Injection Molding: Process Analysis Of Six Recycled Plastics

- Jul 09, 2018-

First,recycled low density polyethylene (LDPE) process


LDPE, the scientific name of high-pressure polyethylene, generally refers to plastic packaging film. Such as: woven bag inner liner film, food packaging film, daily necessities packaging film, greenhouse film. Most of these films are natural, light blue, and black. It is best to separate the color samples before recycling. It is impossible to put the low-pressure film and the PP film together, and it is impossible to put the OPP and the PVC film into it. Recycling and reusing LDPE is the process of regenerating LDPE.


There are four main processes in the entire regenerative LDPE process:

1. The pulverization process. It is better to have a water pulverizing effect. Since some good high pressure membranes are kept clean enough, the membrane can be re-blown without adding new material. Therefore, it is necessary to pay attention to cleaning during the pulverization process. When the pulverized material flows to the water tank, it is best to roll again to further clean the cleaning point.

2. Drying process. Generally, the drying machine is used to dry the remaining water. If it is conditional, it can be dried. This can save electricity costs and improve quality. Of course, attention should be paid to preventing secondary pollution of materials during drying.

3. Granulation process. There are two basic uses for pellets made from special extruders: re-blowing and injection molding. The material from the 60 to 80 mesh filter can be blown again; the material from the 40 to 60 mesh filter can meet the quality requirements of the injection molding. Generally, the high-pressure material blows the film again, and the good blowing color is a little bit blown by the black film and the garbage bag, and the price after the injection of the plastic is lower.

4. The pelletizing process is generally cold water pelletizing. This procedure must pay attention to the labeling when packaging. A kind of blow molding, a kind of injection molding, so as not to make a mistake. In addition, the packaging bag for blow molding must be covered with a liner bag to avoid secondary pollution.


Second, recycled polypropylene (PP) process


Most of PP comes from daily necessities, plastic boxes, foot basins, buckets, rice bran, plastic chairs, stools, woven bags and other packaging woven fabrics, packing belts, etc.

1. First separate the colors of the various materials, because the separation will make the user convenient and the price can be high.

2. Smash and rinse with water, dry the remaining water in the dryer, and then dry and bag. Mix with a mixer and add some color and additives.

3. Special plastic machine for granulation on the car, but the granulation temperature should not be too high, it is easy to be brittle, so we must pay attention to the temperature.

4. Water-cooled pellets, the standard 3X4mm, otherwise the appearance of the good material is not good, not standard.