Paperboard book upset deformation is a technical problem commonly encountered in book printing enterprises. After investigating a large number of books and periodicals printing companies, we learned that the spring and summer environment humidity is relatively large, and the paper-paper books rarely have the problem of lifting and deformation. In autumn and winter, the ambient humidity is small, the air is drier, and customers often complain. The paper book is warped and deformed. In serious cases, it may even require deduction and reprinting. This problem has been plaguing books and periodicals printing companies for many years, and there has never been an effective solution. Therefore, enterprises are often in a passive position when dealing with customer complaints.
In this article, the author combines his own practical experience over the years to talk about his own views on this issue.
Analysis of the Causes of the Deformation of the Board Paper Book
The paperboard book includes a hardcover book made of grayboard as a bookcase and a book made of paperboard with a basis weight of 200-250g/m2, which is very common in book printing enterprises, and is prone to quality problems such as warping deformation. The reasons are mainly the following.
Raw material
The structure of the gray board or the cardboard itself determines that it is easier to warp in production. The gray board or cardboard has a high density and a long fiber, and its water absorption has a great influence on the structure of the board. When water is absorbed, the fibers of the gray board or the cardboard may elongate, but due to the thickness of the gray board or the cardboard, the water absorption amount on both sides may be inconsistent, resulting in different elongation lengths of the gray board or the cardboard fiber, thereby making The gray board or cardboard is deformed. At the same time, when the water is lost, the fibers of the gray board or the cardboard will shrink, but the inconsistency of the water loss on both sides will lead to inconsistent fiber shrinkage and deformation. Although the gray board or cardboard will be deformed due to water absorption and water loss, from the author's many years of production experience, the deformation caused by water loss is more serious than the deformation caused by water absorption. In addition, different brands and different types of gray board or cardboard have different water absorption properties, and the deformation phenomenon is different in production.
2. Ambient temperature and humidity
The environmental temperature and humidity have a great influence on the production of cardboard paper. When the ambient temperature and humidity are lower than the water content of the paper, the paper will lose water, and the degree of water loss of each part of the paper is generally different, which causes the paper to warp and deform. When the ambient temperature and humidity are higher than the water content of the board, it will cause the board to absorb water, which will also cause the board to warp and deform. In these two cases, the degree of deformation is different. The deformation at the time of water loss is much larger than the deformation at the time of water absorption, so the curling deformation of the paperboard always occurs in the dry season in autumn and winter.
3. Production process
When producing a paper-based book, it is necessary to use a white latex shell or a pair of enamel. The white latex contains a lot of water. When the shell is on the upper shell or the crucible, a large amount of water will enter the board, but the moisture does not enter evenly. This leads to inconsistent water content in each part of the board, which leads to the occurrence of the board. Upset deformation.
4. Mode of operation
When producing hardcover books, some enterprises are automatic upper casings. Some enterprises are handmade upper shells. The upper shells are usually evenly coated with the upper shell, so that the water content of the paperboard is more uniform. At the same time, the adhesive used in the automatic upper shell of the machine is different from the adhesive used in the manual upper shell, that is, the solid content of the adhesive is different. The solid content of the adhesive used in the automatic upper shell of the machine is higher than that of the manual upper shell. The solid content of the adhesive is high, the water content is smaller, and it is more difficult to cause the curling deformation of the paperboard book.
5. Process design
No matter whether it is gray board or cardboard, there are lines. Therefore, when the shell is on the upper or opposite of the paper, it needs to be textured. A lot of production experience tells us that for hardcover books, you need to wear the upper shell; for the script, you need to confront the lines. If it does not follow the pattern, serious upset deformation will occur in the later stage of the finished paperboard.
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