FLOORS AND COATINGS FOR CLEAN ROOMS
Among the elements that make up the physical structure of a clean room, the floor and its coating are undoubtedly the elements of greatest demand. It is over these that, daily, there is intense traffic of people, vehicles, raw materials, machines, etc.
The coating is an element that does not work by itself – it depends directly on the substrate on which it will be settled upon. Many of the existing pathologies in the coatings are due to its substrate, usually a concrete floor, which has problems of execution, dimensioning or structure.
Coatings can be classified into two categories: installed and applied.
The installed coatings are usually vinyl blankets, ceramics, stones, etc.
The applied coatings are epoxy, polyurethane, granilite, etc. coatings known technically as High Performance Coatings (HPC).
In this paper, resin-based RADs will be treated as representing almost 100% of coatings applied in clean rooms. Epoxy-based coatings account for around 90% of the market.
The first types of coatings in pharmaceutical plants were the cementitious base coatings, known granilites, Korodur, granitin. Acrylic, polyurethane, epoxy waxes were applied over these coatings until the pores were removed and a waterproofing layer was formed.
This type of coating had two drawbacks: a large number of cracks, due to its excessive stiffness and the high cost of maintenance with waxes and workmanship.
One variation of this type of flooring was the floors clad with natural stones like granite. Also this type of coating ends up requiring the application of waxes, besides having a great amount of grout.
In 1936 a Swiss dentist, Dr. Pierre Castan, invented the epoxy resin. In 1953, in the same country, it began the first coatings based on epoxy resin.
With the increase in the resins supply, the multiplication of companies specializing in the formulation and application of coatings and the increasingly stringent requirements of Brazilian National Sanitary Surveillance Agency (ANVISA), resin-based coatings became popular and became the best Cost benefit option in the market.
Today resin-based coatings are widely used in all areas of the pharmaceutical industry.
The specification of the most correct coating will depend on some factors that are a function of the mechanical and chemical demands of the area to be coated.
1. Coating Thickness – Coating thickness will be defined by two factors: the need for impact resistance and the quality of the substrate (concrete floor). If in the area to be coated there is a constant drop in objects or risk of impact, a thicker coating is required to absorb the impacts. Also if the substrate is very irregular, with a rustic texture, it is necessary to perform a thicker coating to eliminate the imperfections.
2. Coating Texture – Coating texture is intrinsically related to asepsis and sanitizing. A coating with a very rough texture is more resistant to scratches and abrasion, but it can make cleaning difficult. Smooth textures are specified when it is necessary and easier to hygienize the room. In wet rooms you should balance the texture so that it does not get slippery or very non-slip, which would impair the cleaning of the coating.
3. Abrasion resistance – Abrasion or scratch resistance is related to the presence of high hardness materials on the surface of the coating. These materials are usually quartz, glass beads, oxides or ceramic materials. This feature is desired when you have too much crawling of boxes, equipment or high traffic.
4. Aesthetics – Aesthetics has proved to be an important factor as more and more users have demanded technical factors with an aesthetic differential.
4. TYPES OF COATINGS
There are basically three types of coatings and paints. Paints are not considered coatings due to its low thickness and low strength.
- SELF-LEVERING COATING
The self-leveling coating was probably the most used coating in clean rooms and in areas where an extremely smooth and easy-to-clean surface is desired.
Its characteristic is single layer, ranging from 1.5 to 4.0 mm, well flowed, rich in resin, generating a pore-free coating with a smooth and shiny texture.
Its main advantages are the smooth texture, the speed in the application and the good flatness, if well applied.
Its main disadvantages are the low resistance to scratches, medium impact resistance and the sensitivity to rising humidity.
This type of flooring has been loosing space for new generations of flooring because it presents a worn floor appearance in a few months of use.
- SPATULATED AND MORTAR COATINGS
The spatulate coating is the medium thickness coating, ranging from 3 to 6 mm. Due to this feature is the coating that best absorbs impacts.
Its feature is a two-stage coating, mortar and resin-poor finishing paint, which provides a coating with a porous structure, and can have a finish ranging from anti-slip to thick paint with “orange peel” texture. The spatulate coating, when sealed with a high-thickness paint, has no pores on its surface and can be used in clean rooms.
Its major advantages are high impact strength, abrasion, long life and easy maintenance.
Its disadvantages are the less smooth texture, high variability in thickness, low flatness index and high porosity in the internal structure.
- MULTILAYER COATINGS
Multilayer coating is the most versatile, with various finishing possibilities and that balances the characteristics of the self-leveling coating and the spatula.
Its characteristic is a multilayer coating with varied finishes, ranging from a simple paint to a translucent sealer with microspheres of glass.
Its advantages are high resistance to impacts and scratches, numerous possibilities of textures and finishes, high flatness, low variability in thickness, lower cost, long durability and easy maintenance.
Its downside is the need for a longer application period.
5. NEW MATERIALS AND TECHNOLOGIES
The coating market, after a long period of stagnation, without great innovations, has presented new technologies with the use of materials with better performance and innovative application methods.
Among the innovations in materials we have the methacrylic resins, the ceramic aggregates, the carbon fibers and the glass microspheres.
Coatings made with glass microspheres have been rapidly gaining market share because they have high impact strength, abrasion, scratches and aesthetically superior properties. By having in its last layer exclusively micro glass beads and resins, this coating does not have pores or absorption characteristics, they present superior resistance to chemical attacks and color stability.
The new application process is the Pharma, Terrazzo and Soleceram, high performance coatings, which are still very expensive, and are being introduced in Brazil by European companies.
6. FINAL CONSIDERATIONS
The regulations of the National Health Surveillance Agency (ANVISA) require that:
- RDC – 135 – Pharmaceutical Industry
11.5.5 In areas where raw materials, primary packaging materials, intermediate products or bulk materials are exposed to the environment, the interior surfaces (walls, floors and ceilings) shall be coated with a smooth, waterproof, washable and resistant material , Free of joints and cracks, easy to clean, allowing disinfection and not releasing particles.
- Port. 172
188.8.131.52 All surfaces of the handling area shall be lined with sanitizing agents, smooth and impermeable, having rounded corners.
To meet the requirements of ANVISA, the most suitable coatings are resin-based coatings, especially multilayer coatings with two- or three-layer resin finishes and self-leveling coatings.
Alexis Joseph Steverlynck Fonteyne
Vice-presidente da ANAPRE
Diretor da Solepoxy / Propiso