CN112482081B

CN112482081B - High-temperature-resistant aerogel composite inorganic heat-insulating paper and preparation process thereof

Info

Publication number: CN112482081B
Application number: CN202011364704.9A
Authority: CN
Inventors: 郑维金; 王振宇; 张成贺; 岳耀辉
Original assignee: Luyang Energy Saving Materials Co Ltd
Current assignee: Luyang Energy Saving Materials Co Ltd
Priority date: 2020-11-27
Filing date: 2020-11-27
Publication date: 2022-06-03
Anticipated expiration: 2040-11-27
Also published as: CN112482081A

Abstract

The invention provides high-temperature resistant aerogel composite inorganic heat-insulating paper and a preparation process thereof. The preparation process provided by the invention comprises the following steps: a) mixing inorganic fibers, a toughening agent raw material, an inorganic bonding agent and water to obtain slurry; b) mixing the slurry with a flocculating agent, and then taking and forming to obtain a wet fiber paper blank; c) pre-drying the wet fiber paper blank, then soaking the wet fiber paper blank in aerogel precursor sol, and drying the wet fiber paper blank to obtain gel fiber paper; d) performing supercritical drying on the gel fiber paper to obtain high-temperature resistant aerogel composite inorganic heat-insulating paper; the raw materials of the toughening agent are metal oxide and inorganic acid. The preparation process provided by the invention can effectively improve the toughness and high temperature resistance of the fiber paper.

Description

High-temperature-resistant aerogel composite inorganic heat-insulating paper and preparation process thereof

Technical Field

The invention relates to the field of heat insulation materials, in particular to high-temperature-resistant aerogel composite inorganic heat insulation paper and a preparation process thereof.

Background

In the past, the paper industry has mainly used plant fibers as raw materials, and now, technologies for producing paper by using inorganic compounds have gradually been derived. Inorganic fiber paper processed from inorganic substances has good dimensional stability, heat resistance, electrical insulation and the like, and is widely used in the fields of pipeline heat preservation, heat insulation and the like.

At present, the inorganic heat-insulating paper is generally prepared by using glass fiber or ceramic fiber as a base material through the process flow of pulping → copy molding → drying → calcining, organic acrylic binders are often required to be added in the preparation process to ensure the flexibility of the fiber paper, most of the organic binders in the fiber paper are removed through drying and calcining after the copy molding, and a small amount of organic binders are left to ensure that the fiber paper still has certain flexibility after the calcining. However, the preparation process causes weak high temperature resistance of the inorganic heat insulation value, insufficient strength and toughness, easy cracking in folding or winding, and influence on the use effect.

Disclosure of Invention

In view of this, the present invention aims to provide a high temperature resistant aerogel composite inorganic heat insulation paper and a preparation process thereof. The inorganic heat-insulating paper prepared by the method can effectively improve the high temperature resistance and toughness of the fiber paper.

The invention provides a preparation process of high-temperature resistant aerogel composite inorganic heat-insulating paper, which comprises the following steps:

a) mixing inorganic fibers, a toughening agent raw material, an inorganic bonding agent and water to obtain slurry;

b) mixing the slurry with a flocculating agent, and then taking and forming to obtain a wet fiber paper blank;

c) pre-drying the wet fiber paper blank, placing the wet fiber paper blank into aerogel precursor sol for soaking, and drying to obtain gel fiber paper;

d) performing supercritical drying on the gel fiber paper to obtain high-temperature resistant aerogel composite inorganic heat-insulating paper;

the raw materials of the toughening agent are metal oxide and inorganic acid.

Preferably, the metal oxide is selected from one or more of calcium oxide, magnesium oxide, zinc oxide, aluminum oxide, iron oxide and barium oxide;

the inorganic acid is selected from one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid and hydrofluoric acid;

the molar ratio of the metal oxide to the inorganic acid is 1: 1-3.

Preferably, in step c):

the mass ratio of the blank obtained after infiltration to the blank before infiltration is (2.83-5.04) to 1;

the aerogel precursor sol is selected from: one or more of silicon dioxide aerogel precursor sol, zirconium dioxide aerogel precursor sol and aluminum oxide aerogel precursor sol;

the gel in the resulting gel fiber paper is selected from the group consisting of: one or more of silicon dioxide aerogel, zirconium dioxide aerogel and aluminum oxide aerogel.

Preferably, the silica aerogel precursor sol is obtained by: mixing ethyl orthosilicate, an organic solvent, water and a catalyst solution to form a silica aerogel precursor sol;

the catalyst in the catalyst solution is selected from one or more of oxalic acid, hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid and acetic acid;

the concentration of the catalyst solution is 0.05-0.2 mol/L;

the volume ratio of the ethyl orthosilicate to the organic solvent to the water to the catalyst solution is 1 to (1-6) to (0.1-0.4) to (0.05-0.15);

the zirconium dioxide aerogel precursor sol is obtained by the following steps: ZrO (NO)₃)₂·5H₂Mixing O, an organic solvent, water and an accelerator to form a zirconium dioxide aerogel precursor sol;

the ZrO (NO)₃)₂·5H₂The mass ratio of the O, the organic solvent, the water and the accelerant is 1: 7-15: 1-4: 0.08-0.23;

the alumina aerogel precursor sol is obtained by the following method: mixing aluminum isopropoxide, an organic solvent, water and an accelerator to form a zirconium dioxide aerogel precursor sol;

the mass ratio of the aluminum isopropoxide to the organic solvent to the water to the accelerator is 1: 1-8: 1-5: 0.06-0.18;

the promoter comprises an amide promoter and an alkylene oxide promoter;

the amide accelerator is selected from one or more of formamide, N-dimethyl benzamide, succinimide and delta-valerolactam;

the alkylene oxide accelerant is one or more of propylene oxide, ethylene oxide, 1, 2-butylene oxide, 1, 4-butylene oxide and epichlorohydrin.

Preferably, the supercritical drying is CO₂Supercritical drying;

the supercritical drying conditions are as follows: the temperature is 30-55 ℃, the time is 4-12 h, and the pressure is 6-15 MPa.

Preferably, in the step a), the mass ratio of the inorganic fibers to the raw materials of the toughening agent to the inorganic bonding agent is (55-85) to (2-5) to (8-25);

the mass concentration of the slurry is 1-2%.

Preferably, the inorganic fibers are selected from: one or more of aluminum silicate fiber, magnesium silicate fiber, high silica fiber, quartz fiber, polycrystalline mullite fiber and alumina fiber;

the inorganic binder is selected from: one or more of water glass, silica sol and aluminum dihydrogen phosphate.

Preferably, the flocculating agent is selected from one or more of a cationic polyacrylamide solution, an anionic polyacrylamide solution and a nonionic polyacrylamide solution;

the mass concentration of the flocculant is 0.05-1.15%;

the mass ratio of the total mass of the inorganic fibers, the raw materials of the toughening agent and the inorganic bonding agent to the mass of the flocculating agent is (20-30) to 1.

Preferably, in the step c), the pre-drying is hot air drying or microwave drying;

the hot air drying temperature is 100-150 ℃, and the time is 1-3 h;

the microwave drying temperature is 80-120 ℃, and the time is 0.5-1.5 h;

the step d) further comprises, before the supercritical drying: cleaning and aging the gel fiber paper;

the cleaning agent adopted for cleaning is absolute ethyl alcohol or propyl alcohol;

the aging temperature is 20-30 ℃, and the aging time is 1-5 hours.

The invention also provides the high-temperature resistant aerogel composite inorganic heat-insulating paper prepared by the preparation process in the technical scheme.

According to the invention, metal oxide and inorganic acid are used as raw materials for forming the toughening agent, and are mixed with inorganic fiber, an inorganic binder and water, the metal oxide and the inorganic acid form corresponding metal salt (namely the toughening agent) on the surface of the fiber, the metal salt is in a continuous phase which is uniformly wrapped on the surface of the fiber in a flaky structure, the toughness of the inorganic fiber is greatly improved due to the existence of the flaky structure of the continuous phase, meanwhile, metal cations form a highly polymerized polyhydroxy compound in the water, and can adsorb colloid particles of the inorganic binder in the coiled water under the action of a flocculating agent, so that the rigidity strength brought by the drying of the simple inorganic binder is reduced, and finally, the fiber paper has better toughness; it is particularly emphasized that the metal salt of the continuous phase scaly structure must be prepared according to the preparation method of the present invention, and the corresponding metal oxide and the inorganic acid can be generated only under the interfacial effect of the surface of the inorganic fiber, and if the metal salt and the inorganic fiber are directly mixed, the structure can not be formed, and the toughening effect is not provided. And then, the aerogel continuous phase is formed on the surface and in the interior of the fiber paper in situ, so that the toughness and the high temperature resistance of the fiber paper can be further improved.

Experimental results show that the inorganic heat-insulating paper prepared by the invention has the service temperature of over 900 ℃, the tensile strength of more than 0.35MPa, no cracking after being folded and wound, and excellent toughness and high temperature resistance.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is an SEM image of a fiber paper without aerogel composite in example 1.

Detailed Description

The invention provides a preparation process of high-temperature-resistant aerogel composite inorganic heat-insulating paper, which comprises the following steps:

the raw materials of the toughening agent are metal oxide and inorganic acid.

With respect to step a): mixing inorganic fibers, a toughening agent raw material, an inorganic bonding agent and water to obtain slurry.

In the invention, the inorganic fiber is preferably one or more of aluminum silicate fiber, magnesium silicate fiber, high silica fiber, quartz fiber, polycrystalline mullite fiber and alumina fiber. The size of the inorganic fiber is not particularly limited in the invention, and is the size of the conventional fiber raw material for preparing the fiber paper in the field. In the present invention, the source of the inorganic fiber is not particularly limited, and may be a commercially available product.

In the invention, the raw materials of the toughening agent are metal oxide and inorganic acid. Wherein, the metal oxide is preferably one or more of calcium oxide, magnesium oxide, zinc oxide, aluminum oxide, iron oxide and barium oxide. The inorganic acid is preferably one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid and hydrofluoric acid. In the present invention, the inorganic acid may be added in the form of pure acid, i.e. HCl, H₂SO₄The inorganic compound may be added as an acid solution, and the concentration of the acid solution is not particularly limited in the present invention, and may be in the standard of a commercially available acid solution.

In the invention, the dosage ratio of the metal oxide and the inorganic acid is preferably stoichiometric ratio, namely the metal oxide and the acid are completely reacted to generate the corresponding metal acid salt according to the molar ratio of the metal oxide and the acid; specifically, the molar ratio of the metal oxide to the inorganic acid is preferably 1: (1 to 3), and the molar ratio refers to the molar ratio of the metal oxide to the acid compound in the inorganic acid.

In the invention, the inorganic bonding agent is preferably one or more of water glass, silica sol and aluminum dihydrogen phosphate. Wherein, the type of the water glass is not particularly limited, and the water glass is conventional industrial water glass. The silica sol is preferably an acidic silica sol, an alkaline silica sol or a neutral silica sol. In the present invention, the source of the inorganic binder is not particularly limited, and may be any commercially available product.

In the invention, the mass ratio of the inorganic fibers, the raw material of the toughening agent and the inorganic binder is preferably (55-85) to (2-5) to (8-25). In the present invention, the amount of water used is preferably such that the mass concentration of the slurry obtained is 1% to 2%, more preferably 1.5%. In the present invention, the mixing method is preferably: firstly, inorganic fiber, toughening agent and water are stirred and mixed uniformly, and then inorganic bonding agent is added to be stirred and mixed uniformly. And (4) obtaining slurry through the mixing treatment.

With respect to step b): and mixing the slurry with a flocculating agent, and then taking and forming to obtain a wet fiber paper blank.

In the invention, the flocculating agent is preferably one or more of a cationic polyacrylamide solution, an anionic polyacrylamide solution and a nonionic polyacrylamide solution. In the present invention, the mass concentration of the flocculant is preferably 0.05% to 1.15%, and more preferably 1%.

In the invention, a flocculating agent is mixed with the slurry obtained in the step a) and then is molded by copying. The method for forming the wet fiber paper blank by the papermaking is not particularly limited, and the wet fiber paper blank with a certain size can be formed by conventional papermaking operation in the field, namely, papermaking equipment.

In the steps a) to b), the metal oxide and the inorganic acid which are used as raw materials for forming the flexibilizer are directly mixed with the inorganic fibers, the inorganic binding agent and water, and then the flocculating agent is added for carrying out papermaking and forming, wherein the metal oxide and the inorganic acid form corresponding metal salt in situ on the surfaces of the fibers, the metal salt is in a continuous phase which is uniformly wrapped on the surfaces of the fibers in a scale-shaped structure, the toughness of the inorganic fibers is greatly improved due to the existence of the scale-shaped structure of the continuous phase, meanwhile, the metal cations form a highly polymerized polyhydroxy compound in the water, and can adsorb colloid particles of the inorganic binding agent in the tape-wound water under the action of the flocculating agent, so that the rigidity strength caused by the drying of the pure inorganic binding agent is reduced, and finally, the fiber paper has better toughness.

With respect to step c): and pre-drying the wet fiber paper blank, placing the wet fiber paper blank into aerogel precursor sol for soaking, and drying to obtain the gel fiber paper.

In the present invention, the pre-drying is preferably hot air drying or microwave drying. Wherein the temperature of the hot air drying is preferably 100-150 ℃, and more preferably 120 ℃; the time for drying by hot air is preferably 1-3 h, and more preferably 2 h. The temperature of the microwave drying is preferably 80-120 ℃, and more preferably 100 ℃; the time for microwave drying is preferably 0.5-1.5 h, and more preferably 1 h.

In the present invention, the aerogel precursor sol is selected from: one or more of silicon dioxide aerogel precursor sol, zirconium dioxide aerogel precursor sol and aluminum oxide aerogel precursor sol.

According to the invention, the silica aerogel precursor sol is preferably obtained by: and mixing tetraethoxysilane, an organic solvent, water and a catalyst solution to form the silica aerogel precursor sol.

Wherein:

the specification and the source of the tetraethoxysilane are not particularly limited, and the tetraethoxysilane can be obtained by common commercial products, and the specification is as follows: the silica content was 28% and the density was 0.93g/m³。

The organic solvent is preferably one or more of absolute ethyl alcohol, propyl alcohol, methanol, n-butyl alcohol, isobutyl alcohol, ethylene glycol and glycerol.

The catalyst in the catalyst solution is preferably one or more of oxalic acid, hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid and acetic acid. The concentration of the catalyst solution is preferably 0.05-0.2 mol/L, and more preferably 0.1 mol/L. The catalyst solution can promote the hydrolysis reaction of the tetraethoxysilane to form sol.

The volume ratio of the ethyl orthosilicate to the organic solvent to the water to the catalyst solution is preferably 1 to (1-6) to (0.1-0.4) to (0.05-0.15); more preferably 1: 4: 0.2: 0.10.

The preparation process of the sol is preferably as follows: the ethyl orthosilicate, the organic solvent and the water are stirred and mixed uniformly, and then the catalyst solution is added to be stirred and mixed uniformly until transparent sol is formed.

According to the present invention, the zirconia aerogel precursor sol is preferably obtained by: ZrO (NO)₃)₂·5H₂And mixing O, an organic solvent, water and an accelerator to form the zirconium dioxide aerogel precursor sol.

Wherein:

The accelerator is preferably an amide accelerator and an alkylene oxide accelerator, and the addition of the accelerator can promote crosslinking, thereby being beneficial to the formation of gel in the subsequent link. Wherein, the amide accelerator is preferably one or more of formamide, N-dimethyl benzamide, succinimide and delta-valerolactam; more preferably formamide. The alkylene oxide accelerator is preferably one or more of propylene oxide, ethylene oxide, 1, 2-butylene oxide, 1, 4-butylene oxide and epichlorohydrin; more preferably propylene oxide. The mass ratio of the amide accelerator to the alkylene oxide accelerator is preferably (0.05-0.15) to (0.03-0.08), and more preferably 0.10 to 0.06.

The ZrO (NO)₃)₂·5H₂The mass ratio of the O, the organic solvent, the water and the accelerator is preferably 1 to (7-15) to (1-4) to (0.08-0.23); more preferably 1: 10: 2: 0.16.

The preparation process of the sol is preferably as follows: first ZrO (NO)₃)₂·5H₂And O, organic solvent and water are stirred and mixed uniformly, then the amide accelerator is added, stirred and mixed uniformly, and finally the alkylene oxide accelerator is added, stirred and mixed until a transparent sol is formed.

According to the invention, the alumina aerogel precursor sol is obtained by the following method: and mixing aluminum isopropoxide, an organic solvent, water and an accelerator to form the zirconium dioxide aerogel precursor sol.

Wherein:

The accelerator is preferably an amide accelerator and an alkylene oxide accelerator, and the addition of the accelerator can promote crosslinking, thereby being beneficial to the formation of gel in the subsequent link. Wherein, the amide accelerator is preferably one or more of formamide, N-dimethyl benzamide, succinimide and delta-valerolactam; more preferably formamide. The alkylene oxide accelerator is preferably one or more of propylene oxide, ethylene oxide, 1, 2-butylene oxide, 1, 4-butylene oxide and epichlorohydrin; more preferably propylene oxide. The mass ratio of the amide accelerator to the alkylene oxide accelerator is preferably (0.05-0.15) to (0.01-0.03), and more preferably 0.10 to 0.02.

The mass ratio of the aluminum isopropoxide to the organic solvent to the water to the accelerator is preferably 1 to (1-8) to (1-5) to (0.06-0.18); more preferably 1: 5: 3: 0.12.

The preparation process of the sol is preferably as follows: firstly, uniformly stirring and mixing aluminum isopropoxide, an organic solvent and water, then adding an amide accelerator, uniformly stirring and mixing, and finally adding an alkylene oxide accelerator, and stirring until a transparent sol is formed.

According to the invention, the pre-dried fiber paper is soaked in the aerogel precursor sol, the use amount of the aerogel precursor sol is not particularly limited, and the fiber paper can be completely immersed. After soaking, the fiber paper is taken out, redundant sol is extruded out, and a certain soaking amount is controlled. In the present invention, the impregnation amount is preferably controlled to be: the mass ratio of the blank obtained after infiltration to the blank before infiltration is 2.83-5.04: 1; in some embodiments of the invention, the mass ratio is 2.83: 1, 4.82: 1, or 5.04: 1.

In the present invention, the drying is performed after the impregnation treatment. In the present invention, the drying temperature is not particularly limited, and the drying may be performed at normal temperature, and the drying time is preferably 1 to 5 hours, and more preferably 3 hours. After soaking, standing for a period of time at normal temperature, the sol adsorbed by the fiber paper becomes gel, and the gel fiber paper is obtained. Wherein, the gel corresponds to the gel precursor sol, namely the formed gel is selected from one or more of silicon dioxide aerogel, zirconium dioxide aerogel and aluminum oxide aerogel.

In the present invention, after the drying treatment, it is preferable to further perform: cleaning and aging. Wherein, the cleaning agent adopted for cleaning is preferably one or more of absolute ethyl alcohol, propyl alcohol, methanol, normal butanol, isobutyl alcohol, ethylene glycol and glycerol; more preferably in accordance with the organic solvent in the corresponding sol. The cleaning agent is used for repeatedly washing to replace water in the original system and simultaneously wash away acid radicals and other organic components. The aging is preferably normal temperature aging, and can be specifically 20-30 ℃; the aging time is preferably 1-5 h, and more preferably 3 h. In the aging treatment process, the inner particles of the formed gel are bonded and crosslinked spontaneously and continuously, namely the gel network strengthening process is obtained. The gel fiber paper is obtained through the treatment.

With respect to step d): and carrying out supercritical drying on the gel fiber paper to obtain the high-temperature resistant aerogel composite inorganic heat-insulating paper.

In the present invention, the supercritical drying is preferably CO₂Supercritical drying, i.e. with CO₂Is a drying medium. The temperature of the supercritical drying is preferably 30-55 ℃, and more preferably 45 ℃. The time of supercritical drying is preferably 4-12 h, and more preferably 8 h. The pressure for supercritical drying is preferably 6 to 15MPa, and more preferably 11 MPa.

Forming gel on the surface and inside of the fiber paper through the step c), and in the supercritical drying process of the step d), replacing and recovering the organic solvent contained in the gel fiber paper by supercritical drying medium fluid, converting the gel contained in the dried fiber paper into aerogel and forming a continuous phase of the aerogel on the surface and inside of the fiber paper, so that the high temperature resistance of the fiber paper can be improved, and the toughness of the fiber paper can be further improved.

In the heat insulation fiber paper prepared by the preparation process, the content of the inorganic fiber is 55-85%, the content of the metal salt formed by the reaction of the metal oxide and the inorganic acid in the heat insulation fiber paper is 2-5%, and the content of the formed aerogel material in the heat insulation fiber paper is 5-15%.

According to the invention, metal oxide and inorganic acid are used as raw materials for forming the toughening agent, and are mixed with inorganic fiber, an inorganic binding agent and water, the metal oxide and the inorganic acid form corresponding metal salt (namely the toughening agent) on the surface of the fiber, the metal salt is in a continuous phase which is uniformly wrapped on the surface of the fiber in a flaky structure, the toughness of the inorganic fiber is greatly improved due to the existence of the flaky structure of the continuous phase, meanwhile, metal cations form a highly polymerized polyhydroxy compound in the water, and can adsorb colloid particles of the inorganic binding agent in the coiled water under the action of a flocculating agent, so that the rigidity strength caused by drying of the pure inorganic binding agent is reduced, and finally, the fiber paper has better toughness; it is particularly emphasized that the metal salt of the continuous phase scaly structure must be prepared according to the preparation method of the present invention, and the corresponding metal oxide and the inorganic acid can be generated only under the interfacial effect of the surface of the inorganic fiber, and if the metal salt and the inorganic fiber are directly mixed, the structure can not be formed, and the toughening effect is not provided. And then, the aerogel continuous phase is formed on the surface and in the interior of the fiber paper in situ, so that the toughness and the high temperature resistance of the fiber paper can be further improved.

Experimental results show that the inorganic heat-insulating paper prepared by the invention has the service temperature of over 900 ℃ and up to 1200 ℃, the tensile strength of more than 0.35MPa, and the folded and wound material is cracked, so that the inorganic heat-insulating paper has excellent toughness and high temperature resistance. The high-temperature resistant aerogel composite inorganic heat-insulating paper can be applied to the fields of new energy automobiles, industrial kilns, high-temperature pipeline heat insulation and the like.

For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.

Example 1

1.1 preparation

S1, injecting 5.53L of deionized water into a stirrer, adding 66.35g of aluminum silicate fiber, starting stirring, sequentially adding 1.7g of concentrated sulfuric acid (with the concentration of 98%) and 1.38g of zinc oxide, stirring for 5min, and adding 46.1g of alkaline silica Sol (SiO)₂Solid content: 30 percent) and stirring for 5min to uniformly disperse the materials to obtain slurry.

S2, adding 4.61g of cationic polyacrylamide solution (with the concentration of 1%) into the obtained slurry, flocculating, and obtaining a wet fiber paper blank with the specification of 480mm multiplied by 320mm multiplied by 5mm through a paper-making device.

S3, carrying out microwave drying on the wet fiber paper blank at the drying temperature of 100 ℃ for 1h to obtain 82.93g of dry fiber paper blank.

S4, placing 82.93g of the dry fiber paper blank into silica sol for full infiltration, and extruding redundant silica sol to obtain 234.88g of silica sol-adsorbed fiber paper. After standing for 3h at normal temperature (25 ℃), the silica sol adsorbed by the fiber paper becomes silica gel. And repeatedly washing the fiber paper by using absolute ethyl alcohol, and then aging for 3 hours at normal temperature (25 ℃) to obtain the gel fiber paper.

The preparation method of the silica sol comprises the following steps:

53.12mL of tetraethoxysilane (SiO)₂The solid content was 28%, ρ ═ 0.93g/mL), 212.48mL of absolute ethanol (ρ ═ 0.79g/mL), and 10.62mL of deionized water, and the mixture was stirred for 5min, then 5.31mL of oxalic acid solution (concentration: 0.1mol/L) was added, and stirring was continued for 5min until a transparent sol was formed.

S5, putting the obtained gel fiber paper into a supercritical drying kettle and using CO₂Supercritical drying at 45 deg.C for 8 hr under 11MPa to obtain 92.16g of high temperature resistant silica aerogel composite aluminum silicate fiber inorganic heat-insulating paper (rho 120 kg/m)³)。

1.2 characterization

Scanning electron microscope characterization is performed on the fiber paper (i.e., not compounded with aerogel) obtained in step S3, and the result is shown in fig. 1, where fig. 1 is an SEM image of the fiber paper not compounded with aerogel in example 1. It can be seen that the fiber surface is covered with a scaly structure, i.e. the morphology of the metal salt formed by the reaction of the metal oxide with the inorganic acid.

Example 2

S1, 5.53L deionized water is injected into a stirrer, 66.35g magnesium silicate fiber is added, stirring is started, 1.7g concentrated sulfuric acid (with the concentration of 98%) and 1.38g zinc oxide are sequentially added, stirring is carried out for 5min, and 46.1g alkaline silica sol (SiO 2) is added₂Solid content: 30 percent) and stirring for 5min to uniformly disperse the materials to obtain slurry.

S2, adding 4.61g of cationic polyacrylamide solution (with the concentration of 1%) into the obtained slurry, flocculating, and obtaining a fiber paper wet blank with the specification of 480mm multiplied by 320mm multiplied by 5mm through a paper-making device.

S4, placing 82.93g of the dry fiber paper blank into aluminum sol for full infiltration, and extruding out excessive aluminum sol to obtain 418.18g of fiber paper adsorbing the aluminum sol. After being placed at normal temperature (25 ℃) for 3 hours, the aluminum sol absorbed by the fiber paper becomes aluminum gel. And repeatedly washing the fiber paper by using propanol, and aging for 3 hours at normal temperature (25 ℃) to obtain the gel fiber paper.

The preparation method of the aluminum sol comprises the following steps:

55.14g of aluminum isopropoxide, 275.7g of propanol and 165.42g of deionized water are mixed and stirred for 15min, 5.51g of formamide is added and stirred for 30min, and finally 1.11g of propylene oxide is added and stirred for 15min until a transparent sol is formed.

S5, putting the obtained gel fiber paper into a supercritical drying kettle and using CO₂Supercritical drying at 45 deg.C for 8 hr under 11MPa to obtain 92.16g of high temperature resistant aluminum oxide aerogel composite magnesium silicate fiber inorganic heat-insulating paper (rho 120 kg/m)³)。

Example 3

S1, injecting 5.53L of deionized water into a stirrer, adding 66.35g of alumina fiber, starting stirring, sequentially adding 7.3g of hydrochloric acid solution (with the concentration of 36%) and 1.99g of barium oxide, stirring for 5min, and adding46.1g of basic silica Sol (SiO)₂Solid content: 30 percent) and stirring for 5min to uniformly disperse the materials to obtain slurry.

S4, placing 82.93g of the dry fiber paper blank into zirconium sol for full infiltration, and extruding redundant zirconium sol to obtain 400.1g of fiber paper adsorbing the zirconium sol. After standing for 3h at normal temperature (25 ℃), the zirconium sol adsorbed by the fiber paper becomes zirconium gel. And repeatedly washing the fiber paper by using absolute ethyl alcohol, and then aging for 3 hours at normal temperature (25 ℃) to obtain the gel fiber paper.

The preparation method of the zirconium sol comprises the following steps:

36.15g of zirconyl nitrate (ZrO (NO)₃)₂·5H₂O), 361.5g of absolute ethyl alcohol and 72.3g of deionized water, stirring for 15min, adding 3.62g of formamide, stirring for 30min, finally adding 2.18g of propylene oxide, and continuing stirring for 15min until a transparent sol is formed.

S5, putting the obtained gel fiber paper into a supercritical drying kettle and using CO₂Supercritical drying at 45 deg.C for 8 hr under 11MPa to obtain 92.16g of high temperature resistant zirconium dioxide aerogel composite alumina fiber inorganic heat insulating paper (rho 120 kg/m)³)。

Example 4

S1, injecting 5.53L of deionized water into a stirrer, adding 66.35g of alumina fiber, starting stirring, sequentially adding 7.3g of hydrochloric acid solution (with the concentration of 36%) and 1.99g of barium oxide, stirring for 5min, and adding 46.1g of alkaline silica Sol (SiO)₂Solid content: 30 percent) and stirring for 5min to uniformly disperse the materials to obtain slurry.

S4, placing 82.93g of the dry fiber paper blank in zirconium-aluminum composite sol for full infiltration, and extruding redundant sol to obtain 400.1g of fiber paper adsorbing the zirconium-aluminum composite sol. After being placed for 3 hours at normal temperature (25 ℃), the zirconium-aluminum composite sol absorbed by the fiber paper becomes zirconium-aluminum composite gel. And repeatedly washing the fiber paper by using absolute ethyl alcohol, and then aging for 3 hours at normal temperature (25 ℃) to obtain the gel fiber paper.

The preparation method of the zirconium-aluminum composite sol comprises the following steps:

18.07g of zirconyl nitrate (ZrO (NO)₃)₂·5H₂O), 180.75g of absolute ethyl alcohol and 36.15g of deionized water, stirring for 15min, then adding 1.81g of formamide, stirring for 30min, finally adding 1.09g of propylene oxide, and continuing stirring for 15min until a transparent zirconium sol is formed.

27.57g of aluminum isopropoxide, 137.85g of propanol and 82.71g of deionized water are mixed and stirred for 15min, then 2.76g of formamide is added and stirred for 30min, and finally 0.56g of propylene oxide is added and stirred for 15min continuously until a transparent aluminum sol is formed.

And mixing and stirring the zirconium sol and the aluminum sol for 5min to obtain uniform zirconium-aluminum composite sol.

Example 5

S1, injecting 5.53L of deionized water into a stirrer, then adding 66.35g of alumina fiber, starting stirring, then sequentially adding 3.1g of hydrochloric acid solution (with the concentration of 36%), 1.23g of barium oxide and 0.56g of zinc oxide, stirring for 5min, then adding 46.1g of alkaline silica Sol (SiO)₂Solid content: 30 percent) and stirring for 5min to uniformly disperse the materials to obtain slurry.

S4, placing 82.93g of the dry fiber paper blank in zirconium-aluminum composite sol for full infiltration, and extruding redundant sol to obtain 400.1g of fiber paper adsorbing the zirconium-aluminum composite sol. After being placed for 3 hours at normal temperature (25 ℃), the zirconium-aluminum composite sol adsorbed by the fiber paper becomes zirconium-aluminum composite gel. And repeatedly washing the fiber paper by using absolute ethyl alcohol, and then aging for 3 hours at normal temperature (25 ℃) to obtain the gel fiber paper.

18.07g of zirconyl nitrate (ZrO (NO)₃)₂·5H₂O), 180.75g of absolute ethyl alcohol and 36.15g of deionized water, stirring for 15min, adding 1.81g of formamide, stirring for 30min, finally adding 1.09g of propylene oxide, and continuing stirring for 15min until a transparent zirconium sol is formed.

Comparative example 1

The procedure is as in example 1, except that the sol is not impregnated. The method comprises the following specific steps:

s1, injecting 5.53L of deionized water into a stirrer, adding 66.35g of aluminum silicate fiber, starting stirring, sequentially adding 1.7g of concentrated sulfuric acid (with the concentration of 98%) and 1.38g of zinc oxide, stirring for 5min, and adding 46.1g of alkaline silica Sol (SiO)₂Solid content: 30 percent) and stirring for 5min to disperse the materialsAnd (4) homogenizing to obtain slurry.

S3, carrying out microwave drying on the wet fiber paper blank at the drying temperature of 100 ℃ for 1h to obtain 82.93g of non-aerogel composite inorganic heat-insulating paper.

Comparative example 2

The procedure is as in example 1, except that no toughening agent is introduced. The method comprises the following specific steps:

s1, injecting 5.53L deionized water into a stirrer, adding 66.35g aluminum silicate fiber, stirring for 5min, adding 46.1g alkaline silica Sol (SiO)₂Solid content: 30 percent) and stirring for 5min to uniformly disperse the materials to obtain slurry.

S3, carrying out microwave drying on the wet fiber paper blank at the drying temperature of 100 ℃ for 1h to obtain 80.17g of non-toughened fiber paper dry blank.

S4, placing 80.17g of the obtained non-toughened fiber paper dry blank into silica sol for full infiltration, and extruding redundant silica sol to obtain 232.12g of silica sol-adsorbed fiber paper. After standing for 3h at normal temperature (25 ℃), the silica sol adsorbed by the fiber paper becomes silica gel. And repeatedly washing the fiber paper by using absolute ethyl alcohol, and then aging for 3 hours at normal temperature (25 ℃) to obtain the gel fiber paper.

The preparation method of the silica sol comprises the following steps: as in example 1.

S5, putting the obtained gel fiber paper into a supercritical drying kettle and using CO₂Supercritical drying at 45 deg.C for 8 hr under 11MPa to obtain 83.39g of non-toughened silica aerogel composite aluminum silicate fiber inorganic heat-insulating paper (rho 120 kg/m)³)。

Comparative example 3

The procedure is as in example 1, except that no flexibilizer is introduced and no sol is infiltrated. The method comprises the following specific steps:

s1, injecting 5.53L deionized water into the stirrer, adding 66.35g of aluminum silicate fiber, starting stirring, stirring for 5min, adding 46.1g of alkaline silica Sol (SiO)₂Solid content: 30 percent) and stirring for 5min to uniformly disperse the materials to obtain slurry.

S3, carrying out microwave drying on the wet fiber paper blank at 100 ℃ for 1h to obtain 80.17g of non-toughened non-aerogel fiber paper.

Comparative example 4

The procedure is as in example 1, except that zinc sulfate metal salt is used directly as toughener and the metal salt powder is added to the system. The method comprises the following specific steps:

s1, injecting 5.53L deionized water into a stirrer, adding 66.35g of aluminum silicate fiber, starting stirring, directly adding 2.76g of zinc sulfate, stirring for 5min, and adding 46.1g of alkaline silica Sol (SiO)₂Solid content: 30 percent) and stirring for 5min to uniformly disperse the materials to obtain slurry.

S2 to S5 are the same as in example 1.

Example 6

The heat-insulating paper products obtained in examples 1 to 5 and comparative examples 1 to 4 were subjected to performance tests, and the results are shown in Table 1. The test method is characterized in that the test of the use temperature refers to GB/T3003-2017 refractory fiber and a product, and the test of the folded and wound test refers to a GB/T17911-2006 refractory ceramic fiber product test method.

TABLE 1 Properties of products obtained in examples 1 to 5 and comparative examples 1 to 4

	The application temperature is lower	Tensile strength, MPa	Double folding winding test
				Example 1	900	0.42	No crack in folding and winding
Example 2	1050	0.36	No crack in folding and winding
				Example 3	1150	0.44	No crack in folding and winding
Example 4	1200	0.47	No crack in folding and winding
				Example 5	1200	0.43	No crack in folding and winding
Comparative example 1	850	0.31	No crack in folding and winding
				Comparative example 2	900	0.33	Split when folded in half, windable but split after winding
Comparative example 3	850	0.25	Cracking in two folds and failing to wind
				Comparative example 4	900	0.33	Split when folded in half, windable but split after winding

As can be seen from the test results in Table 1, compared with comparative examples 1 to 4, the toughness and the high temperature resistance of the products obtained in examples 1 to 5 are obviously improved, and the inorganic heat-insulating paper prepared in the preparation process provided by the invention is proved to be capable of obviously improving the high temperature resistance of the fiber paper and effectively improving the toughness of the fiber paper.

The above description of the embodiments is only intended to facilitate the understanding of the method of the invention and its core idea. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A preparation process of high-temperature resistant aerogel composite inorganic heat-insulating paper is characterized by comprising the following steps:

the raw materials of the toughening agent are metal oxide and inorganic acid;

the metal oxide is selected from one or more of calcium oxide, magnesium oxide, zinc oxide, aluminum oxide, iron oxide and barium oxide;

the molar ratio of the metal oxide to the inorganic acid is 1: 1-3;

the metal oxide and the inorganic acid form corresponding metal salt in situ on the surface of the fiber, and the metal salt is uniformly wrapped on the surface of the fiber in a continuous phase scaly structure form.

2. The process according to claim 1, wherein in step c):

3. The process according to claim 2, wherein said silica aerogel precursor sol is obtained by: mixing ethyl orthosilicate, an organic solvent, water and a catalyst solution to form a silica aerogel precursor sol;

the concentration of the catalyst solution is 0.05-0.2 mol/L;

the promoter comprises an amide promoter and an alkylene oxide promoter;

the alkylene oxide accelerator is one or more selected from propylene oxide, ethylene oxide, 1, 2-butylene oxide, 1, 4-butylene oxide and epichlorohydrin.

4. The process of claim 1, wherein the supercritical drying is CO₂Supercritical drying;

5. The preparation process of claim 1, wherein in the step a), the mass ratio of the inorganic fibers to the raw material of the toughening agent to the inorganic binder is (55-85) to (2-5) to (8-25);

the mass concentration of the slurry is 1% -2%.

6. The process according to claim 1 or 5, wherein the inorganic fibers are selected from: one or more of aluminum silicate fiber, magnesium silicate fiber, high silica fiber, quartz fiber, polycrystalline mullite fiber and alumina fiber;

7. The preparation process according to claim 1, wherein the flocculating agent is selected from one or more of a cationic polyacrylamide solution, an anionic polyacrylamide solution and a non-ionic polyacrylamide solution;

the mass concentration of the flocculating agent is 0.05% -1.15%;

8. The preparation process according to claim 1, wherein in the step c), the pre-drying is hot air drying or microwave drying;

the hot air drying temperature is 100-150 ℃, and the time is 1-3 h;

the microwave drying temperature is 80-120 ℃, and the time is 0.5-1.5 h;

the step d) may further comprise, before the supercritical drying: cleaning and aging the gel fiber paper;

the aging temperature is 20-30 ℃, and the aging time is 1-5 hours.

9. The high-temperature resistant aerogel composite inorganic heat-insulating paper prepared by the preparation process of any one of claims 1 to 8.