The renovated metal surface treatment of color steel tiles is insufficient and excessively smooth. Before spraying, the substrate has not undergone surface treatment or is not thoroughly treated, resulting in residual moisture, oil stains, oxide skin, etc. on the surface. The adhesion of paint films usually comes from two aspects: on the one hand, the physical attraction and the binding force between small structural domains such as hooking, overlapping, wrapping, and wrapping; On the other hand, it originates from the binding forces generated by various chemical bonds. If the substrate is too smooth, the physical bonding force between the coating and the substrate will weaken, resulting in the paint film not being able to adhere to the substrate and causing the paint film to peel off during the renovation of the color steel tile.
Prevention and control method: Polish the smooth surface to a smooth surface, and thoroughly remove moisture, oil stains, oxide skin, etc.
The incorrect selection of primer for the renovation of color steel tiles has caused the paint film to peel off. For example, the paint film is too hard, making it difficult for the topcoat to adhere or the primer has too much gloss. The mismatch between the primer and topcoat results in poor interlayer adhesion and poor compatibility.
Prevention and control method: Choose intermediate paint or topcoat products that match the primer, and high-performance color steel tile renovation special paint is a prerequisite for doing a good job in the project.
The special paint for renovating color steel tiles should not be sprayed too thick or the paint film layers should not be completely dry. When encountering moisture, the paint film may be in poor dry condition. If the thickness of the topcoat paint film is too thick or due to other reasons, the solvent in the primer cannot be fully utilized, the interface of the interlayer paint film will form a honeycomb shape due to the presence of solvent, causing the coating film to become loose and the strength to decrease, resulting in a decrease in adhesion. Once damaged, it will cause detachment.
Prevention and control method: The paint film of the refurbished color steel tile needs to be dried thoroughly and polished before applying topcoat to increase the adhesion between coatings. But it is also necessary to prevent excessive drying of the primer. After excessive drying of the primer, there is a lack of active polar groups in the primer, resulting in a lack of binding force from chemical bonds between the topcoat and primer, which can reduce interlayer adhesion and lead to detachment. In order to prevent layer peeling, it is also important to note that prolonged exposure of the coated material is strictly prohibited. If the exposure time is too long, the substrate or primer may be easily contaminated by foreign objects such as oil. When the surface undergoes powdering or new chemicals are generated due to prolonged exposure, the topcoat cannot fully contact the primer or substrate, which can also affect the adhesion between coatings and cause the paint film of the color steel tile renovation paint to peel off.
Due to the performance reasons of the special paint for renovating color steel tiles, peeling is not common. Most of it is caused by unclean substrate treatment, or the primer exceeding the specified coating interval and not being cleaned according to requirements. Therefore, the cleaning work before installation must ensure sufficient adhesion between the coatings to avoid the problem of peeling off.
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