In the process of injection molding, if we want the molded parts to exhibit vibrant colors, the use of color masterbatch becomes indispensable. By mixing the required color masterbatch particles with plastic raw material particles and adding them into the injection molding machine for melting and molding, we can obtain colorful plastic products. However, some issues often arise in the injection molding process after adding color masterbatch. This article will provide a detailed analysis of these common issues.
Striped Pigment Bands Appearing in Plastic Molded Products
This issue mainly manifests as striped pigment bands on the surface of plastic products under illumination, affecting the appearance quality of the products. The causes and solutions are as follows:
(1) In terms of plastic physical properties:
Improper temperature control of the injection molding machine results in inadequate mixing of the color masterbatch with the plastic material after entering the barrel. At this point, the temperature settings of the injection molding machine should be adjusted to ensure that the color masterbatch and plastic material can fully blend.
Insufficient back pressure applied to the injection molding machine, leading to poor screw performance. Increasing the back pressure can improve the mixing effect of the screw, allowing the color masterbatch to be more evenly dispersed in the plastic material.
Poor dispersion of the color masterbatch or inadequate plasticization of the plastic material. In this case, a color masterbatch with better dispersion should be used or the plasticization conditions of the plastic material should be adjusted.
(2) In terms of injection molding process:
Slightly increase the temperature of the barrel near the feed port to facilitate the mixing of the color masterbatch with the plastic material.
Apply a certain amount of back pressure to the injection molding machine to improve the mixing effect of the screw.
If the problem still cannot be resolved after the above adjustments, it may be due to issues with the dispersion or compatibility of the color masterbatch and plastic. At this point, the color masterbatch manufacturer should be contacted promptly for professional solutions.
Products Easily Cracking After Using Certain Color Masterbatches
After using certain color masterbatches, products may be prone to cracking. This is usually due to poor quality dispersants or additives used by the plastic manufacturer, leading to poor diffusion and compatibility, which in turn affects the physical and mechanical properties of the products. To solve this problem, reliable dispersants and additives should be selected to ensure that the color masterbatch and plastic material can fully blend without affecting the performance of the products.
Color Too Dark (or Too Light) After Using Color Masterbatch According to Instructions
Sometimes, after using the color masterbatch according to the proportions specified in the instructions, it is found that the product color is too dark or too light. This issue may be caused by the following reasons:
Incorrect color of the color masterbatch, with too little or too much pigment content. At this point, the color of the color masterbatch should be checked and the pigment content adjusted to meet the requirements.
Inaccurate measurement during use. The accuracy of the measuring tool should be ensured, and the color masterbatch should be added precisely according to the proportions specified in the instructions.
Compatibility issues between the color masterbatch and plastic material. This may be due to improper selection of the color masterbatch carrier or arbitrary changes to the plastic material variety by the manufacturer. In this case, a suitable color masterbatch or plastic material variety should be used.
Improper temperature settings of the injection molding machine or excessive residence time of the color masterbatch in the machine. The temperature settings of the injection molding machine should be adjusted, and the residence time of the color masterbatch in the machine should be controlled to ensure color stability.
In summary, various issues may arise in the injection molding process after adding color masterbatch. By carefully analyzing the causes and taking corresponding solutions, we can effectively address these issues and ensure that the quality and appearance of the injection molded parts meet the requirements.
