Everything you need to know about injection molding color masterbatches

Table of Contents

What is color masterbatch?

Color masterbatch is a new type of polymer material colorant with superior coloring properties. Color masterbatch is mainly used as a colorant added in the plastic processing process to make plastic products form their intended colors.

How to store masterbatches?

Color masterbatch is stable because its pigments and additives are attached to the carrier, so it will not change its physical and chemical properties even after a long period of storage.

However, when the temperature rises to a certain level, the color masterbatch and plastic materials will undergo chemical changes.

Therefore, the storage environment of the color masterbatch should be kept cool and prevented from exposure to the sun and humidity.

How to use color masterbatch?

In the process of plastic injection molding, it is often presented in the form of granules, so it is also called color masterbatch or color seed.

The composition is simple and consists of a carrier with color as well as other additives. The produced product can then have a pre-planned color.

The use of masterbatches is very simple, as the desired color masterbatches are mixed with plastic material particles and added to the machine for uniform mixing. Alternatively, it is possible to achieve this effect by hand mixing.

There are some problems and solutions in the process of using masterbatch. Under the sunlight, there are streaks of pigment bands in the products.

Consider two aspects of plastic physical and mechanical properties and the plastic molding process.

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

2. The injection molding machine does not add a certain back pressure, and the mixing effect of the screw is not good.

3. The dispersion of masterbatch is not good or the resin is not plasticized well.

The process can be debugged as follows:

Slightly increase the temperature of the mixing cavity by the drop port part.

1. Apply a certain back pressure to the injection molding machine.

2. If the above debugging is still not good, it may be the dispersion or matching problem of color masterbatch and resin.

After using a certain color masterbatch, the product seems to break easily.

The poor quality of the dispersant or auxiliaries selected causes poor diffusion and mutual solubility, which affects the physical and mechanical properties of the products.

The color is too dark/too light after using the color masterbatch according to the ratio in the instruction manual. Although this problem is simple, there are many possibilities, specifically:

1. The color masterbatch is not carefully tested and the pigment is too little or too much.

2. Inaccurate measurement at the time of use, the phenomenon of random measurement exists in domestic enterprises, especially in small and medium-sized enterprises.

3. The matching of color masterbatch and resin is problematic, which may be due to improper selection of carrier of color masterbatch, or the manufacturer may change the resin variety at will.

4. Improper temperature of the machine, and the color masterbatch stays in the machine for too long.

5. Handling procedure: Firstly, check whether the resin variety matches with the masterbatch and whether the measurement is accurate, and secondly, adjust the machine temperature or speed.

The same color masterbatch, resin, and formula, why are there shades of color in products injected by different injection molding machines?

This is often caused by the injection molding machine. Different injection molding machines have different mechanical conditions due to different manufacturing, usage time, or maintenance conditions, especially the difference in the tightness of the heating element and the barrel, which makes the dispersion of the masterbatch in the barrel different.

Does the pigment migration phenomenon during the storage of masterbatch affect the quality of products?

Some masterbatches have high pigment content (or dyestuff), in this case, the migration phenomenon is normal. Especially for the masterbatch with dyestuff, a serious migration phenomenon will occur.

However, this does not affect the quality of the product, because after the masterbatch is injected into the product, the pigment in the product is at the normal concentration of color development.

After changing to another brand of resin, the color changes with the same masterbatch and formula, why?

There are differences in density and melt index of different resin brands, so the performance of resin will be different, and the compatibility with color masterbatch will be different, thus the color will change.

Why is the luster of some injected products not good?

There are several possibilities as follows:

1. The nozzle temperature of the injection molding machine is too low.

2. The mold finish of the injection molding machine is not good.

3. The molding cycle of the product is too long.

4. The color masterbatch contains too much titanium dioxide.

5. Bad dispersion of color masterbatch.

6. After some time, some plastic products will fade.

7. The quality of the basic pigment used in the production plant is not good, and the drifting phenomenon occurs.

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