What is the reason for the warping of the pit plate?

Pit paper is a kind of smooth kraft paper and corrugated paper (collectively called paper core), and it is one of the important materials of paper packaging. The basic structure of pit paper is a smooth kraft paper and corrugated paper (collectively referred to as paper core) laminated. In the past, kraft paper, partly or completely made of wood pulp, was about 200-250g, with strong breaking resistance and load-bearing capacity. However, in recent twenty or thirty years, due to environmental protection and cost factors, the content of wood pulp in kraft paper has decreased, and the thickness is much thinner when mixed with waste paper, usually between 120 and 160g, and occasionally 200g paper is used. As for paper cores, they are all recycled waste paper, and the thickness ranges from 130 to 160g to 100 to140g. Most of the packages on the market are almost paper products, which are not only much lighter, but also have many styles, and can be decorated with various patterns. There are many kinds of paper packaging. Generally, more expensive items are packed in cartons, shopping bags are mostly paper bags, and more important documents and files are basically packed in kraft paper. Kraft paper has high packaging strength and is stronger than ordinary paper.

The most important use of pit paper is outer packaging. Because of the prosperity of printing technology, there are many styles of pit paper. Today, it not only plays the role of outer packaging, but also plays the role of inner packaging or paper products. Let's talk about the pits that look the same, but they all have different pits. In the early stage of pit pattern, as long as it is A-type, the supporting force is high, but more materials are used, so B-type and C-type corrugations are exhibited under different requirements. B-type corrugations have narrower amplitude, shorter waves and thinner supporting force, but less materials are used. The pit pattern of type C is as wide as that of type A, but shorter than that of type B, so the pit paper of type C is thinner than that of types A and B.. E pit became popular more than ten years ago, F pit appeared a few years ago, and G pit appeared in 20 14-20 15 (pit paper includes A, B, C, E, F, G, H, and there is no D pit), because the packaging box is not designed solely for product maintenance, but more for decoration and publicity. The difference between pits E, F and G is that the pits are thinner and thinner, and the pits are maintainable but not rough. As for some packaging boxes, the cost can be reduced by sticking powder and ash cards on pit paper. For example, fine pits with thin powder and ash cards are not easy to show pits and reduce costs. Now it is more common in the packaging of high-end consumer goods such as cosmetics and mobile phones.