Reasons for the curling of flexo products and solutions
We are a big printing company in Shenzhen China . We offer all book publications, hardcover book printing, papercover book printing, hardcover notebook, sprial book printing, saddle stiching book printing, booklet printing,packaging box, calendars, all kinds of PVC, product brochures, notes, Children's book, stickers, all kinds of special paper color printing products, game cardand so on.
For more information please visit
http://www.joyful-printing.com. ENG only
http://www.joyful-printing.net
http://www.joyful-printing.org
email: info@joyful-printing.net
In flexographic printing, sometimes the paper curls toward the front, which makes the appearance of the product uneven, which affects the customer's use in severe cases.
The reason for this phenomenon is that hot air is helping to dry during the flexo process. When the printing is completed, the water content of the paper itself is smaller than that of the white material before printing. In addition to the printed matter, UV glazing is generally required. In this way, the front side of the print has a UV layer protection, which acts as a separation during contact with the air, resulting in a small extension. On the reverse side, because there is no protective layer, the paper is definitely affected by the humidity of the air, and the deformation of the paper itself is different from the humidity. The reverse side is larger than the front side, which causes the product to curl upward. We might as well make a small experiment: put the UV-coated product on the cup with a certain water temperature, and the water vapor will make the paper surface damp. We can see that the UV faces the mouth of the cup, accepts moisture, and the product is almost no deformation; but if the back is toward the cup, the product will immediately deform and curl toward the front.
After knowing the cause, we can take countermeasures: Apply a layer of material on the back of the paper with a minimum amount to make it a protective layer in contact with the air. For example: argan gum 3% to 5%, this phenomenon is basically solved.