Why is it easy to produce color difference when plastic products are injection molded?

In the molding of plastic products, injection molding is one of the most common molding methods. Various problems can arise during the injection molding process and the finished product. There is a problem that has little effect on the performance of the product, but greatly affects the appearance, that is, the color is poor. Do you know the reason for the color difference?

 

The main factor that produces chromatic aberration

 

1. Plastic masterbatch

The plastic masterbatch itself will produce color difference, especially when the masterbatch itself has a certain base color. Even if the same model but different batches are used, sometimes there will be color differences. Experiments show that the degree of color difference is approximately proportional to the base color of the masterbatch, that is, the greater the difference between the base color of the masterbatch, the greater the color difference of the product.

 

2. Color masterbatch

Color masterbatch is the most important factor that produces color difference. The color quality of plastic products directly depends on the quality of the color masterbatch. The thermal stability, dispersibility and hiding ability of the color masterbatch are not only indicators to test the quality of the color masterbatch, but also have a direct relationship with the color difference. The use of higher-quality masterbatches not only helps to reduce chromatic aberration, but also improves the overall appearance of injection molded products.

 

3. Uneven mixing of color masterbatch and raw materials

The color masterbatch is mainly made of colorant, dispersant, and plastic raw materials. A slight change in the measurement of colorant will have a huge impact on the color of plastic products. A color masterbatch is often made of several colors of colorants, and the proportions between them are different, and the color of the product produced by the obtained masterbatch also changes accordingly. The decomposition rate of colorants is different at different temperatures, and the decomposition rates of different colorants at the same temperature are also different. These will be directly produced at different temperatures of the same color masterbatch. We recommend that you choose functional additive masterbatch, function plastic black masterbatch or functional masterbatch packing films for better performance.

 

 

4. Influence of injection temperature and back pressure

The color of the product is different. Taking the camel PP masterbatch as an example (the colorants mainly include titanium dioxide, phthalocyanine blue, red, etc.), the color of the injection molded product is obviously reddish when the temperature of the barrel is 160 °C, and the color is changed when the temperature rises to 190 °C. White, when the temperature rises above 220 ℃, the color is obviously black. Therefore, the change of injection temperature and back pressure directly affects the temperature of the barrel, thereby affecting the color difference.

 

How can we solve the problem of color difference in plastic products? Follow our next article to tell you the answer.