Board book warping and deforming is a common technical problem encountered by board book printers.
Board books include hardcover books with gray boards as bookcases and books mounted with cardboard with a weight of 200-250 grams per square meter. They are very common in book printing companies and are prone to quality problems such as warping and deforming.
What cause board book warping and deforming?
1. Raw materials
The structure of the gray board or cardboard itself determines that it is easier to warp and deform during board book printing. Gray board or cardboard has high density and long fibers, and its water absorption has a great influence on the structure of board books. When absorbing water, the fibers of the gray board or cardboard will stretch, due to gray board or cardboard has a certain thickness, the amount of water absorbed on both sides will be inconsistent, resulting in different elongation lengths of the fibers of the gray board or cardboard, which makes gray board or cardboard deforming.
At the same time, when water is lost, the fibers of the gray board or cardboard will shrink, but the inconsistent water loss on both sides will cause the fibers to shrink inconsistently, resulting in deformation. Although the gray board or cardboard will deform due to water absorption and water loss, the deformation caused by water loss is more serious than water absorption.
In addition, different brands and types of gray board or cardboard have different water absorption and deformation extent in custom board book printing.
2. Ambient temperature and humidity
The environmental temperature and humidity have a great influence on the printing board books. When the ambient temperature and humidity are lower than the water content of the cardboard, it will cause the cardboard to lose water, and the degree of water loss in each part of the cardboard is generally different, resulting in warping and deformation of the cardboard.
When the ambient temperature and humidity are higher than the water content of the cardboard, it will cause the cardboard to absorb water, which will also cause the cardboard to warp and deform. The degree of deformation in these two cases are different. The deformation when water is lost is much greater than that when water is absorbed, so the warping deformation of board books always occurs in the dry seasons of autumn and winter.
3. Production process
When print a board book, it is necessary to cover or mount with white latex. The white latex contains a lot of water. When the shell is placed or mounted, a large amount of water will enter in the cardboard, but the water does not enter uniformly, which leads to inconsistent moisture content in each part of the cardboard, finally leads to the board books warping and deforming.
4. Production method
When custom board book, some companies use machines to automatically load them, and some companies are artificial shell. Automatic shelling by machines is generally more uniform than the adhesive applied by artificial shell, so that the moisture content of the cardboard is more uniform.
At the same time, the viscosity of the adhesive used for automatic shelling by machine is different from that of the adhesive used for manual shelling, that is, the solid content of the adhesive is different. The solid content of the adhesive should be high, and the water content should be small, and it is less likely to cause board book warping and deforming.
5. Process design
Whether it is gray board or cardboard, all have textures, so when the board book is shelled or mounted, it needs to be carried out according to the texture. A lot of production experience tells us that for custom board books, it is necessary to cover the casing along the grain; for the mounted book, it needs to be mounted along the grain. If it does not follow the grain, the finished cardboard book will have serious warping deformation in the later stage.
In short,raw materials,ambient temperature and humidity, production process, production method ,process design,these five aspects,which are the mainly factors to cause the board book warping and deforming.In next article,we will focus on how to solve board book warping and deforming.
