Second stage of plywood hot press

   The second stage of the hot-press cycle is the pressure-holding stage. The pressurization time specified in the plywood hot-pressing process specification refers to this stage, which refers to the period from when the pressure rises to the specified pressure value to the time when the pressure is reduced. At this stage, the temperature, pressure and time should be paid great attention.

   The function of temperature in hot-press gluing is to accelerate the solidification of protein glue or the polycondensation reaction of synthetic resin glue to complete gluing and evaporate excess water in the slab at the same time. Each glue type has a certain curing temperature. If the hot-pressing temperature is lower than its required curing temperature, the bonding effect will be slow, the hot-pressing time will be prolonged, the bonding strength will be reduced, and even defects such as degumming will occur; if the hot-pressing temperature is too high , the hot pressing time can be shortened, but the temperature difference inside the slab is large, and the internal stress is also large. Under the same pressure conditions, the compression rate and deformation of the slab also increase, and the decomposition of the glue and the brittleness of the glue layer may occur.