Polymer coatings are surface deposits that can be applied to many types of objects. They are designed to provide additional functional features to improve the performance of parts. Such properties include: a reduction in friction, non-stick properties, a low friction coefficient, chemical resistance, abrasion resistance and much more. In addition, many coatings meet the necessary conditions to make them suitable for food contact, which has allowed for considerable development over time.
The main families of polymer coatings
Several families of coatings fall into this large category:
PTFE is the forefather of this technology. Following its discovery in 1938 by Roy Plunkett, the Teflon brand was born, whose main feature is its remarkable non-stick properties.
It is an easily workable material, which has allowed it to spread rapidly across the widest array of fields, including the food and chemical sectors and industrial manufacturing fields in general. Since it also acts as an insulator, it is very often used in the electrical industry.
It can be applied to different types of objects, as if it were paint. Applied as a spray or in a bath, it then undergoes the curing phase which creates its typical characteristics. It is also available as a film or plate. Even today it is a very important and constantly evolving coating.
Part of the natural evolution of PTFE, PFA was created with remarkable resistance to chemical aggressors. This has led to many solutions that, along with the basic characteristics of PTFE, have allowed the use of this coating on applications that were previously impossible.
These are fluoropolymers with non-stick properties, a low friction coefficient and excellent chemical resistance. They are generally multilayer coatings that usually do not withstand particularly high temperatures (around 200-220°C), although they do combine the main characteristics of PTFE and PFA.
Over the years, these solutions have led to the development of numerous other related technologies such as ETFE, polymers with a remarkable resistance to thermal shocks and chemical aggressors.Unlike other polymers, ETFEs are produced via extrusion, which makes them closer to resin films. These films allow the creation of real plates that let light through. EFTE is widely used, for example, for tensile structures, greenhouses, etc.
An important step forward in terms of wear resistance, chemical resistance and hardness came with the discovery of PEEK. Also called a technopolymer, it is a semi-crystalline thermoplastic polymer.
It can be used both to create objects that need to withstand continuous stress, such as ball bearings, pistons, pumps or valves, and as a surface coating, often as an alternative to PTFE, PFA or FEP, especially under extreme environmental conditions.
ECTFE provides chemical resistance in applications where corrosion is a particular concern. ECTFE also provides high electrical insulation. This is a semi-crystalline partially fluorinated polymer whose non-stick characteristics are inferior to other solutions, but whose very low porosity makes it very resistant.
Other solutions are represented by the silicone family, which has incredible non-stick properties, but a lower resistance to abrasion, which is why they are often deposited as thermal spray coatings or, more commonly, as metallic plasmas that provide greater resistance to wear. They are also found as ceramic resins, providing very high surface hardness, low friction coefficient and resistance to abrasion.
The use of polymer coatings in different fields (from food to packaging, from oil & gas to mechanics) has led to continuous development to meet the most important and demanding needs in different industrial fields.