Definition
A squeegee heated coater is a laboratory instrument used to prepare uniform, controllable thickness coatings on the surface of substrates. It uses a synergistic heating system and precision mechanical squeegees to coat liquid, paste, or molten samples onto a flat substrate, which can then be cured, dried, or further analyzed. This equipment is widely used in various industrial research and development fields such as materials science, coating development, electronic materials and textile processing, and is a key tool for preparing standardized coating samples.
How it works:
The core working principle of the squeegee heating coating machine is based on the combination of squeegee coating method and temperature control. Instruments typically contain a heatable base platform, a precision squeegee with adjustable clearance, and a temperature control system. When working, the substrate is fixed on a heated platform and the sample is placed in front of the scraper. As the scraper moves at a set speed, the gap between it and the substrate determines the wet film thickness of the coating. The heating system maintains the stage at a constant temperature to reduce sample viscosity, promote leveling, or simulate specific process conditions. The coating thickness can be preliminarily estimated by the formula: wet film thickness ≈ scraper clearance × sample leveling coefficient, and the actual dry film thickness also needs to consider the solid content and shrinkage rate.
Measurement and calibration methods
The evaluation of coating quality relies on the measurement of coating thickness and uniformity. The thickness of the wet film can be theoretically estimated by the squeegee gap setpoint and the rheological characteristics of the sample. For dry film thickness, a special thickness gauge, such as a micrometer or non-contact optical profiler, should be used to measure the average value at multiple points after the coating has cured. The calibration process focuses on verifying the accuracy of the scraper gap, often calibrated with standard feeler gauges or laser displacement sensors. At the same time, the temperature uniformity of the heating platform needs to be confirmed by a surface thermometer or multi-point thermocouple scanning to ensure that the temperature fluctuation of the entire coating area is within the allowable range.
Influencing factors
Coating quality is affected by a combination of parameters. The scraper gap directly determines the thickness of the wet film, and its machining accuracy and parallelism are crucial. The scraping speed affects the shear rate, which in turn changes the leveling behavior and final uniformity of the sample. The heating temperature affects the film formation and surface defects of the coating by changing the viscosity and volatilization rate of the sample. The rheological properties of the sample itself, such as viscosity, thixotropy, and solids content, are intrinsic factors that determine the feasibility of coating. Environmental conditions such as humidity and dust control can also affect the coating results of certain sensitive materials.
Applications:
Squeegee heating coating machines play an important role in multiple industrial research and development links. In the field of functional coatings, it is used to prepare samples of photovoltaic films, conductive ink coatings or optical films. In materials development, assist in the development of experimental coatings for new coatings, adhesives, or composites. In textile processing, it is used to apply functional coatings such as waterproof and flame retardant for sample testing. In addition, the device is also an important sample preparation tool in the laboratory simulation stage of processes such as battery electrode slurry coating and paper surface treatment.
Selection considerations
Choosing the right scraper heating coating machine requires comprehensive consideration of technical requirements and process conditions. First, clarify the coating width, thickness range and accuracy requirements to determine the scraper system specifications. According to the temperature requirements of the sample, the heating temperature range, temperature control accuracy and thermal uniformity of the platform are evaluated. The adjustable range and stability of the scraping speed need to match the rheological properties of the sample. The material compatibility of the device, especially the corrosion resistance of the part in contact with the sample, needs to be confirmed. In addition, ease of operation, safety protection design, and compliance with relevant industry standards (such as ASTM D823 and other coating standards) are also important reference factors.