Polyester resins products in Kenya are unsaturated synthetic resins formed by the reaction of dibasic organic acids and polyhydric alcohols. Unsaturated polyester resins are thermosets, capable of being cured from a liquid to solid state when the right curing conditions are provided. There is a whole range of polyesters products in Kenya made from different acids, glycols and monomers, all having varying properties. These resins are compounded with varied fillers, reinforcements and cured by using free radical initiators to yield thermoset articles having a wide range of chemical and mechanical properties depending upon the choice of di acids, diols, cross- linking agents, initiators and other additives.

Synresins Limited a company in Nairobi Kenya produces two principle types of polyester resin used as standard laminating systems in the composites industry. Orthophthalic polyester resin is the standard economic resin used by many Kenyans and East & Central Africa people. Isophthalic polyester resin is also now becoming the preferred material in industries such as marine where its superior water resistance and chemical resistance are desirable.

The Synresins Limited’s in Kenya polyester resins are viscous, pale colored liquids consisting of a solution of a polyester in a styrene monomer. The addition of styrene helps to make the resin easier to handle by reducing its viscosity and enabling the resin to cure from a liquid to a solid by ‘cross-linking’ the molecular chains of the polyester, without the evolution of any by-products. These resins can therefore be molded without the use of pressure and are called ‘contact’ or ‘low pressure’ resins.