Smoothness is a technical index for evaluating the degree of unevenness on the surface of the package. It is a physical quantity indicating the smoothness, smoothness and uniformity of the surface of the package. That is, under a certain vacuum condition, a certain volume of air is tested from a package under a certain pressure. The time it takes to flow between the surface and the smooth glass surface is measured in seconds. The higher the number of seconds, the better the smoothness of the package. The better the smoothness of the package, the more uniform and complete the contact between the paper and the printing plate during printing, the more the ink layer on the layout (emboss) or blanket is transferred, and the better the color rendering effect of the printed product.
On the other hand, in the PP plastic case with poor smoothness, the ink transfer is uneven, insufficient, and the paper has strong permeability to the amount of ink, and the color rendering effect is also poor, and it is easy to make the printed ink color and light. Therefore, if the printed product is fine, the finer the network cable and the smaller the diameter of the dot, the more smooth the package should be printed, so that the original can be reproducible.
PP plastic box gloss refers to the degree of specular reflection on the surface of the package, expressed as a percentage. The higher the gloss of the package, the more the surface can reflect light like a mirror, and the brighter the appearance. In fact, in addition to the specular reflection on the surface of the package, there is diffuse reflection, which reduces the gloss of the package. The box with high gloss, the more vivid the printed ink, the better the visual effect of the ink. It can be said that the smoother the package, the higher the gloss, and the higher the gloss of the printed product.
The gloss and smoothness of the PP plastic box are closely related, but the gloss is not smooth, and the shiny surface of the box is not necessarily a smooth surface. From the point of view of the glossiness of the packaging box, it is very practical to select the appropriate packaging box for printing according to the characteristics of the printing. For example, if the layout is text-based, the paper with gloss should be used to avoid reflection, so that the eyes will not be tired for a long time. For the printing of the plate-based layout, PVC PTE PP with high gloss should be used to make the printed ink color uniform, thick and bright.