Modern packaging generally uses paper, plastic, glass, ceramics, and metal as packaging materials. Because paper and plastic are cheap and easy to process, and the raw materials are widely sourced, paper and plastic packaging materials are widely used in daily life. However, plastic packaging materials cannot cause self-degradation, which will cause environmental pollution and other problems. The white pollution problem in China is the most typical example. With the development of society and the requirements of global economic integration, green packaging has gradually become the consensus of the society, and has become another highlight of the development of China's packaging industry. After quantitative evaluation by international authoritative experts, only paper is the most promising green packaging material. In recent years, China's paper-molded products and equipment have developed very rapidly, and have gradually matured. With the continuous promotion of the application range of pulp molded products, the requirements of paper molded products are continuously improved, and the production process of pulp molded products and the design of molds need to be constantly improved and improved.
Process analysis of pulp molded products
1. Process flow
Under normal circumstances, the production process of pulp molded products is shown in Figure 1.The production process can vary according to different customer requirements for products, mainly including slurry preparation, molding, hot press setting, setting, Auxiliary processes such as shaping and packaging.
2. Raw material selection of pulp molded products
The sources of pulp molded products are mainly divided into: pulp, straw pulp and reed pulp, etc., generally bleached commercial pulp (for fast food boxes) or waste paper (for industrial packaging). No secondary pollution occurs during production and use. The product has the advantages of light weight, compression and shock resistance, good cushioning performance, anti-static, strong air permeability and good recyclability. As packaging products, it can replace polystyrene foam (EPS), used in disposable fast food boxes, various electronic products, crafts, medical equipment, mechanical equipment parts, eggs, fruits, flowers, glass products, ceramic products and other Inner packaging of fragile products.
Paper molded products are generally divided into fast food boxes and industrial inner packaging.The production methods are basically the same, except that the raw materials used for the production of fast food boxes are bleached commercial pulp. Oil treatment, equipment and transmission pipelines are mostly made of stainless steel and plastic materials, and the inner wall of the storage tank is lined with ceramic tiles, which also has high hygiene requirements for the plant and operators.
3. Pulp making
Pulping is the first process for producing pulp molded products. The pulping process includes: using a hydraulic pulper to break the pulp board into fiber pulp, screening the broken fiber pulp, removing sand and purifying treatment, and then appropriately dividing the fiber into a broom through a refiner to improve The bonding force between fibers. In the pulping process, strictly controlling the beating degree of various slurries is crucial to the product forming and product quality of the subsequent process. If the beating degree is too high, it will be difficult to filter water during vacuum absorption molding of the product. After drying in the drying tunnel, the product will undergo large shrinkage and deformation (except for in-mold drying). If the beating degree is too low, the bonding strength of the product is low, and the stiffness and compressive strength of the product will be greatly reduced, which will affect the performance of the product.
