Definition
A coil lab coater is a type of laboratory equipment used to uniformly apply a specific functional coating to the surface of a flexible or rigid roll substrate. It provides key technical support for the research and development and performance evaluation of coil coating materials by precisely controlling the coating process parameters and simulating actual production conditions in the laboratory.
How it works:
The equipment unwinds the substrate through the unwinding system, and the tension control system keeps the substrate running smoothly. The coating unit transfers the slurry of a predetermined viscosity to the surface of the substrate, forming a wet film through coating heads such as scrapers, micro-concave rollers or slits. The substrate then enters the drying area, where the coating is cured by hot air or infrared light, and finally the coated coil is collected by the winding system. The whole process is usually equipped with thickness and speed sensors to achieve closed-loop control of process parameters.
Measurement method
Coating performance evaluation requires a combination of multi-dimensional measurements. Wet film thickness can be measured instantly by scraper wet film thickness gauge, and dry film thickness can be measured by eddy current or ultrasonic thickness gauge. The surface topography of the coating uniformity can be observed by optical microscopy, and the coefficient of variation of thickness distribution can be calculated in combination with image analysis software. Adhesion testing is commonly used to scramble the grid, and after the standard grid, use tape to peel off to observe the detachment. The degree of curing can be verified by analyzing the glass transition temperature by differential scanning calorimetry.
Influencing factors
The coating quality is affected by multiple factors. In terms of slurry characteristics, viscosity and rheological properties determine the leveling of the coating, and the solids content affects the drying shrinkage. In the process parameters, the matching relationship between coating speed and drying temperature affects the apparent quality of the coating, and improper tension control may lead to substrate wrinkles. Environmental conditions such as laboratory temperature and humidity changes can cause fluctuations in solvent volatilization rates. Among the equipment factors, the processing accuracy and installation parallelism of the coating head directly affect the lateral uniformity of the coating.
Applications:
The equipment is used in the field of new energy for the development of coating processes for battery electrode pastes, and in the electronics industry for the preparation of functional coatings for flexible circuit substrates. In the field of packaging materials, it uses it to optimize the process of barrier coating, and the research and development of building waterproof materials is through its simulated membrane modification treatment. In addition, it also has important applications in emerging materials such as functional textiles and optical films.
Key points of selection
The selection should comprehensively consider technical parameters and R&D needs. The coating width should cover the common specifications of the target product, and the coating speed range should meet the material requirements of different drying characteristics. The drying system needs to be compatible with a variety of heating methods, and the temperature control accuracy is recommended to be within the standard requirements. The equipment should have the ability to switch multiple types of coating heads, and the control system should support the storage and recall function of process parameters. The equipment material needs to consider corrosion resistance requirements, and the safety protection device should meet the mechanical and electrical safety standards.