Industry Information

Why does silicone tubing require secondary sulfur addition?

  Secondary vulcanization of silicone tube is an essential link, it can make silicone tube products can continue to improve on this basis, not only silicone tube can be secondary vulcanization, such as silicone extrusion and other processes This operation can also be done, such as silicone strips, silicone foam tubes, etc., but it is not recommended to add sulfur twice for products such as LED sleeves, which will affect some light effects. Silicone extrusion is divided into two stages. Pre-vulcanization refers to the oven (forming), and post-vulcanization refers to the oven (perfect), because it is inevitable that some parts will be incompletely vulcanized or vulcanized during the vulcanization process. The product that affects the cross-linking of the silicone tube is some fine particles. In this case, the customer cannot accept the product, so a secondary sulfur addition is required.
  In addition, during the secondary vulcanization process, the silicone tube can be further vulcanized to form a high-quality silicone tube. For example, the conventional industrial grade silicone tube is not particularly strict with the product, so many manufacturers will skip the secondary vulcanization step and ship directly. For example, some customers who have strict product requirements often need to carry out the second step of sulfuration, such as food-grade silicone tubes, medical-grade silicone tubes, and pharmaceutical-grade silicone tubes. The environment of their back-body products is relatively strict. The harsh safety level is also relatively high, so after it is made of food-grade raw materials, it is necessary to add sulfur twice to ensure the safety and stability of the silicone tube. The other is deodorization. At present, most of the silicone extrusion processes use double 24 and platinum vulcanization. However, double 24 silicone tubes will have a pungent smell if they are vulcanized a second time. It will eliminate most of it (it can still be smelled), and the silicone tube of the platinum process has very little odor, and it can be odorless after secondary sulfur addition.
  Secondary vulcanization will further increase the cross-linking density of the silicone tube. As a result, the tensile strength, resilience, degree of swelling, and thermal stability of the silicone tube will be better than those of the silicone tube without secondary vulcanization. If If the silicone tube is not vulcanized twice, some characteristics will decrease. Therefore, in general, it is recommended that silicone products should be vulcanized twice, so that the full potential of the silicone tube can be developed, and it can also make up for some later deficiencies.

With more than 20 years of production management experience, we insist on providing customers with high-quality silicone tubes