Why is ABS color masterbatch particularly prone to color differences?

Different grades of ABS produced in various countries have significant color differences. Even if the same grade of ABS is used, there may be color differences in each batch number. Of course, color differences may also occur after coloring with a color masterbatch. This is due to the characteristics of ABS, and there is no complete solution internationally. However, this color difference is generally not severe.

When using ABS color masterbatch, users must pay attention to this characteristic of ABS.

Common defects of color masterbatch

1. When see under sunlight, there are striped in the product

This issue needs to be considered from two aspects: the physical and mechanical properties of plastics and the plastic forming process:

The temperature of the injection molding equipment is not well controlled, and the color masterbatch cannot be fully mixed with the resin after entering the mixing chamber.

The injection molding machine did not apply a certain amount of back pressure, and the mixing effect of the screw was not good.

1.2 Poor dispersion of color masterbatch or poor resin plasticization.

In terms of technology, the following adjustments can be made: 1. Increase the temperature of the mixing chamber near the discharge port slightly; 2. Apply a certain amount of back pressure to the injection molding machine.

If the above debugging still does not work well, it may be due to the dispersion or matching problem of the color masterbatch and resin, and the color masterbatch manufacturer should be contacted for resolution.

2. After using a certain color masterbatch, the product appears more prone to cracking

This may be due to poor diffusion and miscibility caused by the poor quality of dispersants or additives used by the manufacturer, which affects the physical and mechanical properties of the product.

3. After using according to the proportion specified in the color master manual, the color is too dark (too light)

Although this question is simple,

However, there are many possibilities, specifically:

  • 3.1. Color masterbatch not carefully tested, with too little or too much pigment
  • 3.2. Inaccurate measurement during use, with a large number of domestic enterprises, especially small and medium-sized enterprises, measuring at will
  • 3.3. There are issues with the matching between the color masterbatch and resin, which may be due to improper selection of the carrier for the color masterbatch or the manufacturer’s arbitrary change of resin variety
  • 3.4. Improper machine temperature and prolonged retention of color masterbatch in the machine

Processing procedure: Firstly, check whether the resin variety matches the color masterbatch and whether the measurement is accurate. Secondly, adjust the machine temperature or speed. If there are still problems, contact the color masterbatch manufacturer.

4. Why do products injected by different injection molding machines have different shades of color for the same color masterbatch, resin, and formula?

This is often caused by the injection molding machine. Due to differences in manufacturing, usage time, or maintenance status, different injection molding machines may have different mechanical states, especially the difference in the tightness between the heating element and the material barrel, resulting in different dispersion states of the color masterbatch in the material barrel. This phenomenon can occur.

5. After changing to another brand of resin, the same color masterbatch and formula, but the color has changed. Why is this?

The density and melt index of different grades of resin may vary, resulting in differences in the performance of the resin compared to the color masterbatch

Compatibility may also vary, leading to color changes. Generally speaking, as long as the density and melt index do not differ significantly, the color difference will not be too significant. The color can be corrected by adjusting the amount of masterbatch.

6. Will pigment migration during storage of color masterbatch affect the quality of the product?

Some color masterbatches have high pigment content (or dyes), in which case migration is normal. Especially when dyes are added to the masterbatch, serious migration occurs. But this does not affect the quality of the product, as after the color masterbatch is injected into the product, the pigment is at a normal color concentration in the product.

7. Why do some injection products have poor gloss?

There are various possibilities:

  • 7.1. The nozzle temperature of the injection molding machine is too low
  • 7.2. Poor mold finish of injection molding machine
  • 7.3. The molding cycle of the product is too long
  • 7.4. Too much titanium dioxide contained in color masterbatch
  • 7.5. Poor dispersion of color masterbatch

8. After a period of time, some plastic products may experience discoloration.

The quality of the basic pigments used by the manufacturer is poor, resulting in drift phenomenon.