Why do silicone products turn yellow

The yellowing of silicone products over time, or the yellowing of silicone molds made from them, is a headache for the silicone industry. Let's briefly analyze the reasons below.

1、 Added vulcanizing agent. The properties of vulcanizing agents can be divided into ordinary type and yellowing resistance. Ordinary non yellowing vulcanizing agents can be applied to non exposed silicone products with darker colors or low color requirements, even if the silicone turns yellow, it will not have a significant impact. The anti yellowing vulcanizing agent is applied to products that require exposure, lighter and brighter colors, and have high color requirements. The addition of anti yellowing vulcanizing agent ensures the color of silicone products to a great extent. However, it cannot be ruled out that the poor quality of the vulcanizing agent itself can cause the liquid silicone to appear light yellow during production and molding. In such cases, it is necessary to choose whether to replace the silicone raw material according to the product requirements.

2、 In terms of craftsmanship. During the molding of transparent silicone products, different variable conditions are also the main reason for the color turning yellow after molding. For example, the mold temperature is too high, the curing time is too long, and after secondary sulfur addition, etc.

Although silicone products have excellent weather resistance and aging resistance. But sometimes there is still a yellowing phenomenon of freshly produced silicone products. To avoid this situation, it is necessary to select vulcanizing agents according to the requirements, strictly control the temperature of the mold and the vulcanization time of the product in terms of technology, and pay attention to factors such as the yellowing resistance of the raw materials.