Definition
A wirewound coating rod is a laboratory tool used to prepare uniform wet film coatings on flat substrates. It is usually composed of a metal rod precisely wound with stainless steel wire or nickel-chrome wire, and the thickness of the wet film is controlled through the gap between the wire and the rod. The tool is widely used in the R&D and quality control of coatings, inks, and functional coatings.
How it works:
The wirewound coating rod works on the principle of gap coating. As the rod rolls smoothly on the surface of the liquid-coated substrate, the silk threads wrapped around the rod form a series of gaps, and the liquid is scraped and spread through the gaps, creating a wet film thickness on the substrate that corresponds to the diameter of the silk thread. The relationship between the thickness of the wet film T and the diameter of the silk thread d can be approximated as: T = k × d, where k is the coefficient related to the rheological properties of the liquid.
Measurement method
When using a wire-wound coating rod to prepare a coating, an appropriate amount of sample is placed at one end of the substrate, and the coating rod is pushed with uniform speed and pressure to spread the sample into a film. After coating, it needs to be dried or cured under specified conditions, and then the dry film thickness can be measured by a film thickness gauge, and the thickness consistency of the wet film can be estimated based on the solids content. The operation process should refer to relevant industry standards to ensure that the ambient temperature, humidity and substrate flatness meet the requirements.
Influencing factors
The coating effect is affected by a variety of factors. The diameter of the coated rod wire wire directly determines the thickness range of the wet film; The pushing speed and angle during operation will affect the uniformity of the film layer. Rheological properties such as sample viscosity and leveling may cause edge effects or streaks; The surface energy and flatness of the substrate also affect the adhesion and spreading. In addition, ambient temperature and humidity may alter the volatilization rate of the sample, which can interfere with film layer formation.
Applications:
Wire wound coating rods are widely used in industrial coating performance testing, printing ink suitability evaluation, optical film preparation, electronic material coating development, and paper surface treatment. In the research and development process, it is used to screen formulas and process parameters; In the quality inspection process, it is used for batch consistency verification. Its easy operation and low cost make it a routine coating preparation tool in the laboratory.
Key points of selection
When selecting, the required wet film thickness range should be considered, and the diameter of common silk threads corresponds to different thickness specifications; Choose stainless steel or corrosion-resistant alloy according to the corrosiveness of the sample; The length of the rod should match the width of the common substrate; The handle design affects the comfort and stability of operation. At the same time, the requirements of relevant industry standards for coating film preparation should be referred to to ensure that the accuracy of the tool meets the testing needs. It should be cleaned in time after use to avoid residue affecting the subsequent coating accuracy.