Paint, Resin and Coating

Industrial Paints, Resin and Coating

Industrial paints are pigmented liquids or powders that are used to protect substrates. Industrial paints are used in the aerospace, architectural and construction, automotive, and electronics industries. They are also used in marine, medical, military, optical, pharmaceutical, semiconductor, and textile applications. Some industrial paints are applied with brushes or rollers. Others are applied with spray systems.

Purpose of industrial paint

Industrial paint has two main objectives:

On the one hand, to protect the different supports from the aggressions they may be subjected to, both physically (impacts) and chemically and environmentally (corrosion, weather, etc.).
On the other hand, to give the part a better aesthetic appearance in order to obtain an optimal finish, even increasing its added value.

Types of industrial paint

It is difficult to classify the different types of industrial paints and coatings in a defining way, since there can be different interpretations based on factors such as their composition, their position in the finish system or even according to the way the paint dries and hardens after application.

Depending on the position in the finishing system

For an industrial paint to fulfil its protective and decorative functions, it is essential to know the particularities of each painting system and process. We can classify the industrial paint according to its position in the application coat:

Primer

These are the first coats of paint in direct contact with the substrate, highly pigmented and with a low binder content.

Its mission is to serve as an anchor for the following coats of paint and to prevent rusting on metal surfaces by means of the anti-corrosion pigments it contains.

Intermediate coats of paint

These coats are applied over the primer, generally with the mission of increasing the thickness of the paint system, in order to avoid giving several coats of finish, reducing costs in the application.

The pigment/binder ratio is lower than that of primers but higher than that of finishing paints.

Nowadays, high thickness inter coats are widely used to achieve films of 100 or 200 microns per coat.

Finishing paints

they are those that are applied as last coat of the painting system, either to the primer or to the intermediate coat.

Understanding the Different Types of Industrial Coatings

Industrial coatings appear everywhere. They protect a diverse array of products from corrosion, wear and tear and decay, as well as bringing an aesthetic and colorful appearance to the coated surface or product.

Manufacturers usually apply industrial coatings during the later stages of production. The finishing process, using the formulated coating material, protects the product.

With applications ranging from:

Building products
All other types of transportation equipment
Appliances and machinery
Construction and agricultural equipment
Aviation and shipbuilding industries
Oil, gas and petrochemical industries
Automotive and machinery industries
Hydropower plants

Well-chosen industrial coatings make manufactured products last longer, the variety of possible coated surfaces is huge: All types of metals, wood, concrete, and more.

Types of Coatings

Epoxies

Epoxy coatings are generally two-part curing systems that are mixed with a hardener before application. They are widely used as coatings in (moderate) corrosive environments and are often used for industrial applications applied either in solid or liquid form. The most common coating resin is bisphenol A epoxy. Liquid grades are usually solvent-free systems cured with aliphatic amines, amine adducts, amine terminated polyamides or blends thereof. Bisphenol A epoxies have good chemical resistance to a broad range of chemicals and excellent heat resistance, whereas hardness, abrasion resistance, toughness and adhesion properties depend largely on the cure conditions, hardener-resin ratio and type of hardener. A major drawback of liquid epoxy resins is their relative high viscosity. For this reason, reactive diluents are often added which not only reduce the viscosity but also improve room temperature cure. However, diluents can have a detrimental effect on the performance properties such as hardness and chemical resistance. Diluent-free systems are formulated with bisphenol F resins which have lower viscosities. However, these resins are typically more expensive, and result in less flexible and tough coatings. Other important epoxy resin systems include epoxy esters, nova lacs, and epoxy phenolic. The latter two resins improve heat, solvent and chemical resistance but result in decreased flexibility and often require heat cure to fully crosslink the resin.

Urethanes

Polyurethanes (PUR) are very versatile polymers with properties that can be tailored over a wide range for a large number of coating applications. They are known for their excellent chemical resistance, very good clarity, high gloss, and very good mechanical properties including hardness, flexibility and abrasion resistance. The main building blocks are di isocyanates and polyols. High performance urethane coatings are often formulated with aliphatic iso cyanates which impart good light stability and weathering resistance to the coating whereas aromatic iso cyanates have a tendency to yellow on prolonged exposure to sunlight. The elastomeric portion of the polyurethane is usually a polyester or polyether. Polyester-based urethane coatings have better oxidative stability and higher heat and abrasion resistance than polyether-based urethane coatings, but have lower hydrolytic stability and low-temperature flexibility.
PUR coatings are available as either one-part and two-part curing resins. The one-part urethanes harden by either air-drying/solvent evaporation, moisture-cure or heat-cure. Moisture curing urethanes are frequently used in interior and exterior wood coatings whereas heat curing one-part urethanes are often chosen for more demanding coating applications because they show very good overall performance. However, a heat cure process is costlier and inefficient. The two most important two-part urethane systems are 2k catalyzed and 2k ambient-cured urethanes. The latter is more common. Both systems are often used for auto refinishing, maintenance and protective coatings.

Silicones

Silicones are an important class of inorganic resins that are known for their high temperature and oxidative stability, excellent low temperature flexibility, and high resistance to weathering and many chemicals. Pure silicone paints are fully transparent, have outstanding UV resistance and retain their physical properties over a wide temperature range. They can be formulated to withstand temperatures up to 1200ºF (650ºC). However, these coatings are rather expensive and do not meet the requirements of all applications. To improve certain properties and to lower cost, they are often blended with organic resins such as alkyds, polyesters, acrylics and epoxies. However, this comes at the expense of their heat and chemical resistance.

Silicone coatings find many uses in a large number of industries including building & construction, marine, industrial machineries, medical devices, and automotive & transportation. Important applications include release coats, glazes for baking pans, trays and small kitchen appliances, water-repellent masonry/roof coatings and anti-fouling protection.

Zinc-Rich Coatings

These high performance coatings use zinc dust as a rust and corrosion preventative pigment. Organic zinc coatings are often made with epoxy or polyurethane resin binders, since high performance pigments justify high performance polymers.

Zinc coatings are particularly effective when used on steel, and provide dual function corrosion protection; both a galvanic and a polymeric barrier. Zinc-rich coatings are durable and resist abrasion.