Cardboard box surface coating technology

Because the factors that cause warping are complex and the methods of influence are uncertain, many companies have been bothered by this and have been at a loss. When the ratio of expansion and contraction of colored paper and corrugated cardboard is inconsistent, the warped paperboard will be warped. In other words, if the length of the colored paper or corrugated cardboard is in the horizontal direction and the width is in the vertical direction, the dimensional change will be larger, whereas the change will be smaller. Therefore, we can call it a warpage defect when the coated paperboard and boxed cartons exceed 0.05 and 0.03, respectively.

Accurate stacking

If the vertical stripes of the paperboard are parallel to the short sides, according to the elongation rate of Table 1, the horizontal stripes will be elongated by 42mm and the vertical stripes by 0.1mm.

Improve methods

As can also be seen from the above experiment, the ratio of stretch in the transverse direction of the cardboard is 10 times or more that of the vertical direction. This is why, in the dry season of the sky, the reason why the color box is stacked in the warehouse for a period of time and it is easy to cause a significant upward turn;

From experiment 2 and experiment 3, it can be seen that the colored paper and the corrugated cardboard will all exhibit elongation after absorbing moisture; and the more water absorbed, the greater the extent of its elongation. (See Experiment 6 for details)

Improve the solids content of glue

After finding out the law of cardboard warping on the cover, we can find some ways to improve it. The higher the solids content, the lower the water content of the glue, and the glue with a higher solid content can reduce the amount of glue per unit area of the board, thus ensuring that the water absorbed by the cardboard per unit area is greatly reduced, thereby improving the warpage. . Through measurement, we found that after the coated paperboard, when the camber coefficient exceeds 0.05, it will easily cause die-cutting and affect the die-cutting effect. For paperboards that are finished and warped, the more feasible and effective method is to apply a certain amount of pressure on them. After a certain period of time, the warped paperboard will have a more significant improvement.

Warp Board Warp Definition

In the process of carton cladding, the warpage of the cardboard is often one of the important issues plaguing the paper product processing industry.

Analysis of Causes of Board Warpage in Covering Process

Generally speaking, we can call warping as long as the cardboard is away from the straight state. Through practice, it has been confirmed that the warpage of cardboard can be fundamentally improved as long as a relatively high solid content glue is used, and the accurate paper grain direction is maintained, supplemented by an accurate stacking method. However, as warpage of the quality category, slight warping is not a defect of the product, and warping is only called when the degree of warpage affects the production, appearance and function of the carton. If the ratio of confetti shrinkage is greater than the expansion and contraction ratio of corrugated cardboard, the warpage of the cardboard after the cover is shown as an upward bend; otherwise, it is a downward bend;

Based on the data obtained from the above experiments, we do not lose face:

In order to understand the variation of the size of the coated cardboard and the law of warpage, we conducted some relevant test analysis. Moreover, the shrinkage of colored paper is significantly higher than the shrinkage of corrugated board. In addition to cardboard warpage will cause die-cutting position, reduce efficiency, but also affect the squareness after the box, weakening the carton compressive strength of the whole box.

In addition, in the process of covering the surface, the paperboard that has just completed the cover is stacked and pressed in a positive and negative manner, which can also improve the warpage of the board to some extent. From the results obtained from multiple experiments, the warpage of the board can be significantly improved when the solid content of the glue is kept above 24%.