Crushing and beating pulping
The vertical hydraulic pulper in the waste paper or grass commercial pulp plate fork hydraulic pulper is reused and disintegrated into a pulper. The industrial packaging pulp of the machine is only for the production of 5% to 8% pulp consistency. High-efficiency deconstruction, low consumption and simple structure of the high-altitude paper tank, short-term treatment of pulp, short-term treatment of waste paper pulp in lead-containing sewage treatment into the pulp storage tank. After proper concentration, the pump generator enters the desizing type refiner or continuous refiner, or separates the pulper and the double-circle refiner and the double-circle refiner for slag removal and dispersal according to the needs. And beating, the beaten pulp is discharged to the storage tank or the mixing tank for use. Pulp beating degree is generally 28 ~ 35°SR.
Prepare the pulping
During the beating process, several raw materials can be quantitatively added to the pulping tank according to the designed slurry ratio, and the slurry can be sizing and a small amount of functional additives can be added, such as adding a sizing agent to improve the liquid resistance of the paper molding. Penetration performance, the sizing agent used is generally rosin, paraffin latex or rosin paraffin glue. For pulp prepared from non-bonded waste paper, rosin size equivalent to 3% of the dry fiber mass of the pulp must be added; for pulp prepared from bonded waste paper, 1.5% to 2% of rosin size should be added. Talcum powder can also be added to the pulp as a filler to achieve a higher slurry retention rate. The aqueous suspension containing 20% to 30% of talc powder filler can be stirred at high speed for 6 minutes, diluted with water and added with chemical additives. Treated for 5min, made into filler suspension, and then added to the slurry. Some manufacturers of paper mold tableware also add a small amount of oil repellent, water repellant, wet strength agent and retention aid to the slurry. In the pulp mixing process, an appropriate amount of white water or clear water should be added to adjust the pulp feeding concentration of the paper molding products to 1% to 2%.
Forming or Molding
Forming is a key process in the production of pulp molded products, and it plays a decisive role in the quality, breakage rate, production energy consumption, and production efficiency of paper molded products. According to the different dehydration principles of the molding equipment, there are mainly three molding methods for pulp molding products: vacuum molding, hydraulic molding and compressed air molding.
The vacuum forming method is formed by vacuum suction filtration technology. The forming mold is placed in a pulp solution with a concentration of about 1%, and the mold cavity is vacuumed to form a negative pressure, and the fibers in the pulp are uniformly deposited in the forming process. A wet paper mold is formed on the mold wire on the mold surface, and a large amount of moisture is taken away during vacuum suction. When the wet paper mold reaches the required thickness, the forming mold with the wet paper mold is removed from the slurry and squeezed and dehydrated with the transfer mold until the moisture content of the wet paper mold reaches 75% to 80%, and then the mold is formed. Compressed air is passed through the mold cavity to demold the wet paper mold. This method has high production efficiency and uniform thickness of products. It is suitable for making thin-walled parts that are not too deep, such as egg trays, fruit trays, saucers trays and other products.