How to control the color difference of the finished injection molded products?

Plastic products can be seen everywhere in our daily life, from small computer mice and spoons to large plastic toy tables and chairs. There are many factors affecting the color difference.

Due to the difference in raw materials, formula ratio, and production process, it is easy to lead to the color difference in the appearance of plastic products, which then affects the appearance of final products as well.

Reasons for the color difference of injection molded products

1.Effect of color masterbatch

Color masterbatch is the key factor for color difference. The color quality of plastic products directly depends on the basic color of the masterbatch. The heat resistance, dispersibility, covering ability, and color difference of masterbatch are directly related. Choosing high-quality masterbatch not only helps to reduce the color difference but also improves the overall appearance of injection molded products.

2.The impact of raw materials on plastic products

The characteristics of the resin itself have a great impact on the color and gloss of plastic products. Different resins have different coloring power, and some materials present different colors in the plastic itself, so considering the material and color of the raw material itself has a great impact on the plastic coloring formula design.

The color and light of the raw material is also a factor that should not be neglected in the color matching of plastics, especially when configuring white or light-colored plastics. For plastics with good light resistance, the formulation can be considered according to its original color, while for plastics with poor light resistance, the factor of poor light resistance and easy color change must be considered when considering the coloring formulation to get good results.

3.The impact of plastic products processing technology

In the process of dyeing plastic parts, the temperature and back pressure of injection molding, equipment process, and environmental cleanliness can lead to large deviations in the color of plastic parts. Therefore, it is necessary to keep the consistency of injection molding equipment and environment. The stable injection molding process is the key step to ensure the color deviation of plastic parts within the qualified range.

Ways To Control Color Difference Of Injection Molding Products

1.Eliminate the influence of raw material resin and color masterbatch

Controlling the raw material is the key to completely solving the color difference. Therefore, when producing light-colored products, the obvious impact of different thermal stability of raw material resins on the color fluctuation of products cannot be ignored.

Since most injection molding manufacturers do not produce plastic masterbatch or masterbatch themselves, the focus of attention can be placed on production management and raw material inspection. That is to strengthen the inspection of raw materials in the warehouse.

When producing the same product, we use the same manufacturer and the same brand of masterbatch as much as possible. For the masterbatch, we need to conduct a sample test before mass production both with the last calibration and comparison at this time.

If the color difference is not big, it can be considered qualified, as if there is a slight color difference in the batch of masterbatch, the masterbatch can be re-mixed and used again to reduce the color difference caused by the uneven mixing of the masterbatch itself.

At the same time, we also need to focus on testing the thermal stability of the raw material resin and color masterbatch, and for those with poor thermal stability, we suggest the manufacturer exchange them.

2.Reduce the impact when adjusting the injection molding process

When adjusting the injection process parameters for non-color difference reasons, do not change the injection temperature, back pressure, injection cycle, and the amount of, color masterbatch added as much as possible. Also, observe the effect of the change of process parameters on color at the same time.

As far as possible, avoid using high injection speed, high back pressure, and other injection molding processes that cause the strong shear effect to prevent color differences caused by local overheating or thermal decomposition and other factors.

Strictly control the temperature of each heating section of the barrel, especially the nozzle and the heating section immediately adjacent to the nozzle.

3.Eliminate the impact of uneven mixing of masterbatch with color masterbatch

If the raw material elements have been removed before manufacturing, and color differences are found in the mold injection manufacturing, it is necessary to identify that it is a problem of mixing the masterbatch and plastic masterbatch. Adjust it according to changing the injection temperature or condensation method, knowing the hue trend analysis is easy to ensure.

If you need advice and solutions to your problems, you can contact ZHXTOYS for advice and solutions. ZHXTOYS has more than 30 years of experience in injection molding since its establishment in 1989, with a total of 70 sets of injection molding machines. Currently, we are working closely with companies all over the world, so if you have any ideas, please contact us immediately.

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