Hot Melt Adhesive (EVA). Hot melt adhesive is a kind of solid meltable polymer without water and solvent. At room temperature, EVA sponge is solid, heated to a certain temperature and then melted into a liquid which can be calculated as a cohesive liquid. There are many kinds of hot melt adhesives. The hot melt adhesives used in book binding are vinyl polyvinyl acetate.

The primary component of hot melt adhesives is the resin based on which ethylene and vinyl acetate are copolymerized under high pressure. It determines the basic function of hot melt adhesives. The aging rate of hot melt adhesives is slowed down by adding forward bonding strength tackifiers (rosin), glue viscosity and agglutination speed regulators (baila) and a few antioxidants (such as second tertiary p-methylbenzene brewing). Hot melt glue is mainly used in the binding line of books and periodicals. After preheating the hot melt glue in the glue pot of the binding line, it is coated on the back of the book after milling and hairing.

The main characteristics of hot melt adhesives are:

(1) There is no water and solvent in EVA processing. It is solid at room temperature, and becomes liquid with excellent activity at high temperature, which is not flammable. It is harmless to human body.

(2) Fast agglutination speed. Seven to thirty seconds after leaving the glue pot, it agglomerates without drying or other curing agents, and is fully accustomed to the requirements of high-speed automation. Therefore, it has become a good glue material for the linkage line of the paperback wireless glue factory.

(3) Hot melt adhesives can bind various substances, especially porous homogeneous materials, which have stronger bonding strength and good flexibility after curing.

Hot melt adhesives can be re-used from scratch and have strong chemical resistance. Eva processing is not heat-resistant and its softening point is low. When using hot melt adhesives, heat treatment should be selected to melt solid EVA resin. In order to ensure the quality of wireless binding, the temperature of hot melt adhesive processing should be strictly controlled. The normal working temperature is 150 - 180 C, which is a good bonding temperature for books. The preheating temperature of preheating glue pot is generally lower than the working temperature of 15-20 C. According to the thickness of the book core and the quality of the paper, the gluing temperature is different. The book core is thick and the paper is good. The working temperature of the glue can advance to 175-185 C. The higher the temperature of the glue, the quicker the activity. When the temperature exceeds 200 C, the glue begins to change color and ageing, and the agglutination time becomes longer, resulting in poor bonding quality of wireless binding.