How Does the Galvanized Coil “Transform” into a Color – PPGI Coil?

May 20 12:08 2025

In numerous fields like construction and home appliances, PPGI Steel Coils are widely used due to their rich colors and excellent performance. But did you know that its “predecessor” is the Galvanized Steel Coil? The following will reveal the process of how the Galvanized Sheet Coil is produced into a PPGI Coil.

1. Understanding Galvanized Coils and PPGI Coils

Galvanized Coils Manufacturers coat the coils with a zinc layer on the surface, which mainly serves a rust – proof function and extends the service life of steel. PPGI steel coils take galvanized steel coils as the substrate. After a series of processing, organic coatings are applied to their surface. It not only retains the rust – proof properties of galvanized steel coils but also adds more excellent properties such as beauty and weather resistance.

2. Key Production Steps for Galvanized Steel Factory

(1) Pretreatment Process – Degreasing: The surface of galvanized steel coils may have impurities such as oil and dust. These pollutants are removed by alkaline solutions or chemical degreasing agents to ensure a better combination of the subsequent coating with the substrate. For example, the use of a degreasing solution containing a surfactant can effectively decompose oil molecules.

Chemical Conversion Treatment: Common ones include chromization or chromium – free passivation treatment. It forms a very thin chemical film on the surface of the galvanized layer, aiming to enhance the adhesion between the substrate and the paint while further improving the corrosion resistance. This film is like a “bridge”, enabling the paint to be closely connected to the galvanized steel coil.

(2) Painting Process – Primer Coating: The primer is applied to the pre – treated galvanized coil by means of roller coating or other methods. The main function of the primer is to prevent rust. It contains anti – rust pigments and resins, which can effectively isolate the contact between moisture, oxygen, and the galvanized layer. For example, epoxy primer has good adhesion and rust resistance.

Topcoat Coating: Select topcoat coatings of different colors and performances for coating according to requirements. The topcoat not only endows the PPGI coil with rich colors but also provides protection such as weather resistance and wear resistance. For instance, polyester topcoat has bright colors and good UV resistance, making it suitable for outdoor construction. Some color – coated coils also have back paint to protect the back of the substrate from environmental erosion.

(3) Baking and Curing The painted steel strip enters into the baking furnace and is baked at a certain temperature (usually 180℃ – 250℃). The high temperature makes the resin in the paint undergo a cross – linking reaction, solidifying into a film and forming a firm coating. The baking time and temperature must be precisely controlled. If the temperature is too low or the time is insufficient, the paint film will not be completely cured, affecting the performance; if the temperature is too high or the time is too long, the paint film may turn yellow and its performance may decline.

(4) Post – processing (Optional) Some PPGI Steel coils undergo post – processing like embossing, laminating, etc. after leaving the oven. Embossing can increase the surface beauty and friction, and laminating can protect the coating surface during transportation and processing to prevent scratches.

3. Advantages and Applications of PPGI Steel Coils Through the above process, the galvanized steel coil is successfully “transformed” into a PPGI coil. PPGI Coil is both beautiful and practical. In the field of construction, they can be used for the exterior walls and roofs of factories. With a variety of colors, they are durable and do not fade. In the field of home appliances, such as refrigerators and air – conditioner shells, they are both aesthetically pleasing and wear – resistant. Its excellent comprehensive performance makes it occupy an important position in many industries. From the galvanized coil to the PPGI coil, the seemingly simple transformation actually involves precise technology and a scientific formula. Each production link is indispensable, and they collectively create the excellent performance of the PPGI coil, adding color and convenience to modern industry and life.

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