Analysis of the causes of uneven color of injection plastic bottles

Jun. 08, 2021

Benefiting from many advantages such as light weight, not fragile, cost-effective and easy to process and shape, plastic bottles are widely used in people's production and life. Among many production processes, injection molding is a common and widely used one. Sometimes we may find that some injection molded bottles have uneven colors. What is causing you?

Analysis of the causes of uneven color of injection plastic bottles

plastic injection vial

The main reasons for the uneven color of injection molded plastic vaccine bottles include the following aspects:

1. Poor diffusion of the colorant, which often causes patterns to appear near the gate. It can increase the temperature of the feeding section, especially the temperature at the back end of the feeding section, to make the temperature close to or slightly higher than the temperature of the melting section, so that the masterbatch will melt as soon as possible when entering the melting section, promote uniform mixing with dilution, and increase the chance of liquid mixing.

2. The thermal stability of plastics or colorants is poor. To stabilize the color of the parts, the production conditions must be strictly fixed, especially the material temperature, material quantity and production cycle.

Analysis of the causes of uneven color of injection plastic bottles

10ml injection vial

3. For crystalline plastics, try to make the cooling rate of all parts of the parts consistent. For parts with large wall thickness differences, colorants can be used to mask the color difference. For parts with uniform wall thickness, the material temperature and mold temperature should be fixed.

4. The shape of the part, the form of the gate, and the position of the part have an effect on the filling of the plastic, causing some parts of the part to produce chromatic aberration, and it must be modified if necessary. If the gate is too wide, the turbulence effect will be poor when the molten material passes, and the temperature rise will not be high, so it is not uniform. The ribbon mold cavity should be narrowed.

Plastic bottles may encounter various problems during the production process, such as uneven color, dent, poor gloss, etc. The key is to control the production process and find the cause and solution of the problem to ensure the quality of the finished product.

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