Analysis and Elimination of Uneven Ink Color in Printing Screen Printing of Paper Box

Analysis and Elimination of Uneven Ink Color in Printing Screen Printing of Paper Box

Printing ink color uniformity is one of the important conditions to measure Paper Box product quality. However, the main feature of plate printing products is often that the plate area is large and the amount of ink received is correspondingly large. In this way, in the Paper Box printing process, if the technical process in each link is not properly checked, it is very easy to cause uneven ink color failure, which will affect the product quality. For example, the thickness of the ink layer on the layout of some products is not uniform, or the ink color before and after batches of products is different, and even the process defects such as fish-scale fine spots or streak-like ink marks are produced.

The main reasons for this are as follows:

  1. Poor rubber roller accuracy, improper adjustment of the rubber roller position and too hard gel cause uneven ink distribution

When the head of the rubber roller is worn out or the contact between the rubber roller and the ink string iron roller is poor, more uniform ink distribution and ink transfer cannot be achieved. In addition, when the colloid of the inking roller is too hard, it is easy to slip during the process of inking on the layout, causing printing bar marks and uneven inking, which affects the printing quality of the layout. Yinmao.com supplies matching rubber rollers for original machines such as Heidelberg, Manroland, KBA, Komori, etc. It has the characteristics of longer service life, higher efficiency and more environmental protection.

  2. Ink fountain iron roller grinding loss is serious and the edge of the steel sheet is curvilinear

Causes the ink supply to be out of balance and causes the ink layer to be uneven. When these conditions exist, corresponding repair measures must be taken to keep the iron roller as good as possible concentricity and to grind the edge of the steel sheet into a straight line, so that the ink output of the ink roller on the ink fountain can be controlled flexibly, so as to avoid the occurrence of The color of the print is uneven in the longitudinal direction.

3. Uneven ink color caused by high ink viscosity and thick ink layer

When the stroke amount of the iron roller of the ink fountain is adjusted too small, and the gap between the steel sheet and the iron roller is adjusted too large, the ink layer conveyed by the ink fountain is thick, and it is not easy to be uniformly coated. This is the result of the paper's adsorption to the ink being less than the ink's adhesion on the printing plate. Yinmao.com sells DIC New Century UV3021 ultraviolet curing viscosity reducer online, which can effectively reduce ink viscosity and increase fluidity.

4. The printing pressure is uneven or the plate holder is not solid

The printing ink layer cannot be uniformly transferred to the substrate. When the printing pressure is uneven or insufficient, the ink layer on the layout cannot be uniformly or completely transferred to the substrate, making the ink layer of the printed product inconsistent or inaccurate. In addition, if the embossing process uses a wooden base to print a large area of the plate, because the base is prone to compression deformation and the firmness is insufficient, the ink layer of the printed product tends to be unreal and uneven, and batches of products are also It is easy to appear that the ink color before and after is inconsistent. Therefore, it is advisable to use a metal plate to stick the plate in the letterpress process to ensure the printing quality.

5. The printing area is too large, and the equipment structure and performance are not suitable, resulting in uneven ink layer.

The larger the printing layout, the stronger the adhesion between the ink layer and the printing plate. In this way, due to the imbalance between the adhesion between the ink and the printing plate and the adsorption force of the paper to the ink, it will inevitably occur locally, so The ink layer is cracked, so it cannot be transferred to the paper surface uniformly and completely. Therefore, when printing large-area plate products, it is advisable to use a rotary flatbed printing machine with a circular flattening structure or a rotary rotary printing machine with a circular flattening structure to make the printing ink color uniform. Multi-link bill rotary printing machine, you can buy it on the cat net. It is efficient and labor-saving, and it is worth owning!

6. Insufficient ink flow stroke causes unevenness of ink stripes

The difference in the thickness of the ink layer in the longitudinal position of the printed product is also a common situation in plate printing. This is because of the structural defects of the ink fountain, it cannot be adjusted to a very precise longitudinal inking uniformity. For this reason, some automatic printing presses are equipped with several sets of iron rollers that play the role of inking, and the size of the inking stroke can be adjusted. Adjust at will. When printing products with a large amount of ink, the stringing stroke of the ink string iron roller should also be increased to ensure the uniformity of ink distribution.

7. Printing streaks cause unevenness in the ink layer

The so-called printing "bar marks", also known as "back glue shadows", commonly known as "roller marks". It is also a common process defect in the plate printing process, that is, one or more shadow marks with obvious differences in ink shades appear on the horizontal position of the printed product, which greatly affects the aesthetics of the product. There are many reasons for the printing bar marks, including operational technical reasons and technological factors. Such as uneven or high printing plate pads, heavy printing pressure, too hard and easy to slip or poor adjustment of the height of the inking roller, insufficient number of inking rollers, insufficient ink distribution or wear gap of the rubber roller shaft head, etc. The source of scars. In addition, factors such as ink hue, ink shade difference, and poor adjustment of ink viscosity are also one of the reasons for printing streaks. Therefore, all aspects of the printing technology should be effectively controlled to effectively prevent the printing disadvantages of uneven ink layers. In short, there are many reasons for the uneven color of plate printing ink, which must be carefully analyzed, and corresponding measures should be taken to control the printing process technology to ensure the printing efficiency and quality.

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