In the process of using silicone rubber, the substances migrating to food include small molecule volatile siloxane, siloxane oligomer and high degree of polymerization of siloxane with large molecular weight. Among them, the molecular weight of compounds greater than 1000 Da, usually can not enter the human metabolism and have low toxicity; Because of the high volatility of siloxane monomer, it is easy to remove the siloxane during the processing of silicone rubber. Therefore, the migration risk of siloxane in silicone rubber for food contact should be mainly concerned with polysiloxane.

Siloxane oligomers are volatile, lipid soluble and bioenriched. Studies have found that some siloxane oligomers have endocrine disrupting effects on the immune system, liver system, respiratory system and nervous system, and may even increase the chance of chronic poisoning and cancer.

Based on the source analysis of siloxane in food contact materials, it is suggested that the industry can reduce the migration risk of siloxane in three aspects:

1. Formula adjustment: Silicone rubber in use process due to the aging will be out of siloxane, and main chain, end group, additives, heat, oxygen, water, acid and alkali, ozone and other factors, has a great influence on the life of the silicone rubber, so you can by changing the molecular structure of the silicone rubber, joining methods such as heat resistant additives, and participate in acid and alkali, prolong the service life of silicone rubber, to improve the thermal stability, Thus reduce the migration risk of siloxane in the use of silicone rubber products.

2. Optimize process conditions. Studies have shown that siloxane oligomers with lower molecular weight have higher toxicity and are easy to migrate, while siloxane with higher molecular weight has lower toxicity and requires a long time at high temperature to achieve a large number of migrations. Therefore, the rubber mold can be tempered appropriately in the production process to reduce the residue of low molecular weight siloxane oligomers in the silicon rubber mold, and then reduce its migration to food.

3. Try to avoid long-term contact with foods with high fat content: siloxane oligomers have strong lipophilic properties, and relevant studies have shown that the content of siloxane oligomers in baked foods is positively correlated with the fat content of baked foods. Therefore, the detection and evaluation of siloxane migration should be especially strengthened for the silicone rubber products that are expected to contact oily food, and they should be used under the premise of ensuring safety.