Vulcanization category of HCR silicone rubber:
1. High temperature vulcanized molding: HCR with double 2,5 catalyst
It’s usually used at a temperature of 160-250 degrees. It’s formed by high temperature vulcanization after mixing by adding peroxide (commonly known as double 2,5 catalyst). The advantages are low cost and good stability of product performance. The disadvantages are long molding time and low efficiency.
2. Low temperature vulcanized molding:（HCR with PT catalyst or double 2,4 catalyst）
It is usually used at a temperature of 100-140 degrees. It is vulcanized and molded at low temperature after mixing by adding platinum catalyst or double 2,4 catalyst (generally used for extrusion molding). The products produced by silicone rubber with PT catalyst are softer than those made by double 2,4 catalyst, so the temperature can be a little lower.The advantages are short molding time, high efficiency and large production capacity.
Two-component A/B platinum catalyst is a kind of addition molding silicone rubber catalyst. A/B can be used to form silicone rubber molding. It can be molded and extruded.
Recommended use ratio:
For molding: A: 0.3%, B: 0.8%; For extrusion: A: 0.5%, B: 1.0.
(depending on the specific process)
Features of Platinum catalyst:
- Low curing temperature and fast curing speed;
- After vulcanized molding, the cross-linking of the product is sufficient;
- After curing, the product is tasteless; which passes EU ROHS, US FDA, German LFGB and food grade certification.
Effect of platinum catalyst on silicone rubber:
HCR with platinum catalyst plays an important role in the molding of LSR and HCR silicone rubber. After molding, it is tasteless and non-toxic, which meets the FDA certificate standard,with tasteless, good yellow-resistance, high transparency and high mechanical property. It’s suitable for the production of high transparent silicone parts,such as: medical products, milk bottle, baby products, silicone tube etc.
What are the differences between HCR with PT catalyst and liquid silicon rubber molding?
HCR with Platinum catalyst needs to be practiced by adding platinum catalyst, which is usually formed by extrusion, molding and calendering. Two components of liquid silicone rubber A&B contains platinum catalyst itself, which is generally directly formed by injection molding.