It is difficult to definitively classify the different types of industrial paints and coatings, as there can be different interpretations depending on factors such as their composition, their position in the finishing system or even depending on how the paint dries and hardens after application.
In order for an industrial paint to fulfill its protective and decorative functions, it is essential to know the particularities of each painting system and process. We can classify industrial paint according to its position in the application layer:
Coatings
These are the first coats of paint in direct contact with the substrate, highly pigmented and with a low binder content.
Their mission is to act as an anchor for subsequent layers of paint and to prevent oxidation of metal surfaces thanks to the anti-corrosion pigments it contains.
Intermediate Coats Of Paint
These coats are applied over the plaster, with the mission, in general, of increasing the thickness of the paint system, in order to avoid giving several finishing coats, thus reducing the application costs.
The pigment/binder ratio is lower than that of fillers but higher than that of topcoats.
Nowadays, high thickness intermediate layers are very widely used to obtain films of 100 or 200 microns per layer.
Finishing Paints
As their name suggests, these are the ones that are applied as the last layer of the paint system, either on the plaster or on the intermediate layer.
They are formulated with a low pigment/binder ratio to achieve the best permeability and strength properties. These are normally gloss paints, although there is an increasing demand for satin and matt finishes in the market.
Varnish
These are coatings composed of binder and thinners. The varnishes in industrial painting have two main objectives: on the one hand, to embellish the painted part and, on the other hand, to provide it with additional protection against external agents or mechanical shocks.
There are several types: synthetic varnish, acrylic varnish, polyurethane varnish, glossy effect, matte effect, etc.
Nitrocellulose Paint
Nitrocellulose is one of the oldest resins used in the manufacture of paints and varnishes. This type of paint represented an important step in the development of industrial paint, as it allows to obtain finishes that are easy to apply, fast drying and optimal performance.
Nitrocellulose paints have a series of unique characteristics that allow them to obtain additional advantages in many applications, among which we can mention:
- High solubility in organic solvents.
- Compatibility with different resins and plasticizers.
- Transparent and colorless films.
- Odorless and non-toxic.
- Rapid removal of solvents during application and low retention of residual solvents.
- Fast drying.
- Availability in different viscosities.
Synthetic Paint Or Alkyd Paint
Industrial development was accompanied by the development of chemical synthesis applied for industrial purposes.
Among the many researches carried out to improve the performance of oil-based paints, a synthetic product has been developed, obtained by the reaction of a polybasic acid such as phthalic acid with a polyalcohol such as glycerin, resulting in a polyester.
This polyester could not be used pure because it was extremely hard. The modification of its molecule with an oil gave rise to a product with specific characteristics, classified as an alkyd resin.
The glycerophthalic polyester/oil ratio and/or the type of oil selected gave it specific characteristics in terms of drying, hardness, elasticity, solubility, etc. ; to formulate specific alkyd resins for a given paint use.
It is a type of industrial paint that uses oxygen to complete the chemical reaction and thus provide durable finishes.
These coatings take longer to dry than other types of paint because the oxygen must disperse over the entire paint film for proper application.
Epoxy Paint
Epoxy paint is one of the most widely used industrial coatings. It offers balanced performance for different types of industrial painting projects, thanks to its excellent protection properties against corrosion, impact or abrasion.
It also offers very fast drying times, thus promoting productivity, as well as a high adhesion capacity on different materials and surfaces (iron, zinc, aluminum, etc.).