PVC (polyvinyl chloride) is used in thousands of different applications. If you ask someone how PVC is made, you will probably be met with a blank stare.
Blank stares turn into raised eyebrows when you tell them the main ingredients in PVC are…salt and oil. Really!
Vinyl compound is found in every facet of our daily lives. It is a versatile workhorse material that can be used when making everything from medical tubing to backyard decking to power cable jackets. If you look around you right now, you will find countless objects that have some PVC component.
Curious about how PVC is made?
The first step is separating ethylene out of the oil feedstock.
Ethylene, a natural gas derivative, is supplied by the petrochemical industry. It is captured during a process called thermal cracking. Liquid petroleum is heated in steam furnaces and put under extreme pressure. This creates changes in the molecular weight of the chemicals found in petroleum feedstock. Changing the molecular weight allows ethylene to be identified, segmented and captured. It is then cooled back down to a liquid state.
The other step is extracting chlorine from sea salt.
Chlorine, which is found in salt extracted from sea water, gains an additional electron during the process of electrolysis. By sending a strong current of electricity through salt water solution – strong enough to change its molecular structure – chlorine is separated, then extracted from the mixture.
When ethylene and chlorine are reacted, ethylene dichloride (EDC) is created. This passes through another thermal cracking process, which produces vinyl chloride monomer (VCM).
VCM is sent through a catalyst-containing reactor where polymerization occurs. In lay terms – chemicals cause the VCM molecules to react until they link together.
The linking of VCM molecules creates PVC resin – which is where all vinyl compounds begin.
PVC resin has a nebulous structure and inherently exhibits fire retardant and chemical resistant properties. Custom rigid, flexible and blended vinyl compounds are formulated by mixing vinyl resin with a variety of plasticizers, stabilizers and modifiers to achieve certain properties - scuff and mar resistance, UV resistance, weatherability, color considerations and texturing capability, to name a few.
Making these decisions are what the Teknor Apex R&D teams and process engineers have been assisting our customers with for more than six decades. They continue to formulate new compounds, aided by our suppliers’ ability to continue creating new additives which enable meeting more and more challenging requirements.
Making PVC resin and vinyl compounds are very technical, scientific and labor-intensive processes. There are several industries, and a large and varied job sector, that play a supporting role in providing manufacturers all over the world with the compounds they need, which enables them to make the products we all use every day.
The chemistry may seem complicated, but our excitement comes from asking the right questions of our customers and finding new creative solutions. Innovation is still strong in vinyl compound portfolios!
