The unique properties and shortcomings of pulp molding products

The thickness of the molded product can be controlled by controlling the suction time during the molding process. Since the strength of the vacuum adsorption in each direction is the same, the thickness of the resulting pulp molded product should theoretically be uniform. However, during the suction process, due to the flow rate of the slurry and gravity, there may be uneven thickness of the molded product.

6. Shaping refers to the process of heating, pressurizing and dewatering the wet paper blank directly after forming it. The wet paper blank is dried and set in the mold by shaping. The product processed by the mold has smooth and beautiful surface, accurate size, solid and good rigidity. Pulp molding disposable fast food utensils are made of this mold.

In the process of industrial packaging, some small, precise, large number of small items are packaged in a multi-layer stacked way, and the packaging products used for positioning between each layer need to be shaped if the pulp molding products are used to manufacture. The general industrial packaging products are single-sided work without shaping, wet paper billet directly into the dryer to dry.

7. Due to the filtration resistance of the fiber layer, the dryness of the wet pulp molded by vacuum adsorption can usually only reach 20% to 30%, and the wet blank can only meet the requirements after heating and drying, and the final dryness of the general pulp molded products should reach more than 90%.

Because the wet paper blank will have different degrees of deformation after drying or drying, it must be rounded when the appearance, shape and precision of the product are high. The water content of paper molding products before finishing is 20% ~ 30%, but it is difficult to accurately control the water content of paper molding products in production applications. If the water content is too high, the molding process will consume high energy and take a long time, and if the water content is too low, the molding will become very difficult.

In the process of molding, the general hot pressing temperature is controlled between 150 and 180 ° C, which can be moderately adjusted according to the size of the product, but the hot pressing temperature can not be less than 135 ° C.

8. Auxiliary process Auxiliary processes mainly include integral trimming, sterilization, product packaging, inspection, etc.

Shaping and trimming is to correct the shape of the dried products, calender, remove the net marks left by the mold mesh molding, so that the internal and external surfaces are smooth and smooth, and can be pressed on some words and patterns according to different customers and use requirements, while cutting the burrs on the edge of the product, pressing the indentation that is easy to fold and open the lid.

Sterilization is one of the processes that distinguish food packaging containers (such as egg cartons) from ordinary pulp molding products. At present, there are three main methods for the sterilization of finished products: First, the tunnel type ozone sterilization machine is used to carry out final sterilization of finished products; The second is to sterilize the finished product with ultraviolet light; The third is the use of high temperature drying channel sterilization.

After the dried or finished products are inspected for quality, they are collected, stacked, counted, and packaged in the required quantity, thus completing the entire production process of pulp molded products. The production of pulp molding products, after forming and drying, has more raw edges, irregular appearance and beautiful appearance, and sometimes it is necessary to cut edges to ensure that the product appearance is neat and beautiful.

Third, the structural design of pulp molding products 1.

Traditional polyethylene foamed plastics mainly rely on the elastic modulus of the material to play a role in seismic buffering, while pulp molded products mainly rely on their own structural seismic. Therefore, the structural design of pulp molding products is very important.

Pulp molded products have the strength, stiffness and toughness of general paper products. Products of various complex shapes can be made according to the functional requirements of use. When used as a disposable fast food appliance, the shape is relatively simple and the strength requirements are not high. When used as an industrial inner packaging, its shape is very complex, must meet the three major requirements of industrial inner packaging: First, positioning requirements, paper products must ensure the fixed position of the packed items in the packaging box, requiring the shape of the paper products and the packaged items to be consistent, appropriate contact, accurate size.

The second is the buffering requirements, the paper mold products as a whole should have a certain toughness and flexibility, the surface should also be some soft, and the contact friction with the packaged goods will not damage the shiny surface of the packaged goods, and can eliminate the impact of shock and vibration during transportation and loading and unloading.

The third is the bearing requirements, the paper mold products must have a certain strength and stiffness to support the packaged goods and external pressure.