With the application of TPE in the field of household and daily-use products in recent years, the environmental requirements for TPE are becoming more and more strict. In the field of household products, especially kitchenware, tableware, small appliances (accessories), coasters (lids) and other products for TPE, TPR demand is long.

　　Different countries have different testing standards for food contact material TPE. China uses GB (GB4806.1-94) standard, the EU universal standard is EC/1935/2004 standard EN1186, but within the EU, different countries also have differences, such as Germany is LFGB, France is FrenchDGCC RF 2004-64, in addition to the United States is the FDA (21CFR.177.2600), Japan's and different.

　　Hexane test is an important and common test method in the food grade test standard. At present, the food-grade test standard for TPE, China GB4806.1-94, the U.S. FDA 21CFR177.2600 have adopted this test method, in addition, Japan and Korea use n-heptane to test, the test method is quite close.

　　Food contact materials used in the soft rubber materials, its environmental performance, silicone is the most excellent. Silicone can fully pass the relevant food contact material testing standards, and can pass the n-hexane, olive oil, alcohol residue test. However, the disadvantages of silicone are higher cost, long molding cycle, and material can not be recycled, while TPE, TPR soft material just make up for these shortcomings of silicone. Thus, TPE has the tendency to replace silicone in food contact soft rubber materials in recent years.

　　However, in the face of the most important food contact materials hexane test, TPE, TPR can actually pass the FDA2600 oral contact grade hexane test? The following analysis is done.

　　SBS synthesis: styrene, butadiene as monomer raw materials, cyclohexane as solvent, n-BuLi as initiator, THF as activator, non-termination of the anionic polymerization reaction, SiCl4 as coupling agent last added to the appropriate amount, the reaction is terminated by adding antioxidant. The product is a white translucent elastomer.

　　Usually the polymerization reaction of polymers is incomplete, the solvent cyclohexane and polymer monomer small molecules (usually butadiene, styrene and other small molecules) are always more or less present in the polymer SEBS, SBS, and these small molecules will continue to stay in the SEBS, SBS polymer modified material TPE, TPR system. Because hexane and cyclohexane have good mutual solubility, and hexane can be soluble in most non-polar organic solvents, therefore, TPE, TPR in doing FDA2600 test, hexane as an extractant, those residual in TPE, TPR materials residual small molecules easily precipitated, resulting in test results exceed the standard.

　　According to the above analysis, about whether SEBS, SBS, TPE, TPR can pass the FDA2600 oral contact level test, the conclusion is - it is difficult. Although many domestic TPE, TPR manufacturers are claiming that their products can pass the FDA2600 test, some can also show the FDA test report. But in fact, few manufacturers can really pass the n-hexane test. Even if they can pass, it only refers to TPEs that represent special formulations, and the price of such TPEs is usually very expensive. The usual price and formulation of TPE, TPR materials, is difficult to test through the FDA2600. But some imported models of TPE, customers use feedback is able to pass the FDA2600 or even LFGB test. This shows that the report is only the product of the laboratory and not the real sense of mass production products.

　　When I contacted with the customer, I made it clear that there was no way for our products to fully pass FDA 21CFR177.2600, and the result he got after consulting with the American TPE supplier was exactly the same as what I said. is a problem faced by domestic and foreign manufacturers.