Many friends in the injection molding industry have received feedback from customers that the products they produce will yellow and fade after being used by consumers in the market for a short period of time, such as phone cases, wearable accessories, and so on.
Why does this problem occur?
1. Non-compliant raw materials
The main reason for the yellowing and fading of injection molded products is the improper formulation of colorants in their raw materials. In general, coloring and fading issues can be attributed to raw material problems. As a dedicated technician from an injection molding machine manufacturer, it is essential to have experience in this area.
2. Poor quality raw materials
Injection molded products have very strict requirements for raw materials. It is crucial to choose good quality materials. If the selected materials do not meet the standards, they may not withstand the environmental conditions, temperature, humidity, and oxidation during the formulation process. This can lead to the loss of the material’s inherent anti-yellowing effect, and the addition of catalysts may cause the product to turn yellow.
3. Incorrect formulation can cause product yellowing
In most cases, “ethylene-based resin” is a commonly used silicone resin material in most rubber compounding processes. The proportion of this material is usually required to be below 1%. If it exceeds this range, the materials used by the injection molding factory may exhibit yellowing. Since ethylene-based silicone resin is commonly present in injection molding materials, if the injected products show yellowing, it means that the formulation used by the injection molding manufacturer contains ethylene-based resin exceeding 1% or more, leading to the yellowing problem. Our company will conduct various experiments to confirm whether the raw materials meet the standards.
4. Catalyst issues in raw materials
In practice, without the addition of a catalyst, yellowing effects may occur. Using an appropriate catalyst generally provides a certain anti-yellowing effect. However, different brands of catalysts have different levels of importance in combating yellowing and fading. This is because catalysts are not only formulated for anti-yellowing effects but also need to achieve good sulfurization effects, address odor issues, and improve material dispersibility.
When adjusting other performance factors, it is not possible to simultaneously control multiple properties to achieve a relatively ideal state. Therefore, the injection molded products you purchase may have good tensile toughness initially, but over time, they may exhibit yellowing.
