Definition
The Heated Squeegee Coating Tester is a device used to simulate the coating process under laboratory conditions. It evenly coats a liquid or paste sample onto the surface of the substrate through controlled heating and mechanical scraping to prepare a coating sample for performance testing. This equipment is widely used in the field of material research and development and quality control, providing standardized preparation methods for evaluating the coating suitability and film forming performance of coatings, adhesives, inks and other products.
How it works:
The core working principle of the equipment is based on the squeegee coating method. It is mainly composed of a precision scraper mechanism, a heating platform, a substrate fixture and a control system. When working, a pre-set sample is placed on the substrate and a heating platform maintains a constant temperature of the substrate or scraper to simulate drying or curing conditions in the actual process. The scraper scrapes the sample at a constant speed and pressure under the action of the drive system, and the height of the gap between the scraper and the substrate determines the thickness of the wet film. The basic relationship can be expressed as: wet film thickness ≈ scraper clearance - substrate unevenness compensation. By controlling parameters such as temperature, scraping speed, pressure and gap, coating films with uniform thickness and high reproducibility can be prepared.
Measurement and operation methods
Standard operating procedures follow relevant industry testing specifications. First, the scraper clearance is calculated and set according to the target dry film thickness and sample solids content. The substrate is fixed flat on the heating platform, set and stabilized to the target temperature. Take an appropriate amount of sample and place it at the front end of the scraper travel path. Start the scraping program and move the scraper at a constant speed to complete the coating. After coating, the sample can be cured or dried according to standard procedures. Key measurement parameters include consistency assessment of wet film thickness, typically verifying uniformity by measuring multi-point thickness with a micrometer; and observe the surface condition of the coating to check whether there are any defects such as streaks and bubbles. Some devices integrate online thickness monitoring to improve process control accuracy.
Analysis of influencing factors
The coating quality is affected by the interaction of multiple factors. In terms of scraper parameters, the gap accuracy directly determines the thickness of the wet film. The flatness and material of the knife edge affect the shear state and wear resistance. The scraping speed affects the shear rate and leveling time. In terms of temperature control, the temperature of the platform affects the viscosity, leveling and solvent volatilization rate of the sample, and temperature uniformity is the condition to ensure the consistency of the coating. In terms of sample characteristics, rheological properties such as viscosity and thixotropy determine the spreading behavior at different shear rates. Environmental conditions such as laboratory temperature and humidity can affect solvent volatilization and sample stability. Operational factors such as sample injection volume and settling time before scraping also need to be standardized to ensure reproducibility of results.
Applications:
The equipment plays an important role in several industrial and scientific research fields. In the coatings industry, it is used to prepare standard samples for testing the adhesion, hardness, weather resistance and other properties of paint films. In the field of printed electronics, it is used to prepare conductive ink films and evaluate their square resistance and uniformity. In the adhesive industry, it is used to apply pressure-sensitive adhesive samples and test their adhesiveness. In the research and development of functional coatings, it is used to prepare optical films, waterproof coatings, etc. In battery manufacturing research, it is used to simulate the coating process of electrode slurry. Additionally, it is commonly used in laboratories in textile coatings, paper processing, and composite material pretreatment.
Key points to consider in selection
Equipment selection should comprehensively consider technical parameters and experimental needs. The core parameters include the scraping width, which needs to match the size of the commonly used substrate; The scope and accuracy of scraper gap adjustment should cover the target coating thickness requirements; The heating temperature range and uniformity need to meet the sample process temperature requirements; Scraping speed range and control stability. In terms of functional configuration, you can consider whether you need functions such as multi-tool head switching, substrate vacuum adsorption and fixation, environmental cavity or slope adjustment. The part of the equipment material that comes into contact with the sample should have corrosion resistance and appropriate hardness. The control system should have parameter storage, program programming and data export capabilities to facilitate method standardization. In addition, equipment safety, maintenance convenience, and the supplier's technical support and service capabilities should also be included in the evaluation.