This article introduces a method for determining the intercoat adhesion of chlorinated rubber anti-corrosion paints and similar products. Although this method can only be used for qualitative judgment, it is of great significance in the consideration of Coating material selection and supporting systems because it is consistent with practical applications. The article describes in detail the tools and materials, as well as the test procedures for adhesion between primer and intermediate paint, topcoat and intermediate paint. This method is mentioned in the industry standard HG/T 2798 "Chlorinated rubber anti-corrosion coatings".
1. Introduction
In the coating industry, the evaluation of coating adhesion is one of the key factors to ensure coating performance and service life. This paper introduces a method for measuring the interlayer adhesion of chlorinated rubber anti-corrosion paints and similar products. Although this method can only make qualitative judgments, it is appropriate to the actual use situation and is of great significance to the selection of coatings and the design of supporting systems.
2. Tools and materials
In order to test interlayer adhesion, the following tools and materials are required:
Art Knife: Used to cut coated templates.
Straight ruler: used to measure the size of the coating sample.
Transparent tape: Used as a step in testing to evaluate coating adhesion properties.
Filter Paper: Used to cover the coating with scotch tape prior to testing.
3. Determination method
3.1 Adhesion between primer and intermediate coat
3.1.1 sample preparation A phosphating primer is applied on one side of a steel plate, and two primers are applied after 48 hours (24 hours apart). After 7 days of storage, a xenon lamp accelerated aging test is performed for 180 hours. Take out the sample, leave it for 24 hours and then apply two intermediate coatings (24 hours apart), leave it horizontally and dry for 7 days to prepare three qualified samples.
3.1.2 adhesion test steps
The test sample was hung in the damp heat Test Chamber with a hook for 24 hours, the temperature was 50 ± 1 ℃, and the relative humidity exceeded 95%.
Immediately after removing the sample, gently cover the filter paper over the painted surface to absorb excess moisture.
Using the tip of the art carving knife, cut two lines about 40 mm long in a direction parallel to the short side and separated by 15 mm in the center of the test sample, and cut through the paint film to the baseplate.
At the center of the intersection of the cutting lines, stick scotch tape on the vertical direction of the cutting line. One end of the tape needs to be folded back 20mm to tear.
Press the tape back and forth with your thumb to ensure it adheres firmly to the coating, then quickly tear one end of the tape at right angles to tear the tape off.
Check the torn paint film. If there is no peeling between the primer paint film and the middle paint film of two or more test plates, or the peeling width is less than 3mm, it is judged as "no abnormality".
3.2 Adhesion between topcoat and middle coat
3.2.1 sample preparation Apply a phosphating primer on one side of a steel plate, leave it for 4 hours, then apply an intermediate primer, leave it for 24 hours, then apply a topcoat, leave it for 7 days, and perform a xenon lamp accelerated aging test for 180 hours. Take out the sample, leave it for 24 hours, apply an intermediate layer of paint, then a topcoat, leave it horizontally and dry for 7 days to prepare three qualified samples.
3.2.2 Adhesion Test Step The procedure is the same as in the 3.1.2.
4. Conclusion
Tested by the above method, if there is no peeling between the primer and the middle coat paint or the topcoat and the middle coat paint in the adhesion test of two or more test samples, or the peeling width is less than 3mm, it is determined to be "No abnormality".
5. Reference Standards
The method described in this paper refers to the industry standard HG/T 2798 "Chlorinated Rubber Anticorrosive Coatings".
Conclusion
Interlayer adhesion is one of the important indicators to ensure the stability and durability of coatings. Although this method can only be used qualitatively, it is close to the actual use situation and has important significance for coating selection and supporting system design. In the coatings industry, accurate assessment of adhesion will help ensure the quality and performance of coatings, thereby ensuring long-term application of coatings.
