Definition
The Wire Bar Scraper Coating Proofing Machine is a kind of coating process simulation equipment used in laboratory settings. It is mainly used for formula research and development, process exploration and quality evaluation in the fields of coatings, inks, adhesives, functional coating materials and other fields. The device provides a standardized coating method for low-volume proofing in the laboratory, and the results can be used to predict and guide coating performance in large-scale production.
How it works:
The core working principle of the equipment is based on mechanical scraping and clearance setting. Its core component is a precision-wound stainless steel wire rod wrapped around a wire of a specific diameter, creating a series of parallel spiral bumps with a fixed height on the rod's surface. When operating, an appropriate amount of fluid to be measured is placed at the front end of the substrate, and the wire rod scrapes the fluid at a constant speed and pressure, and the fluid flows through the gap between the rod bulge and the substrate, leaving a wet film on the surface of the substrate. The thickness of the wet film is mainly determined by the diameter of the wire wrapped on the wire rod (i.e., the wire diameter), and theoretically, the thickness of the wet film is about one-tenth of the wire diameter. Its basic relationship can be expressed as:
h ≈ k × d
Among them,h is the thickness of the wet film,d is the diameter of the winding wire,k It is an empirical coefficient related to fluid properties, usually around 0.1. The entire scraping process is usually driven by a motor, ensuring smooth and consistent wire movement and speed consistency.
Measurement and evaluation methods
After coating the proofing machine with a wire rod scraper, the evaluation of the coating is usually divided into two stages: wet film and dry film. In the wet film stage, the uniformity, leveling, and defects such as streaks and shrinkage holes can be observed immediately. Dry film evaluation is performed after the coating has fully cured under set conditions. Key measurement and evaluation parameters include: dry film thickness, which can be obtained by measuring the difference before and after substrate coating using a micrometer or film thickness gauge; The surface state of the coating is checked by visual or optical microscopy for gloss, flatness and defects; Coating adhesion, hardness, wear resistance and other properties need to be tested according to the corresponding material standards (such as ASTM, ISO, GB standards). The value of a proofer is that it provides a reproducible initial sample for these subsequent standardized tests.
Influencing factors
The coating effect is affected by multiple factors. Equipment factors include wire diameter accuracy, surface finish, and scraping speed stability. The wire diameter directly determines the theoretical wet film thickness, and its processing accuracy is crucial. In terms of process parameters, the scraping speed affects the shear rate of the fluid, and too fast speed may lead to uneven film thickness or streaking, while too slow may cause sagging. Operating techniques, such as uniform pressure applied to both ends of the rod and the appropriate amount of fluid poured, can also affect the edge effect and coating width. In addition, the rheological properties of the material itself, such as viscosity, thixotropy, surface tension, etc., are intrinsic factors that determine the final film formation quality. Environmental conditions such as temperature and humidity can affect the volatilization rate and leveling process of fluids.
Applications:
The application of wire rod scraper coating proofing machine covers many industrial research and development fields. In the coatings industry, it is used to develop the color, gloss and film forming properties of architectural coatings, industrial coatings, automotive coatings, etc. In the field of printing inks, it is used to evaluate the printability, color density and dryness of inks on substrates such as paper and plastic films. In the field of electronic materials, it can be used to prepare prototype samples of functional coatings such as conductive coatings and optical films. In addition, it is also a commonly used sample preparation tool in laboratory research in industries such as adhesives, textile coatings, and paper coating.
Equipment selection considerations
When choosing the right wire rod scraper coating proofing machine, multiple technical parameters need to be comprehensively considered. The core is the wire rod specification, and the corresponding wire diameter should be selected according to the target film thickness range. The scrape width should match the size of the commonly used substrate. The drive mode is divided into manual and automatic, and the automatic type provides better speed control and repeatability. The overall rigidity of the equipment, the flatness of the guide rail, and the flatness and fixing method of the substrate platform are the basis for ensuring uniform coating. In addition, consider whether an oven or in-line drying module is needed to meet specific process requirements. The main goal of the selection should be to meet the requirements of the current main test standards, adapt to the characteristics of the material to be tested, and ensure the repeatability of the experimental results.