Patent ID: 7686902

Claim:
A method of fabricating a plaster board comprising: a plaster core having a front surface, a back surface, two opposite side surfaces and two opposite end surfaces thereof, a front surface covering base paper that covers at least the front surface and the two opposite side surfaces of the plaster core, and a back surface covering base paper that adheres to the front surface covering base paper and covers the back surface of the plaster core, in which the plaster core has a high-density hard edge part comprising the side surface, the method comprising the steps of: (a) pouring calcined plaster, water, at feast one kind of additives and/or admixtures into a disk-type rotary mixer and stirring to prepare a calcined plaster slurry, (b) extracting one portion of a slurry of the calcined plaster from at least one fractionation port provided on a peripheral area of the disk-type rotary mixer and providing the one portion of the slurry as a slurry for application onto the front surface covering base paper, (c) spreading one portion of the slurry for application provided on the front surface covering base paper by a spreader roll to form a spread portion of the slurry for application while providing non-spread portions of the slurry for application at both sides of the spread portion, (d) delivering the slurry of the calcined plaster remaining in the disk-type rotary mixer through a delivery pipe provided on the peripheral area of the disk-type rotary mixer to a delivering port of the delivery pipe, (e) pouring a foam into the remaining slurry of calcined plaster through one of the delivery pipe and a foam providing port set on the delivery pipe and uniformly dispersing the foam to prepare a slurry for core, (f) depositing the slurry for core delivered from the delivering port onto the slurry for application applied on the front surface covering base paper, and (g) folding the front surface covering base paper and adhering the back surface covering base paper to a margin of the front surface covering base paper to form a stack and subsequently to dry the stack, wherein a length of the spreader roll in axial directions is greater than 100% and 108% or less of a distance between boundary lines of the front surface and the side surface and a width of the non-spread portion is less than 10 mm, and wherein the slurry for application for the non-spread portions in step (c) conducted prior to step (g) is applied to outsides of scoring lines of the front surface covering base paper which define a width of the plaster board.