In order to make the paper bag more beautiful, the following points should be paid attention to when printing the paper bag by the printing machine.

Tools/raw materials required for paper bag printing

Printing press plate cylinders and blanket cylinders

Paper bag printing method/step

1. Adjust the printing pressure of the printing machine

Portable paper bags are often made of whiteboard paper with a quantitative weight of 250-400g/m2. The paper is relatively thick, which puts forward more stringent requirements for the adjustment of the printing pressure of the printing machine. During adjustment, the center distance between the printing plate cylinder and the blanket cylinder of the printing press remains unchanged, and only the center distance between the impression cylinder and the blanket cylinder needs to be adjusted. When the printing weight is 250-450g/m2 of whiteboard paper, the center distance of the roller can be increased by 0.20-0.40mm. In addition, due to the poor surface smoothness of whiteboard paper, its tightness is far less than that of coated paper. Therefore, it is necessary to increase the printing pressure of the printing machine accordingly. To adjust the printing pressure, you can also use the method of increasing or decreasing the thickness of the blanket lining of the rubber cylinder.

2. Adjust the offset feeding part of the printing machine

When printing whiteboard paper, coated paper, cardboard, and kraft paper, due to a large amount of paper, the air volume of the paper suction nozzle and paper blowing nozzle in the paper feeding part should be increased accordingly; the paper separation nozzle should be replaced with a larger diameter, Thicker rubber apron; the compression spring of the pull gauge can be replaced with a model with a larger diameter, so as to achieve the purpose of non-swing paper feeding and smooth paper feeding.

3. Prevent the back from getting dirty

Handbag printing often has a full version, which is easy to cause the back to be dirty. Therefore, the original barrel of ink should be used as much as possible, some de-sticking agents and anti-sticking agents should be added appropriately, and 6# ink varnish should not be added.

In addition, it can also be solved by powder spraying. However, it should be noted that dusting will affect the surface gloss of the printed matter, pollute the environment, and wear and stick to the part of the offset printing machine, such as the delivery paper.

What needs to be paid attention to is the correct arrangement of the printing color sequence. In order to avoid the back dirt caused by the collision of the paper when the imprint is not dry, the text and line version should be printed first, and then the solid version should be printed.

4. Arrange the printing color sequence of the printing machine

When arranging the printing color sequence, in addition to considering the back dirty, you should also pay attention to the following points.

(1) First print the mesh tone, then print the line and solid. When there are four-color overprinted mesh tone images on the tote bag, as well as text, solid patterns, and lines, in order to ensure the overprinting accuracy and reduce the influence of paper expansion, the printing machine should first print the mesh tone, and then print the lines and solids. , and be able to identify primary and secondary, first difficult and then easy.

(2) First print the dark color, and then print the light color. Due to the weak covering power of the light-colored ink, when it is placed in the back for overprinting, the overprinting machine is slightly inaccurate, and it is not easy to detect, and the overprinting effect is better.

(3) If you encounter whiteboard, cardboard, kraft paper, etc. with uneven moisture content, uneven wrinkling, and poor surface strength, which cause powder and hair loss, you can first print a blank line of water to solve the quality of monochrome printing. ACCIDENT.

The above is the whole content of the paper bag printing that ROYAL brings to you today. I believe that after reading the full text, you will have some understanding of the major elements that need to be paid attention to in the process of printing paper bags, and more printing information will be continuously updated.

ROYAL is a professional manufacturer of corrugated machinery. It not only produces printing machines such as flexo printing machines but also folder gluers, laminating machines, window stickers, etc. If you need packaging and printing equipment, you can log in to the official website and contact us: Hangzhou ROYAL Packing Machinery Co ., Ltd.; Email: [email protected], or tell us your needs directly: https://www.royal-packings.com/Message.html