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Three elements of hot pressing of fireproof and flame retardant board


The effect of temperature. The heat is directly or indirectly transmitted to the surface layer of the fire-retardant slab through the hot pressing plate, and then gradually transmitted to the core layer. Therefore, the heating temperature has become a main factor of hot pressing. High temperature heating can transfer heat to the core layer quickly, which can make the thermosetting adhesive solidify rapidly. Different kinds of adhesives require different curing temperatures. The curing temperature of phenolic adhesive is higher, 180-200 ℃. The use of higher temperature of urea formaldehyde adhesive can accelerate the curing speed, but it can also be cured smoothly at lower temperature, but the time is longer.


 The role of pressure. When the fire-retardant board slab is hot pressed, the pressure used affects the contact area between shavings, the density of particleboard, the flow development of adhesive and so on. In the process of hot pressing, if higher pressure is used in the initial stage, the density of the surface layer of the fireproof and flame retardant board will be large and the density of the core layer will be small, forming a density gradient. The greater the difference of the moisture content of the surface and core layer, the greater the difference of the density gradient of the board. Therefore, the appropriate maximum hot pressing pressure should be selected in the hot pressing process, so as to control the non-uniformity of the density of the fire-resistant and flame-retardant board and produce the board meeting various strength indexes.
The role of time. In the pressurization time, the pressing plate closing time and pressure holding time are more important. Hot pressing time directly affects the production efficiency of hot press. In order to improve the production of the press, it is required to shorten the pressure holding time as far as possible, but pay attention not to shorten it to the extent that it affects the properties of the fire-retardant board. Appropriate pressurization time means that the polycondensation and curing of adhesive reaches the best degree, the moisture vaporization is appropriate, and the moisture content of fireproof and flame retardant board leaving the hot press shall be 8% ± 2%.