Production process of particle board

Hot pressing is a key process in the production of particleboard. Its function is to solidify the rubber material in the slab and consolidate the loose slab into a plate of a specified thickness after pressurization. The process requirements are: ① Appropriate moisture content. When the moisture 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 blistering and delamination of the slab during pressure relief. The moisture content of the core layer should be properly lower than the surface layer to maintain the appropriate plane tensile strength. ② Appropriate hot pressing pressure. Pressure can affect the contact area between the shavings, the thickness deviation of the board and the degree of rubber material 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. ③ Appropriate temperature. Excessive temperature will not only decompose the urea-formaldehyde resin, but also cause the slab to solidify in advance when the temperature rises and produce waste. ④ Appropriate 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 is increased, and the plane tensile strength is significantly reduced. The particle board after hot pressing should undergo a period of humidity adjustment to make the moisture content reach a balanced state, then saw sanding and inspect the packaging. However, it can't be stacked in hot state after pressure relief, otherwise it will increase the brittleness of the plate.

Molding technology refers to the technology of forming products in one operation. There are three mature processes. The hot mold method can use less rubber or no rubber, rely on the activation flow of lignin in the closed hot mold to play the role of gluing, but it needs cooling and demoulding, the heat consumption is large, the productivity is low, and it has been gradually eliminated. The box forming method is to pressurize with a special press and make the product with one pressurization, which is used to manufacture packaging boxes. The hot press molding method mainly manufactures furniture accessories, interior decoration accessories and pallets. The adhesive is mainly urea-formaldehyde resin, and the surface of the product is laminated with a single board or resin-impregnated paper and molded at one time.

In addition, there is a flat molding method in which a template is pressed on the surface of the particleboard that has been made, or the formed slab without hot pressing to make a relief pattern.