In the previous article, we talked about the different grades of silicone products. Many silicone products for home and everyday products are required to meet the food safety standards of FDA or LFGB.
In the work of production inspection, we found that some products have not passed the test even if they are produced according to the hygienic standards of food grade silicone products. Combining years of production experience, we analyze the four possible causes of the problem:
Loose raw material quality requirements
This is the most common reason. Some consumers are over-pursuing low-priced products, which causes manufacturers to prefer raw materials suppliers with low prices when choosing materials. The performance of some raw materials is not stable. The test results of some product testing items are close to the test standards. It is easy to cause some batches of raw materials to fail to meet the standards.
In addition, in the production, sometimes need to add color glue and additives for coloring, these auxiliary materials, it is easy to lead to the product can not pass the test.
Non-standard production process.
Due to the particularity of the safety requirements of silicone tableware, food grade silicone products require very strict production processes. Sufficient time is required to remove volatile substances after molding. In order to pursue fast shipping, some factories rushed to package shipments without sufficient processing time.
The special use environment of the product.
Countries such as the European Union require product testing to be carried out in accordance with its foreseeable and most stringent use. In the actual production process, the entrusting party and the producer only produce according to the product samples, and have no enought understanding of the use and use conditions of the products. They are also blind when dealing with third-party testing, and even obviously inconsistent with the foreseeable use conditions of the products.
The secondary curing of silicone products
Secondary vulcanization is also called post-vulcanization. The effect of secondary vulcanization is to improve the physical properties of the product.
In the manufacturing process of silicone rubber products, it is necessary to use peroxide vulcanization. After the decomposition of the peroxide initiates the reaction of the high polymer, low molecular compounds (such as benzene and benzoic acid) are formed. The presence of low molecular compounds in the rubber will affect the rubber machinery performance.
At the same time, after the silicone rubber is heated and formed in the first stage, the crosslink density is not enough. It is necessary to further vulcanize the reaction to increase the density of the silicone rubber. The tensile strength, rebound resilience,