In the experiment, 108 substrates were treated with 4508 treatment solution and coated with paint films of different thicknesses to test the adhesion represented by the T-bend value. And the soaking test is used as an accelerated test method, and the effect of reducing the adhesion in a short period of time can be achieved through the soaking test.
Figure 4.1 No peeling T-bend value of tapes coated with different thickness topcoats after 108 substrates treated with 4508
Figure 4.2 No peeling T-bend value of 108 substrates treated with 4508 and coated with a layer of primer and topcoat with different thicknesses
From Table 4.1~4.4, it can be seen that according to the cracks, the change of T-bend value with acceleration time is almost the same when one layer of primer plus one topcoat is applied and one layer of primer plus two topcoats. From 4.1 and Figure 4.2, it can be seen that the T-bending value of the tape without peeling and the amount of paint film peeled off from the tape are not the same. The adhesion of two top coats is better than that of only one top coat, indicating that After two layers of topcoat are applied, the blocking effect on the environmental medium is enhanced, and water and oxygen are delayed from penetrating into the interior of the paint film to contact the substrate and promote corrosion of the substrate, thus delaying the generation of corrosion products and improving the adhesion timeliness of the paint film and the substrate.
