What are the reasons for the unstable color of injection molded products


In injection molding production, sometimes the color ch […]

In injection molding production, sometimes the color changes every few days, or even several color deviations within a day. There are still many factors that cause color instability. The main factors that can cause color instability are listed below for comparison and improvement during production.
1. The temperature of the injection molding machine is unstable: when the temperature is high and sometimes low, the color will be unstable. This is a major influencing factor and needs to be checked first.

2. Unstable production cycle: open and stop at all times, if the back pressure is adjusted too large, it will cause running temperature, which will cause the color to change.
3. Too much humidity in the raw material: the toner cannot be spread due to adhesion.
4. Toner quality is poor: it is not heat resistant, or using the wrong toner that is not suitable for the raw material will make the color unstable.
5. Baking temperature is too high or too long: every raw material and pigment has its baking temperature and time range. If it exceeds this range, the color of injection molded parts will change. If the feeding time is more or less, the color that is more affected by the temperature will be unstable, such as the color containing fluorescent materials or light-colored injection molded parts. Therefore, for temperature-sensitive plastics, it is best not to bake the ingredients or use the bottom temperature baking ingredients. It is safest to mix the toner after the ingredients are baked.

6. In the baking hopper, due to the influence of hot air: the toner is locally concentrated, which makes the color deeper and deeper, and there will be too many pits in the injection molded parts that need more pits. At this time, you need to add some diffusion oil to make the toner adhere to the raw material firmly.
7. The blender did not mix the toner and the raw materials according to the mixing process requirements: for example, insufficient mixing time, improper feeding method or order leading to uneven toner, this is also important to check.
8. Inaccurate matching of toner: The amount of each element in each batch of toner formulation has a large deviation, which makes the color deviation when a new batch of pigment is used. This kind of thing happens from time to time.
9. The recycle amount of nozzle material is more and less time: this has a greater impact on light-colored injection molded parts.