How to use hot melt glue correctly to binding books firmly together?
1. Heating temperature
Hot melt adhesive is sensitive to temperature change, temperature will directly affect its bond performance. At a certain temperature, hot melt adhesive will begin to soften, below a certain temperature, hot melt adhesive will become brittle, so the selection of hot melt adhesive must consider the influence of temperature on its bond performance. Because the hot melt glue needs to be heated before use, in order to ensure the quality of the wireless adhesive, we must strictly control the temperature of the hot melt glue in the preheater and the glue pot, especially to control the temperature of the hot melt glue in the glue pot.
The same kind of hot melt adhesive, the higher the temperature, the lower the viscosity, the easier it is to penetrate between the pages, the better the binding quality, but not the higher the temperature is better, if the temperature is too high, the polymer of the main components of hot melt adhesive will occur pyrolysis polymerization reaction, thus reducing the adhesion of hot melt adhesive; But the temperature can not be too low, if the temperature is too low, the fluidity of hot melt adhesive will be reduced, which means that the bond firmness will decline. For ordinary books, the heating temperature of hot melt glue is 150 ~ 180℃, and the preheating temperature of preheater and glue pot is usually 15 ~ 20℃ lower than the working temperature of hot melt glue. For thick book block, good paper books, hot melt adhesive heating temperature can reach 175 ~ 185℃. In addition, in the heating process, the hot melt adhesive needs to be continuously heated to keep it at a constant temperature to avoid temperature changes affecting its performance.
2. Coating time
Because the solidification speed of hot melt adhesive is very fast, there is no need to heat drying, and it can be solidified from the glue pot for 7 to 30 seconds, so we must control the coating time of hot melt adhesive. Only in this time range to complete the coating work, in order to get a good bonding effect, on the contrary, there will be a bond is not strong, stick or stick after the phenomenon of page off.
3. Thickness of rubber layer
In the coating process, the amount of hot melt adhesive will also directly affect the quality of the wireless adhesive. In general, people think that the thicker the adhesive layer thickness, the higher the bond fastness between the pages, in fact, this is a wrong understanding. In the actual production, we found that when the adhesive layer thickness increased to a certain value, the bond firmness showed a downward trend. Therefore, if the pursuit of too thick adhesive layer, not only can not reach our expectations of bonding effect, but will waste hot melt adhesive, increase the thickness of books, affect the reading effect. So the thickness of the adhesive layer should be selected according to the thickness of the book, printing paper variety and hot melt adhesive type.
