The production method of particleboard is divided into flat pressing method of intermittent production, extrusion method and roll pressing method of continuous production according to the different slab forming and hot pressing process equipment. In actual production, the flat pressing method is mainly used. Hot pressing is a key process in the production of particleboard. Its function is to solidify the rubber in the slab, and to consolidate the loose slab into a board with a specified thickness after pressing. The process requirements are: ① Proper moisture content. When the water content of the surface layer is 18-20%, it is beneficial to improve the bending strength, tensile strength and surface finish, and reduce the possibility of bubbling and delamination of the slab during pressure relief. The moisture content of the core layer should be appropriately lower than that of the surface layer to maintain proper planar tensile strength. ②Appropriate hot pressing pressure. Pressure can affect the contact area between the shavings, the thickness deviation of the board and the degree of rubber transfer between the shavings. According to the different density requirements of the product, the hot pressing pressure is generally 1.2 to 1.4 MPa. ③Proper temperature. Excessive temperature will not only decompose the urea-formaldehyde resin, but also cause partial pre-curing of the slab when the temperature rises, resulting in waste. ④ Proper pressure time. If the time is too short, the middle layer resin cannot be fully cured, the elastic recovery of the finished product in the thickness direction will increase, and the plane tensile strength will be significantly reduced. The hot-pressed particleboard should undergo a period of humidity conditioning treatment to make its moisture content reach a balanced state, and then sawing and sanding to inspect the packaging. However, it cannot be stacked in a hot state after the pressure is relieved, otherwise it will increase the brittleness of the board. Molding technology refers to the technology of forming a product in one operation. There are 3 mature crafts. The hot mold method can use less rubber or no rubber, relying on the activation and flow of lignin in the closed hot mold to have a glueing effect, but it requires cooling and demoulding, which consumes a lot of heat and has low productivity, and it has been gradually eliminated. The box forming method is to use a special press to pressurize and produce products at one time, which is used to make packaging boxes. The hot press molding method mainly manufactures products such as furniture accessories, interior decoration accessories and pallets. The adhesive is mainly urea-formaldehyde resin. The surface of the product is laminated with veneer or resin-impregnated paper for one-time molding. In addition, there is a flat molding method in which the surface of the prepared particleboard or the formed slab without hot pressing is pressurized to form a relief pattern.
