Transparent silica gel products will not turn yellow after being put for several years, but sometimes in production, some newly baked transparent silica gel products look yellow, as if they have changed color. Why can transparent silica gel products turn yellow?
1、 Vulcanizing agent
1. The properties of vulcanizing agent can be divided into common type and yellow resistance. Its application scope includes the following two aspects:
2. Ordinary non anti yellow vulcanizing agent, which can be used in some non exposed silica gel products with deep color or low color requirements
3. The Yellow resistant curing agent shall be used for products that need to be exposed, lighter and brighter colors, and have higher color requirements
2、 Technology
During the forming of transparent silica gel products, the main problems are that the color of transparent silica gel products turns yellow after forming:
1. Mold temperature is too high
2. The curing time is too long,
3. After secondary sulfur addition
3、 Poor quality of raw materials
Sometimes we add anti yellow curing agent to the rubber, but the transparent silica gel product still looks yellow after molding, which may be that the anti yellow ability of the raw material is too poor, and the suggestion for the raw material with too poor anti yellow ability is direct refueling.
Summary:
Although silicone products have excellent weatherability and anti-aging properties. But sometimes there are just out of the silica gel products yellow. In order to avoid this situation, the curing agent should be selected according to the requirements. In terms of technology, the mold temperature and product curing time should be strictly controlled. In terms of raw materials, attention should be paid to the Yellow resistance of raw materials.