Plastics are the world's most common synthetic polymers and are used in a variety of everyday applications. Many everyday items are now made exclusively with plastic. Plastics' ease of manufacture, light weight, and designable properties often make them ideal substitutes for glass, wood, paper or metals.
The resin industry has been evolving globally since its commercial infancy back in the 1930s, and now consists of dozens of producers and many thousands of processors. Ever demanding requirements for new products and more cost effective ways of producing them have continuously driven innovation and technology. Many of the early inventors of process technologies for manufacturing resins (Phillips, Hoechst, Unipol) license to a global community of petrochemical firms.
Resin producers manufacture and market branded prime grade resins sold under their specific product nomenclature, whether shipped directly or through an authorized distributor. The producer business is referred to as the contract market while any generic prime or wide-spec volumes move through what is referred to as the spot market. Spot market liquidity has increased dramatically in the last ten years due to fluctuating resin prices which creates a need for frequent inventory adjustments.
Plastics come in two main types, thermoplastics and thermosets. Thermosets can only be melted and formed once through application of heat energy and are considered permanently cured thereafter. They are stronger than thermoplastics on initial use but will completely degrade upon any subsequent heating. Thermoplastics can be melted to a liquid (molten) state then formed and frozen into a solid state by molding or extrusion processes. This process can be repeated several times until heat degradation negates any beneficial properties.
Thermoplastics are further divided into two categories: engineering grades and commodity grades. By volume, the most widely used thermoplastics are the polyolefins, such as polyethylene and polypropylene. Here, the repeating monomer unit is an olefin, ethylene or propylene gas respectively, that is polymerized with the addition of co-monomer and catalyst in a reactor. Polyolefins are considered recyclable because of their thermoplastic properties. The commonality and ease of transport and use of polyolefins allow them to be globally accepted and traded in a high-growth international market.