Ultrasonic Spraying Technology in Film Coating

Ultrasonic Spraying Technology in Film Coating

The present invention relates to a method for preparing thin films by ultrasonic atomization spraying. It utilizes a simple ultrasonic atomization device to atomize the spray liquid into ultrafine droplets, which are then more evenly deposited on the substrate surface with the aid of an auxiliary airflow. This method achieves a coating with uniform, controllable thickness and high-quality appearance. This method addresses the problems of poor coating surface uniformity, poor coating quality, uncontrollable spray volume, and low productivity encountered in existing spraying technologies, achieving the goal of precise spraying. Compared with existing technologies, the present invention offers advantages such as high spraying efficiency, high coating quality, excellent product reproducibility, high solution utilization, and precise control of the spraying area and coating thickness.

Technical Field

The present invention relates to the field of spraying technology, specifically to nano-thin film spraying processing technology, and specifically to a novel method for preparing thin films by ultrasonic atomization spraying.

Background Art

Ultrasonic atomization spraying is a thin film preparation method used to spray thin films onto substrate surfaces. The process generally includes three steps: ultrasonic atomization, spraying, and post-processing. Ultrasonic atomization utilizes the cavitation effect of ultrasound to cause tiny cavitation nuclei (bubbles) in a solution to oscillate, grow, and migrate toward the surface of the solution under the influence of ultrasonic energy. Upon reaching the surface, they burst, forming tiny droplets (mist). Ultrasonic atomization produces fine droplets, uniform distribution, and excellent atomization, making it easy to control and avoiding unnecessary waste in production. Existing spray coating processes primarily utilize compressed air to squeeze the coating liquid through a spray gun and spray it onto the substrate surface. However, this process has inevitable drawbacks, such as insufficient spray uniformity, uncontrollable coating thickness, poor film quality, significant solution rebound, and significant waste.

CN102019264A discloses an ultrafine atomization spraying method. Using ultrasonic or two-fluid nozzles, two or more nozzles perform a two-dimensional scanning motion along the X-Y axis. The atomized chemical liquid is applied to the entire wafer. The wafer is then rotated for a second spraying, and the rotational spraying process is repeated until the target thickness is reached. CN103143472A discloses an ultrasonic atomizing nozzle for soldering flux, consisting of five parts. In the first part, a mist storage chamber and a mist guide channel are separated by a side wall. A mist outlet is provided on one side wall of the mist storage chamber, and an upper mist guide channel opening is provided on the other side wall of the mist storage chamber. The second part is located below the first part and includes a spacer cavity with a lower mist guide channel opening. A flux inlet is installed on the side wall, through which flux is injected. The third part is located below the second part. The fourth part is located below the third part, with an ultrasonic transducer located at the bottom of this part and a bottom air inlet at the other end. The fifth part is the nozzle assembly. An external air source enters through the nozzle air inlet and is then ejected by the nozzle. The generated negative pressure simultaneously ejects the atomized flux stored in the mist storage chamber through the nozzle.

Although a number of ultrasonic atomizing spraying processes and equipment for ultrasonic atomizing spraying have been developed, these processes or equipment have limitations in their scope and application. Some ultrasonic atomization spraying equipment cannot uniformly control the amount of mist emitted at the nozzle, making it difficult to precisely control the thickness of the sprayed coating. Some ultrasonic atomization spraying processes are only suitable for spraying films on smaller substrates. However, the present invention can be used for spraying larger substrates, such as glass curtain walls, as well as coating smaller or even extremely small substrates. It also precisely controls the coating thickness and spraying amplitude (specifically, by adjusting the parameters of the double-layer nozzle) while maintaining the desired appearance quality.

The present invention aims to address the shortcomings of the existing technology by providing an ultrasonic atomization spraying film-forming method that can be better applied to industrial production, agricultural production, and scientific research, where fine processing is required. It can spray the coating liquid onto the substrate surface with maximum precision. The present invention employs the following technical solutions:

An ultrasonic atomization spray film-forming method employs an ultrasonic atomizer to ultrasonically atomize a spray liquid into ultrafine droplets. The method then utilizes an ultrasonic atomization nozzle system, guided by an external auxiliary airflow, to spray the film onto the substrate surface.

The ultrasonic atomization nozzle system comprises a double-layer nozzle comprising an auxiliary airflow inlet pipe as an outer tube, an atomized liquid vapor inlet pipe as an inner tube, and an atomizing nozzle at the end. The atomizing nozzle comprises a double-layer spray nozzle connecting the auxiliary airflow inlet pipe and the atomized liquid vapor inlet pipe.

The ultrasonic atomization spray film-forming method employs an independently designed ultrasonic atomization nozzle system. Ultrasonic waves are used to break up the spray liquid typically used in air spray guns into ultrafine droplets, which are then carried by an external auxiliary airflow and sprayed onto the substrate surface, forming a more uniform thin film. The external auxiliary airflow serves to shape the spray pattern. The present invention controls the droplet particle size and atomization volume by controlling the frequency and power of the ultrasonic wave. The spray flow rate is controlled by controlling the flow rate of the atomized liquid vapor in the inner tube. Controlling the external auxiliary airflow ensures uniform flow of the atomized liquid vapor within the ultrasonic atomizing nozzle. The present invention utilizes a double-layer nozzle structure to create a uniform mist flow at the nozzle that is sprayed onto the substrate surface, forming a coating with uniform, controllable thickness and high-quality appearance.

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