CN106977982A - A kind of nano-pore heat insulating materials coating for surface protection and preparation method thereof - Google Patents

Abstract

The invention discloses a surface protective coating of a nanoporous heat insulating material and a preparation method thereof. The treatment of the solid material includes: mixing the expanded vermiculite particles with liquid aluminum dihydrogen phosphate after high-temperature pretreatment, and adding the zeolite particles according to the submerged amount Liquid aluminum dihydrogen phosphate, ball milled to an average particle size of less than 4 μm; adding ethanol to alkali metal oxides, ball milled to an average particle size of less than 4 μm, immersing mica particles in water, ball milled to an average particle size of less than 4 μm, and then baked and dehydrated at 300°C ; The above-mentioned processed solid material is mixed with liquid aluminum dihydrogen phosphate and sodium methyl silicate in proportion to make a slurry, enter the high-shear mixer and mix for 30-100 minutes at 1500-3000 rpm to spray or brush The method is applied to the nanoporous insulation material substrate to impregnate into the pores, and forms a waterproof protective coating after drying. The invention is dust-free, does not fall off, can resist relatively high collision impact, is waterproof, fireproof and environmentally friendly.

Description

A kind of surface protective coating of nanoporous thermal insulation material and preparation method thereof

technical field

The invention relates to the field of material technology, in particular to a protective coating on the surface of a nanoporous heat insulating material, and also relates to a preparation method for the protective coating on the surface of a nanoporous heat insulating material.

Background technique

Nanoporous thermal insulation material is a new development, mainly for high and low temperature thermal insulation projects. It is a new type of thermal insulation material made by nanotechnology. Its network structure of nanopores (less than 100nm) and its infrared radiation and scattering characteristics of industrial wavelengths can Effectively inhibit solid and gaseous heat conduction, gas convection and radiation heat transfer. Compared with traditional heat insulation materials, nanoporous heat insulation materials can usually reduce the thickness of the heat insulation layer by 3/4, and under the same heat insulation layer thickness, the energy saving rate generally reaches 25-30%, which not only can significantly reduce the energy consumption in production and use consumption, and correspondingly, the size and weight of the equipment can be greatly reduced.

In recent years, due to its excellent heat insulation and flame retardant properties, nanoporous thermal insulation materials have been used in glass industry, industrial furnaces, electrolytic aluminum, electric heating accumulators, elevators, ships, military industries, etc. has been widely used. However, in order to ensure its excellent heat transfer performance, the material does not use organic or inorganic adhesives in conventional production, but mainly adopts powder pressing molding process, so its surface is not wear-resistant, not waterproof, and its overall strength is low, so it cannot be collided. In the conventional process, specially treated glass fiber cloth is generally used as the envelope material for protection, so as to facilitate transportation and installation. This process adopts the one-time molding method of glass fiber cloth envelope and core material, which is suitable for the production of conventional plates that do not require high precision. In some areas that require high precision and require special-shaped structural parts such as curved surfaces, openings, grooves, and steps, the use of glass cloth packaging requires a large number of manual cutting and laminating processes, which increases production costs and makes the process flow More complicated, it is difficult to achieve the goal of industrialized production. In particular, the packaging method of glass fiber cloth still has the problem of dust leakage, which cannot meet the conditions of use in food industry equipment, medical and health equipment, and military optical equipment, thus limiting the application fields of nanoporous thermal insulation materials.

In order to produce structurally stable and dust-free nanoporous insulation components, it is easiest to implement protective coatings on their surfaces. The coating should meet the requirements of stable structure, uniform film formation, strong bonding with the core material, no cracks and dust shedding on the surface, high temperature resistance and thermal shock resistance, and does not affect the performance of the substrate.

A large number of experiments by the inventors have shown that the high-temperature organic and inorganic coatings routinely used in the field of fire-resistant and heat-insulating materials all have coating cracks and peeling off, which are difficult to use. A large number of literature reports related to protective coatings are almost mostly concentrated in the field of porous ceramics with high structural strength. Regarding the coating solution for nanoporous insulation materials, US Patent 5,474,806 discloses a water-based protective coating applied to nano The method on the surface of porous thermal insulation materials. This method believes that due to the hydrophilicity of conventional nanoporous thermal insulation materials, applying a water-based protective coating can easily cause the surface of the material to wet and absorb water. Water will destroy the microporous structure during the drying process. This results in a reduction in thermal insulation performance. Therefore, the patent proposes to use hydrophobic fumed silica to manufacture nanoporous thermal insulation materials, use gas nozzles to burn or heat at high temperatures in the furnace to destroy the organic hydrophobic layer, and generate a thermal insulation material with a hydrophilic surface and a hydrophobic matrix, and then water Sodium silicate adhesive for surface treatment, so that it is easy to wet the surface and adsorb there or form a continuous protective coating, which can achieve wear resistance and impact resistance without causing shrinkage of the base material and damage to the microporous structure . Although the principle of this method is relatively simple, expensive hydrophobic fumed silica needs to be used in the production process, and a high-temperature ablation process that destroys the surface hydrophobic layer needs to be added, resulting in a significant increase in the production cost of the product, and the high-temperature ablation process The temperature and processing time are difficult to control, which determines the thickness of the ablation layer, and then determines the thickness of the coating. In the case of industrial production, the materials are generally placed in stacks, and there is a temperature gradient between the layers. Finally, The thickness of the coating must vary, and the silicate adhesive is not a suitable adhesive for the high-temperature application of nanoporous insulation materials due to its high alkalinity and brittleness. In addition, due to the presence of the organic coating layer on the hydrophobic fumed oxide particles, the bonding strength between the particles is reduced, the overall strength of the material is lower, and it is less wear-resistant. Such a protective layer is probably not worth the candle.

Contents of the invention

The object of the present invention is to overcome the above disadvantages and provide a dust-free, non-shedding, relatively high impact resistance, waterproof, fireproof and environmentally friendly nanoporous heat insulating material surface protective coating.

Another object of the present invention is to provide a method for preparing the protective coating on the surface of the nanoporous heat insulating material.

A surface protection coating of a nanoporous heat insulating material of the present invention has the following formula in parts by weight:

Liquid Aluminum Dihydrogen Phosphate 45-75

Expanded vermiculite 10 -30

Zeolite 3 -6

Mica 8 -12

Silicone water repellent (sodium methyl silicate) 1.9 -7

Alkali metal oxides (zinc oxide, magnesium oxide) 1.5-3

Dispersant (Duramax D-3005) 0.1-0.5

Preferably the parts by weight of each component are as follows:

Liquid Aluminum Dihydrogen Phosphate 60

Expanded vermiculite 15

Zeolite 6

Mica 12

Alkali metal oxides 3

Silicone waterproofing agent (sodium methyl silicate) 3.7

Dispersant (Duramax D-3005) 0.3

A method for preparing a surface protective coating of a nanoporous heat insulating material of the present invention, comprising the following steps:

(1) Handling of solid materials:

a. After the expanded vermiculite particles are pretreated at high temperature, take 2-5 parts and mix them with 1 part of liquid aluminum dihydrogen phosphate, and then use alumina balls in a ball mill for 24-48 hours until the average particle size is less than 4 μm (so that In order to penetrate into the surface pores of nanoporous insulation materials, to avoid only adhering to the surface and easy to fall off);

b. Add the zeolite particles into the liquid aluminum dihydrogen phosphate according to the immersion amount (the solid particles completely absorb the liquid and keep the liquid submerged), and use alumina balls in a ball mill for 24-48 hours until the average particle size is less than 4 μm;

c. Alkali metal oxides are added with ethanol, and ball milled in a ball mill with alumina balls for 24-48 hours until the average particle size is less than 4 μm;

d. After immersing the mica particles in water, mill them in a ball mill with alumina balls for 24-48 hours until the average particle size is less than 4 μm, and then bake and dehydrate at 300°C;

(2) The above-mentioned treated solid material is mixed with liquid aluminum dihydrogen phosphate and sodium methyl silicate according to the following ratio to make a slurry,

Liquid Aluminum Dihydrogen Phosphate 45-75

Expanded vermiculite 10 -30

Zeolite 3 -6

Mica 8 -12

Silicone waterproofing agent (sodium methyl silicate) 1.9-7

Alkali metal oxides (zinc oxide, magnesium oxide) 1.5-3

Dispersant (Duramax D-3005) 0.1-0.5

Enter the high-shear mixer and mix at 1500-3000 rpm for 30-100 minutes, and apply it to the nanoporous insulation material substrate by spraying or brushing to impregnate the pores;

(3) Dry at room temperature for 30 minutes, and then enter the furnace for 3-8 minutes of rapid drying at 80-120°C (due to the high gas content of the substrate, heating for a long time will cause the surface coating to bulge, delaminate or crack, and the temperature Too low phosphate cannot be dehydrated and solidified) The amount of sizing is 1.8-3.0 g/cm ² after drying, forming a 0.3-0.5mm wear-resistant, high-temperature-resistant (same temperature as the base material) waterproof protective coating.

Coating performance test:

Due to the extremely low structural strength of the nanoporous thermal insulation material substrate, the protective coating made by the above method cannot be compared to the coating formed on rigid substrates such as metals, ceramics, concrete, etc., and the bonding strength between the coating and the substrate is limited. Determination can not adopt conventional methods, such as: bending, substrate stretching, filing, abrasion and other experimental methods. In fact, the main purpose of forming a protective coating on the nanoporous thermal insulation material substrate is to facilitate manual operations such as transportation and installation while maintaining the thermal insulation performance of the substrate while achieving moisture resistance and thermal shock resistance, so the protective coating does not need To meet the requirements of those coatings on rigid substrates, it is more suitable to use qualitative methods to express their wear resistance and impact resistance performance by empirical judgment and relative comparison.

1) Wear resistance, impact resistance: If the conventional nanoporous thermal insulation material is not covered with protective glass fiber cloth, it will cause the surface powder to fall off if it is handled with care or stacked, especially the edges, edges, and inversions of special-shaped components. Corners, holes, etc. are easily damaged during transportation and installation, and are not resistant to collisions and impacts. Adopt the test piece of 110*110*20 in the experiment, uncoated material 5cm high drop can cause fracture, and adopt the same test piece of protective coating made by the present invention, drop fracture height to improve to 45cm, and It is easy to install and operate, no powder will fall off when stacked, and the appearance of the film is uniform without cracks.

2) Temperature resistance: according to astmC356 Test Method for Linear Shrinkage of Preformed High-Temperature Thermal Insulation Subjected to SoakingHeat (preformed high-temperature thermal insulation material under soaking linear shrinkage test method) - related national standard: GBT 5486-2008 Inorganic rigid thermal insulation Product test method: adopt the same test block integral body that adopts the protective coating made by the present invention to show satisfactory temperature resistance and thermal shock resistance (in 24 hours, observe in the experiment of soaking 900 degrees without foaming, Fragmentation or denudation. The shrinkage in the length and width direction is 1.7%, and the thickness direction shrinks by 5.5%, which meets the requirements of astmC1676.

3) Water absorption: according to astmC1104/C 1104M Test Method for Determining the WaterVapor Sorption of Unfaced Mineral Fiber Insulation (test method for determining the water vapor adsorption of unfaced mineral fiber) - related national standard: GBT 10299-1988 Test method for hydrophobicity of thermal insulation materials, The same test piece with the protective coating made in accordance with the present invention had a vapor sorption of 6.1% by weight compared to 9.4% by weight of the conventional material.

4) Thermal conductivity: According to the test method of astmC1676, the nanoporous thermal insulation material coated with the present invention has a thermal conductivity of 0.021w/m.k when the average temperature is 100°C, and a thermal conductivity of 0.0275w/m.k when the average temperature is 500°C. The corresponding thermal conductivity of conventional nanoporous insulation materials, when the average temperature is 100°C, the thermal conductivity is 0.020w/m.k, and when the average temperature is 500°C, the thermal conductivity is 0.0270w/m.k, almost no change, which proves that the coating of the present invention does not destroy the substrate structure.

Compared with the prior art, the present invention has obvious advantages and beneficial effects. From the above technical solutions, it can be seen that a large number of experiments and researches in the early stage of the present invention have proved that the main reason why it is difficult to form a stable protective coating on the surface of the nanoporous thermal insulation material is that in addition to its low surface strength, the internal nanoporous structure is rich in a large amount of air. (The volume ratio of the gas content even reaches 90%). When the ambient temperature changes, due to the change of the gas volume, there will be different degrees of gas exchange with the outside world, and the thermal expansion and contraction of the coating structure and the substrate will cause Micro-deformation on the surface of the material, while traditional coatings are mostly air-tight materials, coating on the surface of nanoporous thermal insulation materials will cause cracks and peeling off. In order to avoid this phenomenon, the skeleton material constituting the coating should have thermal expansion and gas permeability, that is, the coating skeleton material should have the characteristics of expanding or shrinking as a function of temperature. It should have a bedding structure to ensure the stability of the coating. Such a protective coating, even if it is water-based, as long as the coating is thin, the absorbed moisture will not damage the microporous structure during the drying process. Therefore, the coating formulation of the present invention uses 45wt%-75wt% (45-75 parts by weight) of liquid aluminum dihydrogen phosphate as a binder, 10wt%-35wt% (10-35 parts by weight) of expanded vermiculite and 3wt%- 10wt% (3-10 parts by weight) of zeolite as coating aggregate, 8 wt%-18 wt% (8-18 parts by weight) of mica particles as coating stabilization material, 1.5 wt%-7wt% (1.5-7 wt. parts) alkali metal oxides as a hardener and 2wt%-7wt% (2-7 parts by weight) of silicone as a waterproofing agent to form a complete coating formulation. Among them, aluminum dihydrogen phosphate is used as the adhesive to achieve low-temperature and high-strength bonding, and it has strong compatibility with various inorganic high-temperature materials, especially it can produce needle-shaped crystals with silicon dioxide on the surface of nanoporous heat-insulating materials. , improve the adhesion, it can withstand high temperature of 1700 ℃, covering the temperature range of nanoporous insulation materials; the coating skeleton material uses expanded vermiculite and zeolite, which can make full use of the expansion and gas permeability of vermiculite to resist the impact of ambient temperature The zeolite has a stable hollow structure and micron-scale ultra-fine pores, and when combined with expanded vermiculite, it can ensure the formation of an integrated structure inside and outside the pores during the coating curing process, and strengthen the curing strength; the coating auxiliary material uses mica to utilize its flakes When added into the coating, it can be used as a stabilizer for the coating. When the coating structure undergoes fine three-dimensional changes, mica can help it change and prevent microstructural damage such as cracking; adding alkali metal oxides such as zinc oxide and magnesium oxide etc. can accelerate the hardening of the coating; organic silicon (sodium methyl silicate) is easily soluble in water, and can be well blended with other coating formulations of the present invention, and can form a layer of mesh waterproof on the surface of the nanoporous heat insulating material substrate The breathable membrane has good waterproof effect, anti-seepage and moisture-proof advantages, and avoids moisture absorption into the substrate. The coating of the invention is dust-free, does not fall off, can resist relatively high collision impact, is waterproof and fireproof, and will not release toxic gas and smoke during use.

detailed description

Example 1

A method for preparing a surface protective coating of a nanoporous heat insulating material, comprising the following steps:

(1) Handling of solid materials:

a. Mix the expanded vermiculite particles after high temperature pretreatment at 800°C for 1 hour with liquid aluminum dihydrogen phosphate at a ratio of 4:1, and then ball mill in a ball mill for 48 hours before use;

b. Add the zeolite particles into the liquid aluminum dihydrogen phosphate according to the immersion amount (the solid particles completely absorb the liquid and keep the liquid submerged), and then ball mill in the ball mill for 48 hours before use;

c. Alkali metal oxides (zinc oxide, magnesium oxide at a ratio of 3:1) are added to ethanol (the solid particles are completely absorbed by the liquid and kept submerged in the liquid), and ball milled in a ball mill for 48 hours for later use;

d. After immersing the mica particles in water, mill them in a ball mill for 48 hours, then bake them at 300°C for 1 hour and dehydrate them for later use;

(2) The above-mentioned treated solid material and liquid aluminum dihydrogen phosphate and sodium methyl silicate are in the following ratio

Liquid Aluminum Dihydrogen Phosphate 60

Expanded vermiculite 15

Zeolite 6

Mica 12

Zinc oxide 3

Sodium methyl silicate 3.7

Dispersant (Duramax D-3005 purchased from Rohm and Haas, France) 0.3

Mix to make a slurry, enter a high-shear mixer and mix for 75 minutes at 3000 rpm, and apply it to the nanoporous thermal insulation material matrix by spraying or brushing;

(3) Dry at room temperature for 30 minutes, and then enter the oven for 5 minutes at 80-120°C for 5 minutes of rapid drying. The amount of sizing is 2.3 g/cm ² after drying, and a protective coating of about 0.4 mm is formed.

Coating performance test:

1) Abrasion resistance, impact resistance: The appearance of the coating is uniform, without cracks and shedding. The test block of 110*110*20 is used, and the drop fracture height is 45cm.

2) Temperature resistance: Tested according to the astmC356 standard, no blistering, cracking or erosion was observed in the 24-hour, 900-degree soaking experiment. The shrinkage in the length and width direction is 1.7%, and the shrinkage in the thickness direction is 5.5%, which meets the requirements of astmC1676.

3) Water absorption: Tested according to astmC1104/C 1104M standard, the weight percentage of vapor adsorption is 6.1%.

4) Thermal conductivity: According to the test method of astmC1676, the nanoporous thermal insulation material coated with the present invention has a thermal conductivity of 0.021w/m.k when the average temperature is 100°C, and a thermal conductivity of 0.0275w/m.k when the average temperature is 500°C.

Example 2

A method for preparing a surface protective coating of a nanoporous heat insulating material, comprising the following steps:

(1) Handling of solid materials:

a. Mix the expanded vermiculite particles after high temperature pretreatment at 800°C for 1 hour with liquid aluminum dihydrogen phosphate at a ratio of 4:1, and then ball mill in a ball mill for 48 hours before use;

b. Add the zeolite particles into the liquid aluminum dihydrogen phosphate according to the immersion amount (the solid particles completely absorb the liquid and keep the liquid submerged), and then ball mill in the ball mill for 48 hours before use;

c. Alkali metal oxides (zinc oxide, magnesium oxide at a ratio of 3:1) are added to ethanol (the solid particles are completely absorbed by the liquid and kept submerged in the liquid), and ball milled in a ball mill for 48 hours for later use;

d. After immersing the mica particles in water, mill them in a ball mill for 48 hours, then bake them at 300°C for 1 hour and dehydrate them for later use;

(2) The above-mentioned treated solid material and liquid aluminum dihydrogen phosphate and sodium methyl silicate are in the following ratio

Liquid Aluminum Dihydrogen Phosphate 75

Expanded vermiculite 10

Zeolite 3

Mica 8

Magnesium oxide 2

Sodium methyl silicate 1.9

Dispersant (Duramax D-3005) 0.1

Mix to form a slurry, enter a high-shear mixer and mix for 75 minutes at 3000 rpm, and apply it to the nanoporous insulation material substrate by spraying or brushing to impregnate the pores;

(3) Dry at room temperature for 30 minutes, then enter the furnace for 8 minutes at 80-120°C for 8 minutes of rapid drying, the amount of sizing is after drying, the weight of the insulator is 1.8 g/cm ² , and a protective coating of about 0.3 mm is formed.

Coating performance test:

1) Abrasion resistance, impact resistance: The appearance of the coating is uniform, without cracks, and without falling off. The test block of 110*110*20 is used, and the drop fracture height is 37cm.

2) Temperature resistance: Tested according to the astmC356 standard, no blistering, cracking or erosion was observed in the 24-hour, 900-degree soaking experiment. The shrinkage in the length and width direction is 1.5%, and the shrinkage in the thickness direction is 5.7%, which meets the requirements of astmC1676.

3) Water absorption: Tested according to astmC1104/C 1104M standard, the vapor adsorption weight percentage is 7.3%.

4) Thermal conductivity: According to the test method of astmC1676, the nanoporous thermal insulation material coated with the present invention has a thermal conductivity of 0.020w/m.k when the average temperature is 100°C, and a thermal conductivity of 0.0251w/m.k when the average temperature is 500°C.

Example 3

A method for preparing a surface protective coating of a nanoporous heat insulating material, comprising the following steps:

(1) Handling of solid materials:

a. Mix the expanded vermiculite particles after high temperature pretreatment at 800°C for 1 hour with liquid aluminum dihydrogen phosphate at a ratio of 4:1, and then ball mill in a ball mill for 48 hours before use;

b. Add the zeolite particles into the liquid aluminum dihydrogen phosphate according to the immersion amount (the solid particles completely absorb the liquid and keep the liquid submerged), and then ball mill in the ball mill for 48 hours before use;

c. Alkali metal oxides (zinc oxide, magnesium oxide at a ratio of 3:1) are added to ethanol (the solid particles are completely absorbed by the liquid and kept submerged in the liquid), and ball milled in a ball mill for 48 hours for later use;

d. After immersing the mica particles in water, mill them in a ball mill for 48 hours, then bake them at 300°C for 1 hour and dehydrate them for later use;

(2) The above-mentioned treated solid material and liquid aluminum dihydrogen phosphate and sodium methyl silicate are in the following ratio

Liquid Aluminum Dihydrogen Phosphate 45

Expanded vermiculite 30

Zeolite 5

Mica 11

Zinc oxide or magnesium oxide 1.5

Sodium methyl silicate 7

Dispersant (Duramax D-3005) 0.5

Mix to form a slurry, enter a high-shear mixer and mix for 75 minutes at 3000 rpm, and apply it to the nanoporous insulation material substrate by spraying or brushing to impregnate the pores;

(3) Dry at room temperature for 30 minutes, then enter the oven for 3 minutes at 80-120°C for 3 minutes of rapid drying, the amount of sizing is 2.7 g/cm ² after drying, and a protective coating of about 0.4 mm is formed.

Coating performance test:

1) Wear resistance, impact resistance: The appearance of the coating is basically uniform, with a few cracks, but no shedding. A 110*110*20 test block is used, and the drop fracture height is 49cm.

2) Temperature resistance: Tested according to the astmC356 standard, no blistering, cracking or erosion was observed in the 24-hour, 900-degree soaking experiment. The shrinkage in the length and width direction is 1.9%, and the shrinkage in the thickness direction is 7.5%, which meets the requirements of astmC1676.

3) Water absorption: Tested according to astmC1104/C 1104M standard, the vapor adsorption weight percentage is 4.7%.

4) Thermal conductivity: According to the test method of astmC1676, the nanoporous thermal insulation material coated with the present invention has a thermal conductivity of 0.0218w/m.k when the average temperature is 100°C, and a thermal conductivity of 0.0278w/m.k when the average temperature is 500°C.

The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Any simple modification, Equivalent changes and modifications still fall within the scope of the technical solution of the present invention.

Claims (6)

1. a kind of nano-pore heat insulating materials coating for surface protection, its formulation weight part is as follows：

Liquid phosphoric acid aluminum dihydrogen 45-75

Expanded vermiculite 10-30

Zeolite 3-6

Mica 8-12

Waterproofing agent of organosilicon 1.9-7

Alkali metal oxide 1.5-3

Dispersant 0.1-0.5.

2. a kind of nano-pore heat insulating materials coating for surface protection as claimed in claim 1, its formulation weight part is as follows：

Liquid phosphoric acid aluminum dihydrogen 60

Expanded vermiculite 15

Zeolite 6

Mica 12

Alkali metal oxide 3

Waterproofing agent of organosilicon 3.7

Dispersant 0.3.

3. nano-pore heat insulating materials coating for surface protection as claimed in claim 1 or 2, wherein：Waterproofing agent of organosilicon is methyl Sodium metasilicate.

4. nano-pore heat insulating materials coating for surface protection as claimed in claim 1 or 2, wherein：Alkali metal oxide is oxidation Zinc or magnesia.

5. nano-pore heat insulating materials coating for surface protection as claimed in claim 1 or 2, wherein：Dispersant is Duramax D- 3005。

6. a kind of preparation method of the coating for surface protection of nano-pore heat insulating materials, comprises the following steps：

（1）The processing of solid material：

A. after expanded vermiculite particle is pre-processed through high temperature, 2-5 parts are taken to be mixed with 1 part of liquid phosphoric acid aluminum dihydrogen, then using oxidation In the ball mill of aluminium ball ball milling 24-48 hours to average grain diameter be less than 4 μm；

B. zeolite granular is added into liquid phosphoric acid aluminum dihydrogen by submergence amount, it is small using ball milling 24-48 in the ball mill of alumina balls It is less than 4 μm up to average grain diameter；

C. alkali metal oxide adds ethanol, using ball milling in the ball mill of alumina balls 24-48 hour to average grain diameter less than 4 μm；

D. after mica particles water logging is not had, it is less than 4 using ball milling in the ball mill of alumina balls 24-48 hours to average grain diameter μm, by 300 DEG C of baking dehydrations；

（2）The above-mentioned solid material handled well and liquid phosphoric acid aluminum dihydrogen, sodium methyl silicate are mixed and made into slurry in following ratios,

Liquid phosphoric acid aluminum dihydrogen 45-75

Expanded vermiculite 10-30

Zeolite 3-6

Mica 8-12

Sodium methyl silicate 1.9-7

Zinc oxide or magnesia 1.5-3

Dispersant Duramax D-3005 0.1-0.5

Into in high shear mixer with 1500-3000 rpm mixing 30-100 minutes, it is applied to and receives with spraying or painting way To be impregnated into hole on metre hole heat-insulating material matrix；

（3）Dry 30 minutes at normal temperatures, enter back into and carry out rapid draing in 3-8 minutes, starching quantity in stove at 80-120 DEG C After drying, adiabatic 1.8-3.0 grams of body weight gains/cm², form the protective coating of 0.3-0.5mm waterproof.