Classification Of Hot Melt Adhesives For Bookbinding

To ensure bookbinding speed, different types of hot melt adhesive should be selected according to different machine speeds. Hot melt adhesives are divided into three types according to binding speed: low-speed hot melt adhesive (approximately 3600 books/hour), medium-speed hot melt adhesive (approximately 8000 books/hour), and high-speed hot melt adhesive (approximately 10000 books/hour). The open time and curing time of hot melt adhesive are closely related to the binding speed. Open time refers to the time between the application of hot melt adhesive to one substrate and its subsequent bonding with another substrate. Open time indicates that the two substrates must be bonded within a specified time to ensure adhesion strength. The recommended open time is 15-20 seconds for low-speed machines, 5-10 seconds for medium-speed machines, and 2-7 seconds for high-speed machines.

The curing time of hot melt adhesive refers to the time required for the cover and book block to cool after being bonded within the specified time before being turned and pressed. If the hot melt adhesive is not fully cured and set before being turned or cut, the spine of the book will deform, and the hot melt adhesive will stick to the blade during cutting, affecting product quality. When using hot melt adhesive, it should be selected appropriately based on the length of the conveyor belt, the conveyor speed, and seasonal changes. The curing time of hot melt adhesive is generally 3-5 minutes.

Classified by paper type: Hot melt adhesives can be divided into those for coated paper and those for general paper. Different types of paper require different hot melt adhesives because the surface smoothness, permeability, and thermal conductivity of the paper vary.

Classified by binding application: Hot melt adhesives are divided into side adhesives and back adhesives. Hot melt adhesives used for side adhesives have good fluidity, low viscosity, long open and curing times, and high bonding strength. Book side adhesives need to be thin, uniform, and firmly bonded to ensure book quality and meet cutting requirements.

Classified by adhesive color: Additionally, for products of the same grade, yellow glue is better than white glue (although instructions generally require white glue). 302 series glues can meet the requirements of viscosity, hardness, and color.