The selection of prepainted steel sheet mainly refers to the selection of mechanical properties, substrate type (coating type) and coating weight, front coating performance and reverse coating performance. Purpose, environmental corrosiveness, service life, durability, processing method and degree of deformation are important factors that should be considered when selecting materials.
Choice of front coating properties
The choice of front coating performance mainly refers to the choice of coating type, coating thickness, coating color difference, coating gloss, coating hardness, coating flexibility/adhesion, coating durability and other properties.
Paint type
Topcoat
Commonly used topcoats include polyester, silicon-modified polyester, high-durability polyester and polyvinylidene fluoride. There are certain differences in hardness, flexibility/adhesion, corrosion resistance, etc. of different topcoats. Polyester is currently the most widely used coating. It has average durability, good hardness and flexibility, and is affordable. The durability, gloss, and color retention of silicone-modified polyester are improved, but the flexibility of the coating is slightly reduced. High-durability polyester not only has the advantages of polyester, but also has improvements in durability, making it highly cost-effective. Polyvinylidene fluoride has excellent durability and good flexibility of the coating, but its hardness is relatively low, available in fewer colors, and expensive. For detailed performance indicators of various topcoats, please refer to relevant information or consult experts. The topcoat is mainly determined based on factors such as use, environmental corrosivity, service life, durability, processing method and degree of deformation.
Primer
Commonly used primers include epoxy, polyester and polyhelium ester. There are certain differences in adhesion, flexibility, corrosion resistance and other aspects of different primers. Epoxy has good bonding strength with the substrate and has high corrosion resistance, but it is not as flexible as other primers. Polyester has good bonding strength with the substrate and excellent flexibility, but its corrosion resistance is not as good as epoxy. Polyester is a primer with relatively good overall properties. For detailed performance indicators of various primers, please refer to relevant information or consult experts. The primer is usually determined by the manufacturer based on the production process, use, environmental corrosivity and matching relationship with the topcoat.
coating thickness
The corrosion resistance of ppgi coils is closely related to the thickness of the coating. Generally, the corrosion resistance increases as the thickness of the coating increases. Appropriate coating thickness should be determined based on environmental corrosiveness, service life, and durability.
Coating color difference
Color difference may occur during the production and use of color coated boards. Since color difference is affected by production batches, color depth, usage time, usage environment, purpose and other factors, it is usually negotiated between the supply and demand parties when ordering.
coating gloss
The coating gloss is mainly selected based on the purpose and usage habits. For example, color-coated boards for domestic construction usually choose medium and low gloss, and color-coated boards for home appliances usually choose high gloss.
Coating hardness
Coating hardness is the coating's ability to resist scratches, friction, collisions, dents and other mechanical effects. It is closely related to the scratch resistance, abrasion resistance, indentation resistance and other properties of the color-coated board. It is mainly based on the use. , processing method, storage and transportation conditions, etc. to choose.
Coating flexibility/adhesion
Coating flexibility/adhesion is closely related to the processability of prepainted steel sheet, and the selection is mainly based on the processing method, degree of deformation, etc. When the deformation speed is fast and the deformation degree is large, the color-coated plate with high impact energy value and small T-bending value should be selected.
Coating durability
Coating durability is the performance of color-coated boards during use, and is usually measured by the length of service life. Coating durability is mainly affected by factors such as coating type, coating thickness, and environmental corrosiveness. The true durability of a coating can be determined through atmospheric exposure testing. Durability can also be evaluated through artificial aging tests. The neutral salt spray resistance test is one of the simplest and most commonly used artificial aging test methods, and the ultraviolet lamp accelerated aging test is also a commonly used artificial aging test. In addition, color-coated boards may be used in special environments such as acid rain and humidity. In this case, corresponding artificial aging tests should be selected for evaluation. It should be noted that artificial aging tests usually cannot fully simulate the actual use environment.
Other properties
In some cases, color coated plates may need to have better resistance to organic solvents, acid and alkali resistance, pollution resistance, etc. Attention should also be paid to such special properties. Selection of reverse coating properties
The reverse coating is usually determined by the manufacturer based on the purpose and use environment. When the environment is not highly corrosive, the reverse side is usually coated with only one layer, mainly for decoration. If insulation material is pasted on the reverse side, this should be noted when ordering so that the manufacturer can apply coating with good bonding properties on the reverse side. When the environment is highly corrosive, a second layer should be applied to improve corrosion resistance.
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