Paint film adhesion and test
The adhesion of paint film is an important index to evaluate the bonding quality of coating film and substrate. It covers the binding force of the physical and chemical interaction between the coating film and the substrate surface, which is directly related to the stability and performance of the coating film. In coating engineering, adhesion is a key factor to ensure that the coating film is stably attached to the surface of the substrate without falling off or cracking. This paper will introduce the concept of film adhesion, test methods and the importance of these test methods in film evaluation.

The concept of film adhesion
Film adhesion refers to the strength of the physical and chemical bond between the film and the substrate. It takes into account the compatibility between the film and the substrate surface, the wettability and the substrate surface roughness. Excellent adhesion means that the film adheres tightly to the surface of the substrate without peeling or cracking due to external impact or stress.

Paint film adhesion and test method thereof

Test method for adhesion of paint film
The test methods of adhesion can be divided into two categories according to their directness and indirectness: direct method and indirect method.

Direct method – Pulling method (GB 5210-85) : This method mainly measures the force required to peel the coating film from the surface of the substrate by applying a pulling force. In the process of pulling the film, the force required to measure can reflect the adhesion of the film. However, this method may be unstable during operation.

Indirect method – Circle method and grid method: Circle method and grid method are a common indirect method. The scribbling method (GB/T 1720-89) uses a scribbling adhesion tester to draw the film into a circular rolling line through a scribbling needle, and the adhesion is evaluated according to the integrity of the scribing. The grid method (GB/T 9286) uses a high-alloy steel grid cutter to cut the grid on the coating film, and the adhesion is assessed by the integrity of the cut.

The significance of adhesion test of paint film
The adhesion test of paint film plays an important role in the evaluation of paint film. Good adhesion ensures that the film is firmly attached to the surface of the substrate and is not affected by external stresses. The test results of the adhesion can guide the selection, application and quality control of the coating, thus ensuring that the coating film has a stable performance in practical use.

Paint film adhesion and test method thereof

Sum up
Film adhesion is one of the key factors to evaluate the quality and performance of the film. The adhesion test method can be carried out by direct method and indirect method, among which the circle method and the grid method are commonly used indirect method. Through the film adhesion test, we can understand the combination between the film and the substrate, so as to provide strong support for the selection, application and quality control of the paint. Excellent adhesion ensures that the film remains intact under various environmental conditions, extending the service life of the film and improving the appearance quality