Particleboard Manufacturing Process

Particleboard production methods, based on different blank forming and hot pressing equipment, are divided into intermittent flat pressing and continuous extrusion/roll pressing. In actual production, flat pressing is the primary method. Hot pressing is a crucial step in particleboard production, its function being to solidify the adhesive in the blank and bind the loose blank into a board of a specified thickness under pressure. The process requirements are:

 

① Appropriate moisture content. A surface moisture content of 18-20% is beneficial for improving bending strength, tensile strength, and surface smoothness, and reduces the possibility of bubbling and delamination during pressure release. The core layer moisture content should be appropriately lower than the surface layer to maintain appropriate planar tensile strength.

 

② Appropriate hot pressing pressure. Pressure affects the contact area between particles, board thickness deviation, and the degree of adhesive transfer between particles. Depending on the product's density requirements, the hot pressing pressure is generally 1.2-1.4 MPa.

 

③ Appropriate temperature. Excessive temperature not only decomposes urea-formaldehyde resin but also causes premature curing of the board blank during heating, resulting in defective products.

 

④ Appropriate pressing time. If the time is too short, the middle layer resin cannot fully cure, leading to increased elastic recovery in the thickness direction and a significant decrease in planar tensile strength. After hot pressing, the particleboard should undergo a period of humidification to reach a balanced moisture content before sawing, sanding, inspection, and packaging. However, it should not be stacked hot after depressurization, as this will increase the brittleness of the board. Molding technology refers to a technique that forms a product in a single operation. There are three mature processes. Hot molding can use less or no adhesive, relying on the activation and flow of lignin in a closed hot mold for bonding, but it requires cooling and demolding, consumes a lot of heat, and has low productivity; it has been gradually phased out. Box forming uses a special press to press the product in one operation, used for manufacturing packaging boxes. Hot pressing is mainly used to manufacture furniture parts, interior decoration accessories, and pallets. Urea-formaldehyde resin is the primary adhesive used, and the surface of the product is laminated with veneer or resin-impregnated paper, forming the product in one step. In addition, there is a planar molding method, which uses a template to press embossed patterns onto the surface of pre-made particleboard or unpressed slab blanks.