CN115505282A

CN115505282A - Sunlight reflection ceramic coating and preparation method and construction method thereof

Info

Publication number: CN115505282A
Application number: CN202211012232.XA
Authority: CN
Inventors: 金伟
Original assignee: Hangzhou Ginkgo Technology Co ltd
Current assignee: Hangzhou Ginkgo Technology Co ltd
Priority date: 2022-08-23
Filing date: 2022-08-23
Publication date: 2022-12-23
Anticipated expiration: 2042-08-23
Also published as: CN115505282B

Abstract

The invention discloses a sunlight reflecting ceramic coating, a preparation method and a construction method thereof; the coating composition, calculated as 100%, was as follows: silica sol: 25-27%, silane: 30-32%, titanium dioxide: 16-18%, precipitated barium sulfate: the addition amount is 10-15% of the titanium dioxide, and the filler: 8-10%, single-walled carbon nanotubes: 0.1-0.15%, dispersant: 1-2%, leveling agent: 1.5-2%,25% formic acid: 0.7-0.8%, deionized water: and (4) the balance. The ceramic coating of the invention is added with titanium dioxide and precipitated barium sulfate, thus increasing the reflectivity to sunlight; the hydrolytic polymerization of bifunctional silane is more prone to form linear macromolecules, so that the cross-linked pore structure of molecules is reduced, the sunlight absorption of the coating is reduced, and the reflectivity is increased; by controlling the sand blasting roughness and the coating thickness, the flatness of the coating surface is increased, and the reflectivity of the coating is increased.

Description

Sunlight reflection ceramic coating and preparation method and construction method thereof

Technical Field

The invention belongs to the technical field of coatings, and relates to a sunlight reflecting ceramic coating, a preparation method and a construction method thereof; in particular to a sunlight high-reflection heat dissipation ceramic coating with good weather resistance, a preparation method and a construction method thereof.

Background

The solar photo-thermal power station adopts a light-heat-electricity power generation mode according to the solar photo-thermal power generation principle, thousands of heliostats reflect sunlight to the surface of a heat absorber positioned at the top of a sun tower to form high temperature of more than 800 ℃. The steam with the temperature of more than 500 ℃ is generated by the heat transfer medium, and the steam turbine is pushed to generate electricity. In a solar photothermal power station, mechanical equipment, power generation equipment and the like are arranged below a heat absorber on the top of a tower, metal plates are used for protecting the periphery of the equipment, so that the equipment is prevented from being damaged at high temperature, the service life of the equipment is prolonged, a sunlight reflecting and radiating coating is coated on the surface of each metal plate, the temperature of the space around the equipment is reduced, the equipment is prevented from working at high temperature for a long time, the service life of the equipment is prolonged, and high sunlight reflectivity and excellent radiating performance are required.

The sunlight reflecting and heat dissipating coating needs to be irradiated by sunlight for a long time, most of the existing sunlight reflecting and heat dissipating coatings are organic coatings, and the coatings have poor washing resistance and weather resistance and short service life, so that the coatings generally fall off in 1-2 years, and a new coating needs to be coated on the surface of a metal guard plate after treatment.

Through the search of the existing patent documents, chinese patents with the authorization numbers of ZL201880069987.9, 201610837280.0 and 201610837286.8 disclose the technical scheme of the sunlight reflecting coating, organic resins such as polyester resin, polyamide resin and modified acrylic resin are used as film forming substances, the sunlight reflecting coating has the washing resistance which can only reach more than 1 ten thousand times and the weather resistance which is about 2000h, and the requirement of outdoor use cannot be met. Commercial coatings for reflecting and radiating only reflect 80% -90% of sunlight on the market, and the reflectivity of the sunlight needs to be improved urgently.

Disclosure of Invention

The invention aims to overcome the defects that the film-forming substance of the existing sunlight reflecting and heat dissipating coating in the prior art is organic resin, the washing resistance and the weather resistance of the organic resin are not ideal, the service life is short under the environment of long-term wind, sunlight and rain, the coating generally falls off within 1-2 years, and commercial coatings for reflecting and heat dissipating on the market can only reflect 80-90 percent of sunlight and cannot meet the outdoor use requirement, and the like, and provides a sunlight reflecting ceramic coating, a preparation method and a construction method thereof.

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

< first aspect >

The invention relates to a sunlight reflection heat dissipation ceramic coating composition (a technical scheme is designed by increasing two aspects of reflectivity and heat dissipation rate of a coating), and the formula is as follows by 100 percent:

silica sol: 25-27%, silane: 30-32%, titanium dioxide: 16-18%, precipitated barium sulfate: the addition amount is 10-15% of the titanium dioxide, and the filler: 8-10%, single-walled carbon nanotubes: 0.1-0.15%, dispersant: 1-2%, leveling agent: 1.5-2%,25% formic acid: 0.7-0.8%, deionized water: and (4) the balance.

Wherein:

in the system of the invention, silica sol is a main film forming material, and is common in commercial products, such as: aksu silica sol Bindzil2034DI, nissan chemical ST-30, grace AS-40, etc.

In the system, silane is an auxiliary film forming substance and is one or more of difunctional silanes such as dimethyl dimethoxy silane, dimethyl diethoxy silane, methyl vinyl dimethoxy silane, methyl phenyl dimethoxy silane, diisobutyldimethoxy silane, diisopropyl dimethoxy silane and the like. The bifunctional silane is more prone to form a linear polymer after hydrolytic polymerization under an acidic condition, and reduces the macromolecular pore structure of the ceramic coating, thereby reducing the absorption of sunlight and increasing the reflectivity.

The titanium white is white pigment, and the rutile titanium white is selected in the invention, and the medium particle size is 0.25-0.3 μm. For example: dupont R706, japan stone source titanium dioxide R-930, and the like. Since the maximum light reflection is provided by all visible light in the white reflectance spectrum, white pigments are used in the reflective coating, and the higher the whiteness, the higher the reflectance. The titanium dioxide has two types of rutile type and anatase type, the rutile type titanium dioxide has better weather resistance and gloss retention, and the rutile type titanium dioxide with better weather resistance is selected for the coating which needs to be exposed in sunlight for a long time. The smaller the particle size of the titanium dioxide, the higher the whiteness value, which is mainly because the smaller the particle size of the titanium dioxide, the larger the surface area and the stronger the light reflection.

In the system, precipitated barium sulfate is used as an extender pigment with 8000 meshes, the addition amount of the precipitated barium sulfate is about 10-15% of that of titanium dioxide, and Blanc fixed micro superfine precipitated barium sulfate of Germany Shahar Ri chemical Co. In the system of the invention, the barium sulfate has two functions: firstly, barium sulfate has high reflectivity within the wavelength range of 300-400 microns, so that a paint film can be protected from photo-aging, and the weather resistance of the coating is improved; and secondly, the whiteness of the coating can be improved without reducing the covering power by adding a small amount of the water-based paint. Thereby increasing the reflectivity of the coating to light. The addition amount of barium sulfate is too small, and the effect is not obvious; the addition of barium sulfate is too much, the hiding power of the coating is affected because barium sulfate has no hiding power, and the use amount of titanium dioxide needs to be increased to maintain the hiding power of the coating, so that the cost of the coating is increased.

As an embodiment of the invention, the filler comprises one or more of mica powder, silicon micropowder, kaolin, alumina powder, organic bentonite and the like.

Carbon nanotubes are the most ideal functional filler for heat-dissipating coatings and are one of the best heat-conducting materials known in the world. Carbon nanotubes are classified into single-walled carbon nanotubes and multi-walled carbon nanotubes, wherein: the thermal conductivity coefficient of the single-walled carbon nanotube is 6600W/m.k, which is more than 2 times of that of the multi-walled carbon nanotube, so that the single-walled carbon nanotube is selected in the system of the invention, and the heat dissipation performance of the coating can be better improved. The carbon nano tube is black, so the addition amount is not too much, otherwise, the effect of absorbing sunlight is greater than the effect of heat dissipation, and the heat dissipation effect cannot be achieved. The carbon nano tube enables the coating to automatically radiate heat to the atmospheric space, accelerates heat exchange, reduces the temperature of the surface and the internal space of the object, and plays a role in protecting internal equipment.

In the system, 25% formic acid is a sol-gel reaction catalyst, and the pH value of the coating after the reaction is adjusted to be 4.0-5.0.

< second aspect >

The invention relates to a preparation method of a sunlight reflection heat dissipation ceramic coating composition, which comprises the following steps:

s1, preparing a carbon nano tube dispersion liquid: taking sodium dodecyl benzene sulfonate as a surfactant, and performing ultrasonic dispersion to obtain a carbon nanotube suspension;

s2, preparing color paste: uniformly mixing silica sol, titanium dioxide, precipitated barium sulfate, a filler, a dispersing agent and deionized water, grinding until the fineness reaches 20 +/-5 mu m, adding the carbon nano tube suspension, and continuously stirring for 20-40 minutes to obtain color paste;

s3, preparing the reflective heat dissipation coating: firstly, adding the leveling agent into silane, then adding 25% formic acid, uniformly mixing, adding into the color paste, uniformly mixing, and stirring for reaction to obtain the sunlight reflection heat dissipation ceramic coating composition.

And S1, sodium dodecyl benzene sulfonate is used as a surfactant, and a carbon nano tube suspension with good dispersibility is obtained by using a mode of ultrasound plus the surfactant and can be stably suspended for more than 8 months. In one embodiment, the surfactant is sodium dodecyl benzene sulfonate water solution with concentration of 5000-8000 mg/L; the ultrasonic treatment is carried out for 10-12 hours under the ultrasonic condition of 25 +/-5 ℃ and 600W.

In some embodiments, sodium dodecyl benzene sulfonate is prepared into a solution with the concentration of 5000-8000mg/L by deionized water, 20ml of the solution is added into a centrifuge bottle, then carbon nano tubes are added, the centrifuge bottle is placed into an ultrasonic machine, and ultrasonic treatment is carried out for 10-12 hours under the ultrasonic condition of 600W at 25 +/-5 ℃ to obtain stable carbon nano tube suspension. In the step, the concentration of the surfactant and the ultrasonic conditions (time and power) can influence the dispersion of the carbon nanotubes, so that the suspension amount of the carbon nanotubes can be saturated under the optimized conditions, the effect is exerted to the maximum extent, and the carbon nanotubes can exist stably.

As one embodiment, in step S2, the milling is ball mill milling for 1 to 2 hours. The stirring was continued for 20-40 minutes.

In step S3, the stirring reaction is carried out at a rotation speed of 100 to 180 rpm for 8 to 12 hours.

In step S3, 25% formic acid is added to adjust the pH of the reacted coating to between 4.0 and 5.0.

< third aspect >

The invention relates to a construction method of a sunlight reflection heat dissipation ceramic coating composition, which comprises the following steps:

a1, pretreatment of a base material: the base material is a 304 nickel-based steel pipe, and the base material is subjected to sand blasting treatment until a surface with the roughness of 1.5-3 mu m is formed;

a2, coating: preheating a base material to 40-60 ℃, and then coating by adopting spraying or brushing;

and A3, curing.

In the step A1, the adhesion between the coating and the base material can be increased after sand blasting treatment; however, the roughness needs to be well controlled, the roughness is too small, the adhesion between the coating and the base material is not good, the surface roughness is too large, the surface flatness of the coating is not enough, and the reflectivity of the coating is influenced. Preferably, the emery sand blasting treatment of 100-120 meshes is adopted.

As an embodiment, the thickness of the coating in step A2 is 30 to 40 μm. The film thickness is too thin, the covering power of the white pigment is insufficient, the total reflection of the white pigment to light cannot be exerted, and the reflection of the coating to sunlight can also be influenced due to too thin coating and insufficient surface flatness; the coating is too thick, the adhesion is poor and the cost is high.

As an embodiment, the curing in step A3 is performed at 80-100 ℃ for 10min; curing at 230-260 deg.c for 20min.

Compared with the prior art, the invention has the following beneficial effects:

(1) The ceramic coating of the invention is added with titanium dioxide and precipitated barium sulfate, thus increasing the reflectivity to sunlight; the hydrolytic polymerization of the bifunctional silane is more prone to form linear macromolecules, so that the cross-linked pore structure of molecules is reduced, the sunlight absorption of the coating is reduced, and the reflectivity is increased; by controlling the roughness of the sand blasting and the thickness of the coating, the flatness of the surface of the coating is increased, and the reflectivity of the coating is increased.

(2) The invention utilizes the mode of ultrasound and surfactant to obtain the carbon nano tube suspension with saturated suspension amount and good dispersibility by controlling the parameters of the dispersion process, thereby preparing the stable ceramic coating, exerting the function of the carbon nano tube to the maximum extent, exciting the resonance effect of the metal surface by the carbon nano tube, obviously improving the far infrared emission efficiency and accelerating the rapid heat dissipation from the surface of the base material.

(3) The paint has inorganic film forming matter to form Si-O-Si inorganic structure, and has washing resistance and weather resistance superior to available organic paint and service life as long as 5 years.

Detailed Description

The present invention will be described in detail with reference to examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that numerous modifications and adaptations can be made by those skilled in the art without departing from the inventive concepts herein. All falling within the scope of the present invention.

Example 1

This example provides a solar reflective and heat dissipating ceramic coating composition having the composition shown in table 1.

The coating of this example was prepared as follows:

(1) Preparing a carbon nano tube dispersion liquid: preparing sodium dodecyl benzene sulfonate into a solution with the concentration of 6000mg/L by using deionized water, adding 20ml of the solution into a centrifugal bottle, adding a carbon nano tube, putting the centrifugal bottle into an ultrasonic machine, and carrying out ultrasonic treatment for 10 hours under the ultrasonic conditions of 25 ℃ and 600W to obtain a stable carbon nano tube suspension;

(2) Preparing color paste: uniformly mixing silica sol, titanium dioxide, precipitated barium sulfate, a filler, a dispersing agent and deionized water, grinding for 1.5 hours by using a ball mill, adding the carbon nano tube dispersion liquid prepared in the step (1) after the fineness reaches 20 mu m, and continuously stirring for 30 minutes to obtain color paste;

(3) Preparing a reflective heat dissipation coating: firstly, adding the leveling agent into silane, then adding 25% formic acid, uniformly mixing, then adding into the color paste obtained in the step (2), uniformly mixing, and reacting for 10 hours at 150 revolutions per minute to obtain the reflective heat-dissipation coating.

The coating construction steps of this example are as follows:

(1) Pretreatment of a base material: the base material is a 304 nickel-based steel pipe, and is subjected to sand blasting treatment by using 120-mesh carborundum before coating to form a surface with the roughness of 2 mu m;

(2) Coating: the base material is preheated to 60 ℃ by adopting a spraying or brushing mode, and then is coated, wherein the coating thickness is 30-40 mu m;

(3) And (3) curing: 100 ℃ for 10min, and then 260 ℃ for 20min.

Examples 2 to 4

Examples 2 to 4 provide solar reflective heat dissipating ceramic coating compositions having the compositions shown in table 1. The coating preparation was the same as in example 1.

Comparative examples 1 to 5

Comparative examples 1 to 5 provide solar reflective heat-dissipating ceramic coating compositions, the compositions of which are shown in table 1. The coating preparation was the same as in example 1.

Table 1 coating composition and amount (wt.%) of examples and comparative examples

In table 1, akkusu silica sol Bindzil2034DI was used as the silica sol; the titanium dioxide is rutile titanium dioxide with the medium particle size of 0.25-0.3 mu m; the precipitated barium sulfate is Blanc fixed micro superfine precipitated barium sulfate; single-walled carbon nanotubes: purity of 90% and specific surface area of 385m ² (ii)/g; the dispersant can be BYK180, BYK190, BYK2010, BYK2001 and the like, and BYK180 is selected from Table 1; BYK333, BYK345 and the like can be selected as the leveling agent, and BYK333 is selected from Table 1.

Testing of key properties

The main performance tests, the test items and the methods of the coatings prepared in the above examples and comparative examples are shown in Table 2, and the test results are shown in tables 3 to 5:

TABLE 2

TABLE 3

TABLE 4

TABLE 5

Test of heat dissipation effect of coating

The coatings prepared in the above examples and comparative examples were subjected to a coating heat dissipation effect test: taking a 304 nickel-based steel pipe, coating a reflective heat-dissipation coating on the upper end of the steel pipe, taking a blank contrast with the lower end not coated with the coating, placing the steel pipe in an outdoor natural environment, receiving sunlight irradiation, and testing the surface temperature of the part coated with the coating when the surface temperature of a blank sample reaches 40 ℃, 50 ℃,60 ℃ and 70 ℃.

The coating steps are as follows:

(1) Pretreatment of a base material: the 304 nickel-based steel pipe is subjected to sand blasting treatment by using 100-mesh carborundum until the roughness of the surface is 2 mu m;

(2) Coating: preheating the base material to 50 ℃, and then spraying, wherein the coating thickness is 35 mu m;

(3) And (3) curing: first 90 ℃ X10 min, then 250 ℃ X20 min.

The test results are shown in table 6:

TABLE 6

The foregoing description has described specific embodiments of the present invention. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention.

Claims

1. A sunlight reflecting and heat dissipating ceramic coating composition is characterized by comprising the following components in percentage by 100 percent:

silica sol: 25-27%, silane: 30-32%, titanium dioxide: 16-18%, precipitated barium sulfate: the addition amount is 10-15% of titanium dioxide, and the filling material: 8-10%, single-walled carbon nanotubes: 0.1-0.15%, dispersant: 1-2%, leveling agent: 1.5-2%,25% formic acid: 0.7-0.8%, deionized water: and (4) the balance.

2. The solar reflective heat dissipating ceramic coating composition according to claim 1, wherein the silane is one or more selected from the group consisting of dimethyldimethoxysilane, dimethyldiethoxysilane, methylvinyldimethoxysilane, methylphenyldimethoxysilane, diisobutyldimethoxysilane, and diisopropyldimethoxysilane.

3. The solar reflective and heat dissipating ceramic coating composition according to claim 1, wherein the titanium is rutile type titanium dioxide, and the medium particle size is 0.25 to 0.3 μm.

4. The solar reflective and heat dissipating ceramic coating composition according to claim 1, wherein the filler comprises one or more of mica powder, silica powder, kaolin, alumina powder, organobentonite, and the like.

5. A method for preparing the solar reflective and heat dissipating ceramic coating composition according to any one of claims 1 to 4, comprising the steps of:

s1, preparing a carbon nano tube dispersion liquid: taking sodium dodecyl benzene sulfonate as a surfactant, and performing ultrasonic dispersion to obtain a carbon nano tube suspension;

6. The method for preparing the solar reflective and heat dissipating ceramic coating composition according to claim 5, wherein in the step S1, the surfactant is an aqueous solution of sodium dodecylbenzenesulfonate having a concentration of 5000 to 8000 mg/L; the ultrasonic treatment is carried out for 10-12 hours under the ultrasonic condition of 25 +/-5 ℃ and 600W.

7. The method for preparing the solar reflective heat dissipation ceramic coating composition according to claim 5, wherein in step S2, the grinding is ball mill grinding for 1-2 hours; the time for continuing stirring is 20-40 minutes; in the step S3, the stirring reaction is carried out for 8 to 12 hours under the condition of the rotating speed of 100 to 180 revolutions per minute.

8. The method for preparing the solar reflective and heat dissipating ceramic coating composition according to claim 5, wherein in the step S3, 25% formic acid is added to adjust the pH of the reacted coating to be between 4.0 and 5.0.

9. A method of applying the solar reflective and heat dissipating ceramic coating composition according to any one of claims 1 to 4, comprising the steps of:

and A3, curing.

10. The construction method of the solar reflective and heat dissipating ceramic coating composition according to claim 9, wherein in step A1, a sand blasting treatment is performed with 100 to 120 mesh diamond grains; in the step A2, the coating thickness is 30-40 μm; in the step A3, the curing is firstly performed for 10min at the temperature of 80-100 ℃; curing at 230-260 deg.c for 20min.