Heating Gypsum Particleboard Production Process

Gypsum-bonded Particle Board (GPB) is one of wood based panels which is manufactured using the semidry process, wherein gypsum is used as bonding material, wood particles as strengthen materials and suitable amount of water and buffer are also added into the process. Since professor Kossalz and Doctor Lempfer found the semidry process in 1980's, GPB has been produced under the room temperature. However, in the past research, the quantity of heat emitted from gypsum curing is found to have some effect on the properties of GPB. With this cognition in mind, heating method is used for fabricating GPB and various analyze methods are used for testing on GPB with better quality, which are expected to find the reason of properties enhancing of GPB.In several of GPB, which is produced in different temperature, the GPB made with 30℃achieved better qualities. So herein we put emphasis on the analysis of properties of GPB, which is manufactured under 30℃. The properties of GPB are analyzed by using five high-tech instruments: Differential scanning calorimetry, Fourier-transform infrared spectrophotometry, Thermo Gravimetric Analyzer, X-ray Diffractometer, Scanning electron microscope. The result showed that one reason for enhancing properties of GPB is that heating method facilitates to make up the quantity of heat of gypsum curing which dispersed into atmosphere and through which the strength of gypsum is increased. And another reason is that the shape of gypsum crystal is changed because of heating method, which provide better continuity of gypsum economy and bonding strength resulting to the corresponding of the improvement of the strength of gypsum.For further to find how heating method have some effect on GPB, Nano SiO2, titanated coupling agent NDZ 401, silane coupling agent KH550 and silane coupling agent KH570 are added into GPB under heating. From the result, we can find that the addition of 3% of Nano SiO₂ is helpful for the improvement of the properties of GPB. This may because Nano dispersed into particles and fill the bore of them, which improve the strength of particles. However, the addition of coupling agents has fewer effects on the properties of GPB. At last, the same density principle with the GPB made in room temperature we can obtain from the GPB, which is manufactured under 30℃and having 3% nano material. That is various properties of GPB are strengthened with the increasing of dentist of GPB.