1. Breaking and beating
Put the waste paper or grass-like commercial pulp board into the hydraulic pulper and make it break again into pulp. Industrial packaging products are commonly used in the production of horizontal hydraulic pulpers, and the pulp concentration during disintegration is 5%-8%. Its advantages only play a role in dispersing the paper fiber, no cutting effect, high disintegration efficiency, short disintegration time, less power consumption, simple structure, small footprint, and can handle more dopants and metal impurities Waste paper. The crushed pulp falls into the storage tank, adjusts the appropriate concentration, and pumps it to an intermittent beater or a continuous refiner or refiner for beating, or the crushed pulp is crushed according to production needs. After the high-concentration cleaner, fiber deconsolidator and double-disc refiner, the de-slagging, deconstructing and beating are carried out, and the prepared slurry is discharged to the storage tank or the slurry distribution tank for standby. The degradation degree of beating is generally 28 degrees -35 degrees.
2. Prepare slurry
In the process of beating, several kinds of raw materials can be quantitatively added to the slurry tank according to the designed slurry ratio, and the slurry can be sized and a small amount of functional additives can be added. If a sizing agent is added to increase the liquid penetration resistance of the paper molded product, the sizing agent used is generally rosin, paraffin wax latex or rosin paraffin wax glue. It is worth mentioning that the product cannot be called environmentally friendly paper support after adding this additive. For non-bonding waste paper product pulp, add rosin glue equivalent to 3% of the absolute dry fiber mass of the pulp; for bonded waste paper products For pulp, 1.5%-2% rosin glue should be added. Talcum powder can also be added to the pulp as a filler to achieve a higher retention rate of the slurry. An aqueous suspension containing 20%-30% of the talc filler can be treated in a mixer at high speed for 6 minutes, and then diluted with water and added with chemical aids. It is treated for another 5 minutes to make a filler suspension, which is then added to the slurry. Some manufacturers also added a small amount of oil repellent, water repellent, wet strength agent and retention aid to the slurry. In the pulping process, an appropriate amount of white water or clean water should be added to adjust the pulp loading concentration to 1%-2% for the production of molded products.
3. Paper molding
Forming is a key process in the production process of paper trays, and it plays a decisive role in the quality, breakage rate, production energy consumption, and production efficiency of paper molded products. According to the dehydration principle of forming equipment, there are three main forming methods for paper trays: vacuum forming method and hydroforming method.
(1) The vacuum forming method is formed by vacuum suction filtration. The forming mold is placed in a pulp solution with a concentration of about 1%, and the cavity of the mold is vacuumed to form a negative pressure, and the fibers in the pulp are evenly deposited in the forming On the mold surface of the mold, a large amount of moisture is taken away during vacuum suction. When the required thickness of the part is reached, the molding die is removed from the slurry for extrusion and dehydration until the water content of the part is 75%-80%, and then compressed air is passed into the cavity of the mold to demold the wet paper mold. This method has high production efficiency and uniform thickness of the product. It is suitable for making thin parts that are not too deep, such as paper trays for packaging eggs, fruits, dishes, tray boxes, etc.
(2) The hydroforming method uses hydraulic pressure to generate higher extrusion pressure through hydraulic drive mechanical devices. Its working principle is to inject a quantitative amount of pulp into the molding cavity, and the upper molding die is squeezed downward under the action of hydraulic pressure, so that the pulp is molded on the mesh mold in the molding cavity, and water is discharged from the lower end of the mesh mold. The parts are removed from the mold by vacuum adsorption and transferred to the next process. Due to the high molding pressure, this method is suitable for the production of shallow pan products with heavier basis weight and higher density.
