AR coating (anti-reflective coating) has been widely used because it can significantly increase the transmittance of glass and increase the output power of photovoltaic modules. According to incomplete statistics, about 90% of PV modules are currently equipped with AR coating. Photovoltaic glass. This paper briefly introduces the coating process of AR coating photovoltaic glass, and makes a preliminary discussion on the process adaptability of different types of AR coating. Jinhua Fireproof Glass Factory
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AR coating photovoltaic glass processing process
The processing technology of AR coating photovoltaic glass, after the tempering process, produces compressive stress on the surface of the glass, and tensile stress is generated inside, so that the photovoltaic glass obtains high strength. At the same time, after the heat treatment of the AR coating, the internal organic matter is decomposed, leaving the inorganic porous SiO2 film sintered on the glass surface, thereby ensuring the long-term weather resistance of the AR coating.
AR coating coating process introduction
Rubber roller: main coating roller, active roller, EPDM or PU material, diameter 300mm, according to AR coating properties, hardness is available in the range of 30-45HS; Wenzhou fire glass customization
Steel roller: feeding roller, driving roller or driven roller, also called anilox roller, the liquid tank is located between the rubber roller and the steel roller, and the liquid is applied to the rubber roller through the mesh on the steel roller, mainly stainless steel and chrome plating material. At present, there are also ceramic-like materials with a diameter of 150mm. According to the difference in solid content of AR coating, the number of mainstream anilox rolls is 60/70/80/100 mesh;
Pressing roller: generally chrome-plated steel roller with a diameter of 100mm, its main function is to make AR coating evenly distributed on the surface of the rubber roller;
Flexible scraper (optional): mainly used to remove surface defects such as perimeter marks on the glass surface
Factors affecting the thickness of AR coating
Considering that different AR coating thicknesses have significant differences in power gain of photovoltaic modules using the same battery, the actual production process requires strict control of the thickness of the AR coating. The AR coating dry film is mainly determined by the wet film thickness of the coating process, affecting The factors of the wet film thickness are as follows.
The center distance of the rubber roller and the steel roller D: the center distance of the rubber roller and the steel roller determines the liquid storage capacity of the liquid tank. The larger the D value, the more the liquid volume of the rubber roller at the same rotation speed, the corresponding The thicker the wet film thickness;
The number of steel rolls: the lower the mesh number of the steel roll, the wider the width of the relative net, that is, the larger the liquid amount of the steel roll, the thicker the corresponding wet film thickness.
The linear speed of the rubber roller/steel roller: the faster the linear speed of the rubber roller/steel roller, the more the amount of the solution applied to the glass surface in the same time, the thicker the corresponding wet film;
Conveyor speed: The slower the conveyor speed, the more the amount of solution applied to the glass surface in the same time, the thicker the wet film. Wenzhou fire glass customization
In addition, the temperature and humidity of the coating chamber will also have a significant effect on the thickness of the AR coating. Considering that the roll coater has a large exposed surface, this will increase the evaporation of the solvent in the AR coating solution and cause a change in the solid content of the reflux solution, which has a significant influence on the uniformity of the AR coating film thickness. It is a challenge to the roll coating process to ensure the stability of the solid content in the reflux solution and to ensure the uniformity of the AR coating film thickness.
Process adaptability of different AR coatings
According to the type of solvent used in AR coating, AR coating can be divided into aqueous coating and solvent phase AR coating. The solvent used in the aqueous phase AR coating is deionized water. The solvent used in the solvent phase AR coating is ethanol, isopropanol. And some non-volatile ethers.
In order to investigate the effect of solvent volatilization on the performance of AR coating solution, the same amount of aqueous phase solution and solvent phase solution were placed in an environment of 24 degrees Celsius and 47% relative humidity. The amount of solution was obtained by measuring the remaining amount of solution at different times. The curve as a function of time is as follows. (See the map for details)
It can be seen from the above table that the aqueous phase AR coating solution is relatively stable, the amount of solution changes little with time, and continuous production of uniform film thickness AR coating glass can be achieved without adding additional fresh solvent in the actual production process; The amount of phase solution will change with time, and the solid content of the reflux solution will also change accordingly, which will affect the consistency of the film thickness. Due to the volatilization of the solvent, it is necessary to calculate the amount of fresh solvent to be replenished according to the amount of volatilization of the solvent in the reflux solution. The volatilization rate of the solvent may vary for different environmental conditions, and the actual production process needs to be changed according to the environment. The amount of additive in the fresh solvent is adjusted accordingly to ensure the consistency of the thickness of the AR coating. Jinhua Fireproof Glass Factory
Summary
In this paper, the coating process of AR photovoltaic glass is briefly introduced, and the process adaptability of different types of AR coating is discussed. The aqueous phase AR coating is easy to achieve continuous production of uniform film thickness AR coating glass because of less solvent evaporation and stable process. Solvent phase AR coating has a problem of large amount of solvent volatilization. The production process should add fresh solvent to the reflowed AR coating solution according to the change of environment to ensure the stability of the solid content of the solution. It requires complicated process operation to achieve uniform film thickness. Stable production of glass.