Injection molding two-color or mixed-color plastic products are prepared by mixing the same raw materials into two different colors, and plasticizing two kinds of color melts by two injection molding machines of the same structure and the same specifications, and then injecting them through a nozzle. Inside the mold. The molded plastic products are color-separated, mixed or irregular, and the appearance effect is not obtained by ordinary injection molding and surface modification.
The alternating plasticizing melts in the two injection molding machines of the same specification are completed by nozzle injection, and are controlled by the program control valve between the plasticizing cylinder and the nozzle. The two-color injection molding machine structure, when plasticizing injection, two plastic injection devices can simultaneously inject two different color melts through the same rotating mandrel nozzle at the same time, the same amount, the same pressure, and the same injection speed. In the molding die, thus, injection molded articles of different pattern patterns can be produced. Two sets of plastic injection device and mold device with the same specifications and the same structural form. The working method of this type of injection molding machine is as follows. After the two plasticizing injection devices complete the first injection at the same time, two sets of molding molds of the same structure are rotated around the central axis by 180 ° C, and then two sets of injection devices are injected into the forming mold by two sets of injection devices. . By performing the action of injecting different colors of molten material into the same molding die in two steps, a two-color injection molded article can be obtained.
The production process characteristics of injection molding two-color plastic products are as follows:
1. The two-color injection molding machine consists of two sets of plastic injection devices with the same structure and specifications. The nozzles should have a special structure according to the production method, or two sets of molding dies with the same structure that can be rotated and transposed. When plasticizing injection, the process parameters such as melt temperature, injection pressure and injection melt amount in the two sets of plasticizing injection devices are required to be the same, and the fluctuation of process parameters in the two sets of devices should be minimized.
2. Compared with ordinary injection molded plastic products, the two-color injection molding plastic products should adopt higher parameter values for the melt temperature and injection pressure during injection. The main reason is that the mold flow path in the two-color injection molding is relatively long, the structure is relatively complicated, and the flow resistance of the injection melt is large.
3. For two-color injection molding plastic products, raw materials with good thermal stability and low melt viscosity should be selected to avoid decomposition due to high temperature of the melt and long residence time in the flow channel. The plastics used in many applications are polyolefin resins, polystyrene and ABS materials.
4. When the two-color plastic products are injection-molded, in order to make the two different color melts melt well in the mold during molding and ensure the molding quality of the injection molded products, a higher melt temperature and a higher temperature should be adopted. Mold temperature, high injection pressure and injection rate.
