Definition
The Adjustable Squeegee Coating Tester is a precision piece of equipment used in laboratories to simulate coating processes. It mechanically applies a liquid or slurry evenly to the surface of the substrate, creating a wet film of controlled thickness. This equipment is mainly used in material research and development and quality control to help users evaluate the rheological properties of coating fluids, coating uniformity, and the properties of the film after drying.
How it works:
The core working principle of the equipment is based on the gap control between the scraper and the substrate. The coating solution is placed at the front end of the substrate, and when the scraper moves at a constant speed, the cutting edge at the bottom scrapes away the excess coating solution, and the liquid left on the substrate forms a uniform wet film through surface tension and leveling. The thickness of the wet film is mainly determined by the height of the gap between the scraper and the substrate, and the relationship can be approximately expressed as:
h ≈ k · g
where h is the thickness of the wet film, g is the height of the mechanical gap, and k is the correction coefficient related to the rheological characteristics of the coating solution. The equipment is often equipped with precision fine-tuning mechanisms, allowing operators to adjust the gap with micron-level accuracy.
Measurement method
When using this equipment for coating tests, it is necessary to follow a systematic operation process. First, the substrate is fixed flat on the workbench, and the scraper gap is calibrated by a thickness gauge. Place an appropriate amount of coating solution in the area in front of the scraper and start the device to translate the scraper at a constant speed. After coating, the wet film thickness can be measured directly with an online thickness gauge or offline testing using a film thickness gauge after the coating has cured. To obtain reliable data, multiple replicates of the same parameters are often required.
Influencing factors
The quality of the coating is affected by a combination of factors. The speed of scraper movement affects the shear rate, which changes the leveling behavior of the coating fluid. The physical properties of the coating solution, such as viscosity, surface tension and solid content, directly affect the uniformity and defect formation of the coating. Environmental conditions such as temperature and humidity can alter the volatilization rate of solvents, resulting in differences in coating surface morphology. The surface energy, roughness and flatness of the substrate will also affect the spreading effect of the coating solution. The operator's technical level, especially the calibration accuracy of the scraper gap and the control of the amount of coating fluid, plays a key role in the repeatability of the results.
Applications:
The equipment has application value in many industrial and scientific research fields. In the field of new energy, it is used in the development of coating processes for battery electrode slurries. In the field of electronic materials, we assist in the preparation of functional films and conductive coatings. In the coatings industry, it is used to verify the construction performance of colored paints, varnishes and other products. In the paper and packaging industry, we support the development of functional coatings and barrier layers. In addition, it has corresponding applications in the fields of adhesives, ceramic slurries and composites.
Equipment selection considerations
Choosing a suitable squeegee coating testing machine requires comprehensive consideration of technical parameters and actual needs. The coating width should cover the common size range of the target product. The gap adjustment range and accuracy need to meet the expected film thickness requirements. The equipment should offer adjustable scraper movement speeds to accommodate the coating needs of materials with different viscosities. In terms of material, the parts that come into contact with the coating fluid need to be corrosion-resistant. The ease of operation, safety protection design and maintenance of the equipment are also important considerations. It is recommended to conduct a comprehensive evaluation based on the physical properties of the main test materials and industry testing standards.