Selection of raw materials for printing labels

When using flexographic printing labels, the choice of raw and auxiliary materials will directly affect the quality of printed products, so its choice should not be limited to unit price, but should be the first element of the quality of printed products, and the synthesis of the product The cost is aggregated and analyzed for selection. The major raw and auxiliary materials that need to be considered are mainly paper and ink.

1. Paper

In general, the label pattern is mainly on the ground, which puts certain requirements on the smoothness, whiteness and glossiness of the paper. If you want to get a satisfactory label printing effect in the field, the smoothness of the paper must be high to ensure that the printed product has a uniform density value, so that the surface of the printed product will not cause hair loss. Because the paper with high glossiness and whiteness can enhance the contrast between the ink and the paper, and make the picture more clear, the flexographic ink shows a more vivid effect. Therefore, when choosing the flexo label paper, The two indicators of gloss and whiteness are particularly important. The paper's opacity has more influence on the quality of flexo labels than the above two indicators. Therefore, the whiteness and glossiness of the paper should be selected under the condition that the paper opacity is consistent, and the general whiteness should be Above 85%, the gloss should be higher than 55%.

In addition, since flexo printing generally uses web printing, the tensile strength of the paper is an important selection indicator. Only good tensile strength can ensure that the paper stays steady and continuous throughout the printing process, and the label maintains good overprint accuracy. In addition, the surface strength of the paper is also an important selection indicator, only the paper has a good surface strength The printing in the field is full, and there will be no occurrence of prints or uneven colors on the printed surface.

2. Ink

Since the label is given a vivid color, the proportion of the pigment in the ink will be increased to some extent, but this will have a certain impact on printing. The proportion of pigment is too high (above 35%), the viscosity of the ink will increase, and the thixotropy of the ink will become larger. In the printing process, the transfer of ink will be affected. At this time, the ink must be stirred as necessary. And as far as possible, place the ink in a suitable temperature (20°C).

When selecting the ink, the particle size of the ink and the drying performance of the ink should also be considered. Especially when there are large areas of color patches on the label, and there are text, lines or halftone images, it is necessary to consider the different requirements for the ink drying speed for different patterns, so as to make the prints clean and tidy (there is no paste version , hair pulling phenomenon). In addition, too coarse pigments can cause some wear on the anilox roller, and should also be noticed when choosing the ink.

In short, in the selection of raw materials, we should strive to save, but we can not only consider the price factor, we should consider from the perspective of comprehensive cost, according to the product pass rate. The rate of working hours, etc., is used for comprehensive evaluation and selection of suitable printing materials.