CN115505282B

CN115505282B - Sunlight reflecting ceramic coating and preparation method and construction method thereof

Info

Publication number: CN115505282B
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: 2023-10-03
Anticipated expiration: 2042-08-23
Also published as: CN115505282A

Abstract

The application discloses a sunlight reflective ceramic coating, a preparation method and a construction method thereof; the paint composition, in 100%, is as follows: silica sol: 25-27%, silane: 30-32% of titanium dioxide: 16-18%, precipitated barium sulfate: the addition amount is 10-15% of titanium dioxide, and the filler is: 8-10%, single-wall carbon nano tube: 0.1-0.15%, dispersant: 1-2% of leveling agent: 1.5-2%,25% formic acid: 0.7-0.8%, deionized water: the balance. Titanium white and precipitated barium sulfate are added into the ceramic coating, so that the reflectivity of sunlight is increased; the hydrolysis polymerization of the difunctional silane is more prone to forming linear macromolecules, so that the cross-linked pore structure of molecules is reduced, the absorption of sunlight by the coating is reduced, and the reflectivity is increased; by controlling the sand blasting roughness and the thickness of the coating, the evenness of the surface of the coating is increased, and the reflectivity of the coating is increased.

Description

Sunlight reflecting ceramic coating and preparation method and construction method thereof

Technical Field

The application 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 photo-thermal-electric power generation mode according to a solar photo-thermal power generation principle, and thousands of heliostats reflect sunlight to the surface of a heat absorber positioned at the top of a solar tower to form high temperature of more than 800 ℃. Steam with the temperature of more than 500 ℃ is generated through the heat transfer medium, and the steam turbine is driven to generate electricity. In a solar photo-thermal power station, under a heat absorber at the top of a tower, mechanical equipment, power generation equipment and the like are arranged, the periphery of the equipment is protected by a metal plate, in order to avoid damage to the equipment at high temperature and prolong the service life of the equipment, the surface of the metal plate is coated with a layer of sunlight reflection heat dissipation coating, the reflection heat dissipation coating is extremely important for reducing the temperature of the space around the equipment and avoiding long-term working at high temperature of the equipment, and the service life of the equipment is prolonged, so that high sunlight reflectivity and excellent heat dissipation performance are required.

The sunlight reflection heat dissipation coating needs to receive sunlight irradiation for a long time, most of the existing sunlight reflection heat dissipation coatings are organic coatings, and the coatings are poor in scrubbing resistance and weather resistance and short in service life, and generally fall off after 1-2 years of coating, so that a new coating needs to be coated after the surface treatment of a metal guard plate.

According to the search of the prior patent literature, the Chinese patent with the application numbers of ZL201880069987.9 and 201610837280.0 and 201610837286.8 discloses a technical scheme of solar light reflective coating, which adopts organic resins such as polyester resin, polyamide resin and modified acrylic resin as film forming substances, wherein the solar light reflective coating has the scouring resistance of only more than 1 ten thousand times and the weather resistance of about 2000 hours, and cannot meet the requirement of outdoor use. Commercial coatings for reflecting and radiating are only capable of reflecting 80% -90% of sunlight, and reflectivity of the sunlight is required to be improved.

Disclosure of Invention

The application aims to overcome the defects that the film forming substance of the existing sunlight reflective heat dissipation coating in the prior art is organic resin, the organic resin is not ideal in scrubbing resistance and weather resistance, the service life is short in long-term wind, sun, rain and sun exposure environments, the coating generally falls off in 1-2 years, and commercial coatings for reflective heat dissipation only can reflect 80-90% of sunlight and cannot meet the outdoor use requirements in the market, and the like.

The application aims at realizing the following technical scheme:

< first aspect >

The application relates to a sunlight reflection heat dissipation ceramic coating composition (a technical scheme is designed by increasing the reflectivity and the heat dissipation rate of a coating), which comprises the following components in percentage by 100 percent:

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

Wherein:

in the system of the application, silica sol is the main film forming substance, and common commercial products such as: ackefir silica sol Bindzil2034DI, ST-30 of Nissan chemistry, graves AS-40, etc.

In the system, silane is an auxiliary film forming substance, and is one or more of di-functional silanes such as dimethyl dimethoxy silane, dimethyl diethoxy silane, methyl vinyl dimethoxy silane, methyl phenyl dimethoxy silane, diisobutyl dimethoxy silane, diisopropyl dimethoxy silane and the like. The difunctional silane is more prone to form a linear polymer after hydrolytic polymerization under acidic conditions, so that the macromolecular pore structure of the ceramic coating is reduced, the absorption of sunlight is reduced, and the reflectivity is increased.

The titanium dioxide is white pigment, and the rutile titanium dioxide is selected in the application, and the medium particle diameter is 0.25-0.3 mu m. For example: dupont R706, japanese Dan Yuan titanium dioxide R-930, etc. All visible light in the white reflective spectrum can bring about maximum light reflection, so that the reflective coating uses white pigment, and the higher the whiteness, the higher the reflectivity. 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 for the coating which needs to be exposed to sunlight for a long time, the rutile type titanium dioxide with better weather resistance is selected. The smaller the particle size of the titanium white powder, the higher the whiteness value, mainly because the smaller the particle size of the titanium white powder, the larger the surface area and the enhanced light reflection.

In the system, precipitated barium sulfate is taken as an extender pigment, the addition amount of the precipitated barium sulfate is about 10-15% of that of titanium pigment, and Blanc fixe micro superfine precipitated barium sulfate of German Sha Ha Liben chemical company is selected. In the system of the application, the barium sulfate has two functions: firstly, barium sulfate has very high reflectivity in the wavelength range of 300-400 microns, can protect a paint film from photo-aging, and improves the weather resistance of a coating; secondly, the whiteness of the coating can be improved without reducing the covering power by adding a small amount of water-based paint. Thereby increasing the reflectivity of the coating to light. The adding amount of barium sulfate is too small, and the effect is not obvious; the addition of too much barium sulfate can affect the hiding power of the coating because barium sulfate has no hiding power, and the amount of titanium pigment needs to be increased to maintain the hiding power of the coating, which can increase the cost of the coating.

As an embodiment of the present application, the filler includes one or more of mica powder, silica micropowder, kaolin, alumina powder, organobentonite, and the like.

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

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

< second aspect >

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

s1, preparing a carbon nano tube dispersion liquid: sodium dodecyl benzene sulfonate is used as a surfactant, and carbon nano tube suspension is obtained by ultrasonic dispersion;

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 nanotube suspension, and continuously stirring for 20-40 minutes to obtain color paste;

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

In the step S1, sodium dodecyl benzene sulfonate is used as a surfactant, and a mode of ultrasound and the surfactant is utilized to obtain the carbon nano tube suspension with good dispersibility, and the carbon nano tube suspension can be stably suspended for more than 8 months. As one embodiment, the surfactant is an aqueous solution of sodium dodecyl benzene sulfonate with a concentration of 5000-8000 mg/L; the ultrasonic treatment is carried out at 25+/-5 ℃ and 600W for 10-12 hours.

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 centrifugal bottle, then carbon nano tubes are added, the centrifugal bottle is placed into an ultrasonic machine, and ultrasonic treatment is carried out for 10-12 hours at 25+/-5 ℃ under 600W ultrasonic conditions, so that a stable carbon nano tube suspension is obtained. 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 suspension amount can play a role to the greatest extent, and the suspension amount can exist stably.

In step S2, as an embodiment, the milling is ball milling for 1 to 2 hours. Stirring was continued for 20-40 minutes.

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

In one embodiment, in step S3, 25% formic acid is added to adjust the pH of the coating to between 4.0 and 5.0 after the reaction.

< third aspect >

The application 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 304 nickel-based steel pipe, sand spraying treatment is carried out until the 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 spraying or brushing;

a3, curing.

In the step A1, the adhesive force between the coating and the substrate can be increased after the sand blasting treatment; however, the roughness needs to be controlled well, the roughness is too small, the adhesion between the coating and the substrate is poor, the surface roughness is too large, the surface smoothness of the coating is insufficient, and the reflectivity of the coating is affected. Preferably, 100-120 mesh carborundum blasting is used.

As an embodiment, the coating thickness in step A2 is 30-40. Mu.m. 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, the coating is too thin, the surface flatness is insufficient, and the reflection of the coating to sunlight can be influenced; the coating is too thick, the adhesion becomes poor and the cost is high.

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

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

(1) Titanium white and precipitated barium sulfate are added into the ceramic coating, so that the reflectivity of sunlight is increased; the hydrolysis polymerization of the difunctional silane is more prone to forming linear macromolecules, so that the cross-linked pore structure of molecules is reduced, the absorption of sunlight by the coating is reduced, and the reflectivity is increased; by controlling the sand blasting roughness and the thickness of the coating, the evenness of the surface of the coating is increased, and the reflectivity of the coating is increased.

(2) According to the application, by controlling parameters of a dispersion process in an ultrasonic and surfactant mode, the carbon nanotube suspension with saturated suspension amount and good dispersibility is obtained, so that the stable ceramic coating is prepared, the effect of the carbon nanotubes is exerted to the greatest extent, the carbon nanotubes can excite the resonance effect of the metal surface, the far infrared emission efficiency is remarkably improved, and the rapid heat dissipation from the surface of the substrate is accelerated.

(3) The main film forming matter of the coating is inorganic matter, and finally the inorganic structure of Si-O-Si is formed, and the coating has better scouring resistance and weather resistance than the existing organic coating, and the service life can be prolonged to about 5 years.

Detailed Description

The present application will be described in detail with reference to examples. The following examples will assist those skilled in the art in further understanding the present application, but are not intended to limit the application in any way. It should be noted that several modifications and improvements can be made by those skilled in the art without departing from the inventive concept. These are all within the scope of the present application.

Example 1

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

The paint preparation procedure of this example was as follows:

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

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

The paint construction steps of this embodiment are as follows:

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

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

(3) Curing: 100 ℃ for 10min and 260 ℃ for 20min.

Examples 2 to 4

Examples 2 to 4 provide a solar light reflecting and heat dissipating ceramic coating composition having the composition shown in table 1. The paint preparation was the same as in example 1.

Comparative examples 1 to 5

Comparative examples 1 to 5 provide a solar light reflecting and heat dissipating ceramic coating composition having the composition shown in table 1. The paint preparation was the same as in example 1.

Table 1 coating compositions and amounts (wt.%) of examples and comparative examples

In Table 1, the silica sol was selected from Ackesu silica sol Bindzil2034 DI; the titanium dioxide is rutile titanium dioxide with the medium grain diameter of 0.25-0.3 mu m; the precipitated barium sulfate is Blanc fixe micro superfine precipitated barium sulfate; single-wall carbon nanotubes: organic chemical institute of adults, purity 90%, specific surface area 385m ² /g; the dispersing agent can be BYK180, BYK190, BYK2010, BYK2001 and the like, and BYK180 is selected in the table 1; the leveling agent can be BYK333, BYK345, etc., and BYK333 is selected in Table 1.

Primary performance test

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

TABLE 2

TABLE 3 Table 3

TABLE 4 Table 4

TABLE 5

Coating heat dissipation effect test

The coatings prepared in the above examples and comparative examples were subjected to a coating heat dissipation effect test: the method comprises the steps of taking a 304 nickel-based steel pipe, coating a reflective heat-dissipating coating on the upper end, coating no coating on the lower end as a blank contrast, placing the steel pipe in an outdoor natural environment, receiving sunlight irradiation, and testing the surface temperature of a blank sample to 40 ℃, 50 ℃,60 ℃ and 70 ℃ and coating the surface temperature of a part of the coating.

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 meshes of silicon carbide until the surface with the roughness of 2 mu m;

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

(3) Curing: 90 ℃ for 10min and then 250 ℃ for 20min.

The test results are shown in table 6:

TABLE 6

The foregoing describes specific embodiments of the present application. It is to be understood that the application is not limited to the particular embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the claims without affecting the spirit of the application.

Claims

1. A solar reflective heat dissipating ceramic coating composition characterized by comprising, in 100%, the following composition:

silica sol: 25-27%, silane: 30-32% of titanium dioxide: 16-18%, precipitated barium sulfate: 8000 meshes, the addition amount is 10-15% of titanium pigment, and the filler is: 8-10%, single-wall carbon nano tube: 0.1-0.15%, dispersant: 1-2% of leveling agent: 1.5-2%,25% formic acid: 0.7-0.8%, deionized water: the balance;

the silane is one or more of dimethyl dimethoxy silane, dimethyl diethoxy silane, methyl vinyl dimethoxy silane, methyl phenyl dimethoxy silane, diisobutyl dimethoxy silane and diisopropyl dimethoxy silane;

the composition is prepared by a method comprising the steps of:

s1, preparing a carbon nano tube dispersion liquid: sodium dodecyl benzene sulfonate is used as a surfactant, and carbon nano tube suspension is obtained by ultrasonic dispersion; the surfactant is sodium dodecyl benzene sulfonate aqueous solution with the 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;

2. The sunlight reflecting and heat dissipating ceramic coating composition according to claim 1, wherein the titanium dioxide is rutile titanium dioxide with a medium particle size of 0.25-0.3 μm.

3. The solar light reflective heat dissipating ceramic coating composition of claim 1, wherein the filler comprises one or more of mica powder, silica micropowder, kaolin, alumina powder, and organobentonite.

4. The solar light reflective heat dissipating ceramic coating composition of claim 1 wherein in step S2, the milling is ball milling for 1-2 hours; continuously stirring for 20-40 minutes; in the step S3, the stirring reaction is carried out for 8-12 hours under the condition of rotating speed of 100-180 rpm.

5. The solar light reflective heat dissipating ceramic coating composition of claim 1 wherein in step S3, 25% formic acid is added to adjust the pH of the reacted coating to between 4.0 and 5.0.

6. A method of constructing a solar reflective heat dissipating ceramic coating composition according to any one of claims 1-5, comprising the steps of:

a2, coating: preheating a substrate to 40-60 ℃, and then adopting spraying or brushing to carry out coating, wherein the coating thickness is 30-40 mu m;

a3, curing.

7. The method for constructing a solar light reflecting and heat dissipating ceramic coating composition according to claim 6, wherein in step A1, 100-120 mesh silicon carbide blasting is used; the solidification in the step A3 is carried out at 80-100 ℃ for 10min; and curing at 230-260 ℃ for 20min.