WO2019101006A1

WO2019101006A1 - Hydrophobic self-cleaning anti-stokes fluorescence and radiation refrigeration coating with surface temperature lower than atmospheric temperature day and night and preparation method therefor

Info

Publication number: WO2019101006A1
Application number: PCT/CN2018/115847
Authority: WO
Inventors: 张卫东; 薛晓; 杨卓; 李艳稳; 张涛; 冯雅; 钟辉智; 田春雨; 张红强; 张子英; 张荣普; 秦杰
Original assignee: 中国建筑股份有限公司; 中建工程研究院有限公司; 中国建筑科学研究院
Priority date: 2017-11-23
Filing date: 2018-11-16
Publication date: 2019-05-31
Also published as: CN107828289B; CN107828289A

Abstract

Disclosed are a hydrophobic self-cleaning anti-Stokes fluorescence and radiation refrigeration coating with the surface temperature being lower than the atmospheric temperature day and night and a preparation method therefor, the coating comprising 35-50 parts by weight of a hydrophobic styrene-acrylic emulsion, 10-20 parts by weight of a luminous pigment, 3-10 parts by weight of a stearate, 1-6 parts by weight of a talcum powder, 20-30 parts by weight of titanium dioxide, 3-5 parts by weight of auxiliaries, and 5-15 parts by weight of water. The method for preparing the coating comprises first mixing the components other than a thickening agent and a film-forming auxiliary, stirring and dispersing same at a high speed, then adding the thickening agent and the film-forming auxiliary, and uniformly dispersing same to obtain the coating.

Description

Reflexive Tokes Fluorescence and Radiation Cooling Coating with Hydrophobic Self-cleaning Surface Temperature and Temperature Below Day Temperature and Preparation Method thereof

Technical field

The invention relates to the field of refrigeration coatings, in particular to a reflection of a Tokax fluorescent and radiant refrigeration coating with a hydrophobic self-cleaning surface temperature and a temperature below day and night, and a preparation method thereof.

Background technique

Rethinking Tork Night Light Cooling, also known as laser cooling, refers to the use of a low-energy pump laser to excite a refrigeration unit with a luminescent center. The refrigeration unit spontaneously radiates high-energy photons to achieve the physical phenomenon of object cooling. The idea of using materials' anti-Stokes fluorescence to cool solid materials was originally proposed by Pringsheim in 1929. However, until 1995, researchers such as Epstein of the Los Alamos National Laboratory in the United States observed a cooling effect of 0.3 K below room temperature on a cerium-doped glass under vacuum (RIEpstein, MIBuchwald, BCEdwards, TRGosnell, CEMungan, Observation of laser-induced fluorescent cooling of a solid. Nature 377 (1995) 500-503). Since then, laser cooling of erbium-doped solid materials, erbium-doped solid materials, and semiconductor materials has made great progress. Under vacuum, laser cooling can reduce the temperature of solid materials to 150K below room temperature. However, laser cooling of all of these solid materials strictly requires the refrigeration unit to have a quantum efficiency close to 1, a low energy single beam pump laser, and minimal or even negligible parasitic heat transfer. To date, worldwide, the use of sunlight instead of the usual pump laser to excite coating materials to achieve reflection in an open environment has never been achieved.

Radiation cooling refers to the way in which infrared radiation is used to directly release heat into the space through the atmospheric window. The absolute temperature outside the atmosphere is about 3K (-270 ° C) and is an excellent heat sink. In the atmospheric window (8-13 μm), the atmosphere is transparent to the infrared radiation of surface objects. Therefore, in order to achieve radiant cooling, the refrigerant must have strong selective radiation in the atmospheric window. The obvious sign of radiant cooling is that the surface temperature of the refrigerant is always lower than the temperature, and then the temperature of the radiator is lowered below the temperature by conduction, thereby achieving the purpose of radiant cooling.

Because there is no solar heat, radiant cooling at night has been realized since the 1960s. In order to achieve daytime radiant cooling, the refrigerant must be selectively radiated in the atmospheric window region, and must have a very high reflectivity in the solar spectrum to reduce the solar heat absorbed by the radiator. This is because when there is sunlight on the surface of the radiator, due to the wide absorption band of the black body, the absorbed solar radiation energy (700-900 W/m ² ) is much higher than the power of the radiant cooling (generally less than 100 W/m ² ). Therefore, it is very difficult to achieve daytime radiation. In fact, it is difficult to achieve selective radiation materials with both solar short-wave high reflectivity and infrared long-wave high emissivity. Therefore, most of the current radiant cooling can only achieve nighttime radiant cooling.

As for the coating material, it has a high infrared emissivity, and particularly has an excellent radiation selectivity in an atmospheric window of 8 to 13 μm. In order to achieve daylight radiant cooling of the coating material, the solar reflectance must be increased to more than 94%. However, the current solar coatings of the existing cooling coatings are all less than 90%. Therefore, the existing commercial cooling paint can only cool down, and it is impossible to achieve daytime radiation cooling at the same time.

Until 2014, scientists at Stanford University in the United States successfully manufactured a nanophoton daytime radiation chiller. The refrigerator employs an electron beam evaporation method in which 20 nm of titanium is first plated on a 750 μm thick 200 mm diameter silicon wafer, 200 nm thick silver is deposited on the titanium, and seven layers of silicon dioxide and cerium oxide are alternately deposited on the silver. Using the 200 nm silver plated on the silicon wafer, the solar reflectivity of the chiller was increased to 97%, and the infrared radiance of the atmospheric window was increased to 67% using the above seven layers of selective radiation in the atmospheric window. When the radiant cooler was placed on a dry, sunny California winter, at a temperature of about 20 ° C, a radiant cooler surface was observed at noon (13:00 to 14:00) with an illumination intensity of 800 to 870 W/m ² . The temperature was lower than the temperature (4.9 ± 0.15) ° C, and the measured cooling power was (40.1 ± 4.1) W / m ² . The convection and conductivity at the time of the test were 6.9 W/m ² /K.

The research is a major breakthrough, and the researchers are aware that daytime radiation cooling is fully achievable. Therefore, the paper is published in Nature 2014 (APRaman, MA Anoma, L. Zhu, E. Rephaeli, S. Fan, Passive radiative cooling below ambient air temperature under direct sunlight. Nature 515 (2014) 540-544). However, the technology has the following problems: 1 using nano-sized photonic technology, complex structure, high precision requirements, is not conducive to large-scale production; 2 using precious metal silver and rare metal oxide cerium oxide, expensive (2 oxidation铪 price 4,000 yuan / kg). 3 The experimental results obtained correspond to the dry, sunny, sunny, 20°C California winter, and the climate is not representative; 4 the cooling demand appears in the summer, and the summer cooling effect should be given; 5 according to the method of the paper, Tongji The results of the University's Professor Simulation show that in Shanghai, where the mid-latitude represents the region, the surface temperature can be reduced by 2.3 °C in summer and the cooling power is 20.1 W/m ² . In Bangkok, where the high latitude is representative, the surface temperature can only be reduced by 0.1 in summer. °C;6 How to connect the refrigerator to the building, how to lay a sufficient area of silver-plated silicon plate on the top of the building.

Inspired by this technology, scholars at the University of Colorado in 2016 created a polymethylpentene film filled with photon resonance glass beads that increased the infrared radiance of the atmospheric window to 93%. The film was then overlaid on a 750 μm thick silicon wafer plated with 200 nm thick silver to increase the solar reflectance to 96%. When the radiant cooling film is placed in the dry sunny Colorado autumn sun, when the light intensity is 900 W/m ² , by forcing the surface temperature to be equal to the temperature, the convective and conduction heat transfer conditions are excluded, and the measured noon average is obtained. The cooling power is 93 ± 10 W/m ² . The results of the study were published in Science in 2017 (Y.Zhai, Y.Ma, SN.David, D.Zhao, R.Lou, G.Tan, R.Yang, X.Yin.Scalable~manufactured randomized glass~polymer Hybrid metamaterial for daytime radiative cooling. Science 355 (2017) 1062-1066).

The innovation of this research is that only a thin film is fabricated, which replaces the complex nano-sized photonic structure and the infrared emissivity of the atmospheric window is mentioned to 0.96. Because the forced surface temperature is always equal to the temperature, the effects of convection and conduction heat transfer are eliminated, and the net noon cooling power under ideal conditions is obtained. However, the technology has the following problems: 1 using precious metal silver to improve the solar reflectivity; 2 the durability of the film to be tested; 3 how to arrange the roof technology on the silicon wafer needs to be solved; 4 can not be directly used on the wall And the illumination of the building is stronger. 5 In practical applications, when the film-added silicon wafer is exposed to an open environment, the influence of convection and conduction heat transfer cannot be eliminated, that is, such high cooling power cannot be achieved.

In summary, the use of sunlight and outer space as a source of sustainable heat, the reflection of the Tokes luminous cooling and radiant cooling two refrigeration mechanisms integrated into a single coating material, to achieve day and night below the temperature without the need for refrigerant, passive consumption without electricity Refrigeration technology has considerable market prospects.

Summary of the invention

The object of the present invention is to provide a refrigerating material which can be directly applied to a building facade and a roof, and a preparation method thereof, which reflects the exterior temperature of the building during daytime and nighttime by reflecting on Tokex fluorescence and radiant cooling. Real-time temperature to achieve the same purpose of cooling buildings without the use of freon and electric energy. After the film is formed into a film, the surface can be made hydrophobic and self-cleaning, which is convenient for the user to clean and maintain at a later time and save labor costs.

One aspect of the present invention provides a reflective Toxex fluorescent and radiant cooling coating having a hydrophobic self-cleaning surface temperature and a temperature below day and night, comprising 35 to 50 parts by weight of a hydrophobic styrene-acrylic emulsion, 10 to 20 parts by weight of a luminescent pigment, and 3 to 10 parts by weight. Parts of stearate, 1 to 6 parts by weight of talc, 20 to 30 parts by weight of titanium dioxide, 3 to 5 parts by weight of auxiliary agent, and 5 to 15 parts by weight of water.

Further, the contact angle of the styrene-acrylic emulsion with water after film formation was 97.5°.

Further, the luminous pigment is an aqueous pigment; the color of the luminous pigment is one of purple, sky blue or yellowish green.

Further, the stearate is one or more of calcium stearate, zinc stearate, and potassium stearate.

Further, the titanium dioxide is rutile type titanium dioxide.

Further, the auxiliary agent is selected from one or more of a dispersing agent, a wetting agent, an antifoaming agent, an anti-settling agent, a thickener, a leveling agent, and a film forming aid.

Further, the reflection of the Tokes fluorescent and radiant cooling coating film after drying is more than 105°.

Further, the surface of the refrigerating coating has an average particle diameter of 50.27 μm.

The invention also provides a preparation method for preparing the above-mentioned hydrophobic self-cleaning surface temperature and the temperature below day and night is lower than the temperature, and the specific steps are as follows:

Step 1: Weighing hydrophobic styrene-acrylic emulsion, luminous pigment, stearate, talc, titanium dioxide, auxiliary and water for use;

The auxiliary agent includes a dispersing agent, a wetting agent, an antifoaming agent, an anti-settling agent, a leveling agent, a thickener and a film forming aid;

Step 2: mixing the hydrophobic styrene-acrylic emulsion, the luminous pigment, the stearate, the talc, the titanium dioxide, the dispersing agent, the wetting agent, the defoaming agent, the anti-settling agent, the leveling agent and the water weighed in the first step High speed stirring and dispersion for 90 to 120 minutes;

Step 3: adding a thickener and a film-forming auxiliary agent to the stirred and dispersed solution in the second step, and dispersing uniformly.

Further, the stirring time of the third step is at least 30 minutes.

The beneficial effects of the present invention are embodied in:

1. The invention provides a reflective Toxex fluorescent and radiant cooling coating with a hydrophobic self-cleaning surface temperature and a temperature lower than the temperature, and a preparation method thereof, and has the advantages of low cost and simple preparation process. The laminating process can be completed using a conventional paint application process, which is convenient to use. It does not require pump lasers to reflect on Toxex fluorescence refrigeration, nor does it require expensive silver-plated silicon wafers for radiant cooling. It can be applied on a large scale, filling the gaps in the prior art.

2. The hydrophobic self-cleaning surface temperature provided by the present invention is lower than the temperature. The main advantage of the Tokes fluorescent and radiant cooling coating compared with the existing solar thermal reflective coating material is that the solar heat reflective coating material only The temperature can be lowered, and the object to be coated cannot be cooled. In other words, the surface temperature of the coating is much lower than that of the surface without the heat-reflecting coating, but it is always higher than the real-time temperature. However, the hydrophobic self-cleaning surface temperature provided by the present invention is lower than the temperature. The reflection of the Toks fluorescent and radiant cooling coating is directly applied to the roof and the façade, and the surface temperature of the coating is lower than whether it is sunny day or night. Real-time temperature, exposed to open air, with a cooling capacity of up to 57 watts per square meter, can be used on a large scale for energy-saving design of new buildings and energy-saving renovation of existing buildings. When the temperature is below 35 °C, the exterior walls and roofs are coated with The room temperature of the coating can be maintained below 28 °C.

3. The hydrophobic self-cleaning surface temperature of the present invention provides a hydrophobic self-cleaning function, which is excellent in hydrophobic self-cleaning function, and can effectively prevent the ash from being caused when used on a building facade. The solar reflectance is reduced while the coating has excellent weatherability. It is convenient for users to clean and maintain later, saving labor costs.

Other features and advantages of the present invention will be set forth in the description in the description which follows. The main objects and other advantages of the invention may be realized and obtained by means of the invention particularly pointed out in the appended claims.

DRAWINGS

Figure 1 shows the test results of the roof of the model house.

Figure 2 shows the test results of the outer surface temperature of the west wall of the model house.

Figure 3 shows the results of the indoor temperature test of the model room.

Figure 4 shows the light intensity during the seven-day outdoor test period from August 15 to 21, 2017.

Fig. 5 is a view showing the surface morphology of the coating of Example 1 under a scanning electron microscope.

Figure 6 is a contact angle diagram of water droplets of the coating of Example 1.

Detailed ways

As used herein, the terms "comprising," "including," "containing," "having," are meant to be non-limiting, that is, other steps and other ingredients that do not affect the result are added. The above terms encompass the terms "consisting of" and "consisting essentially of." Materials, equipment and reagents are commercially available unless otherwise stated.

One aspect of the present invention provides a reflective Toxex fluorescent and radiant cooling coating having a hydrophobic self-cleaning surface temperature and a temperature below day and night, comprising 35 to 50 parts by weight of a hydrophobic styrene-acrylic emulsion, 10 to 20 parts by weight of an aqueous luminous pigment, 3 to 3 10 parts by weight of stearate, 1 to 6 parts by weight of talc, 20 to 30 parts by weight of titanium dioxide, 3 to 5 parts by weight of an auxiliary agent, and 5 to 15 parts by weight of water.

According to the present invention, the contact angle of the styrene-acrylic emulsion with water after film formation is from 97.5 to 111°.

According to the present invention, the luminescent pigment is an aqueous pigment; the color of the luminescent pigment is one of purple, sky blue or yellow-green.

According to the invention, the stearate is one or more of calcium stearate, zinc stearate, potassium stearate.

According to the invention, the titanium dioxide is rutile titanium dioxide.

According to the invention, the auxiliary agent is selected from one or more of a dispersing agent, a wetting agent, an antifoaming agent, an anti-settling agent, a thickener, a leveling agent, and a film-forming auxiliary.

According to the present invention, the reflective Tokes fluorescent and radiant cooling coatings have a contact angle with water of more than 110° after film drying. The surface energy depends only on the dispersion component, and the Lewis acid and Lewis base components are both 0 mN/m. Therefore, the reflexive Tokes fluorescent and radiant cooling coatings provided by the present invention have excellent acid and alkali resistance.

Step 1: Weighing hydrophobic styrene-acrylic emulsion, aqueous luminescent pigment, stearate, talc, titanium dioxide, auxiliary agent and water for use;

Step 2: mixing the hydrophobic styrene-acrylic emulsion, aqueous luminescent pigment, stearate, talc, titanium dioxide, dispersant, wetting agent, antifoaming agent, anti-settling agent, leveling agent and water weighed in step one After high-speed stirring and dispersion for 90 to 120 minutes;

Step 3: adding a thickener and a film-forming auxiliary agent to the stirred and dispersed solution in the second step, and uniformly dispersing, and the stirring time is at least 30 minutes.

In fine weather, between 9:30 and 14:30 on a summer day with a light intensity of 900-1000 watts/m2, the roof surface temperature can be reduced to an average below 6-7 °C; at 14:30-20: Between 00 o'clock, the surface temperature can be lowered to below 8 to 10 ° C. The measured cooling power was 57 watts/square meter when exposed to an open environment. Considering the heat loss caused by conduction and convection below temperature, the actual cooling power under ideal conditions should be higher than 100 watts/square meter.

Since the model room was required for long-term outdoor experiments, it was not possible to perform outdoor field test verification for all the examples. The present invention will be described below with reference to Examples 1 to 4 which have undergone two months of outdoor experiments.

Table 1 Examples 1 to 4 reactants and reaction time

Table 1 shows the details and reaction time of each component of Examples 1 to 4 of the reflection of the hydrophobic and self-cleaning surface temperature of the present invention.

Table 2 Components and amounts of the auxiliary agents of Examples 1-4

Table 2 is a breakdown of the components and amounts of the auxiliary agents in Examples 1 to 4.

Table 3 Basic performance test results of Embodiments 1 to 4

Table 3 shows the results of the conventional physicochemical properties, optical properties and accelerated aging experiments of the reflection of the hydrophobic self-cleaning surface temperature and the temperature below the temperature. It can be seen that according to the preparation method provided by the present invention, the reflected reflectance of the Tokes fluorescent and radiant refrigerating coatings in the excited state is above 0.92, the surface hydrophobic angle is greater than 105°, and the performance is superior and resistant. Acid and alkali, the number of scrubs is not less than 10,000 times.

The reflective Tokes fluorescent and radiant cooling coatings prepared in Example 1 were applied to the roof and the facade of a 2m×2m×2.3m concrete model room at a coating thickness It is 200-300 μm; the control experiment is to maintain the concrete color of the model room of the same specification. Detect its cooling, as shown in Figures 1-4:

Figure 1 shows the outdoor test results of the roof surface of the model house for seven consecutive days from August 15 to 21, 2017. In the figure, from top to bottom, the surface temperature of the model house roof surface, the temperature, and the surface temperature of the roof coating of the model house coated with the refrigerating paint are sequentially represented. It can be clearly seen from Fig. 1 that the coating of the refrigerating coating provided by the invention can effectively reduce the surface temperature of the roof coating of the model house and keep the roof surface temperature of the model room lower than the temperature.

Figure 2 shows the outdoor test results of the outer surface temperature of the west wall of the model house for seven consecutive days from August 15 to 21, 2017. In the figure, from top to bottom, the outer surface temperature of the model western wall, the temperature, and the outer surface temperature of the model western wall coated with the refrigerating paint are sequentially represented. It can be clearly seen from Fig. 2 that the coating of the refrigerating coating provided by the invention can effectively reduce the temperature of the outer surface of the west wall of the model house, and the temperature of the outer surface of the west wall of the model house is always lower than the temperature.

Figure 3 shows the results of the indoor temperature test of the model room for seven consecutive days from August 15 to 21, 2017. As is clear from Fig. 3, the application of the refrigerating coating provided by the present invention can effectively reduce the indoor temperature of the model room. When the temperature is lower than 34 °C, the indoor temperature of the model room with the cooling coating on the roof and facade can be maintained below 27 °C.

Fig. 5 is a view showing the surface morphology of the coating of Example 1 under a scanning electron microscope. It can be seen that the average particle diameter of the surface of the refrigerating paint is about 50.27 μm.

Fig. 6 is a contact angle diagram of water droplets of Example 1. After multiple measurements, the average contact angle is 110°, and it can be seen that the refrigerating coating has excellent hydrophobic properties.

The present invention provides a hydrophobic self-cleaning surface temperature that is lower than the temperature and reflects the Toks fluorescent and radiant cooling coatings, and integrates the two refrigeration mechanisms of reflexing Toxex fluorescence refrigeration and radiant cooling into a single-layer coating system for the first time. Passive cooling that stays up below the temperature is achieved.

In summary, the following conclusions can be drawn from Figures 1 to 6:

1. Whether it is sunny or cloudy (except precipitation), day or night, the surface temperature of the model house roof and the western wall coated with refrigerating paint is lower than the temperature, much lower than the concrete surface without coating. The most obvious time for temperature and cooling is from 3 pm to late afternoon.

2. Through the sectional heating experiment, the measured actual cooling power of the coating material exposed to an open environment is 57 watts/square meter. Considering that the atmosphere and surrounding objects are inevitably heated by non-radiative means (convection and conduction) below the temperature, the non-radiative heat transfer coefficient at a wind speed of 3 m/s is 12 w/m 2 /degree, if To suppress or even eliminate non-radiative heat transfer, the nominal cooling power of the coating will be greater than 100 watts per square meter.

3. The invention relates to a reflective self-cleaning surface temperature which is lower than the temperature and reflects the Toks fluorescent and radiant cooling coating, and has excellent hydrophobic self-cleaning function, which can effectively prevent the ash caused by the façade of the building. The solar reflectance is reduced while the coating has excellent weatherability. It is convenient for users to clean and maintain later, saving labor costs.

The embodiments described above are only intended to describe the preferred embodiments of the present invention, and are not intended to limit the scope of the present invention, and various embodiments of the present invention may be made by those skilled in the art without departing from the spirit of the invention. Modifications and improvements are intended to fall within the scope of the invention as defined by the appended claims.

Claims

Hydrophobic self-cleaning surface temperature is lower than the temperature of the reflection of the Toks fluorescent and radiant cooling coating, characterized by containing 35 to 50 parts by weight of hydrophobic styrene-acrylic emulsion, 10 to 20 parts by weight of luminescent pigment, 3 to 10 parts by weight The stearate, 1 to 6 parts by weight of talc, 20 to 30 parts by weight of titanium oxide, 3 to 5 parts by weight of an auxiliary agent, and 5 to 15 parts by weight of water.
The reflective Toxex fluorescent and radiant cooling coating according to claim 1, wherein the styrene-acrylic emulsion has a contact angle with water of 97.5° after film formation.
The reflective Tokes fluorescent and radiant cooling coating according to claim 1, wherein the luminous pigment is an aqueous pigment; the luminous pigment is purple or sky blue. Or one of yellow-green.
The reflective Toxic fluorescent and radiant cooling coating according to claim 1, wherein the stearate is calcium stearate, zinc stearate, and stearic acid. One or more of potassium acid.
The reflective Toxex fluorescent and radiant cooling coating according to claim 1, wherein the titanium dioxide is rutile titanium dioxide.
The reflective xox fluorescent and radiant cooling coating according to claim 1, wherein the auxiliary agent is selected from the group consisting of a dispersing agent, a wetting agent, an antifoaming agent and an anti-settling agent. One or more of a thickener, a leveling agent, and a film forming aid.
The reflective Toxex fluorescent and radiant cooling coating of the hydrophobic self-cleaning surface temperature according to claim 1, wherein the reflection of the Toxex fluorescent and radiant cooling coating is contact with water after drying. The angle is greater than 105°.
The reflective Toxex fluorescent and radiant cooling coating according to claim 1, wherein the surface of the refrigerating coating has an average particle diameter of 50.27 μm.
The method for preparing a reflective Toxex fluorescent and radiant cooling coating having a hydrophobic self-cleaning surface temperature and a temperature lower than a temperature according to any one of claims 1 to 8, wherein the specific steps are as follows:

Step 1: Weighing hydrophobic styrene-acrylic emulsion, luminous pigment, stearate, talc, titanium dioxide, auxiliary and water for use;

The auxiliary agent includes a dispersing agent, a wetting agent, an antifoaming agent, an anti-settling agent, a leveling agent, a thickener and a film forming aid;

Step 2: mixing the hydrophobic styrene-acrylic emulsion, the luminous pigment, the stearate, the talc, the titanium dioxide, the dispersing agent, the wetting agent, the defoaming agent, the anti-settling agent, the leveling agent and the water weighed in the first step High speed stirring and dispersion for 90 to 120 minutes;

Step 3: adding a thickener and a film-forming auxiliary agent to the stirred and dispersed solution in the second step, and dispersing uniformly.
The method for preparing a reflective Toxex fluorescent and radiant cooling coating according to claim 9, wherein the stirring time of the third step is at least 30 minutes.