one embodiment of the present invention, rare earth compounds can also be added to the silica sol in step S1, and the rare earth compounds are rare earth metal salts or rare earth metal oxides, such as yttrium metal salts, scandium metal salts, La series metal salts ( Specifically, at least one of neodymium metal salts, ytterbium metal salts), yttrium metal oxides, scandium metal oxides, La-based metal oxides (specifically neodymium metal oxides, ytterbium metal oxides), and the like. Also for example, the rare earth compound is a combination of two or more, specifically, a combination of yttrium metal salt and scandium metal salt.

According to one embodiment of the present invention, in step S1, the rare earth compound is at least one of rare earth metal nitrate, rare earth metal oxalate, and rare earth metal carbonate. Specifically, it is rare earth metal nitrate hydrate, for example, the rare earth compound is Y(NO ₃ ) ₃ ·4H ₂ O, Sc(NO ₃ ) ₃ ·6H ₂ O, Nd(NO ₃ ) ₃ ·6H ₂ O, Yb( At least one of NO ₃ ) ₃ ·5H ₂ O and the like. Nitrates, oxalates or carbonates are used in the present invention. The introduction of ions further realizes the control of the content of halide ions in the airgel.

According to one embodiment of the present invention, in step S2, the specific process of preparing the rare earth compound solution includes: dissolving the rare earth compound in water, heating and reacting, and cooling to room temperature to obtain the rare earth compound solution.

According to one embodiment of the present invention, in step S2, the rare earth compound is a rare earth metal salt or a rare earth metal oxide, such as yttrium metal salt, scandium metal salt, La series metal salt (specifically neodymium metal salt, ytterbium metal salt ), yttrium metal oxide, scandium metal oxide, La-based metal oxide (specifically neodymium metal oxide, ytterbium metal oxide) and the like. Also for example, the rare earth compound is a combination of two or more, specifically, a combination of yttrium metal salt and scandium metal salt.

According to one embodiment of the present invention, in step S2, the rare earth compound is at least one of rare earth metal nitrate, rare earth metal oxalate, and rare earth metal carbonate. Specifically, it is rare earth metal nitrate hydrate, for example, the rare earth compound is Y(NO ₃ ) ₃ ·4H ₂ O, Sc(NO ₃ ) ₃ ·6H ₂ O, Nd(NO ₃ ) ₃ ·6H ₂ O, Yb( At least one of NO ₃ ) ₃ ·5H ₂ O and the like. In the present invention, nitrates, oxalates or carbonates are used to avoid the introduction of halide ions, and further realize the content control of halide ions in the airgel.

According to one embodiment of the present invention, in the process of preparing the rare earth compound solution in step S2, a water bath is used for heating. The heating temperature may be 40°C-60°C, for example, 45-50°C; the heating time may be 20min-60min, for example, the heating time may be 30min-35min.

According to an embodiment of the present invention, in the process of preparing the rare earth compound solution in step S2, the mass ratio of the rare earth nitrate to water may be (3-4):1.

According to an embodiment of the present invention, in step S3-1, the template polymer is selected from, for example, PVA powder; specifically, the PVA powder can be 1788 type.

According to an embodiment of the present invention, in step S3-1, the mass fraction of the high molecular polymer solution may be 10%-12%.

According to an embodiment of the present invention, in step S3-1, the water may be ultrapure water.

According to one embodiment of the present invention, in step S3-1, the prepared polymer solution can be stirred for 6h-8h to completely dissolve the PVA powder in water.

According to one embodiment of the present invention, in step S3-1, the pH value of the silica sol is 8.5-9.0, the concentration is 2-4mol/L, the mass fraction is 15-25%, and the density is 0.957g/cm ³ .

According to one embodiment of the present invention, in step S3-2, the mass ratio of the high molecular polymer solution to the silica sol can be, for example, 1:1, 1:2, 1:3, 1:4, 1: 5 or 1:6.

According to one embodiment of the present invention, in step S3-2, the SiO ₂ precursor spinnable sol is obtained by stirring after mixing; specifically, the stirring time may be 0.5h-3h.

According to an embodiment of the present invention, in step S3-3, the inner diameter of the electrospinning needle is 0.50 mm to 0.60 mm; specifically, the parameters of the electrospinning can be: relative humidity 25% to 45 %, the extrusion speed is 0.9~1.5ml/h, the voltage is 12~16kv, the distance between the receiving device and the spinneret is 8~10cm, the spinning time is 1h~4h, the metal drum is used as the receiving device, and the drum speed 40~70r/min.

According to one embodiment of the present invention, in step S3-3, place in an oven to remove static electricity, specifically, place in an oven at 40-50° C. for 30 minutes to 1 hour to remove static electricity.

According to an embodiment of the present invention, in step S3-3, the calcination procedure may be: heating from room temperature to 800°C at a heating rate of 5°C/min, and holding at 800°C for 1 hour.

According to one embodiment of the present invention, in step S3-3, it can be calcined at 900-1300°C, and the calcining program is controlled as follows: from room temperature to 900-1300°C, the heating rate is 5°C/min, and The highest temperature is kept for 1h.

According to one embodiment of the present invention, in step S4, the hydrophobic modifier is prepared by the following method: the silane coupling agent and ethanol are mixed according to the mass ratio of 3: (8-12), and 0.5-2wt% Dilute nitric acid to adjust the pH value of the mixed solution to about 3, stir for 1h to 2h to hydrolyze to obtain a hydrophobic modifier; specifically, the silane coupling agent can be KH-570, KH-550, KH-560, chlorine Trimethylsilane, Tridecafluorooctyltriethoxysilane, Heptadecafluorodecyltriethoxysilane, Tridecafluorooctyltrimethoxysilane, Heptadecafluorodecyltrimethoxysilane, Acetoxy Trimethylsilane, benzyldimethylchlorosilane, benzyltrichlorosilane, benzyltriethoxysilane, tert-butyltrimethylchlorosilane, dichloroisobutylmethylsilane, n-butyltrichlorosilane, At least one of cycloethyltrichlorosilane, 3-chlorocyclopentylsilane or dibutyl silicon dichloride.

According to an embodiment of the present invention, in step S4, the hydrophobic modification is carried out in a vacuum drying oven; specifically, the temperature of the drying oven may be 40-80°C, and the treatment time is 4h-8h.

According to one embodiment of the present invention, in step S4, the drying is performed in an oven; specifically, it is performed in an air atmosphere. The purpose of drying is to remove residual solvent. Specifically, the drying temperature is 50-70°C, and the drying time is 6h-10h.

According to one embodiment of the present invention, in step S5, after adding the gel catalyst, reinforcing fibers and fiber dispersants may be added. Specifically, the fiber dispersant can be at least one of sodium lauryl sulfonate, polyethylene glycol, sodium lauryl sulfate, sodium hexametaphosphate and the like. In the present invention, a gel catalyst is added to convert the rare earth silica sol into a rare earth doped gel. Specifically, the gel catalyst can be one or more of ammonia water, dimethylformamide, ammonia water ethanol dilution, etc. .

According to one embodiment of the present invention, in step S6, the drying method may be normal temperature and pressure drying, critical drying, supercritical drying, and the like.

Specifically, at least one of CO ₂ , methanol, and ethanol can be selected as the drying medium for the critical drying and supercritical drying.

Specifically, the drying conditions at normal temperature and pressure may be to dry at 60, 80 and 120° C. for 2 hours respectively to obtain the final product.

Specifically, the conditions for the carbon dioxide supercritical drying are: in the case of ethanol as the solvent, soak with liquid carbon dioxide for 3 days at 5°C and 5.5MPa, and release the replaced ethanol; then raise the temperature to 35°C and 10.5MPa And keep it for 3 hours, then slowly release the pressure to normal pressure at a rate of 0.5MPa/h to obtain the final product.

Specifically, the condition of the ethanol supercritical drying is that after raising the temperature and pressure to the critical point according to a preset program, the fluid inside the reactor is released at a slow speed at a constant temperature until the internal and external pressures are balanced. Before heating up, N2 can be used to pre-fill the reactor. The pressure of pre-filling N2 is 1-4MPa. When the temperature rises above 240°C, the heating rate is 0.5-2°C/min. When the pressure exceeds 8MPa, turn on the cooling device, slowly release the pressure, and release After the pressure was reduced to normal pressure, _N2 was introduced to purge the reactor, and after cooling to room temperature, the final product was obtained.

[Application of thermal insulation materials or thermal insulation composite materials]

The present invention also provides the application of the thermal insulation material or thermal insulation composite material, which can be used for thermal insulation in a high temperature and humid environment.

According to an embodiment of the present invention, due to the flexibility and low thermal conductivity of the thermal insulation material, it can be used for thermal insulation under conditions of limited space.

[Smoke exhaust duct]

The present invention also provides a smoke prevention and exhaust air duct, the smoke prevention and exhaust air duct includes a metal pipe, the inner wall and/or outer wall of the metal pipe is provided with a heat shielding layer, the heat shielding layer includes a heat insulating layer, and the heat insulating layer Including the above-mentioned thermal insulation material or the above-mentioned thermal insulation composite material, or, the thermal insulation layer includes a skeleton, a filler, an anti-shrinkage additive and a high-temperature-resistant additive.

According to an embodiment of the present invention, the heat shielding layer further includes at least one of a heat conducting layer and a heat reflecting layer.

According to one embodiment of the present invention, the filler includes silica aerogel, aluminum silicate aerogel, alumina aerogel, composite silica aerogel, rare earth doped silica aerogel at least one of . Exemplarily, the filler has a core-shell structure, wherein the shell is aluminum silicate and/or alumina aerogel, the core is silica aerogel, or the shell is silica aerogel and the core is aluminum silicate and/or alumina aerogels. Alternatively, the airgel may be a silica/alumina composite aerogel in which silica is composited with alumina.

Further, the skeleton is made of fiber material, which may be at least one of aluminum silicate fiber, alumina fiber, glass fiber, mullite fiber, and SiO ₂ ceramic nanofiber.

Further, the high temperature resistant additive may be aluminum silicate, quartz powder, silicon micropowder and the like.

The technical solutions in the present invention will be further described below in conjunction with specific embodiments. These embodiments are only used to provide a further understanding of the present invention, and as a part of the description, they are used together with the above-mentioned drawings to explain the present invention. But it does not constitute a limitation to the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope of the present application.

The embodiment of the present invention adopts electrospinning technology, silica sol is the main raw material, and polyvinyl alcohol is the spinning aid. The specific preparation method of the thermal insulation material includes the following steps:

1. prepare high molecular polymer solution, described solution is formulated by PVA powder and ultrapure water; PVA powder adopts 1788 type, the mass fraction of the prepared polymer solution is 10～12%, makes PVA The powder dissolves completely in water.

2. Prepare the SiO ₂ precursor spinnable sol, mix the polymer solution with the silica sol and stir evenly to obtain the precursor sol with electrospinning performance; the pH value of the silica sol is 8.5-9.0, the concentration is 3.19mol/L, the mass The fraction is 19.1%, and the density is 0.957 g/cm ³ . The PVA aqueous solution and the silica sol are mixed according to a mass ratio of 1:(1-6), and stirred for 0.5-3 hours to obtain a precursor sol.

3. Electrospin the obtained _SiO2 precursor to obtain PVA/ _SiO2 composite ceramic nanofiber membrane, and place it in an oven to remove residual static electricity; the 10mL syringe used for electrospinning, the inner diameter of the electrospinning needle 0.50~0.60mm, the electrospinning parameters are: relative humidity 25%~45%, extrusion speed 0.9~1.5ml/h, voltage 12~16kv, distance between receiving device and spinneret 8~10cm, The spinning time is 1h-4h, and the metal drum is used as the receiving device, and the drum speed is 40-70r/min. The prepared PVA/SiO ₂ ceramic nanofiber membrane is placed in an oven at 40-50°C for 30min-1h to remove static electricity.

4. The prepared PVA/SiO ₂ composite ceramic nanofiber membrane is placed in a box furnace and calcined to remove organic matter, and a flexible SiO ₂ ceramic nanofiber membrane is obtained; the calcination procedure for removing organic matter is: from room temperature to 800 °C °C, the heating rate is 5 °C/min, and it is kept at 800 °C for 1 h. In addition, the _SiO2 ceramic nanofiber membrane was calcined at 900-1300 °C, and the calcination program was controlled as follows: from room temperature to 900-1300 °C, the heating rate was 5 °C/min, and the highest temperature was kept for 1 h.

5. Mix the silane coupling agent and ethanol according to a certain mass ratio, and drop dilute nitric acid to hydrolyze it to prepare a hydrophobic modifier; the silane coupling agent for preparing a hydrophobic modifier is KH-570. The silane coupling agent and ethanol were mixed according to the mass ratio of 3:10, the pH value of the mixed solution was adjusted to about 3 with 1 wt% dilute nitric acid, and stirred for 2 hours to hydrolyze to obtain a hydrophobic modifier.

6. Soak the SiO ₂ ceramic nanofiber membrane in the hydrophobic modifier; place it in a vacuum drying oven during modification, the temperature of the drying oven is 60°C, and the treatment time is 4-8 hours.

7. Take out the wet SiO ₂ ceramic nanofibers in step 6 and place them in an oven, and dry them in an air atmosphere to remove residual solvents. The drying temperature is 50-70°C, and the drying time is 6-10 hours.

Specific examples are given below. It should be understood that the specific embodiments described below are only used to explain the present invention, not to limit the present invention.

Example 1

As shown in Fig. 1, the present embodiment provides a kind of thermal insulation material, and its preparation method comprises the following steps:

1) At room temperature, weigh 5g of polyvinyl alcohol powder and dissolve it in 45g of ultrapure water to prepare a polymer solution with a mass fraction of 10wt%;

2) Mix and stir 5 g of the above-mentioned polymer solution and 10 g of neutral silica sol (polymer solution and silica sol in a mass ratio of 1:2) at room temperature for 2 hours to obtain an electrospun precursor sol;

3) Put the above-mentioned spinning solution into a 10ml syringe, use a spinning needle with an inner diameter of 0.50mm, control the humidity at 35% during electrospinning, the operating voltage of the equipment is 14kV, and the injection rate is 1.1ml/h. The drum is a receiving device, the rotating speed is 50r/min, and the distance between the spinneret and the tin foil is 10cm, and electrospinning is carried out to prepare PVA/SiO _Composite nanofiber membrane;

4) Place the PVA/ _SiO2 composite nanofiber membrane obtained in step 3) in an oven at 50°C for 30 minutes to remove static electricity and facilitate storage and subsequent operations;

5) The above-mentioned PVA/SiO ₂ composite nanofiber film is peeled off from the tin foil, and placed in a box furnace to be calcined in an air atmosphere so as to remove organic components to obtain SiO ₂ ceramic nanofibers with flexibility. The parameters of the calcination process are : From room temperature to 800°C, the heating rate is 5°C/min, and the temperature is kept at 800°C for 1 hour;

6) At room temperature, add 6g of silane coupling agent (KH-570) to 20g of ethanol, stir to mix and add 1wt% dilute nitric acid dropwise, adjust the pH of the mixed solution to 3, and stir for 2h to make the silane coupling The coupling agent is fully hydrolyzed to obtain a hydrophobic modifier;

7) Soak the _SiO2 ceramic nanofiber membrane in step 5) in the hydrophobic modifier prepared in step 6), and place it in a vacuum oven at 60°C for 4 hours;

8) Take the _SiO2 ceramic nanofiber membrane in step 7) out of the hydrophobic modifier, and place it in a 60°C oven to dry for 8 hours to remove the solvent to obtain a _SiO2 ceramic nanofiber membrane with hydrophobic properties, that is, the insulation barrier of the present invention. hot material;

9) The interior of the SiO ₂ ceramic nanofiber membrane prepared above is a three-dimensional interpenetrating network structure composed of ceramic fibers, the average diameter of the ceramic fibers is 313nm, and the thermal conductivity is 0.053W/mK.

FIG. 2 is a SEM image of the _SiO2 ceramic nanofiber membrane prepared in Example 1. Fig. 3 is the TG curve of the SiO ₂ ceramic nanofiber membrane prepared in Example 1. Figure 4 is the hydrophobically modified _SiO2 ceramic nanofiber membrane prepared in Example 1.

Example 2

The effect of different PVA content on the performance of thermal insulation materials was studied.

The thermal insulation material was prepared by the same method as in Example 1, wherein the amount of PVA was specifically shown in Table 1.

Table 1 also gives the density, fiber average diameter and thermal conductivity of _SiO2 ceramic nanofiber membranes with different PVA content. As can be seen from Table 1, preferably, in the case of 10wt% PVA solution and silica sol at a ratio of 1:2, the SiO ₂ ceramic nanofiber membrane has the lowest thermal conductivity and the best thermal insulation performance; the higher the proportion of silica sol, the SiO ₂ The higher the density of the ceramic nanofiber membrane.

Table 1. Physical properties of thermal insulation materials with different amounts of PVA (heat treatment temperature 800°C)

Table 2 shows the tensile strength of thermal insulation materials prepared with different PVA content. It can be seen from Table 2 that in the case of 10wt% PVA solution and silica sol at a ratio of 1:2, the thermal insulation material has the best tensile strength. Compared with other ratios, thermal insulation materials have the best tensile properties.

Table 2. Tensile strength of thermal insulation materials prepared with different PVA contents

The mass ratio of sample 10wt% PVA solution to silica sol	Tensile strength (MPa)
1:1	2.01
1:2	4.15
1:3	1.17
1:4	0.86
1:5	0.54
1:6	0.51

Table 3 shows the tensile strength of thermal insulation materials after different heat treatments. It can be seen from Table 3 that the mass ratio of 10wt% PVA solution to silica sol is 1:2, and the tensile strength is different after different heat treatments. Under heat treatment conditions, the thermal insulation material has the highest tensile strength and the best tensile performance of the material.

Table 3. Tensile strength of _SiO2 ceramic nanofiber membranes after heat treatment at different temperatures

heat treatment temperature

Tensile strength (MPa)

800℃	2.04
900°C	4.15
1000℃	2.85
1100°C	2.10
1200℃	0.58

Example 3

This implementation provides a thermal insulation material, the preparation method of which is different from Example 1 in that 7g of 10wt% PVA aqueous solution and 7g of silica sol (the mass ratio of 10wt% PVA to silica sol is 1:1) are used in step 2). ) uniformly mixed to form an electrospinning precursor sol. The prepared SiO ₂ ceramic nanofiber membrane has an average diameter of 263nm and a thermal conductivity of 0.063W/mK.

Example 4

This implementation provides a thermal insulation material, the preparation method of which is different from Example 1 in that step 2) uses 5g of 10wt% PVA aqueous solution and 10g of silica sol (the mass ratio of 10wt% PVA to silica sol is 1:2 ) uniformly mixed to form an electrospinning precursor sol. The prepared SiO ₂ ceramic nanofiber membrane has an average diameter of 283nm and a thermal conductivity of 0.053W/mK.

Example 5

This implementation provides a thermal insulation material, the preparation method of which is different from Example 1 in that 2g of 10wt% PVA aqueous solution and 10g of silica sol (the mass ratio of 10wt% PVA to silica sol is 2:5) are used in step 2). ) uniformly mixed to form an electrospinning precursor sol. The prepared _SiO2 ceramic nanofiber membrane has an average diameter of 350nm.

Example 6

This implementation provides a thermal insulation material. The preparation method is different from Example 1 in that step 3) is replaced by: put the above spinning solution into a 10ml syringe, use a spinneret with an inner diameter of 0.60mm, and electrospin The control humidity is 25% when spinning, the working voltage of the equipment is 16kV, the injection rate is 1.5ml/h, the tin foil roller is used as the receiving device, the speed is 60r/min, and the distance between the spinning needle and the tin foil is 8cm, and electrospinning is carried out To prepare PVA/SiO ₂ composite nanofibrous membrane. The average diameter of the PVA/SiO ₂ composite nanofiber membrane is 315nm, the average fiber diameter of the SiO ₂ ceramic nanofiber membrane after removing organic matters is 298nm, and the thermal conductivity is 0.054W/mK.

Example 7

This implementation provides a thermal insulation material. The difference between its preparation method and Example 1 is that the calcination temperature in step 5) is 900°C, and the control parameters of the calcination process are: from room temperature to 900°C, and the heating rate is 5°C /min, and held at a final temperature of 900°C for 2h. The fiber interpenetrating network of the SiO ₂ ceramic nanofiber membrane calcined at 900°C to remove organic matter was higher than that of Example 1, from 2.037MPa to 4.145MPa.

Example 8

This implementation provides a thermal insulation material, the preparation method of which is different from Example 1 in that in step 7), the _SiO2 ceramic nanofiber membrane in step 5) is soaked in the hydrophobic modifier prepared in step 6), and placed in Modification treatment in a vacuum oven at 60°C for 8 hours. Then place it in an oven at 60°C and dry it in air atmosphere for 10h to obtain a _SiO2 ceramic nanofiber membrane with good hydrophobic properties.

Example 9

This implementation provides a thermal insulation material, the preparation method of which is different from that of Example 1 in that in step 3), the PVA/ _SiO2 composite nanofiber membrane prepared by electrospinning is stacked in multiple layers, and laminated after stacking Or hot pressing to prepare a felt-like material.

Example 10

This embodiment provides a thermal insulation material, the preparation method of which comprises the following steps:

1) At room temperature, weigh 5g of polyvinyl alcohol powder and dissolve it in 45g of ultrapure water to prepare a polymer solution with a mass fraction of 10wt%;

2) At room temperature, 5 g of the above polymer solution and 10 g of neutral silica sol (polymer solution and silica sol in a mass ratio of 1:2) were mixed and stirred for 2 hours to obtain a precursor sol for electrospinning;

3) Put the above-mentioned spinning solution into a 10ml syringe, use a spinning needle with an inner diameter of 0.50mm, control the humidity at 35% during electrospinning, the operating voltage of the equipment is 14kV, and the injection rate is 1.1ml/h. The drum is the receiving device, the rotating speed is 50r/min, the distance between the spinning needle and the tin foil is 10cm, and electrospinning is carried out to prepare PVA/SiO Composite nanofiber membrane;

4) Place the PVA/SiO2 composite nanofiber membrane obtained in step 3) in an oven at 50° C. for 30 minutes to remove static electricity and facilitate storage and subsequent operations;

5) The above-mentioned PVA/SiO2 composite nanofiber film is peeled off from the tin foil, and placed in a box furnace to be calcined in an air atmosphere so as to remove organic components to obtain SiO2 ceramic nanofibers with flexibility. The parameters of the calcining process are: from The temperature is raised from room temperature to 800°C, the heating rate is 5°C/min, and the temperature is kept at 800°C for 1 hour;

6) At room temperature, add 6g of silane coupling agent (KH-570) to 20g of ethanol, stir to mix and add 1wt% dilute nitric acid dropwise, adjust the pH of the mixed solution to 3, and then stir for 2h to make the silane coupling The coupling agent is fully hydrolyzed to obtain a hydrophobic modifier;

7) Soak the SiO2 ceramic nanofiber membrane in step 5) in the hydrophobic modifier prepared in step 6), and place it in an oven at 60° C. for 4 hours;

8) Take out the SiO2 ceramic nanofiber membrane in step 7) from the hydrophobic modifier, and place it in a 60° C. oven to dry for 8 hours to remove the solvent to obtain a SiO2 ceramic nanofiber membrane with hydrophobic properties;

9) The SiO prepared above The interior of the ceramic nanofiber membrane is a three-dimensional interpenetrating network structure composed of ceramic fibers, and the average diameter of the ceramic fibers is 338nm.

Example 11

This implementation provides a thermal insulation material, the preparation method of which is different from that of Example 10 in that the calcination temperature in step 5) is selected as 900°C, and the control parameters of the calcination process are: from room temperature to 900°C, with a heating rate of 5 °C/min with a final temperature of 900 °C for two hours. The fiber interpenetrating network of the SiO2 ceramic nanofiber membrane calcined at 900° C. to remove organic matter was higher than that in Example 1, from 2.037 MPa to 4.145 MPa.

Example 12

This embodiment provides a thermal insulation composite material, the preparation method of which comprises the following steps:

(1) Silica sol preparation: Silica sol is prepared by mixing silicon source, water, alcohol solvent, and silicon micropowder, adding a hydrolysis catalyst to the silica sol to accelerate the hydrolysis of the silicon source, and obtain silica sol faster. The silicon source can be sodium silicate, ethyl orthosilicate, methyl orthosilicate, tetrapropoxysilane, tetrabutoxysilane, dimethyldimethoxysilane or dimethyldiethoxysilane or its combination. The particle size range of silica powder is 600 mesh-1500 mesh. The hydrolysis catalyst can be selected from hydrochloric acid, oxalic acid, nitric acid, sulfuric acid, phosphoric acid or a combination thereof. The alcohol solvent can be methanol, ethanol or a combination thereof. An opacifying agent can also be added to the silica sol to enhance the temperature insulation performance at high temperature, and the opacifying agent includes titanium dioxide, carbon black, SiC, potassium hexatitanate, ZrO2 _, etc. Further, titanium dioxide may be anatase titanium dioxide. Further, the titanium dioxide can be fluorine-doped or nitrogen-doped titanium dioxide nanoparticles to enhance the shading effect of infrared radiation.

(2) Preparation of rare earth silica sol: preparing a rare earth compound into a rare earth solution, and mixing the rare earth solution with the silica sol to obtain the rare earth silica sol. The rare earth compound can be yttrium metal salt, scandium metal salt, neodymium metal salt, ytterbium metal salt; yttrium metal oxide, scandium metal oxide, neodymium metal oxide, ytterbium metal oxide.

Further, yttrium metal salt can be yttrium nitrate, yttrium chloride, yttrium oxalate, yttrium carbonate; scandium metal salt can be scandium nitrate, scandium chloride, scandium oxalate, scandium carbonate; neodymium metal salt can be neodymium nitrate, neodymium chloride , yttrium oxalate, neodymium carbonate; ytterbium metal salt can be ytterbium nitrate, ytterbium chloride, ytterbium oxalate, ytterbium carbonate.

Further, the rare earth solution may contain one or one of the above rare earth compounds.

(3) Preparation of fiber prefabricated parts: preparing a high molecular polymer solution, which is prepared from PVA powder and ultrapure water; preparing SiO precursor spinnable sol, mixing the polymer solution with silica sol and stirring evenly to obtain a The precursor sol of electrospinning performance; the above obtained SiO2 precursor is electrospun to obtain PVA/SiO2 composite ceramic nanofiber membrane, and it is placed in an oven to remove residual static electricity; the prepared PVA/SiO2 The composite ceramic nanofiber membrane is calcined in a box furnace to remove organic matter, and obtain flexible SiO2 ceramic nanofibers.

(4) Modification of fiber prefabricated parts: SiO2 ceramic nanofiber membrane is soaked in the hydrophobic modifier, and hydrophobic modifier contains silane coupling agent and ethanol, and SiO2 ceramic nanofiber membrane is vacuum-dried after soaking.

(5) Gel preparation: add a gel catalyst to the rare earth silica sol, pour it into the modified fiber preform, and then let it stand for 24-72 hours to obtain a gel.

Furthermore, the reinforcing fiber and the fiber dispersant can also be added after adding the gel catalyst. The fiber dispersant can be sodium lauryl sulfonate, polyethylene glycol, sodium lauryl sulfate, sodium hexametaphosphate, etc.

The rare earth silica sol is transformed into a rare earth doped gel by adding a gel catalyst, and the gel catalyst is ammonia water, dimethylformamide, ammonia water ethanol dilution and the like.

(6) Drying: drying the rare earth doped gel to obtain a rare earth doped airgel-ceramic nanofiber composite material. The drying method may be normal temperature and normal pressure drying, critical drying, supercritical drying and the like. The drying medium of critical drying and supercritical drying can be CO2, methanol or ethanol. The obtained rare earth-doped airgel-ceramic nanofiber composite material can be used as a thermal insulation layer.

The conditions for drying at normal temperature and pressure are to dry at 60, 80 and 120° C. for 2 hours respectively, and finally obtain white SiO ₂ airgel powder.

The condition of carbon dioxide supercritical drying is that in the case of ethanol as the solvent, soak with liquid carbon dioxide at 5°C and 5.5MPa for 3 days, and release the replaced ethanol; then raise the temperature to 35°C and 10.5MPa and keep it for 3h, then Slowly release the pressure to normal pressure at a rate of 0.5 MPa/h to obtain the final product.

The condition of ethanol supercritical drying is that after raising the temperature and pressure to the critical point according to the preset program, the fluid inside the reactor is released at a slow speed at a constant temperature until the internal and external pressures are balanced. Before heating up, _N2 can be used to pre-fill the reactor. The pressure of pre-filling _N2 is 1-4MPa. When the temperature rises above 240°C, the heating rate is 0.5-2°C/min. When the pressure exceeds 8MPa, turn on the cooling device and release the pressure slowly. , after releasing the pressure to normal pressure, N ₂ was introduced to purge the reactor, and after cooling to room temperature, the final product was obtained.

Example 13

The present invention also provides a smoke prevention and exhaust air duct, the smoke prevention and exhaust air duct includes a metal pipe, the inner wall and/or outer wall of the metal pipe is provided with a heat shielding layer, the heat shielding layer includes a heat insulating layer, and the heat insulating layer Including the above-mentioned thermal insulation material or the above-mentioned thermal insulation composite material, or, the thermal insulation layer includes a skeleton, a filler, an anti-shrinkage additive and a high-temperature-resistant additive.

According to an embodiment of the present invention, the heat shielding layer further includes at least one of a heat conducting layer and a heat reflecting layer.

According to one embodiment of the present invention, the filler includes silica aerogel, aluminum silicate aerogel, alumina aerogel, composite silica aerogel, rare earth doped silica aerogel at least one of . Exemplarily, the filler has a core-shell structure, wherein the shell is aluminum silicate and/or alumina aerogel, the core is silica aerogel, or the shell is silica aerogel and the core is aluminum silicate and/or alumina aerogels. Alternatively, the airgel may be a silica/alumina composite aerogel in which silica and alumina are composited.

Further, the skeleton is made of fiber material, which may be at least one of aluminum silicate fiber, alumina fiber, glass fiber, mullite fiber, and SiO ₂ ceramic nanofiber.

Further, the high temperature resistant additive may be aluminum silicate, quartz powder, silicon micropowder and the like.

Further, the anti-smoke air duct has a quick connection function, specifically, the anti-smoke air duct is quickly spliced by a front air duct unit and a rear air duct unit. The main structure of each air duct unit includes a metal main frame, an inner wall heat shielding layer attached to the inner wall of the frame, an outer wall heat shielding layer attached to the outer wall of the frame, and a fire-resistant sealant attached to the outside of the outer wall heat shielding layer. Wherein, the heat shielding layer of the inner wall, the metal main body frame, the heat shielding layer of the outer wall, and the outer refractory sealant are sequentially covered and connected, and the connection method can be physical or chemical connection methods such as rivet fixing and adhesion. The heat shielding layer of the inner wall and the heat shielding layer of the outer wall can be composed of a single layer or multiple layers of a heat insulating layer, a heat conducting layer and a heat reflecting layer. In addition, in order to enable the air duct units to be closely connected to achieve the functions of airtightness, heat insulation, and thermal bridge prevention, each end of each air duct unit is provided with an extension layer and a receiving area.

Further, the smoke prevention air duct includes a front air duct, a rear air duct, a mounting seat, a positioning rod and a positioning cylinder; one end of the front air duct is detachably connected to the rear air duct; the mounting base is symmetrically arranged On the sides of the front air duct and the rear air duct, the positioning rod and the positioning cylinder are correspondingly arranged on the opposite sides of the mounting seats on both sides, and the positioning rod and the positioning cylinder are slidingly fitted; The inner wall and/or outer wall of the front air duct is provided with a heat shielding layer, and the inner wall and/or outer wall of the rear air duct is provided with a heat shielding layer; the heat shielding layer includes at least one of a heat insulating layer, a heat conducting layer, and a heat reflecting layer ; The heat insulation layer is attached to the inner wall and/or outer wall of the front air duct and the rear air duct.

Further, the smoke prevention air duct includes a front air duct and a rear air duct; one end of the front air duct is detachably connected to the rear air duct; both ends of the front air duct and the rear air duct are respectively provided with angle steel Flange; the inner wall and/or outer wall of the front air duct is provided with a heat shielding layer, and the inner wall and/or outer wall of the rear air duct is provided with a heat shielding layer; the heat shielding layer includes a heat insulating layer, a heat conducting layer and a heat reflecting layer At least one of them; the heat insulation layer is attached to the inner wall and/or outer wall of the front air duct and the rear air duct.

Preferably, the above connection assembly includes: a surrounding fixing hoop 120 made of metal or other high temperature resistant materials, bolts 121 and nuts 122, as shown in FIG. 7 . The encircling fixing collar 120 also includes a limit hole, and the width of the encircling fixing collar 120 is not less than the length of the outer wall heat shielding layer 200 extending from the air duct.

The fixing method after the two air duct units are connected can be as follows: the surrounding fixing hoop 120 covers the gap between the metal pipe 100 of the two air duct units and the heat shielding layer 200, the bolts 121 pass through the corresponding limiting holes, and the nuts 122 Tighten securely.

The above technical solution provides a smoke prevention and exhaust air duct structure that can be quickly connected and fixed and has a heat insulation function. The fast connection between the smoke prevention and exhaust air ducts is realized, the work efficiency is improved, and the smoke prevention and exhaust airtightness of the air ducts and the fire resistance performance will not be reduced at the same time, and the practicability is strong. The technical scheme can realize quick connection between two air ducts, improves work efficiency, and at the same time ensures that the air duct's anti-smoke airtightness and fire resistance performance will not be reduced, and has strong practicability.

Further, the present invention provides a technical solution, the inventors made the silica airgel part in the composite silica/aluminosilicate airgel particles or silica/alumina airgel particles Further modification and optimization, although silica airgel and aluminum-containing airgel are composited, the silica airgel itself may shrink and collapse under high temperature conditions. Adding anti-shrinkage additives (such as silicon micropowder) to silica airgel can inhibit and reduce the shrinkage and collapse of silica airgel through the crystal form change and volume change of silica micropowder at high temperature, and further improve the composite silica. /The temperature resistance of aluminum silicate airgel particles or composite silica/alumina airgel particles can further improve the temperature resistance of composite airgel, enhance the performance of heat insulation layer and improve the high temperature of anti-smoke and fire-resistant ventilation pipes Performance.

The application of enhanced airgel materials in the smoke exhaust duct, such as the addition of composite silica/aluminum silicate airgel particles or composite silica/alumina airgel particles for thermal insulation, can achieve better Low heat transfer coefficient and high temperature, so that the airgel material can be used in the field of anti-smoke and exhaust ducts, enhance the heat resistance of the anti-smoke and exhaust ducts, and make the anti-smoke and exhaust ducts work normally when a fire occurs effect. The application of airgel heat insulation material in the smoke prevention and exhaust duct can also reduce the space occupied by the heat insulation material.

This technical solution can also solve the problem that the heat insulation material used in the smoke prevention and exhaust duct in the prior art will absorb water, cause the heat insulation structure to collapse, have a short life, and at the same time occupy a large space due to the high thermal conductivity. In practice, when the air duct in the fire site is partially heated, the structure of the air duct will change and collapse, and the air duct will have defects, resulting in changes in the wind pressure inside the duct, air leakage, and a decrease in the exhaust performance of the air duct. The volume of airgel will shrink in volume at high temperature (above 800 degrees Celsius), which will lead to structural changes and reduce thermal insulation performance. The technical problem to be solved in the embodiment of the present invention is that the thermal insulation layer material will shrink and collapse the internal silica microstructure at high temperature. Problems with materials shrinking and collapsing at high temperatures.

Further, the inventors improved and optimized the filler in the thermal insulation layer, synthesized and used a silica/alumina composite aerogel composed of silica and alumina, and the silica in the composite aerogel The silicon portion provides excellent thermal insulation, and the alumina portion provides excellent temperature resistance. The combination of alumina and silica molecules can inhibit and reduce the shrinkage, melting and crystal form change of silica molecules at high temperature on the microscopic level, and reduce the powder shedding of the thermal insulation layer (airgel felt) on the macroscopic level, making The filler still has thermal insulation performance under high temperature conditions, and maintains relatively good physical and chemical properties to meet the use requirements.

Further, the inventor improved the internal structure of the silica airgel material by modifying and optimizing the silica airgel, and made the aluminum oxide/aluminum oxide with better fire resistance but slightly worse heat insulation performance Salt materials are combined with silica airgel to form composite silica airgel particles with an outer shell of aluminum oxide/aluminum salt and a core of silica airgel, or to form a shell of silica airgel with a The inner core is a composite silica airgel particle of aluminum oxide/aluminum salt. In this way, the silica airgel can be kept stable at high temperature, and at the same time, the composite particles have good heat insulation performance, and can also maintain good physical and chemical properties. Applying it to the heat insulation layer can meet the requirements of smoke prevention and ventilation. Pipeline usage requirements.

Furthermore, the inventors doped the silica airgel with rare earths. Specifically, since the rare earth doping can increase the use temperature of the silica airgel, the application of the airgel under high temperature and extreme conditions can be expanded. It can control the density and microstructure of the aerogel, and further control the anion content in it, thereby controlling the thermal conductivity of the aerogel and its performance at high temperatures. Rare earth elements that can be doped include yttrium, scandium, neodymium and ytterbium.

This technical solution solves the problem that airgel cannot meet the heat resistance and fire prevention requirements of the smoke and exhaust duct, and at the same time makes the heat insulation layer have the characteristics of good heat preservation, sound attenuation and sound absorption, moisture resistance, small air leakage, long service life, and reasonable cost performance. The inventors also found that although silica airgel has very good thermal insulation performance, its high temperature resistance has a certain degree of defects. Traditional silica airgel begins to melt when it exceeds 600°C, and nanopores begin to melt when it exceeds 800°C. Collapsed, when the temperature is higher than 1000 ℃, the heat preservation effect has been basically lost, and it cannot meet the requirements of the standard for smoke prevention and exhaust ducts.

This technical solution can also solve the problem that the heat insulation material used in the smoke prevention and exhaust duct in the prior art will absorb water, cause the heat insulation structure to collapse, have a short life, and at the same time occupy a large space due to the high thermal conductivity. In practice, when the air duct in the fire site is partially heated, the structure of the air duct will change and collapse, and the air duct will have defects, resulting in changes in the wind pressure inside the duct, air leakage, and a decrease in the exhaust performance of the air duct.

Example 14

The present invention also provides a smoke-exhaust and fire-resistant ventilation duct. The smoke-exhaust and fire-resistant ventilation duct includes a metal pipe, the inner wall and/or outer wall of the metal pipe is provided with a heat shielding layer, and the heat shielding layer includes a high-temperature expansion layer and a heat-insulating layer. It includes at least one of a heat conduction layer and a heat reflection layer, and the heat insulation layer adopts the above-mentioned thermal insulation material or thermal insulation composite material.

According to an embodiment of the present invention, the high-temperature expansion layer includes a high-temperature foaming agent, multifunctional carbon particles, and a stabilizer. The foaming temperature of the high-temperature foaming agent is greater than 500°C, and the high-temperature foaming agent is silicon carbide powder or granules. The multifunctional carbon particles can be graphite, graphene. The stabilizer is manganese dioxide. The thickness of the high-temperature expansion layer is 1-5mm, and the thickness after expansion is 20-100mm. A preferred solution is to further include airgel particles to improve the thermal insulation performance of the high-temperature expansion layer. The mass proportion of airgel particles added is 3-5%. The high-temperature expansion layer may also contain a water reducer, which is sodium tripolyphosphate or sodium hexametaphosphate.

The study found that when the high-temperature expansion layer encounters high temperature, the silicon carbide will expand and foam, the thickness of the high-temperature expansion layer will increase, and the thermal conductivity will decrease. case of thermal radiation. Protect the structural stability of the anti-smoke exhaust duct under high temperature conditions. When the high-temperature expansion layer is not foamed (below 500°C), the multi-functional carbon particles have a relatively good heat conduction function because they are still in a tightly pressed state, which can quickly disperse heat and reduce local overheating. When the temperature exceeds 500°C, the overall temperature cannot be lower than the temperature that the exhaust duct can withstand through heat conduction and dispersion. The high-temperature expansion layer expands and foams, and the multifunctional carbon particles in it are not tightly connected due to being dispersed. Thermal conductivity disappears, the high-temperature expansion layer changes from a heat-conducting function to a functional layer with high-temperature heat-insulating properties. At the same time, under this condition, these multifunctional carbon particles can absorb infrared rays and act as a sunscreen, further improving the heat insulation performance under high temperature conditions.

Example 15

In one technical solution involved in the present invention, there is provided a smoke prevention and exhaust air duct with a fast connection and fixing structure, and the air duct is formed by splicing air duct units.

Among them, the main structure of each air duct unit is shown in Figure 7 and Figure 8, including the metal main frame, the inner wall heat shielding layer attached to the inner wall of the frame, the outer wall heat shielding layer attached to the outer wall of the frame, and the outer wall heat shielding layer. Fire-resistant sealant attached to the outside of the layer. Wherein, the heat shielding layer of the inner wall, the metal main body frame, the heat shielding layer of the outer wall, and the outer refractory sealant are sequentially covered and connected, and the connection method can be common physical or chemical connection methods such as rivet fixing and adhesion. The heat shielding layer of the inner wall and the heat shielding layer of the outer wall can be composed of a single layer or multiple layers of heat insulating layer, heat conducting layer and reflective layer. In addition, in order to enable the air duct units to be closely connected to achieve the functions of airtightness, heat insulation, and thermal bridge prevention, each end of each air duct unit is provided with an extension layer and a receiving area.

Preferably, the metal main frame is a color steel plate.

Preferably, the surface of the metal body frame is coated with an antibacterial coating.

Wherein, the extension layer refers to the structural layer extending outward from the main structure along the direction parallel to the pipe wall at one end of an air duct unit. The receiving area refers to the other end of the extension layer on the air duct unit, which is reserved for connecting with the extension layer of another air duct unit. When two air duct units are connected, it should be the end with the extension layer and the The ends with the receiving area are connected, and after the connection, the two air duct units can be closely fitted at the joint and fixed by the connecting component at the joint. Depending on the structure of the extension layer, at the end with the receiving area, the structure of the air duct unit can be extended in a single layer or multi-layer according to the structure of the extension layer, so that it can be attached to the extension layer when the air duct unit is connected. The part of the structure that is extended at the receiving end is defined as the extended receiving layer.

Preferably, there are two air duct units to be connected, and the two air ducts have the same structure, both of which include the main body of the air duct unit, the extension layer and the receiving area, excluding the extension receiving layer. The main body of the air duct unit is composed of a metal pipe, a heat shielding layer on the inner wall of the metal pipe, and a heat shielding layer on the outer wall of the metal pipe. The extension length in the direction is the same as the reserved width of the receiving area along the direction parallel to the pipe wall.

The connection method is: one end of an air duct unit with an extension layer is connected to the end of another air duct unit with a receiving area, and the metal pipes of the two air duct units are in contact, and the extended outer wall heat shield is in contact. One air duct unit has an outer wall heat shield extending from one end of the extension layer, and covers the metal pipe at the other end of the air duct unit having a receiving area. After connecting, the two air duct units fit tightly and are fixed by the connecting components.

Preferably, the above-mentioned connection assembly includes: a surrounding fixing hoop made of metal or other high-temperature-resistant materials, bolts, and nuts. Wherein the wrap-around fixing hoop also includes limit holes, and the width of the wrap-around fixing hoop is not less than the length of the heat shielding layer of the outer wall extending from the air duct.

The fixing method after the two air duct units are connected can be as follows: the surrounding fixing hoop covers the gap between the metal pipes of the two air duct units and the heat shielding layer, the bolts pass through the corresponding limiting holes, and are tightened with nuts.

The air duct can be rectangular, the length of the long side of the air duct is b≤500mm, the distance between the supports and hangers is d≤2800mm; Side length b≤2000mm, support and hanger spacing d≤1400.

The size of the rectangular duct can be 120mm, 160mm, 200mm, 250mm, 320mm, 400mm, 500mm, 630mm, 800mm, 1000mm, 1250mm, 1600mm, 2000mm, 2500mm, 3000mm, 3500mm, 4000mm.

Preferably, the two air duct units to be connected are respectively provided with angle steel flange structures for connection at both ends, and the flanges are made of metal or other high temperature resistant materials. The two angle steel flange structures on both sides of the connection joint of the pipe unit can be closely fitted and fixed by the connection component.

Preferably, the above connection assembly includes: a plurality of bolts and nuts made of metal or other high temperature resistant materials. The connection method is that the nut passes through the limit hole on the corresponding angle steel flange, and is fixed and locked by bolts.

Example 16

In order to achieve the performance of temperature insulation and high temperature resistance, conventional smoke control and exhaust ducts usually use thicker heat insulation materials and higher grade refractory materials to block heat transfer, so as to meet the requirements of temperature insulation and high temperature resistance. The inventors have found that, in an emergency, the smoke prevention and exhaust duct is often partially affected by high temperature, thereby affecting its structural stability. Most of the rest of the smoke prevention and exhaust positions have not reached the design limit and have performance problems. Therefore, the inventor believes that the method of heat conduction, heat insulation and temperature resistance can be used to diffuse the local high temperature to the rest of the smoke prevention and exhaust duct, reduce the local high temperature so that the smoke prevention and exhaust duct can withstand higher temperatures.

In a technical solution involved in the present invention, a smoke prevention air duct is provided, the smoke prevention air duct includes a metal pipe 100, the inner wall and/or outer wall of the metal pipe 100 is provided with a heat shielding layer 200, and the heat shielding layer 200 includes At least one of the heat insulating layer 210 , the heat conducting layer 220 , and the heat reflecting layer 230 . The thermal insulation layer can use the thermal insulation material mentioned above or the thermal thermal insulation composite material mentioned above.

The heat conduction layer 220 can be a metal heat conduction plate, such as high heat conduction metal materials such as copper and aluminum; it can also be a heat conduction metal structure, such as a hollow heat conduction interlayer; it can also be the heat conduction layer 220 of a device provided with a heat pipe.

The heat conducting layer 220 , the heat reflecting layer 230 , and the heat insulating layer 210 are sequentially stacked to form the heat shielding layer 200 . Another arrangement is that the heat reflection layer 230 , the heat conduction layer 220 , and the heat insulation layer 210 are stacked in sequence to form the heat shielding layer 200 . The heat insulating layer 210 is attached to the inner wall and/or the outer wall of the metal pipe 100 .

A smoke prevention air duct includes a front air duct 140 and a rear air duct 150, and one end of the front air duct 140 is detachably connected to the rear air duct 150.

Further, the smoke prevention and exhaust air duct also includes a mounting base 160, a positioning rod 161 and a positioning cylinder 162. The mounting base 160 is symmetrically arranged on the sides of the front air duct 140 and the rear air duct 150, and the positioning rod 161 and the positioning cylinder 162 correspond to They are arranged on opposite sides of the mounting bases 160 on both sides, and the positioning rod 161 and the positioning cylinder 162 are slidably matched, as shown in FIG. 8 .

Further, a first connection assembly and a second connection assembly are provided between the front air pipe and the rear air pipe; the first connection assembly includes a limit hole, a guide hole, a limit rod and a nut, and the limit hole runs through the vertical The upper and lower ends of the groove, the guide hole runs through the upper and lower ends of the vertical rod, and the guide hole corresponds to the limit hole, the limit rod is matched with the guide hole, and the nut is threaded on the limit rod. top.

Example 17

In order to achieve the performance of temperature insulation and high temperature resistance, conventional smoke control and exhaust ducts usually use thicker heat insulation materials and higher grade refractory materials to block heat transfer, so as to meet the requirements of temperature insulation and high temperature resistance. The inventors have found that, in an emergency, the smoke prevention and exhaust duct is often partially affected by high temperature, thereby affecting its structural stability. Most of the rest of the smoke prevention and exhaust positions have not reached the design limit and have performance problems. Therefore, the inventor believes that the method of heat conduction, heat insulation and temperature resistance can be used to diffuse the local high temperature to the rest of the smoke prevention and exhaust duct, reduce the local high temperature so that the smoke prevention and exhaust duct can withstand higher temperatures.

In one technical solution involved in the present invention, a smoke prevention air duct is provided, the smoke prevention air duct includes a metal pipe, the inner wall and/or outer wall of the metal pipe is provided with a heat shielding layer, and the heat shielding layer includes a heat insulating layer, a heat conducting At least one of layer, heat reflective layer. The thermal insulation layer can use the thermal insulation material mentioned above or the thermal thermal insulation composite material mentioned above.

The heat conduction layer can be a metal heat conduction plate, such as copper, aluminum and other metal materials with high heat conduction performance; it can also be a heat conduction metal structure, such as a hollow heat conduction interlayer; it can also be a heat conduction layer of a device provided with a heat pipe.

The heat conducting layer, the heat reflecting layer and the heat insulating layer are stacked in sequence to form the heat shielding layer. Another arrangement is that the heat reflection layer, the heat conduction layer, and the heat insulation layer are stacked in sequence to form a heat shielding layer. The thermal insulation layer is attached to the inner wall and/or outer wall of the metal pipe.

The form of the heat conduction layer includes silica gel heat dissipation film, graphite heat dissipation film, metal heat conduction plate, heat pipe heat conduction plate. The material of the metal heat conducting plate can be a copper plate or an aluminum plate. The form of the heat conduction layer can also be a channel with a heat conduction structure, such as a double-layer hollow metal heat conduction plate. The range of thermal conductivity of the heat conducting layer at 800°C is 20W/m·K-50W/m·K.

Setting a heat conduction layer on the smoke exhaust duct can enhance the heat conduction and heat dissipation performance of the smoke exhaust duct, prevent local high temperature, and prevent the internal silica airgel particles from melting at high temperatures such as 600 ° C, so that the heat insulation layer can be used at high temperatures It can still maintain the structure stability under the circumstances, and meet the use requirements of the smoke prevention and exhaust duct.

The inventor also believes that the local high temperature can be reduced by setting a heat absorbing layer inside the smoke prevention and exhaust duct, so that the smoke prevention and exhaust duct can withstand higher temperatures.

In one technical solution involved in the present invention, a smoke prevention air duct is provided, the smoke prevention air duct includes a metal pipe, the inner wall and/or outer wall of the metal pipe is provided with a heat shielding layer, the heat shielding layer includes a heat insulating layer, and the heat insulating The layer can use the above heat insulation material or the above heat insulation composite material, and the heat shielding layer can also include at least one of a heat conducting layer, a heat reflecting layer, and a heat absorbing layer.

A preferred method is that the heat conducting layer, the heat reflecting layer, the heat absorbing layer and the heat insulating layer are stacked in sequence to form the heat shielding layer. The heat conducting layer, the heat reflecting layer, the heat absorbing layer and the heat insulating layer are stacked in sequence to form a heat shielding layer. Another arrangement is that the heat reflective layer, the heat absorbing layer, and the heat insulating layer are stacked in sequence to form a heat shielding layer. The thermal insulation layer is attached to the inner wall and/or outer wall of the metal pipe.

The heat absorbing layer is composed of heat storage materials. The heat storage materials can be phase change materials, heated volatile materials, etc., and can also be preset cooling materials such as preset water tanks, preset carbon dioxide tanks, etc., which can be released when encountering high temperatures. The loaded water, carbon dioxide and other cooling carriers absorb heat. The phase change material can absorb heat and keep the temperature constant, so that in the case of local high temperature, the absorbed heat produces a phase change without increasing the temperature, thereby protecting the airgel structure of the heat insulation layer from collapsing, so that the heat insulation layer maintains the heat insulation effect , so that the entire heat shielding layer can still maintain the temperature insulation effect at high temperatures.

Phase change materials are molten salts, and molten salts include carbonates, chloride salts, and fluoride salts.

Installing a heat absorbing layer in the smoke exhaust duct can reduce the temperature of the smoke exhaust duct, prevent local high temperature, and prevent the internal silica airgel particles from melting at high temperatures such as above 600°C, so that the airgel heat insulation can reach the use Require.

The heat insulating layer, the heat conducting layer, the heat reflecting layer and the heat absorbing layer are fixed to each other by bonding and hot pressing. The outside of the heat shielding layer can also be wrapped with glass fiber cloth and aluminum foil to prevent the filler from breaking and falling off.

The invention breaks through the characteristics of poor mechanical properties and brittleness of traditional ceramics, has good softness, and also retains the high temperature resistance characteristics of _SiO2 materials. First, combining the characteristics of electrospinning, the high molecular polymer solution is mixed with neutral silica sol to prepare spinnable sol; then, under certain humidity and temperature conditions, electrospinning is used to prepare organic/inorganic hybrid nanofiber membranes; In an air atmosphere, the calcination temperature was controlled to remove the organic components in the fiber membrane to obtain a SiO ₂ ceramic nanofiber membrane; finally, the prepared SiO ₂ ceramic nanofiber membrane was hydrophobically modified by using a silane coupling agent. The present invention adopts the commercialized silica sol as raw material, has simple process, short preparation period, and good formability. Experiments show that the _SiO2 ceramic nanofiber membrane prepared by the present invention has a three-dimensional interpenetrating network structure composed of ceramic fibers and has low thermal conductivity. The average fiber diameter is 200-350nm, the thickness of the ceramic fiber membrane is 0.102-0.1836mm, the tensile strength is 0.51-4.145Mpa, and the thermal conductivity is 0.04141-0.07416W/mK. The _SiO2 ceramic nanofiber membrane of the present invention has good mechanical properties, light weight, and good hydrophobicity, and is expected to be applied in aerospace fields and high-temperature and humid environments to realize high-efficiency heat insulation.

The above-mentioned embodiments are only preferred embodiments of the present invention, and should not be considered as limiting the implementation scope of the present invention. All equivalent changes and improvements made according to the application scope of the present invention shall still belong to the scope covered by the patent of the present invention.

Claims (26)

1. A kind of thermal insulation material, it is characterized in that, described thermal insulation material is a kind of membrane material or felt material, is a kind of flexible material; In the described thermal insulation material, comprise SiO ₂ ceramic nanofibers constitute three-dimensional The interpenetrating network structure, the average diameter of the fiber is 200nm-350nm.
2. The thermal insulation material according to claim 1, wherein the thermal insulation material has at least one of the following properties:

   1) High temperature resistance, can be used at 800 ~ 1200 ℃;

   2) The density (g/cm) is between 0.08 and 0.20;

   3) The thermal conductivity is 0.04～0.08W/mK;

   4) The tensile mechanical strength is 0.5-4.5MPa;
3. The thermal insulation material according to claim 1 or 2, characterized in that, the thermal insulation material further includes an opacifying agent;

   And/or, the fiber is a nano hollow fiber with a hollow structure.
4. The thermal insulation material according to claim 3, characterized in that, the surface of the thermal insulation material has hydrophobic functional groups.
5. The thermal insulation material according to claim 3, characterized in that the thickness of the film-like material is 0.5mm-5.0mm.
6. The thermal insulation material according to claim 3, characterized in that the thickness of the felt-like material is 0.5cm-5cm.
7. A method for preparing the thermal insulation material according to any one of claims 1-6, characterized in that the method comprises the following steps:

   1) preparation of spinning aids: template polymer and water to prepare high molecular polymer solution as spinning aids;

   2) prepare SiO ₂ precursor spinnable sol: mix high molecular polymer solution and silica sol in step 1), obtain SiO ₂ precursor spinnable sol; The weight ratio of described high molecular polymer solution and silica sol is 1: (1~6);

   3) Preparation of thermal insulation material: the _SiO2 precursor spinnable sol in step 2) is prepared by electrospinning to obtain a film-like material or a felt-like material, and after the static electricity is removed, it is calcined to obtain the thermal insulation material;

   Preferably, the method further comprises the steps of:

   4) Preparation of thermal insulation material with hydrophobic properties: The thermal insulation material in step 3) is subjected to hydrophobic modification treatment with a hydrophobic modifier, and dried to obtain the thermal insulation material with hydrophobic properties.
8. The preparation method of thermal insulation material according to claim 7, characterized in that, the template polymer is PVA powder; the PVA powder is 1788 type.
9. The preparation method of thermal insulation material according to claim 7, characterized in that the mass fraction of the high molecular polymer solution is 10% to 12%.
10. The preparation method of thermal insulation material according to claim 7, characterized in that the pH value of the silica sol is 8.5-9.0, the concentration is 2-4mol/L, the mass fraction is 15-25%, and the density is 0.957 g/cm ³ .
11. The preparation method of thermal insulation material according to claim 7, characterized in that, the mass ratio of the high molecular polymer solution to the silica sol can be 1:1, 1:2, 1:3, 1 :4, 1:5 or 1:6.
12. The preparation method of thermal insulation material according to claim 7, characterized in that the inner diameter of the electrospinning needle is 0.50 mm to 0.60 mm; the parameters of the electrospinning are: relative humidity 25% to 45%, extrusion The output speed is 0.9~1.5ml/h, the voltage is 12~16kv, the distance between the receiving device and the spinneret is 8~10cm, the spinning time is 1h~4h, the metal drum is used as the receiving device, and the drum speed is 40~ 70r/min.
13. The preparation method of thermal insulation material according to claim 12, characterized in that, the needle is a coaxial cannula needle, and the coaxial cannula needle comprises an inner layer needle and an outer layer needle, and the inner layer needle The cannula is kept coaxial within the outer needle.
14. The preparation method of thermal insulation material according to claim 13, characterized in that, the inner layer needle flows the polymer solution, and the _SiO2 precursor flowing between the inner layer needle and the outer layer needle can be spun Sol.
15. A thermal insulation composite material, characterized in that the composite material is a composite of the thermal insulation material described in any one of claims 1-6 and silica aerogel or rare earth doped silica aerogel thing.
16. The thermal insulation composite material according to claim 15, characterized in that, the composite material is a composite of the above thermal insulation material and silica airgel, the composite includes a skeleton and a filler, and the thermal insulation The material is used as a skeleton, and the silica airgel is used as a filler;

    Alternatively, the composite material is a composite of the above thermal insulation material and rare earth doped silica aerogel, the composite includes a skeleton and a filler, the thermal insulation material serves as a skeleton, and the rare earth doped silica Airgel as filler.
17. The thermal insulation composite material according to claim 15 or 16, characterized in that, the airgel further includes microsilica powder;

    And/or, the aerogel further includes an opacifying agent.
18. The thermal insulation composite material according to claim 17, wherein the opacifying agent includes at least one of titanium dioxide, carbon black, SiC, potassium hexatitanate, and ZrO ₂ .
19. The thermal insulation composite material according to claim 18, characterized in that the titanium dioxide is anatase titanium dioxide.
20. The thermal insulation composite material according to claim 18, wherein the titanium dioxide is fluorine-doped or nitrogen-doped titanium dioxide nanoparticles.
21. A method for preparing a thermal insulation composite material according to any one of claims 15-20, characterized in that said method comprises the following steps:

    S1. Prepare silica sol: prepare silica sol by mixing silicon source, water, and alcohol solvent;

    S2. Prepare rare earth silica sol: configure a rare earth compound solution, and mix the rare earth compound solution with the above silica sol to obtain a rare earth silica sol;

    S3. preparing a fiber preform, comprising the following steps:

    S3-1. Preparation of spinning aids: template polymer and water to prepare polymer solution as spinning aids;

    S3-2. Prepare SiO ₂ precursor spinnable sol: mix the polymer solution and silica sol in step S3-1 to obtain SiO ₂ precursor spinnable sol;

    S3-3. Preparing fiber preforms: preparing the _SiO2 precursor spinnable sol in step S3-2 by electrospinning to obtain film-like materials or felt-like materials, after removing static electricity, calcining to obtain fiber preforms;

    S4. Modification of the fiber preform: using a hydrophobic modifier to perform hydrophobic modification on the fiber preform in step S3, and drying to obtain a fiber preform with hydrophobic properties;

    S5. Preparation of gel: After adding a gel catalyst to the silica sol in step S1 or the rare earth silica sol in step S2, pour it into the fiber preform in step S3 or the modified fiber preform with hydrophobic properties in step S4 , stand still, obtain gel;

    S6. Drying: drying the gel in step S5 to obtain the thermal insulation composite material.
22. According to the preparation method of thermal insulation composite material according to claim 21, it is characterized in that, the rare earth compound solution is configured from a rare earth metal salt, and the rare earth metal salt is yttrium metal salt, scandium metal salt, La series metal One or a combination of salts.
23. The preparation method of thermal insulation composite material according to claim 22, characterized in that the La series metal salt is neodymium metal salt or ytterbium metal salt.
24. The preparation method of thermal insulation composite material according to claim 22, characterized in that the yttrium metal salt is Y(NO ₃ ) ₃ ·4H ₂ O.
25. The application of the thermal insulation material according to any one of claims 1-6 or the thermal insulation composite material described in any one of claims 15-20 is characterized in that it is used for thermal insulation in a high temperature and humid environment.
26. An anti-smoke air duct, the anti-smoke air duct includes a metal pipe, the inner wall and/or outer wall of the metal pipe is provided with a heat shielding layer, the heat shielding layer includes a heat insulating layer, and the heat insulating layer includes claim 1 - The thermal insulation material described in any one of claims 6 or the thermal insulation composite material described in any one of claims 15-20.

    

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