The use of EVA hot melt adhesive in binding

1. Preheating of EVA hot melt adhesive

Before using EVA hot melt adhesive, the solid adhesive must be preheated and melted. There are two preheating methods: one is oil bath preheating. Another method is to preheat with an electric heating plate, which means using an electric heating plate device to preheat directly in the preheating furnace. The preheating time is generally 2 hours. When the gel reaches the required heating temperature and has good fluidity, the glue is released into a working glue pot with a temperature of 160~180 ℃ through a thermostatic pipe,used for binding books, etc.

• Adhesion and adaptability of EVA hot melt adhesive

In the actual production process, the adhesive strength of hot melt adhesive will vary with heating temperature, different adhesive materials, milling width and depth, adhesive thickness, and the operating speed of the binding machine, resulting in different adhesive effects.

• Heating temperature of hot melt adhesive

The softening point of hot melt adhesive is generally above 80 ℃. That is to say, when heated to; 80°C  At this point, the colloid will begin to soften and melt. This temperature is only the melting temperature of hot melt adhesive. In order to melt it to the point where it can bond books, the heating temperature must be raised to 140-180 ° C. At this temperature, the viscosity and strength of the colloid can be suitable for book binding.

• The relationship between book paper and glue temperature

The temperature for gluing should also vary depending on the quality of the book paper. This is not only because the fibers of the paper are different, but more importantly, due to the different types and textures of the paper, the thermal conductivity of the colloids is different, which changes the cooling rate. Taking the thermal conductivity of copperplate paper and non copperplate paper as an example, the former has a faster adhesive cooling rate than the latter. Because the inorganic substances contained in copperplate paper are about 10 times higher than those in non copperplate paper, adhesive paper, etc., and the inorganic substances have good thermal conductivity, which can make the hot melt adhesive cool faster

For example, when the adhesive temperature is 170 ℃, the tensile test value of hot melt adhesive for non copperplate paper can meet the expected requirements, while the tensile test value for copperplate paper cannot. Therefore, when applying adhesive to copperplate paper, it is necessary to increase the temperature of the adhesive solution to enhance its strength.

The relationship between the opening time of EVA hot melt adhesive and the operating speed of production equipment.

In wireless binding production, three time stages must be strictly controlled when using hot melt adhesive, namely opening time, curing time, and drying time for cooling and hardening. Opening hours refer to the time when glue is applied to the back of a book. The curing time is the time it takes for the cover and back of a book to stick together. Cooling, hardening, and drying time refers to the time it takes for a book with a cover to cool and solidify after curing. Only after these three stages of time can this book be finalized and achieve the expected shape.