How to Solve the Printing Problem of Kraft Paper Bag Paper?

March 03,2022

With the increasing awareness of environmental protection, plastic bags are gradually eliminated and replaced by environmentally friendly kraft paper bags. So you may have questions, how should we solve the printing problem of kraft paper bag paper? As a professional Kraft Paper Tin Tie Bags supplier, today we will answer for you.


kraft paper bag


  1. Lack of color: because kraft paper has its background color, before printing the content of the four-color dot, print white ink one or two times in the printing area, and then print the four-color content after the white ink is dry.


  1. Due to the loose and porous structure of kraft paper and long fiber, a layer of varnish can be printed before printing. It can improve the following problems: a large amount of ink during printing; Paper is easy to lose hair and powder.


  1. For kraft paper with high gram weight, the damage to printing hardware during printing: stop humidifying the kraft paper before printing to make the paper soft.


  1. Low gram kraft paper has waves when printing and wrinkling when it is serious: it is suggested to reduce the width of the paper (and the interval from the mouth of the paper to the end of the plate) or cut and flatten the web paper in advance and place it for some time (press heavy objects above the board and belt).


  1. Printing blistering: this kind of phenomenon is caused by coated cow cards and lack of interlayer separation strength (poor quality of papermaking starch). Ensure that the ink on the printer runs evenly, add ink viscosity reducer on the ink roller appropriately, and clean the rubber tape. If the printed content is on the spot, use strong colored ink to reduce the proportion of ink. If it is black on the spot, you can use outlets (such as 80% black screen + 20% blue screen).


  1. The ink is difficult to dry after printing: this problem can be solved by passing a layer of water and oil on the surface after printing.


  1. Bronzing: increase the pressure/temperature when it cannot be ironed (if the bronzing material emits blue light, the temperature transition is too high), and vice versa.


Partial UV process: due to the long fiber and rough characteristics of kraft paper, some UVs will have trachoma/blistering. The UV oil used in kraft paper is different from ordinary UV oil. It needs "anti soaking UV oil", and the screen printing screen should use high mesh, usually 150-180 mesh screen.


  1. Die-cutting: if it is thick paper, the thread pressing knife can be changed to a needle and thread knife, which is easy to fold and not easy to rebound. The knife should be sharp and the material should be good (if the order quantity is large, the Japanese knife can be used as the knife mold).


Bump / concave: the pressure should be large, and deep pressing should avoid paper rebound.


  1. Glue: the glue used for kraft paper is generally high-density and high viscosity glue (which can be properly mixed with all-purpose glue), and the traditional hot-melt glue is also applicable. Gluing the box can polish the sharp position (and glue water level) before gluing.
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