In early years, molded pulp products, with the waste paper as its element, were manufactured with special equipment and molds as various shapes of packaging products and objects through a unique process of solid modelling. Molded pulp products were first applied to transport packaging pieces for agricultural products such as eggs and fruit, then gradually expanding the scope of applied research.
Nowadays, high-quality molded pulp products made from such raw materials as reed, straw shell, sugarcane, wheat straw, bamboo and wood, are not only more and more widely used in protective packaging for such industrial products as electronic products, household appliances, instruments, glass and ceramic products, small machinery, but also for retail packaging of consumer durable foods.
The pulp is mainly composed of such low-cost natural materials as renewable and recyclable fiber, producing the high value and environmentally friendly packaging products, which greatly not only reduces the environmental pollution produced by styrofoam, but also paves a bright way for the recycling of waste paper.
2.1 The process of pulping, compounding and forming
Through such processes as crushing and grinding, the raw materials of reed, rice husk and sugar cane, wheat straw, bamboo, wood and recycled paper, are formed into fiber suspending in the water, to make the protoplasm. And in line with the characteristics of the product, a series of auxiliary operations such as controlling the length or the concentration of the fibre of protoplasm or adding functional additives (brightener, waterproof, etc.) or dyes can be carried out in the process to form the pulp that meets the needs of production.
Equipment: Pulper, Slurry and sand removal pond, Forming pond, etc.
A series of methods such as vacuum forming and slip casting are mainly applied in the molding, forming the fiber of protoplasm as the shape formulated by the mold. Among them, the vacuum forming is commonly used in the process with high efficiency.
Equipment: Forming machine
2.2 The process of drying
In the process, drying machine, mainly utilizing such materials as fuels, oils, gases, electricity or steam and heat-conducting oil as its heat source, heats up the air to dry the molded pulp products, and then takes advantage of its fan to evaporate the water out of the products, achieving the purpose of rapid drying.
Equipment: Drying machine (Heating method: gas, oil, steam or electric heating)
2.3 The process of shaping and trimming
After forming and drying, the pulp packaging have been basically shaped. Then we will heat up hot plate with electricity or other mediums such as heat-conducting oil to make the products with high temperature (150-250 ℃) and make use of the pneumatic or hydraulic pressure to squeeze the paper products in order to get the products with neat and beautiful appearance, better toughness and shock resistance.
Equipment: Shaping and trimming machine
2.4 The process of packing
The pulp molded products which have been produced through a series of processes, are inspected, packed and stored. Besides, manual packing or automatic packing machines can be used for counting and packing in line with the characteristics of the product.
Equipment: Automatic packing machines