阅读说明：本技术 一种气凝胶型稀土复合保温材料及其制备方法 (Aerogel type rare earth composite thermal insulation material and preparation method thereof ) 是由 罗炎 于 2021-01-12 设计创作，主要内容包括：本发明属于保温材料技术领域,具体涉及一种气凝胶型稀土复合保温材料及其制备方法。本发明研制的产品中,包括二氧化硅气凝胶；所述二氧化硅气凝胶孔隙的孔壁表面,吸附有聚多巴胺层,所述聚多巴胺层表面吸附有稀土氧化物；所述二氧化硅气凝胶孔隙的孔径分布范围为20-40nm。另外,还包括纳米聚丙烯酸酯颗粒,所述纳米聚丙烯酸酯颗粒分散于二氧化硅气凝胶孔隙中；还包括二氧化钛气凝胶。在制备产品时,将正硅酸乙酯、无水乙醇、包覆有多巴胺的氧化铝颗粒混合分散后,滴加氨水,待氨水滴加完毕后,通入空气,再经静置老化后,调节pH,超声浸渍后,再加入稀土盐溶液,调节pH,洗涤,干燥,得气凝胶型稀土复合保温材料。(The invention belongs to the technical field of thermal insulation materials, and particularly relates to an aerogel type rare earth composite thermal insulation material and a preparation method thereof. The product developed by the invention comprises silicon dioxide aerogel; a polydopamine layer is adsorbed on the surface of the pore wall of the pores of the silicon dioxide aerogel, and rare earth oxide is adsorbed on the surface of the polydopamine layer; the pore diameter distribution range of the pores of the silicon dioxide aerogel is 20-40 nm. In addition, the aerogel also comprises nano polyacrylate particles, wherein the nano polyacrylate particles are dispersed in the pores of the silica aerogel; also comprises titanium dioxide aerogel. When the product is prepared, the ethyl orthosilicate, the absolute ethyl alcohol and the alumina particles coated with dopamine are mixed and dispersed, ammonia water is dripped, after the ammonia water is dripped, air is introduced, the mixture is kept stand and aged, the pH value is adjusted, the mixture is ultrasonically immersed, then the rare earth salt solution is added, the pH value is adjusted, and the aerogel type rare earth composite thermal insulation material is obtained after washing and drying.)

1. An aerogel type rare earth composite thermal insulation material is characterized by comprising silicon dioxide aerogel;

a polydopamine layer is adsorbed on the surface of the pore wall of the pores of the silicon dioxide aerogel, and rare earth oxide is adsorbed on the surface of the polydopamine layer;

the pore diameter distribution range of the pores of the silicon dioxide aerogel is 20-40 nm.

2. The aerogel type rare earth composite thermal insulation material as claimed in claim 1, further comprising nano polyacrylate particles, wherein the nano polyacrylate particles are dispersed in the pores of the silica aerogel.

3. The aerogel type rare earth composite thermal insulation material as claimed in claim 1, wherein the rare earth oxide is any one of scandium oxide, cerium oxide and lanthanum oxide.

4. The aerogel type rare earth composite thermal insulation material as claimed in claim 1, further comprising titanium dioxide aerogel.

5. The preparation method of the aerogel type rare earth composite thermal insulation material is characterized by comprising the following specific preparation steps:

(1) selecting alumina particles with the particle size distribution range of 20-40nm, performing ultrasonic dispersion on the alumina particles in an aqueous solution, adding dopamine and ascorbic acid under the protection of inert gas, continuing to disperse uniformly, filtering under the protection of inert gas, and performing vacuum drying to obtain nano alumina particles coated with dopamine and ascorbic acid, namely pretreated alumina particles;

(2) mixing and dispersing tetraethoxysilane, absolute ethyl alcohol and pretreated alumina particles, dropwise adding ammonia water, introducing air after the ammonia water is dropwise added, standing and aging, adjusting the pH to 3.0-4.0, ultrasonically dipping, adding a rare earth salt solution, adjusting the pH to 8.5-9.0, washing for 3-5 times by using the absolute ethyl alcohol, and performing vacuum freeze drying to obtain the aerogel type rare earth composite heat insulation material.

6. The preparation method of the aerogel type rare earth composite thermal insulation material as claimed in claim 5, wherein the specific preparation steps further comprise adding the nano acrylate emulsion while dropwise adding ammonia water.

7. The method for preparing the aerogel type rare earth composite thermal insulation material as claimed in claim 5, wherein the rare earth salt solution is any one of scandium nitrate, cerium nitrate and lanthanum nitrate.

8. The method for preparing the aerogel type rare earth composite thermal insulation material according to claim 5, wherein the step (2) further comprises: tetrabutyl titanate is added before ammonia is added dropwise.

Technical Field

The invention belongs to the technical field of heat insulation materials. More particularly, relates to an aerogel type rare earth composite thermal insulation material and a preparation method thereof.

Background

With the improvement of building energy-saving standards and the progress of energy-saving technology, the building external wall thermal insulation material is continuously developed towards the directions of light weight, multiple functions, energy conservation and environmental protection. Aerogel is a light nano-porous material with a three-dimensional network structure formed by cross-linking colloidal particles or high polymer molecules. The composite material has the characteristics of good heat insulation, sound absorption, shock absorption, hydrophobicity, non-flammability, weather resistance and the like, and is mainly applied to the high-end fields of aerospace, industrial high-temperature devices, heat insulation and preservation and the like. Therefore, compared with the existing organic heat-insulating material or inorganic heat-insulating material, the aerogel nano-porous heat-insulating material has remarkable advantages. In recent years, a silicon dioxide aerogel material as a novel nanometer light, multifunctional, energy-saving and environment-friendly material gradually enters the visual field of people by using the unique properties (low density, high specific surface area, low thermal conductivity, high light transmittance and the like), and particularly, the aerogel material as an efficient energy-saving and heat-insulating material has been mainly concerned by researchers; the composite material is light in weight, fireproof, transparent, heat-insulating, green and environment-friendly, and has many advantages compared with the traditional building external wall heat-insulating material. Therefore, the method utilizes means such as simulation and the like to research aiming at the potential application of the silica aerogel material in the building heat insulation material, and has important significance for the application of the silica aerogel material in building energy conservation.

The pure aerogel has low strength, poor toughness, complex preparation process and high cost, and becomes a key factor influencing large-scale application of the pure aerogel in the field of building energy conservation. If the aerogel composite material is applied to an external wall heat insulation system of a building, various problems are faced, and therefore, improvement and improvement of the strength and toughness of the aerogel are particularly necessary.

The SiO2 aerogel fiber composite thermal insulation material is compounded by taking silicon dioxide aerogel as a main component and taking a fiber reinforced cementing material as a framework through a special manufacturing process. The preparation process is complex, so that the application field of the composite material is limited, and the composite material is mainly applied to high-end fields needing high-efficiency heat insulation and preservation, such as aerospace, heat supply network pipelines, ships and industrial high-temperature devices. Therefore, the development of aerogel thermal insulation materials with high mechanical strength, simple and convenient manufacturing process and lower cost is a field worth exploring and developing in the construction research of energy-saving buildings.

Disclosure of Invention

The invention aims to overcome the defects and shortcomings that the service life of a product is limited due to the fact that the interaction force in the conventional aerogel material is weak and the mechanical property of the aerogel material cannot be effectively maintained for a long time, and provides an aerogel type rare earth composite thermal insulation material and a preparation method thereof.

The invention aims to provide an aerogel type rare earth composite thermal insulation material.

The invention also aims to provide a preparation method of the aerogel type rare earth composite thermal insulation material.

The above purpose of the invention is realized by the following technical scheme:

an aerogel type rare earth composite thermal insulation material comprises silicon dioxide aerogel;

a polydopamine layer is adsorbed on the surface of the pore wall of the pores of the silicon dioxide aerogel, and rare earth oxide is adsorbed on the surface of the polydopamine layer;

the pore diameter distribution range of the pores of the silicon dioxide aerogel is 20-40 nm.

According to the technical scheme, the poly dopamine layer is introduced into the hole wall of the aerogel pore structure in the silicon dioxide aerogel system, and the rare earth oxide is further adsorbed on the surface of the poly dopamine layer, so that on one hand, the original heat diffusion mode in the aerogel structure is changed, and a polymer layer exists between the aerogel solid structure and the rare earth oxide, so that a 'broken bridge' of heat transfer is formed, and the heat insulation performance of an aerogel product is further improved; on the other hand, due to the existence of polydopamine, the bonding fastness between the aerogel and the rare earth oxide can be effectively improved, and the desorption of the rare earth oxide is avoided; moreover, the distribution range of the pore diameters of the silicon dioxide aerogel pores is controlled in a relatively narrow range, the consistency of internal channels can be guaranteed, local cracking caused by uneven local stress is avoided in the using process, the mechanical property of the product is improved, and the service life of the product is effectively prolonged.

Further, the aerogel also comprises nano polyacrylate particles, wherein the nano polyacrylate particles are dispersed in the pores of the silica aerogel.

According to the technical scheme, a small amount of nano polyacrylate particles are introduced into an aerogel network system, so that on one hand, the heat conduction performance of the polymer nano particles is poor, and the heat conduction coefficient is different from that of silicon dioxide, so that the heat insulation performance of an aerogel structure can be further improved; on the other hand, the existence of nanometer polyacrylate granule can effectively be as the elastic adhesive in aerogel network structure, makes aerogel system possess good toughness, when receiving external force impact, can be with stress dispersion conduction inside fast, has promoted the life of product.

Further, the rare earth oxide is any one of scandium oxide, cerium oxide, and lanthanum oxide.

Further, the composite material also comprises titanium dioxide aerogel.

According to the technical scheme, the titanium dioxide aerogel is introduced into the system, the titanium dioxide and the silicon dioxide are utilized to form the complex composite aerogel, and in a microscopic aspect, because the molecular sizes of the titanium dioxide and the silicon dioxide are different, and because the crystallization speeds of the titanium dioxide and the silicon dioxide during crystallization are different, a crystal boundary is easy to exist between the titanium dioxide and the silicon dioxide, a 'broken bridge' can be formed at the crystal boundary in the heat conduction process, and the heat insulation performance of the product is further improved; moreover, from the macroscopic aspect, because titanium dioxide aerogel alternates between silica aerogel, can form complicated three-dimensional network structure, promoted the mechanical properties of product.

A preparation method of an aerogel type rare earth composite thermal insulation material comprises the following specific preparation steps:

(1) selecting alumina particles with the particle size distribution range of 20-40nm, performing ultrasonic dispersion on the alumina particles in an aqueous solution, adding dopamine and ascorbic acid under the protection of inert gas, continuing to disperse uniformly, filtering under the protection of inert gas, and performing vacuum drying to obtain nano alumina particles coated with dopamine and ascorbic acid, namely pretreated alumina particles;

(2) mixing and dispersing tetraethoxysilane, absolute ethyl alcohol and pretreated alumina particles, dropwise adding ammonia water, introducing air after the ammonia water is dropwise added, standing and aging, adjusting the pH to 3.0-4.0, ultrasonically dipping, adding a rare earth salt solution, adjusting the pH to 8.5-9.0, washing for 3-5 times by using the absolute ethyl alcohol, and performing vacuum freeze drying to obtain the aerogel type rare earth composite heat insulation material.

In the technical scheme, dopamine is coated on the surfaces of aluminum oxide particles, then the aluminum oxide particles are added into the hydrolysis process of tetraethoxysilane, in the hydrolysis process of tetraethoxysilane, a hydrolysis product grows on the surfaces by taking a polydopamine layer on the surfaces of the pretreated aluminum oxide particles as a nucleation interface, gel is finally formed, in addition, in the process of adjusting the pH value to be acidic, hydrogen ions enable the aluminum oxide particles to be dissolved and disappear and leave pores, and the polydopamine layer on the interface of the aluminum oxide and the gel is remained on the pore walls of the gel.

Further, the specific preparation steps further comprise adding the nano acrylate emulsion while dropwise adding ammonia water.

Further, the rare earth salt solution is any one of scandium nitrate, cerium nitrate and lanthanum nitrate.

Further, the step (2) further comprises: tetrabutyl titanate is added before ammonia is added dropwise.

Detailed Description

The present invention is further illustrated by the following specific examples, which are not intended to limit the invention in any way. Reagents, methods and apparatus used in the present invention are conventional in the art unless otherwise indicated.

Unless otherwise indicated, reagents and materials used in the following examples are commercially available.

Example 1

Selecting alumina particles with the particle size distribution range of 20-40nm, and mixing the alumina particles with water according to the mass ratio of 1: 8, after mixing, carrying out ultrasonic dispersion for 10min under the condition that the ultrasonic frequency is 50kHz to obtain dispersion liquid, then adding dopamine with the mass being 1% of that of the dispersion liquid and ascorbic acid with the mass being 0.1% of that of the dispersion liquid into the dispersion liquid under the protection of inert gas, continuing carrying out ultrasonic dispersion for 10min under the condition that the ultrasonic frequency is 50kHz, then filtering under the protection of inert gas, collecting filter cakes, and carrying out vacuum freeze drying on the obtained filter cakes under the conditions that the temperature is-15 ℃ and the vacuum degree is 80Pa to constant weight to obtain nano alumina particles coated with the dopamine and the ascorbic acid, namely the pretreated alumina particles;

according to the weight parts, 80 parts of ethyl orthosilicate, 300 parts of absolute ethyl alcohol, 8 parts of pretreated alumina particles, 10 parts of tetrabutyl titanate, 8 parts of a rare earth salt solution with the mass fraction of 5%, 5 parts of nano acrylate emulsion and 20 parts of ammonia water with the mass fraction of 3% are taken in sequence; the rare earth salt solution is scandium nitrate;

mixing ethyl orthosilicate, tetrabutyl titanate, absolute ethyl alcohol and pretreated alumina particles in a reactor, ultrasonically dispersing for 60min under the condition that the ultrasonic frequency is 60kHz to obtain dispersion liquid, dropwise adding ammonia water into the dispersion liquid at the speed of 3mL/min through a dropping funnel while stirring under the stirring state at the rotating speed of 300r/min, adding a nano acrylate emulsion in the dropwise adding process of the ammonia water, continuously introducing air into materials in the reactor at the speed of 10mL/min for 5min after the dropwise adding of the ammonia water is finished, standing and aging for 24h under the room temperature condition, then adjusting the pH value of the materials in the reactor to 3.0, ultrasonically impregnating for 30min under the condition that the ultrasonic frequency is 80kHz, then adding a rare earth salt solution into the reactor, adjusting the pH value of the materials in the reactor to 8.5 to obtain wet gel, washing the wet gel for 3 times by using the absolute ethyl alcohol, and (3) carrying out vacuum freeze drying to constant weight under the conditions that the vacuum degree is 80Pa and the temperature is-30 ℃, and discharging to obtain the aerogel type rare earth composite thermal insulation material.

Example 2

Selecting alumina particles with the particle size distribution range of 30-40nm, and mixing the alumina particles with water according to the mass ratio of 1: 9, after mixing, carrying out ultrasonic dispersion for 20min under the condition that the ultrasonic frequency is 55kHz to obtain dispersion liquid, then adding dopamine with the mass being 3% of that of the dispersion liquid and ascorbic acid with the mass being 0.2% of that of the dispersion liquid into the dispersion liquid under the protection of inert gas, continuing carrying out ultrasonic dispersion for 20min under the condition that the ultrasonic frequency is 55kHz, then filtering under the protection of inert gas, collecting filter cakes, and carrying out vacuum freeze drying on the obtained filter cakes under the conditions that the temperature is-20 ℃ and the vacuum degree is 100Pa to constant weight to obtain nano alumina particles coated with dopamine and ascorbic acid, namely the pretreated alumina particles;

according to the weight parts, 100 parts of ethyl orthosilicate, 400 parts of absolute ethyl alcohol, 12 parts of pretreated alumina particles, 20 parts of tetrabutyl titanate, 9 parts of rare earth salt solution with the mass fraction of 8%, 8 parts of nano acrylate emulsion and 30 parts of ammonia water with the mass fraction of 4% are taken in sequence; the rare earth salt solution is cerium nitrate;

mixing ethyl orthosilicate, tetrabutyl titanate, absolute ethyl alcohol and pretreated alumina particles in a reactor, ultrasonically dispersing for 80min under the condition that the ultrasonic frequency is 70kHz to obtain dispersion liquid, dropwise adding ammonia water into the dispersion liquid at the speed of 4mL/min through a dropping funnel while stirring under the stirring state at the rotating speed of 400r/min, adding a nano acrylate emulsion in the dropwise adding process of the ammonia water, continuously introducing air into materials in the reactor at the speed of 20mL/min for 10min after the dropwise adding of the ammonia water is finished, standing and aging for 32h under the room temperature condition, then adjusting the pH of the materials in the reactor to 3.5, ultrasonically impregnating for 50min under the condition that the ultrasonic frequency is 100kHz, then adding a rare earth salt solution into the reactor, adjusting the pH of the materials in the reactor to 8.8 to obtain wet gel, washing the wet gel for 4 times by using the absolute ethyl alcohol, and (3) carrying out vacuum freeze drying to constant weight under the conditions that the vacuum degree is 120Pa and the temperature is-35 ℃, and discharging to obtain the aerogel type rare earth composite thermal insulation material.

Example 3

Selecting alumina particles with the particle size distribution range of 35-40nm, and mixing the alumina particles with water according to the mass ratio of 1: 10, performing ultrasonic dispersion for 30min under the condition that the ultrasonic frequency is 60kHz to obtain dispersion liquid, adding dopamine with the mass being 5% of the dispersion liquid and ascorbic acid with the mass being 0.3% of the dispersion liquid into the dispersion liquid under the protection of inert gas, performing ultrasonic dispersion for 30min under the condition that the ultrasonic frequency is 60kHz, filtering under the protection of inert gas, collecting filter cakes, and performing vacuum freeze drying on the obtained filter cakes under the conditions that the temperature is-30 ℃ and the vacuum degree is 120Pa to constant weight to obtain nano alumina particles coated with the dopamine and the ascorbic acid, namely pretreated alumina particles;

according to the weight parts, 120 parts of ethyl orthosilicate, 500 parts of absolute ethyl alcohol, 15 parts of pretreated alumina particles, 30 parts of tetrabutyl titanate, 10 parts of a rare earth salt solution with the mass fraction of 10%, 10 parts of nano acrylate emulsion and 40 parts of ammonia water with the mass fraction of 5% are taken in sequence; the rare earth salt solution is lanthanum nitrate;

mixing ethyl orthosilicate, tetrabutyl titanate, absolute ethyl alcohol and pretreated alumina particles in a reactor, ultrasonically dispersing for 100min under the condition that the ultrasonic frequency is 80kHz to obtain dispersion liquid, dropwise adding ammonia water into the dispersion liquid at the speed of 5mL/min through a dropping funnel while stirring under the stirring state at the rotating speed of 500r/min, adding a nano acrylate emulsion in the dropwise adding process of the ammonia water, continuously introducing air into materials in the reactor at the speed of 30mL/min for 15min after the dropwise adding of the ammonia water is finished, standing and aging for 36h under the room temperature condition, then adjusting the pH value of the materials in the reactor to 4.0, ultrasonically impregnating for 60min under the condition that the ultrasonic frequency is 120kHz, then adding a rare earth salt solution into the reactor, adjusting the pH value of the materials in the reactor to 9.0 to obtain wet gel, washing the wet gel for 5 times by using the absolute ethyl alcohol, and (3) carrying out vacuum freeze drying to constant weight under the conditions that the vacuum degree is 150Pa and the temperature is-40 ℃, and discharging to obtain the aerogel type rare earth composite thermal insulation material.

Comparative example 1

This comparative example differs from example 1 in that: dopamine was not added and the remaining conditions were kept unchanged.

Comparative example 2

This comparative example differs from example 1 in that: tetrabutyl titanate is not added, and the rest conditions are kept unchanged.

Comparative example 3

This comparative example differs from example 1 in that: the alumina powder with the equal mass and the particle size distribution range of 1-200nm is adopted to replace the alumina particles with the particle size distribution range of 20-40nm, and the rest conditions are kept unchanged.

The products obtained in examples 1 to 3 and comparative examples 1 to 3 were subjected to performance tests, and the specific test methods and test results were as follows:

testing of mechanical properties:

the aerogel products prepared in the above embodiments and comparative examples are placed on a universal material testing machine to test the flexural strength under certain deformation when the aerogel products are bent at three points, and the mechanical properties of the material are represented according to the flexural strength.

A three-point bending beam experiment model is selected to measure the flexural strength of the product, the size of the product is 40mm multiplied by (3 +/-0.5) mm, the span is 30mm, and the advancing speed of a pressure head is 15 mm/min. The flexural strength under 70% strain (deformation) is taken to characterize the product when the flexural strength is tested, and the specific test results are shown in table 1;

testing of thermal conductivity coefficient:

respectively preparing samples of each example and each comparative example, preparing two samples with the same size for a single example or each comparative example, placing the samples on the upper side and the lower side of a heat source, placing the heat source between the two samples, and testing by adopting the transient hot wire principle, wherein the specific test results are shown in table 1;

	flexural strength/MPa	Thermal conductivity/(W/(m.K))
			Example 1	1.96	0.032
Example 2	1.98	0.029
			Example 3	2.02	0.028
Comparative example 1	1.85	0.045
			Comparative example 2	1.76	0.046
Comparative example 3	1.82	0.052

The test results in table 1 show that the product obtained by the invention not only has excellent mechanical properties, but also has a low thermal conductivity coefficient, and can exert good heat preservation and heat insulation properties.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.