The main factors affecting the binding fastness of perfect-bound hardcover books
The factors that affect the fastness of wireless binding are: the quality of the surface treatment of the book back, the temperature of the hot melt glue, the thickness of the glue on the back of the hardcover book, and the degree of compression between the book backs. Hardcover book cover and back etc.
Hardcover book back cover quality and rework quality
The roughening quality of hardcover book back milling is the main factor affecting the fastness of glue binding. The quality of the backside processing is characterized by the macroscopic and microscopic geometry of the backside paper, which can be represented by the arithmetic mean of the macroscopic unslip of the paper tail. During the process of milling and roughening the back of the book, the fibers on the edge of the paper are loosened to form a rough surface, and the glue penetrates into the paper surface along the fibers and adheres to each other. The back of the book is not rough, the milling is smooth, the bonding surface between the paper and the glue is small, and the penetration and adhesion of the glue in the paper cannot be guaranteed. After the back of the book is sanded, a rough surface is formed. Likewise, the glue does not penetrate easily into the paper because paper wool and air collect on the surface of the back of the book, preventing the glue from contacting the paper. Grinding the back creases with a dull knife will result in a rough back, which will also affect the fastness of the glue mount.
temperature of hot melt
Different types of hot melt adhesives have different bonding properties. For the same hot melt adhesive, as the temperature increases, the lower the viscosity, the better the wetting between the rough book back and the page. The better the fastness. When the temperature is too high, the polymer that is the main component of the hot melt adhesive may undergo thermal depolymerization, thereby reducing the adhesive force of the hot melt adhesive. If the temperature is too low, the fluidity of the glue will become poor, affecting the adhesion fastness of the glue. At present, the hot melt adhesive commonly used in printing factories has good viscosity and wettability in the temperature range of 170 ° C ~ 185 ° C, so it needs to be continuously heated and maintained at a constant temperature during use.
Adhesive layer thickness
As the thickness of the hot melt adhesive layer increases, the bond fastness increases. When the thickness of the adhesive layer increases to a certain value, the adhesive fastness begins to decrease. It can be seen that using an excessively thick hot melt adhesive layer not only wastes glue, but also reduces the adhesion fastness and destroys the overall structure of the book.
The thickness of the hot-melt adhesive should be determined according to the thickness of the publication, the type of printing and cover paper, and the type and quality of the hot-melt adhesive. Generally speaking, under the condition that the latter two conditions are basically the same, the fastness of glue binding depends on the thickness of the book block. Regardless of whether the fiber direction of the paper is parallel to the back of the book block, the adhesion fastness of the thin book block is the best, the adhesion fastness of the medium thickness book block is the second, and the adhesion fastness of the thick book block is the second. The thickest book blocks are poor.
The results of this study show that for book blocks with different thicknesses, the appropriate thickness of the adhesive layer should be selected. For example, when printing a book with a thickness of 10 to 12 mm on letterpress paper, the thickness of the hot melt adhesive layer is 0.4 mm. For publications with a thickness of 20mm and above, the thickness of the hot melt adhesive must reach 0.8 to 1.0mm. The degree of compression between the cover and the book block. The cover should fit the back and sides of the book firmly, without wrinkles, and the back should be a neat rectangle.
