- Zinc oxide
- Styrenated phenol
- Zinc stearate
- Stearic acid etc.
Among the vulcanization accelerators a class exists of products which are defined as “secondary accelerators“, useful as activators for thiazole-based primary accelerators. Example of such products is diethylamine. It is used to produce vulcanization accelerators such as zinc diethyldithiocarbamate and tetraethylthiuram disulphide.
The Tyre industry remains the largest single market for ZnO. It has more than half of the total worldwide demand of 1,200,000 metric tons. Traditionally ZnO is used in rubber formulations in concentrations of 3–8 parts per hundred rubber. Its addition also protect rubber from fungi (see medical applications) and UV light.
It is generally a feed supplement. It is used in the manufacturing of veterinary products as well as in the process of synthesis of micro nutrients. It increases the durability and strength of rubber by linking together the rubber polymers & is used in the manufacture of seven grades of rubber and is used in the making of transparent rubber products.
Styrenated Phenol (STP) is a clear, yellow, viscous liquid. It is a stabilizer for dry rubber and latex compounds such as SBR, BR, NBR, EPDM, CR. The rubber articles that use Styrenated phenol are sheets and straps, rubber tubing, conveyor belt covers and latex dipped products (such as industrial gloves, surgical gloves, feeding bottle teat). Other products such as balloons, hot water bottles, injection bottle caps, rubber rollers and Footwear related items use styrenated phenol.
It is an “activator” for rubber vulcanization by sulfur and accelerators. As discovered in the early days of vulcanization, zinc has a beneficial effect on the reaction of the sulfur with the polyolefin. The stearate is a form of zinc that is highly soluble in the non-polar medium of the polyolefins.
It is used because it is comparatively light in weight and so can be transported quite easily and in large quantities. It is used for chemical coatings and resist moisture.
Stearic acid is the common name for octadecanoic acid, which is a saturated fatty acid stearic acid for rubber vulcanization accelerator. It is required as a part of all type of sulphur vulcanizing system. Stearic acid activates accelerators in presence of zinc oxide forming zinc stearate.
There are plenty of functions of stearic acid. In rubber industry besides its use as activators with sulphur vulcanizing, it is also used as dispersing agent as plasticizer and as antisticking to mould and rolls. Stearic acid is a common, naturally occurring fatty acid widely used as an inexpensive primary emulsifying agent.