Multi-temperature-zone multi-layer composite thermal insulation material and preparation method thereof

Abstract

The application relates to the field of thermal insulation materials, and discloses a multi-temperature-zone multi-layer composite thermal insulation material and a preparation method thereof. The composite thermal insulation material comprises at least one high-temperature-zone thermal insulation layer, at least one medium-temperature-zone thermal insulation layer and at least one low-temperature-zone thermal insulation layer; the high-temperature-zone thermal insulation layer, the medium-temperature-zone thermal insulation layer and the low-temperature-zone thermal insulation layer all comprise inorganic fiber substrates, inorganic thermal insulation powders, SiC particles and sodium silicate colloid; the particle size of the SiC particles in the high-temperature-zone thermal insulation layer, the medium-temperature-zone thermal insulation layer and the low-temperature-zone thermal insulation layer increases and the content decreases. Firstly, by optimizing the particle size and content of SiC in each thermal insulation layer, it can be ensured that the positive effect is greater than the negative effect after introducing SiC in the thermal insulation layers of different temperature zones, so that the thermal insulation performance of the composite material is improved; secondly, by introducing the sodium silicate colloid into the composite thermal insulation material, the thermal insulation performance of the composite thermal insulation material under pressure is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of thermal insulation materials, in particular to a multi-temperature-zone multi-layer composite thermal insulation material and a preparation method thereof. BACKGROUND

[0002] The battery energy storage part and the energy conversion part in the battery pack exist in the same space, and under overcharging, needle puncture, and collision, a chain reaction of heat release is easily caused, resulting in smoke, fire, and even explosion and other thermal runaway accidents. Thermal runaway is the most serious safety accident of power batteries, which directly threatens the life safety of users. In recent years, the thermal runaway propagation problem of the battery pack is mainly solved by thermal protection technology. That is, protective materials are arranged between battery monomers, between battery modules, and between the battery box and the passenger compartment to increase the thermal resistance of heat transfer from the thermal runaway cell to other parts of the battery, so as to hinder the spread of thermal runaway.

[0003] Similarly, the current research on thermal runaway of power battery systems also mainly focuses on solving the thermal runaway safety problem triggered by the thermal runaway of single cells and then spreading to the entire battery pack. Because when a single cell triggers thermal runaway, its heat production increases sharply, and the heat dissipation is much smaller than the heat production, which causes heat to be rapidly transferred to the surrounding cells, rapidly triggering large-scale thermal runaway of the surrounding cells, forming a safety hazard. It can be said that the thermal runaway of the single cell is the source of the thermal runaway of the entire battery pack. Therefore, the thermal protection between cells usually increases the thermal insulation material between the cells to block the spread of thermal runaway from the runaway cell to the surrounding cells, and to reduce the damage and the accompanying destruction of the battery pack.

[0004] Currently, the thermal insulation material between the cells is usually prepared by impregnation, spraying, or supercritical method to prepare aerogel thermal insulation sheets with different substrates. The distribution of aerogel powder in these thermal insulation sheets is uneven. The aerogel powder is mixed with ceramic fibers and different functional additives to form a ceramic fiber aerogel mixed slurry, and then the product thickness is controlled by a filter screen, vacuum suction of part of the water, and drying in an oven. After rolling or slicing, a ceramic fiber aerogel thermal insulation sheet is obtained. Although the distribution of aerogel powder in the material is relatively uniform, in the case of external extrusion, inorganic thermal insulation powder is easily extruded from the substrate, thereby causing the thermal insulation performance of the product to decrease.

[0005] In addition, since the aerogel material (for example, SiO2 aerogel) cannot form a thermal barrier to infrared light in the 3-8 μm band, although the extinction coefficient of the light shielding agent is significantly higher than that of the aerogel material in this range, the introduction of the light shielding agent can effectively improve the thermal conductivity of the aerogel material in the short-wave range, thereby inhibiting high-temperature thermal radiation and further improving the thermal insulation performance of the thermal insulation material. However, researchers have found that the introduction of the light shielding agent can increase the solid-phase thermal conductivity of the material while inhibiting thermal radiation, that is, if the light shielding agent is not properly selected or used, the thermal insulation performance of the aerogel material may be reduced.

[0006] In summary, how to improve the thermal insulation performance of the thermal insulation material under pressure and how to balance the inhibition of thermal radiation (positive effect) and the increase of solid-phase thermal conductivity (negative effect) caused by the introduction of the light shielding agent are technical problems that need to be solved. SUMMARY

[0007] To solve the above technical problems, the present application provides a multi-temperature-zone multi-layer composite thermal insulation material and a preparation method thereof. First, the present application improves the thermal insulation performance of the composite thermal insulation material under pressure by introducing sodium silicate colloid into the composite thermal insulation material. Second, according to the specific use environment, the present application optimizes the particle size and content of SiC particles in each thermal insulation layer, so that the positive effect is greater than the negative effect after the introduction of SiC particles in the thermal insulation layer of different temperature intervals, thereby improving the comprehensive thermal insulation performance of the composite thermal insulation material.

[0008] The specific technical solutions of the present application are as follows:

[0009] In a first aspect, the present application provides a multi-temperature-zone multi-layer composite thermal insulation material, which comprises at least one high-temperature-zone thermal insulation layer, at least one medium-temperature-zone thermal insulation layer, and at least one low-temperature-zone thermal insulation layer from near to far from the heat source.

[0010] The high-temperature-zone thermal insulation layer, the medium-temperature-zone thermal insulation layer, and the low-temperature-zone thermal insulation layer all comprise an inorganic fiber substrate, inorganic thermal insulation powder, SiC particles, and sodium silicate colloid dispersed in the inorganic fiber substrate.

[0011] The particle size of the light shielding particles in the high-temperature-zone thermal insulation layer, the medium-temperature-zone thermal insulation layer, and the low-temperature-zone thermal insulation layer is 1.3-2.5 μm, 2.5-4 μm, and 4-7 μm, respectively, and the content is 0.4-0.6 wt%, 0.3-0.35 wt%, and 0.1-0.2 wt%, respectively.

[0012] Firstly, in order to solve the problem that the existing thermal insulation material is easily extruded under pressure, thereby causing the thermal insulation performance to decrease, the present application introduces sodium silicate colloid into the composite thermal insulation material, and in the preparation process, the sodium silicate aqueous solution (i.e. water glass) is uniformly distributed in the inorganic fiber substrate to form a water glass sol, and then the hydration film in the water glass sol is destroyed by a physical dehydration method, so that the water glass sol becomes a viscous liquid, a semi-solid and then a colloid (sodium silicate) in sequence after losing water. The sodium silicate colloid has a certain strength, so that the hardness of the composite thermal insulation material can be improved, and the anti-pressure deformation capacity is better, thereby improving the thermal insulation performance of the composite thermal insulation material after being pressed.

[0013] Secondly, as described in the background section, although the addition of light shielding agent in the thermal insulation material can effectively improve the light shielding performance of inorganic thermal insulation powder such as aerogel in the short-wave range, thereby playing a role in inhibiting high-temperature radiation. However, the introduction of light shielding agent will also increase the solid-phase heat conduction, which will reduce the thermal insulation performance of the thermal insulation material. Therefore, only when the positive effect of adding light shielding agent is enough to cover its negative effect, can the thermal insulation performance of the thermal insulation material be improved. Therefore, the present application has carried out in-depth research: (a) the present application selects SiC particles as light shielding agent, which is not easy to oxidize at high temperature (> 300℃), and has good high-temperature stability; (b) the present application finds through research that in the incident light wavelength range of 3.0-6.0μm, when the SiC particle size is about 2.0μm, the spectral extinction coefficient of the composite thermal insulation material is the largest; in the incident light wavelength range of 5.5-9.0μm, when the SiC particle size is about 3.0μm, the spectral extinction coefficient of the composite thermal insulation material is the largest; and the maximum spectral extinction coefficient decreases with the increase of the particle size of the light shielding agent, so the optimal addition particle size of SiC particles gradually decreases with the increase of temperature.

[0014] In addition, as to the SiC particle content: when the temperature is about 200℃, the main heat transfer mode of the composite thermal insulation material containing SiC particles is gas-solid heat conduction, and the contribution of radiation heat transfer is small. At this time, the SiC particles have a small effect on the equivalent thermal conductivity of the composite thermal insulation material, and the thermal conductivity of the composite thermal insulation material is the lowest when the SiC particle content is 0.1-0.2wt%. With further increase of the SiC particle content (>0.2wt%), the decrease of the radiation thermal conductivity is less than the increase of the gas-solid heat conduction thermal conductivity, and the equivalent thermal conductivity of the composite thermal insulation material increases with the increase of the SiC particle content, so that too much SiC particles will have an adverse effect. When the temperature is increased to 300℃, the gas-solid heat conduction thermal conductivity of the composite thermal insulation material is basically unchanged, but the radiation thermal conductivity is significantly increased, at this time, the radiation heat transfer becomes the main heat transfer mode, and the radiation heat transfer rapidly decreases with the increase of the SiC particle content. However, when the SiC particle content is further increased, since the thermal conductivity of the SiC particles is much higher than that of the inorganic fiber substrate, the gas-solid heat conduction becomes the main heat transfer mode again. At this time, the thermal conductivity of the composite thermal insulation material is the lowest when the SiC particle content is about 0.3-0.35wt%. Similarly, when the temperature is further increased to above 500℃, the optimal content of the SiC particles needs to be increased to about 0.4-0.6wt%. Therefore, with the increase of the temperature, the SiC content needs to be gradually increased.

[0015] In summary, according to the present application, by optimizing the particle size and content of the SiC particles in each thermal insulation layer, the positive effect is greater than the negative effect after the introduction of the SiC particles in the thermal insulation layer in different temperature ranges, so that the overall thermal insulation performance of the composite thermal insulation material is improved.

[0016] As preferred, the thermal insulation temperatures of the high-temperature zone thermal insulation layer, the medium-temperature zone thermal insulation layer and the low-temperature zone thermal insulation layer are 500-800℃, 300-500℃ and <300℃, respectively.

[0017] According to the composition of the high-temperature zone thermal insulation layer, the medium-temperature zone thermal insulation layer and the low-temperature zone thermal insulation layer in the composite thermal insulation material of the present application, as preferred, the content of the inorganic fiber substrate in the high-temperature zone thermal insulation layer, the medium-temperature zone thermal insulation layer and the low-temperature zone thermal insulation layer is 30-70wt%, the content of the inorganic thermal insulation powder is 20-50wt%, and the content of the sodium silicate colloid is 1-3wt%.

[0018] It is found that the content of sodium silicate is critical. If the content of sodium silicate is too high, the thermal conductivity of the sodium silicate colloid is higher than that of air, and the excessive generation of the sodium silicate colloid will also reduce the porosity of the thermal insulation layer, so that the excessive sodium silicate will reduce the thermal insulation performance of the composite thermal insulation material; if the content of sodium silicate is too low, the improvement effect is limited. Therefore, the content of sodium silicate is controlled within the above range, and the effect is better.

[0019] Preferably, the material of the inorganic fiber substrate is selected from one or more of glass fiber, high-silica fiber, aluminum silicate fiber, alkaline earth silicate fiber, and mullite fiber, preferably aluminum silicate fiber.

[0020] The inorganic thermal insulation powder is selected from one or more of inorganic aerogel powder, fumed silica, precipitated silica, hollow glass microspheres, hollow ceramic microspheres, expanded vermiculite, and expanded perlite.

[0021] Preferably, the multi-temperature-zone multi-layer composite thermal insulation material has a cold face temperature of ≤110℃ after 5 min at 700℃, 0.9 MPa, and a pressure.

[0022] In a second aspect, the present application provides a method for preparing a multi-temperature-zone multi-layer composite thermal insulation material, comprising:

[0023] 1) Add a dispersing agent and a wetting agent to water and stir until uniform, then add inorganic thermal insulation powder, SiC particles, and inorganic fiber one after another and stir after each addition to obtain a slurry; perform papermaking on the slurry, filter and dry to obtain a sheet, then apply a sodium silicate aqueous solution (i.e., water glass) to the surface of the sheet by means of surface gluing, perform negative pressure suction on the sheet to make the sodium silicate uniformly distributed inside the material, and then dry to obtain a high-temperature-zone thermal insulation layer, a medium-temperature-zone thermal insulation layer, and a low-temperature-zone thermal insulation layer.

[0024] 2) Stack the high-temperature-zone thermal insulation layer, the medium-temperature-zone thermal insulation layer, and the low-temperature-zone thermal insulation layer one after another to obtain a multi-temperature-zone multi-layer composite thermal insulation material.

[0025] Preferably, the SiC particles have polyacrylic acid grafted onto their surface, and the preparation method comprises: modifying the SiC particles with an alkenyl silane coupling agent to obtain SiC particles with alkenyl groups grafted onto their surface, and then copolymerizing the SiC particles with acrylic acid monomers under high-energy electron beam irradiation to obtain SiC particles with polyacrylic acid grafted onto their surface.

[0026] The present application finds that SiC particles tend to be lost during the papermaking process, thereby affecting the thermal insulation performance of the composite thermal insulation material. To this end, the SiC particles are modified by grafting polyacrylic acid onto their surface (first modify the SiC particles with an alkenyl silane coupling agent to make them have alkenyl groups on their surface, and then use the alkenyl groups to copolymerize with acrylic acid), and after the above modification, a small amount of polyacrylic acid can promote the flocculation of inorganic fibers to a certain extent during the papermaking process, thereby wrapping the SiC particles in the inorganic fiber substrate and reducing the loss rate. Moreover, compared with adding polyacrylic acid alone, the SiC particles with polyacrylic acid grafted onto their surface can produce interfacial bonding force with the inorganic fibers, and have higher stability.

[0027] As preferred, the energy of the high-energy electron beam is 30-60 kGy, and the amount of the acrylic acid is 10-20 wt% of the SiC particles.

[0028] The present application finds that the amount of the polyacrylic acid used in the modification process has a significant impact on the high-temperature radiation inhibition capability of the SiC particles. If the amount of the polyacrylic acid is too small, the effect of reducing the loss of the SiC particles is limited; otherwise, if the amount is too large, the surface of the SiC particles will be wrapped in a large area, thereby affecting the light-shielding performance.

[0029] As further preferred, the monomer for copolymerization further includes phosphoric acid acrylate, and the mass ratio of the acrylic acid to the phosphoric acid acrylate is (4-6):1.

[0030] In order to further improve the bonding force between the SiC particles and the inorganic fibers in the papermaking forming process, a proper amount of phosphoric acid acrylate can be added to the acrylic acid monomer. After copolymerization, the bonding force between the polymer and the inorganic fibers can be further improved, thereby further reducing the loss rate of the SiC particles.

[0031] As preferred, the dispersant is selected from one or more of polyvinyl alcohol, polyethylene oxide, silane coupling agent, sodium dodecyl benzene sulfonate, and sodium isopropyl naphthalene sulfonate.

[0032] As preferred, the wetting agent is selected from one or more of sodium hydroxyethyl cellulose, sodium carboxymethyl cellulose, bentonite, and diatomite.

[0033] As preferred, in the raw materials of the high-temperature zone heat insulation layer, the medium-temperature zone heat insulation layer, and the low-temperature zone heat insulation layer, the dispersant accounts for 0.5-5 wt%, and the wetting agent accounts for 0.5-5 wt%.

[0034] Compared with the prior art, the present application has the following beneficial effects:

[0035] (1) The present application introduces sodium silicate colloid into the composite heat insulation material. In the preparation process, the sodium silicate aqueous solution (i.e., water glass) is uniformly distributed in the inorganic fiber substrate to form a water glass sol. Then, the hydrated film in the water glass sol is destroyed by a physical dehydration method, so that the water glass sol loses water and sequentially changes into viscous liquid→ semi-solid→ sodium silicate colloid. The sodium silicate colloid has a certain strength, thereby improving the hardness of the composite heat insulation material and having better resistance to compression deformation.

[0036] (2) According to the specific use environment, the present application optimizes the particle size and content of the SiC particles in each heat insulation layer, so that after introducing the SiC particles into the heat insulation layer of different temperature intervals, the positive effect is greater than the negative effect, thereby improving the comprehensive heat insulation performance of the composite heat insulation material.

[0037] (3) The application can promote the flocculation of inorganic fibers to a certain extent by surface grafting modification of SiC particles with polyacrylic acid, so as to wrap SiC particles in the inorganic fiber substrate, reduce the loss rate, and further improve the heat insulation performance of the composite heat insulation material. DETAILED DESCRIPTION

[0038] The application will be further described below in combination with examples.

[0039] Total examples

[0040] First, a multi-temperature zone multi-layer composite heat insulation material includes at least one high-temperature zone heat insulation layer, at least one medium-temperature zone heat insulation layer, and at least one low-temperature zone heat insulation layer from near to far to the heat source.

[0041] The high-temperature zone heat insulation layer, the medium-temperature zone heat insulation layer, and the low-temperature zone heat insulation layer all include an inorganic fiber substrate, inorganic heat insulation powder, SiC particles, and sodium silicate colloid dispersed in the inorganic fiber substrate.

[0042] The particle size of the SiC particles in the high-temperature zone heat insulation layer, the medium-temperature zone heat insulation layer, and the low-temperature zone heat insulation layer is 1.3-2.5 μm, 2.5-4 μm, and 4-7 μm, respectively, and the content is 0.4-0.6 wt%, 0.3-0.35 wt%, and 0.1-0.2 wt%, respectively.

[0043] In some specific embodiments, the heat insulation temperature of the high-temperature zone heat insulation layer, the medium-temperature zone heat insulation layer, and the low-temperature zone heat insulation layer is 500-800℃, 300-500℃, and <300℃, respectively.

[0044] In some specific embodiments, the content of the inorganic fiber substrate in the high-temperature zone heat insulation layer, the medium-temperature zone heat insulation layer, and the low-temperature zone heat insulation layer is 30-70 wt%, the content of the inorganic heat insulation powder is 20-50 wt%, and the content of the sodium silicate colloid is 1-3 wt%.

[0045] In some specific embodiments, the material of the inorganic fiber substrate is selected from one or more of glass fiber, high-silica fiber, aluminum silicate fiber, alkaline earth silicate fiber, and mullite fiber, preferably aluminum silicate fiber.

[0046] In some specific embodiments, the inorganic heat insulation powder is selected from one or more of inorganic aerogel powder, fumed silica, precipitated silica, hollow glass microspheres, hollow ceramic microspheres, expanded vermiculite, and expanded perlite.

[0047] In some specific embodiments, the thickness of a single layer of the high-temperature zone heat insulation layer, the medium-temperature zone heat insulation layer, and the low-temperature zone heat insulation layer is 0.5-2 mm.

[0048] In some specific embodiments, the multi-temperature-zone multi-layer composite thermal insulation material has a cold face temperature of ≤110℃ after 5min at 700℃ and 0.9MPa pressure.

[0049] Secondly, a preparation method of the multi-temperature-zone multi-layer composite thermal insulation material, comprising:

[0050] 1) adding a dispersing agent and a wetting agent into water and stirring uniformly, sequentially adding inorganic thermal insulation powder, SiC particles with different contents, and inorganic fibers, and stirring uniformly after each addition to obtain a slurry; performing papermaking on the slurry, and obtaining a sheet after water filtration, and then spraying a sodium silicate aqueous solution on the surface of the sheet by means of surface spraying, and passing the sheet through the spraying head at a speed of 2m / min and performing negative pressure suction below the sheet to make the sodium silicate uniformly distributed in the material, and then drying to obtain a high-temperature-zone thermal insulation layer, a medium-temperature-zone thermal insulation layer, and a low-temperature-zone thermal insulation layer.

[0051] 2) sequentially stacking the high-temperature-zone thermal insulation layer, the medium-temperature-zone thermal insulation layer, and the low-temperature-zone thermal insulation layer to obtain the multi-temperature-zone multi-layer composite thermal insulation material.

[0052] In some specific embodiments, the SiC particles are grafted with polyacrylic acid, and the preparation method comprises: modifying the SiC particles with an alkenyl silane coupling agent to obtain SiC particles grafted with alkenyl groups, and copolymerizing the SiC particles with acrylic acid monomers under high-energy electron beam irradiation to obtain SiC particles grafted with polyacrylic acid; during the high-energy electron beam irradiation, the energy of the high-energy electron beam is 30-60kGy, and the amount of the acrylic acid is 10-20wt% of the SiC particles.

[0053] In some specific embodiments, the SiC particles are modified with an alkenyl silane coupling agent solution, the solvent of the alkenyl silane coupling agent solution is 90-98vol% of an ethanol aqueous solution, and the concentration of the alkenyl silane coupling agent is 3-7wt%.

[0054] In some more specific embodiments, the reaction temperature of the modification is 50-70℃, and the reaction time is 50-70min.

[0055] In some more preferred embodiments, the comonomer further comprises acrylic acid phosphate, and the mass ratio of acrylic acid to acrylic acid phosphate is (4-6):1.

[0056] In some specific embodiments, the dispersant is selected from one or more of polyvinyl alcohol, polyethylene oxide, silane coupling agent, sodium dodecyl benzene sulfonate, and sodium isopropyl naphthalene sulfonate. In some specific embodiments, the wetting agent is selected from one or more of sodium hydroxyethyl cellulose, sodium carboxymethyl cellulose, bentonite, and diatomite. In some specific embodiments, the dispersant accounts for 0.5-5 wt% and the wetting agent accounts for 0.5-5 wt% in the raw materials of the high-temperature zone thermal insulation layer, the medium-temperature zone thermal insulation layer, and the low-temperature zone thermal insulation layer.

[0057] (I) Effect of different SiC particle contents:

[0058] Test Example 1

[0059] A method for preparing a multi-temperature zone multi-layer composite thermal insulation material, comprising the following steps:

[0060] (1) Preparation of the low-temperature zone thermal insulation layer:

[0061] Add water in a dispersion tank;

[0062] Add the dispersant silane coupling agent KH550 at a content of 0.9 wt% (accounting for all raw materials, excluding water), and the wetting agent sodium carboxymethyl cellulose at a content of 1 wt% (accounting for all raw materials, excluding water), at a rotation speed of 1000 rpm, and stirring for 8 min;

[0063] Add the inorganic thermal insulation powder fumed silica at a content of 40 wt% (accounting for all raw materials, excluding water), at a rotation speed of 1000 rpm, and stirring for 10 min;

[0064] Add SiC with an average particle size of about 5 μm at a content of 0.2 wt% (accounting for all raw materials, excluding water);

[0065] Add the aluminum silicate fiber at a content of 56.9 wt% (accounting for all raw materials, excluding water), at a rotation speed of 1000 rpm, and stirring for 8 min; add the adhesive polyethylene butylal at a content of 1 wt% (accounting for all raw materials, excluding water), at a rotation speed of 800 rpm, and stirring for 3 min; pump the prepared slurry into a headbox, and filter and dewater through a paper machine to obtain a sheet; pass through a drying tunnel at 130°C for 10 min to dry.

[0066] (2) Preparation of the medium-temperature zone thermal insulation layer:

[0067] Add water in a dispersion tank;

[0068] Add the dispersant silane coupling agent KH550 at a content of 0.9 wt% (accounting for all raw materials, excluding water), and the wetting agent sodium carboxymethyl cellulose at a content of 1 wt% (accounting for all raw materials, excluding water), at a rotation speed of 1000 rpm, and stirring for 8 min;

[0069] Add inorganic thermal insulation powder fumed silica, content 40wt% (all raw materials, excluding water), speed 1000 rpm, stirring time 10 min;

[0070] Add SiC with average particle size of about 3 μm, content 0.3% (all raw materials, excluding water);

[0071] Add aluminum silicate fiber, content 56.8wt% (all raw materials, excluding water), speed 1000 rpm, stirring time 8 min; add adhesive polyethylene butyral, content 1wt% (all raw materials, excluding water), speed 800 rpm, stirring time 3 min; pump the prepared slurry into the headbox, filter and take out the sheet through the paper machine; pass through the drying tunnel at 130℃, dry for 10 min.

[0072] (3) Preparation of high-temperature zone thermal insulation layer:

[0073] Add water in the dispersion tank;

[0074] Add dispersant silane coupling agent KH550, content 0.9wt% (all raw materials, excluding water), wetting agent sodium carboxymethyl cellulose, content 1wt% (all raw materials, excluding water), speed 1000 rpm, stirring time 8 min;

[0075] Add inorganic thermal insulation powder fumed silica, content 40wt% (all raw materials, excluding water), speed 1000 rpm, stirring time 10 min;

[0076] Add SiC with average particle size of about 1.5 μm, content 0.5wt% (all raw materials, excluding water);

[0077] Add aluminum silicate fiber, content 56.6wt% (all raw materials, excluding water), speed 1000 rpm, stirring time 8 min; add adhesive polyethylene butyral, content 1wt% (all raw materials, excluding water), speed 800 rpm, stirring time 3 min; pump the prepared slurry into the headbox, filter and take out the sheet through the paper machine; pass through the drying tunnel at 130℃, dry for 10 min.

[0078] (4) Stack in order of high-temperature zone thermal insulation layer (single layer thickness of 1 mm, number of layers of 1 layer), medium-temperature zone thermal insulation layer (single layer thickness of 1 mm, number of layers of 1 layer), low-temperature zone thermal insulation layer (single layer thickness of 1 mm, number of layers of 1 layer), and then vacuum package with PET film to obtain a multi-temperature zone multi-layer composite thermal insulation material.

[0079] Test Example 2

[0080] The difference between this test example and Test Example 1 is that SiC is not added in each thermal insulation layer (the difference is replaced by aluminum silicate fiber).

[0081] Test Example 3

[0082] The difference between this test example and Test Example 1 is that the average particle size of SiC in each thermal insulation layer is 5 μm, and the content is 0.2wt% (the difference is adjusted by aluminum silicate fiber).

[0083] Test Example 4

[0084] The difference between this test example and Test Example 1 is that the average particle size of SiC in each thermal insulation layer is 3 μm, and the content is 0.3wt% (the difference is adjusted by aluminum silicate fiber).

[0085] Test Example 5

[0086] The difference between this test example and Test Example 1 is that the average particle size of SiC in each thermal insulation layer is 1.5 μm, and the content is 0.5wt% (the difference is adjusted by aluminum silicate fiber).

[0087] Performance test

[0088] The thermal conductivity of the low-temperature zone thermal insulation layer, the medium-temperature zone thermal insulation layer and the high-temperature zone thermal insulation layer obtained in each test example was detected respectively according to GB / T10294-2008; then the thermal insulation performance of the composite thermal insulation material was tested, the high-temperature zone thermal insulation layer surface of the composite thermal insulation material was placed on a heating table with a constant temperature of 700℃, and a pressure of 0.9MPa was applied, and the temperature of the low-temperature zone thermal insulation layer surface of the composite thermal insulation material was detected. The test results are shown in Table 1:

[0089] Table 1

[0090]

[0091] From the comparison of the data in Table 1, it can be found that in Test Example 1, different particle sizes and contents of SiC are added in each thermal insulation layer, and the thermal conductivity of each thermal insulation layer is significantly reduced; in Test Examples 3-5, the difference from Test Example 1 is that the particle size and content of SiC added in each thermal insulation layer are the same, that is, no gradient SiC is set. From the data of Test Example 3, it can be found that the thermal conductivity of the medium-temperature zone thermal insulation layer and the high-temperature zone thermal insulation layer is significantly higher than that of Test Example 1, and even slightly higher than that of Test Example 2, except for the low-temperature zone thermal insulation layer. This shows that in the medium-temperature zone thermal insulation layer and the high-temperature zone thermal insulation layer of Test Example 3, the negative effect of adding SiC is greater than the positive effect, resulting in an increase in thermal conductivity instead of a decrease. Similarly, similar results also appear in Test Examples 4 and 5.

[0092] (II) Influence of sodium silicate colloid:

[0093] Test Example 6

[0094] A preparation method of a multi-temperature-zone multi-layer composite thermal insulation material, comprising the following steps:

[0095] (1) Preparation of a low-temperature-zone thermal insulation layer:

[0096] Add water in a dispersion tank;

[0097] Add a dispersant silane coupling agent KH550 with a content of 0.9 wt% (accounting for all raw materials, excluding water), a wetting agent sodium carboxymethyl cellulose with a content of 1 wt% (accounting for all raw materials, excluding water), a rotating speed of 1000 rpm, and a stirring time of 8 min;

[0098] Add inorganic thermal insulation powder fumed silica with a content of 40 wt% (accounting for all raw materials, excluding water), a rotating speed of 1000 rpm, and a stirring time of 10 min;

[0099] Add SiC with an average particle size of 5 μm and a content of 0.2 wt% (accounting for all raw materials, excluding water);

[0100] Add aluminum silicate fibers with a content of 56.9 wt% (accounting for all raw materials, excluding water), a rotating speed of 1000 rpm, and a stirring time of 8 min; pump the prepared slurry into a headbox, and filter and take out a sheet through a paper machine;

[0101] Control the flow rate to spray a sodium silicate aqueous solution with a concentration of 40 wt% on the surface of the sheet by means of surface gluing, the sheet passes through the gluing head at a speed of 2 meters / min, and negative pressure suction is performed below the sheet, so that the sodium silicate aqueous solution is uniformly distributed in the material; the content of the sodium silicate colloid is 1 wt% (accounting for all raw materials, excluding water);

[0102] Pass through a drying channel at 130°C for 10 min to dry.

[0103] (2) Preparation of a medium-temperature-zone thermal insulation layer:

[0104] Add water in a dispersion tank;

[0105] Add a dispersant silane coupling agent KH550 with a content of 0.9 wt% (accounting for all raw materials, excluding water), a wetting agent sodium carboxymethyl cellulose with a content of 1 wt% (accounting for all raw materials, excluding water), a rotating speed of 1000 rpm, and a stirring time of 8 min;

[0106] Add inorganic thermal insulation powder fumed silica with a content of 40 wt% (accounting for all raw materials, excluding water), a rotating speed of 1000 rpm, and a stirring time of 10 min;

[0107] Add SiC with an average particle size of 3 μm and a content of 0.3% (accounting for all raw materials, excluding water);

[0108] Add aluminum silicate fiber, content 56.8wt% (all raw materials, excluding water), 1000 rpm, stirring time 8 min; the prepared pulp is pumped into the headbox, and the sheet is dewatered and cast by the paper machine;

[0109] By the way of surface glue, control the flow rate of sodium silicate aqueous solution with a concentration of 40wt% is sprayed to the surface of the sheet, the sheet passes through the glue head at a rate of 2 meters / min, and negative pressure suction is carried out under the sheet, so that the sodium silicate aqueous solution is uniformly distributed in the material; the sodium silicate colloid content is 1wt% (all raw materials, excluding water);

[0110] Through the drying channel 130℃, 10min drying.

[0111] (3) Preparation of high temperature zone thermal insulation layer:

[0112] Add water in the dispersion tank;

[0113] Add dispersant silane coupling agent KH550, content 0.9wt% (all raw materials, excluding water), wetting agent carboxymethyl cellulose sodium, content 1wt% (all raw materials, excluding water), 1000 rpm, stirring time 8 min;

[0114] Add inorganic thermal insulation powder fumed silica, content 40wt% (all raw materials, excluding water), 1000 rpm, stirring time 10 min;

[0115] Add SiC with an average particle size of 1.5μm, content 0.5wt% (all raw materials, excluding water);

[0116] Add aluminum silicate fiber, content 56.6wt% (all raw materials, excluding water), 1000 rpm, stirring time 8 min;

[0117] The prepared pulp is pumped into the headbox, and the sheet is dewatered and cast by the paper machine;

[0118] By the way of surface glue, control the flow rate of sodium silicate aqueous solution with a concentration of 40wt% is sprayed to the surface of the sheet, the sheet passes through the glue head at a rate of 2 meters / min, and negative pressure suction is carried out under the sheet, so that the sodium silicate aqueous solution is uniformly distributed in the material; the sodium silicate colloid content is 1wt% (all raw materials, excluding water);

[0119] Through the drying channel 130℃, 10min drying.

[0120] (4) The high-temperature zone thermal insulation layer (1 mm in thickness of a single layer, 1 layer in number), the medium-temperature zone thermal insulation layer (1 mm in thickness of a single layer, 1 layer in number), and the low-temperature zone thermal insulation layer (1 mm in thickness of a single layer, 1 layer in number) are sequentially stacked in order and then vacuum packaged with a PET film to obtain a multi-temperature zone multi-layer composite thermal insulation material.

[0121] Test Example 7

[0122] The difference between the present test example and Test Example 6 is that the content of the sodium silicate colloid in each layer is 2wt% (the difference is replaced with aluminum silicate fiber).

[0123] Test Example 8

[0124] The difference between the present test example and Test Example 6 is that the content of the sodium silicate colloid in each layer is 3wt% (the difference is replaced with aluminum silicate fiber).

[0125] Test Example 9

[0126] The difference between the present test example and Test Example 6 is that the content of the sodium silicate colloid in each layer is 4wt% (the difference is replaced with aluminum silicate fiber).

[0127] Performance Test

[0128] The composite thermal insulation materials obtained in Test Examples 6-9 are subjected to performance tests, and compared with Test Example 1, and the results are shown in Table 2:

[0129] Table 2

[0130]

[0131] From the comparison of the data in Table 2, it can be seen that, compared with Test Example 1, the cold surface temperature of Test Examples 6-8 is significantly reduced after adding an appropriate amount of sodium silicate colloid, indicating that the addition of sodium silicate colloid can significantly improve the thermal insulation performance of the composite thermal insulation material under pressure (the cold surface temperature is tested under a pressure of 0.9 MPa); in Test Example 9, the addition amount of sodium silicate colloid is 4wt%, and it is found that the cold surface temperature is higher than that of Test Example 1, which is because the thermal conductivity of the colloid formed by the dehydration of sodium silicate aqueous solution is higher than that of air, and the porosity of the composite thermal insulation material is excessively reduced, thus resulting in a decrease in the thermal insulation performance of the composite thermal insulation material. In summary, the preferred addition amount of sodium silicate colloid is 1-3wt%.

[0132] (Three) Effect of Surface Modified SiC:

[0133] Test Example 10

[0134] A preparation method of a multi-temperature zone multi-layer composite thermal insulation material, comprising the following steps:

[0135] (1) Preparation of the low-temperature zone thermal insulation layer:

[0136] Add water in the dispersion tank;

[0137] Add dispersant silane coupling agent KH550, content 0.9wt% (all raw materials, excluding water), wetting agent sodium carboxymethyl cellulose, content 1wt% (all raw materials, excluding water), speed 1000rpm, stirring time 8min;

[0138] Add inorganic thermal insulation powder fumed silica, content 40wt% (all raw materials, excluding water), speed 1000rpm, stirring time 10min;

[0139] Add surface modified SiC with average particle size of 5μm, content 0.2wt% (all raw materials, excluding water);

[0140] Add aluminum silicate fiber, content 55.9wt% (all raw materials, excluding water), speed 1000rpm, stirring time 8min; Pump the prepared slurry into the headbox, and filter through the paper machine to obtain a sheet;

[0141] Control the flow rate by surface sizing to spray sodium silicate solution with a concentration of 50wt% onto the surface of the sheet, and the sheet passes through the sizing head at a speed of 1.8m / min, and negative pressure suction is performed below the sheet to make sodium silicate uniformly distributed in the material; The content of sodium silicate colloid is 2wt% (all raw materials, excluding water);

[0142] Pass through the drying tunnel at 130℃ for 10min to dry.

[0143] (2) Preparation of the thermal insulation layer in the medium temperature zone:

[0144] Add water in the dispersion tank;

[0145] Add dispersant silane coupling agent KH550, content 0.9wt% (all raw materials, excluding water), wetting agent sodium carboxymethyl cellulose, content 1wt% (all raw materials, excluding water), speed 1000rpm, stirring time 8min;

[0146] Add inorganic thermal insulation powder fumed silica, content 40wt% (all raw materials, excluding water), speed 1000rpm, stirring time 10min;

[0147] Add surface modified SiC with average particle size of 3μm, content 0.3% (all raw materials, excluding water);

[0148] Add aluminum silicate fiber, content 55.8wt% (all raw materials, excluding water), speed 1000rpm, stirring time 8min; Pump the prepared slurry into the headbox, and filter through the paper machine to obtain a sheet;

[0149] The surface of the sheet is sprayed with a 50wt% sodium silicate solution by means of surface spraying, the flow rate is controlled, the sheet passes through the spraying head at a speed of 1.8 meters / min, and negative pressure suction is performed below the sheet, so that the sodium silicate is uniformly distributed in the material; the sodium silicate colloid content is 2wt% (all raw materials, excluding water);

[0150] Pass through the oven at 130°C for 10min to dry.

[0151] (3) Preparation of high-temperature zone thermal insulation layer:

[0152] Add water in the dispersion tank;

[0153] Add the dispersant silane coupling agent KH550, the content is 0.9wt% (all raw materials, excluding water), and the wetting agent carboxymethyl cellulose sodium, the content is 1wt% (all raw materials, excluding water), the stirring speed is 1000rpm, and the stirring time is 8min;

[0154] Add inorganic thermal insulation powder fumed silica, the content is 40wt% (all raw materials, excluding water), the stirring speed is 1000rpm, and the stirring time is 10min;

[0155] Add surface-modified SiC with an average particle size of 1.5μm, the content is 0.5wt% (all raw materials, excluding water);

[0156] Add aluminum silicate fibers, the content is 55.6wt% (all raw materials, excluding water), the stirring speed is 1000rpm, and the stirring time is 8min; the surface of the sheet is sprayed with a 50wt% sodium silicate solution by means of surface spraying, the flow rate is controlled, the sheet passes through the spraying head at a speed of 1.8 meters / min, and negative pressure suction is performed below the sheet, so that the sodium silicate is uniformly distributed in the material; the sodium silicate colloid content is 2wt% (all raw materials, excluding water);

[0157] Pump the prepared slurry into the headbox, and then filter and dry the sheet through the paper machine;

[0158] Pass through the oven at 130°C for 10min to dry.

[0159] (4) Stack them in the order of high-temperature zone thermal insulation layer (single layer thickness is 1mm, and the number of layers is 1), medium-temperature zone thermal insulation layer (single layer thickness is 1mm, and the number of layers is 1), and low-temperature zone thermal insulation layer (single layer thickness is 1mm, and the number of layers is 1), and then vacuum package them with a PET film to obtain a multi-temperature zone multi-layer composite thermal insulation material.

[0160] The surface-modified SiC was prepared by adding SiC to a 98 vol% aqueous solution of ethanol containing 5 wt% of γ-methacryloxypropyltrimethoxysilane to prepare a dispersion containing 10 wt% of SiC, mechanically stirring the reaction at 60°C for 30 min, filtering, and drying to obtain SiC grafted with alkenyl groups on the surface. The SiC grafted with alkenyl groups on the surface was added to an ethanol solution containing 1.5 wt% of acrylic acid at a mass ratio of 1:10, ultrasonically treated until uniformly dispersed, and subjected to high-energy electron beam irradiation (energy: 50 kGy) in nitrogen. The obtained product was filtered, washed with ethanol three times, and vacuum-dried to obtain SiC grafted with polyacrylic acid on the surface.

[0161] Test Example 11

[0162] The difference between this test example and Test Example 10 is that the surface-modified SiC was prepared as follows: SiC was added to a 98 vol% aqueous solution of ethanol containing 5 wt% of γ-methacryloxypropyltrimethoxysilane to prepare a dispersion containing 10 wt% of SiC, mechanically stirred at 60°C for 30 min, filtered, and dried to obtain SiC grafted with alkenyl groups on the surface. The SiC grafted with alkenyl groups on the surface was added to an ethanol solution containing 2.5 wt% of acrylic acid at a mass ratio of 1:10, ultrasonically treated until uniformly dispersed, and subjected to high-energy electron beam irradiation (energy: 50 kGy) in nitrogen. The obtained product was filtered, washed with ethanol three times, and vacuum-dried to obtain SiC grafted with polyacrylic acid on the surface.

[0163] Test Example 12

[0164] The difference between this test example and Test Example 10 is that the surface-modified SiC was prepared as follows: SiC was added to a 98 vol% aqueous solution of ethanol containing 5 wt% of γ-methacryloxypropyltrimethoxysilane to prepare a dispersion containing 10 wt% of SiC, mechanically stirred at 60°C for 30 min, filtered, and dried to obtain SiC grafted with alkenyl groups on the surface. The SiC grafted with alkenyl groups on the surface was added to an ethanol solution containing 1.2 wt% of acrylic acid and 0.3 wt% of acrylic acid phosphate at a mass ratio of 1:10, ultrasonically treated until uniformly dispersed, and subjected to high-energy electron beam irradiation (energy: 50 kGy) in nitrogen. The obtained product was filtered, washed with ethanol three times, and vacuum-dried to obtain SiC grafted with polyacrylic acid on the surface.

[0165] Performance Test

[0166] The composite thermal insulation materials obtained in Test Examples 10-12 were subjected to performance tests, and compared with Test Example 7. The test results are shown in Table 3.

[0167] Table 3

[0168]

[0169] From the data of Table 3, it can be seen that, compared with Test Example 7, the surface modified SiC used in Test Examples 10-12. Among them, from the comparison of Test Examples 9-11, it can be found that the use of an appropriate amount of acrylic acid (Test Example 10) has a positive effect on the heat insulation performance of the composite heat insulation material after copolymerization modification with SiC. However, if the amount of acrylic acid is too high (Test Example 11), it will have a negative effect. This may be because the excessive amount of polyacrylic acid grafting will cause the surface of the SiC particles to be wrapped in a large area, thereby affecting its performance. In addition, from Test Example 12, it can be known that the addition of an appropriate amount of acrylic phosphate during copolymerization modification can further improve the heat insulation performance of the composite heat insulation material.

[0170] The raw materials and equipment used in the present application are conventional raw materials and equipment in the art unless otherwise specified; the methods used in the present application are conventional methods in the art unless otherwise specified.

[0171] The above is only a preferred embodiment of the present application, and does not limit the present application in any way. Any simple modification, change and equivalent transformation of the above embodiment according to the technical essence of the present application still falls within the protection scope of the technical solution of the present application.

Claims

1. A multi-zone multilayer composite thermal insulation material, characterized by: The high temperature zone heat insulation layer, the medium temperature zone heat insulation layer and the low temperature zone heat insulation layer are sequentially arranged from the heat source to the far end. The high temperature zone heat insulation layer, the medium temperature zone heat insulation layer and the low temperature zone heat insulation layer each comprise 30-70wt% inorganic fiber base material, 20-50wt% inorganic heat insulation powder, SiC particles and 1-3wt% sodium silicate colloid dispersed in the inorganic fiber base material. The particle size of the SiC particles in the high temperature zone heat insulation layer, the medium temperature zone heat insulation layer and the low temperature zone heat insulation layer is 1.3-2.5μm, 2.5-4μm and 4-7μm respectively, and the content is 0.4-0.6wt%, 0.3-0.35wt% and 0.1-0.2wt% respectively. The heat insulation temperature of the high temperature zone heat insulation layer, the medium temperature zone heat insulation layer and the low temperature zone heat insulation layer is 500-800℃, 300-500℃ and <300℃ respectively.

2. The multi-temperature zone multi-layer composite heat insulation material according to claim 1, wherein: The material of the inorganic fiber base material is selected from one or more of glass fiber, high silica fiber, aluminum silicate fiber, alkaline earth silicate fiber and mullite fiber. The inorganic heat insulation powder is selected from one or more of inorganic aerogel powder, fumed silica, precipitated silica, hollow glass microspheres, hollow ceramic microspheres, expanded vermiculite and expanded perlite.

3. The multi-zone multi-layer composite thermal insulation of claim 1, wherein: The cold surface temperature is ≤110℃ after 5min under 700℃, 0.9MPa, pressure.

4. A process for the production of a multi-zone multilayer composite thermal insulation according to any one of claims 1 to 3, characterized in that Comprise: 1) Add dispersant and wetting agent into water and stir evenly, then add inorganic heat insulation powder, SiC particles and inorganic fiber successively and stir evenly after each addition to obtain slurry; The slurry is papered, filtered and then a sheet is obtained, and then sodium silicate aqueous solution is sprayed on the surface of the sheet by surface spraying, and the sheet is subjected to negative pressure suction and drying to obtain the high temperature zone heat insulation layer, the medium temperature zone heat insulation layer and the low temperature zone heat insulation layer respectively; 2) Stack the high temperature zone heat insulation layer, the medium temperature zone heat insulation layer and the low temperature zone heat insulation layer successively to obtain the multi-temperature zone multi-layer composite heat insulation material.

5. The method of claim 4, wherein: The SiC particles are grafted with polyacrylic acid, and the preparation method is as follows: the SiC particles are modified with alkenyl silane coupling agent to obtain SiC particles grafted with alkenyl groups, and then copolymerization is carried out with acrylic acid monomer under high-energy electron beam irradiation; the energy of the high-energy electron beam is 30-60kGy, and the amount of acrylic acid is 10-20wt% of the SiC particles.

6. The method of claim 5, wherein: The copolymerized monomers also include acrylic acid phosphate, and the mass ratio of acrylic acid to acrylic acid phosphate is (4-6):

1.

7. The method of claim 4, wherein: The dispersant is selected from one or more of polyvinyl alcohol, polyethylene oxide, silane coupling agent, sodium dodecylbenzenesulfonate and sodium isopropyl naphthalene sulfonate.

8. The method of claim 4, wherein: The wetting agent is selected from one or more of sodium hydroxyethyl cellulose, sodium carboxymethyl cellulose, bentonite and diatomite.

9. The method of claim 4, wherein: In the raw materials of the high temperature zone heat insulation layer, the medium temperature zone heat insulation layer and the low temperature zone heat insulation layer, the dispersant accounts for 0.5-5wt%, and the wetting agent accounts for 0.5-5wt%.

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