Key to resolving color discrepancies in blow-molded products is controlling raw materials. The likelihood of color discrepancies caused by raw materials is significantly reduced when all parameters are controlled with new materials. However, introducing recycled materials can lead to color discrepancies due to factors like inconsistent color values and uneven mixing during addition. When adding returned materials during production, it is necessary to adjust the addition ratio and mixing time based on the properties of the returned materials to ensure uniformity of the raw materials and reduce color discrepancies in blow-molded products.

1. Raw materials and color master issues

When using masterbatches, enhance the inspection of raw materials upon entry. For blow molding, aim to have the same manufacturer produce the same product, using the same brand of masterbatch and color masterbatch. If a change in the color masterbatch manufacturer is required, conduct sample testing and only begin mass production upon meeting the standards.

2. Inconsistent blending of raw materials and color masterbatch

Improper mixing of raw materials and masterbatch can also alter the product's color. When the masterbatch is well-mixed with the raw materials and suction-fed into the hopper, static electricity causes the masterbatch to separate from itself, easily adhering to the hopper walls. This inevitably leads to fluctuations in the masterbatch quantity during the blow molding cycle, resulting in color variations. An effective solution is to use a hot air dryer instead of a water suction machine to prevent color powder and masterbatch granules from separating due to manual addition, thus avoiding color discrepancies.

3. The issue of barrel temperature affecting color variation

During the blow molding process, issues such as the failure of heating rings or uncontrolled burning of heating control components can lead to drastic temperature fluctuations in the barrel, resulting in color discrepancies. Generally, color discrepancies caused by the failure of heating rings are accompanied by uneven plasticization, while uncontrolled burning of the heating control section often leads to air spots, severe discoloration, or even coking. Therefore, it is essential to regularly inspect the heating components during blow molding. If any damage or loss of control is detected, they should be replaced and repaired promptly to minimize the likelihood of such color discrepancies.

4. Issues during the adjustment of production processes

During the production process, when adjusting the blowing process parameters, try to keep the blowing temperature, back pressure, blowing cycle, and color masterbatch usage unchanged. At the same time, observe the impact of the process parameters on the color.