The oily ink was used for this test. The test results are shown in Figure 9. It can be seen from the figure that even with the same printing area, the carton of the band printing method b) has the highest pressure reduction resistance, and even if the printing area of ​​the band printing method b) is only 10% to 20%, the carton is resistant to pressure. The reduction rate is almost the same as in full printing.

In recent years, due to advances in printing technology, water-based inks have been used, and printing pressure has been lower than in the past. However, the impact caused by printing cannot be ignored.

In the design of corrugated boxes, we must understand that corrugated boxes are transport packages. Their mission is to transport the goods safely to their destinations. Therefore, we must not be overly concerned with printing beautifully. There are a lot of graphics and colors printed, but we ignore them. The cartons are resistant to pressure and there is a risk of accidents during the storage and transportation of the packed products. Because the more pictures and pictures, the cardboard is pressed more flat, more printed in one color and more compressed once. The flatter the cardboard, the lower the pressure resistance of the carton.

Of course, corrugated carton packs for some products, such as corrugated cartons for home appliances, are not just transport packages, but they also have the role of sales packaging. In order to enhance the advertising function on the packaging box, to attract customers, the more printed images on corrugated boxes, the more colors are printed. In order to take into account whether corrugated boxes are adequately resistant to stress during storage and transportation, there are only two solutions:

1 increase the paper quality, or add four corner columns in the four corners of the box to offset the loss of pressure resistance of the carton during printing;

2 Use color paper cartons instead.

However, no matter which method is used, it will lead to an increase in the cost of packaging.

â–²6. The effect of hand-punch hole and vent hole on the pressure resistance of corrugated box

For the carton with heavier and larger products, for the convenience of loading and unloading, the handle hole is often opened on the side of the carton, and the ventilation holes are required for the carton of fresh fruits and vegetables. These hand-pull holes or vents obviously reduce the pressure resistance of the carton, and the greater the area occupied by the holes, the lower the pressure resistance of the carton will be lowered. The following experiments investigated the effect of the position of the hand-punch hole on the pressure resistance of the carton.

The test box is a single corrugated carton box of A. The outer dimensions of the box are 360mm x 300mm x 250mm, and the dimensions of the handle holes are 60mm x 20mm. Measure the pressure resistance of the carton when the position of the hand-punch hole changes in the vertical direction and when the left-right direction changes. Through the experiment, the following conclusions are drawn:

1 The closer the position of the hand-punch hole is to the upper cover or bottom, the lower the pressure resistance of the carton;

2 The position of the hand-punch hole is further away from the center, the lower the pressure resistance of the carton;

3 From the above results, the position of the handle hole is preferably as close as possible to the center of the up, down, left, and right sides. When the handle hole is in the central part of the carton, the pressure resistance is reduced by about 2% to 4%, and when the handle holes are at the upper and lower ends or the left and right sides of the carton, the pressure resistance is reduced by about 10%.

In addition, the shape of the handle holes or vents can also have an effect on the pressure resistance of the carton.

â–²7. Corrugated box internal liner impact on carton pressure

It is reasonable to say that the addition of partitions in the box means that the pressure resistance of the carton should be increased. It can indeed be seen that the pressure resistance of the carton increases during the test of the laboratory, but it is not obvious when the stacking is actually performed. Therefore, based on actual results, the partition should be added to the site where the actual stress is the weakest.

In addition to the above influencing factors, the indentation lines of the corrugated box, especially the transverse pressure lines (the form of the pressure reel of the corrugated board machine and the depth of the pressure line), also have an impact on the resistance of the corrugated box. When doing empty-box pressure test of corrugated boxes, sometimes the double peak phenomenon as shown in Fig. 10 can be observed from its pressure-deformation curve. This is usually the proof of the impact of cross-pressure lines on the pressure resistance of corrugated boxes. The first peak is usually the yield of the carton on the transverse pressure line. If the pressure continues to increase, the pressure can rise back to the entire carton.

Someone asked, which peak should be the pressure resistance of the carton when double peaks occur? The key is whether the deformation (compression amount) of the carton has an adverse effect on the contents when the second peak is reached. Because the carton's resistance to pressure is not necessarily the maximum pressure the carton can withstand, the carton's resistance to stress is sometimes measured as the pressure at which the deformation of the carton reaches a predetermined value.

(Author/Shenzhen Meiying Sen Environmental Packaging Technology Co., Ltd. Cai Shaoling)

Guangdong Packaging 2005 Phase IV