To improve difference properties of latex, generally emulsions, dispersion and solutions are added as compounding ingredients.
Surface active agents are used to stabilize the latex by reducing the surface free energy. The stabilization means delay the coagulation of latex. There are different types of surfactants as follows,
- Anionic surfactants: carboxylates, Sulfonates
- Cationic surfactants: Acetyl tri methyl ammonium bromide
- Amphoteric surfactants: Water soluble proteins
- Nonionic surfactants: Poly ethylene fatty acids
- Vulcanizing system: is used to increase the strength. Generally the vulcanizing agent is S (sulfur). Primary activators like ZDC (zinc dithio carbonate) and secondary activators like thiurum, thiosole are also used.
- Viscosity modifiers: are used to control skin thickness.
- Softeners: are used to increase the softness of rubber. Examples are vegetable oils, organic esters, petroleum oils etc.
- Fillers: are used to increase stiffness of rubber. Examples are carbon black, TiO2, CaCO3, ZnS etc.
- Antioxidants: there are two types called Staining Antioxidants and non-staining Antioxidants. Examples are staining- Amines, non staining- phenolic compounds
They are coagulants, heat sensitizers, flame retardants, colorants etc.
The equipment like Ball mills, Attrition mill, and colloidal mills are used in latex compounding.