Although the industry concentrates efforts to massify the production of more environmentally friendly paints, there are still products made with solvents on the market. Is the issue one of costs or lack of environmental awareness?By Vanesa Restrepo
At a time when the concept of green and ecological dominates the market, and a large part of consumers have based their purchasing decisions on a label that contains the words green, environmental or sustainable, even the paints and coatings industry formulates products with solvents and VOC contents higher than those recommended by international standards.
The reasons are multiple: from the lack of regulation in Latin countries regarding the grams of solvent allowed per liter of paint, ignorance of the benefits of water-based systems and high solids, lack of research and own developments among producers, among others.
The presence of solvents in the paints that are marketed creates a serious environmental problem. Not only because these solvents contain volatile organic compounds that destroy the ozone layer, but also because when using them some applicators mix the paints with more solvents, in order to decrease their viscosity or increase performance. As a result, there is an increase in the percentages of VOCs that go into the atmosphere, in addition to the contamination of the water by solvents that is generated when brushes, rollers, guns and other application elements are washed near the sewers, or when paint and solvent residues are poured into them that will no longer be used on the site.
And where are they used?
The architectural segment, which presents greater informality among the applicators, is the one with the lowest share of solvents within the total of products available in the market. According to Hugo de Notta's exhibition at the European Coating Show, by 2006 83.2% of the global architectural paint market was water-based, and by 2011 it is estimated that the figure could exceed 85.7%, thanks to the expansion of regulations and the creation of legislation in each country.
However, in the industrial, maritime and aerospace sectors, the growth of new systems (water and high solids) has been gradual and slower, due to the fact that superior performances are required in certain aspects such as resistance to chemical or environmental attacks, durability, adhesion and anticorrosive capacity.
Julián Restrepo, Innovation Coordinator at the Colombian company Invesa, points out that solvent-based systems are still used in the wood and industrial lines, as there are many technicians who believe that the new systems could be more expensive. "Awareness is needed, we need to sell a little more the advantages of water-based, not only environmentally but also economically (...) In woods, for example, people are still unaware of the new systems and are frightened to mention that they are water-based, so they think: 'This is wood. If I apply water to it, then what happens?' That's where we need to show the advantages to make it more attractive to switch."
The intensive use of solvents is also felt in Peru, where the issue goes through quality and costs. According to Jaime Baldeón, New Product Development Coordinator of CPPQ S.A, a paint formulation company in that Andean country, the lack of regulation is evident in the type of products that are marketed. "Many manufacturers are still using solvents above regulations. Small factories produce products with high solvent content and since there is no government requirement, customers buy them because they are cheap, and the manufacturer sells them because it needs to sell," he explains.
Looking for replacements
When thinking about new systems to replace the solvents used in current formulations, the main question remains the performance of the products. According to Julián Restrepo, most of the products that are marketed today as solvents have some replacement of equal or slightly lower performance, which does not affect their performance and durability.
Among the solvents that are still used in plants, aromatics such as benzene and xylene stand out, because according to manufacturers they are easier to work with some resins. Similarly, alcohols and esters are used for polyurethanes, as well as some ketones that are used in epoxies and polyurethanes.
Restrepo is adamant that aromatic solvents are large contaminants, so their use should be discontinued. He notes that substances such as varsol and xylene are also common given their low cost, and recommended that toluenes and benzenes be eliminated quickly.
However, in the lines of coatings for wood and the industrial line, products containing this type of substance are still marketed, sometimes at levels higher than 250 grams per liter, which is recommended by international standards.
At a slow pace
The replacement of the rest of the solvents that are still in the paints and coatings market is subject to the regulation issued by Latin American governments, especially with regard to marine paints, since there is still a real impact on ecosystems on account of some compounds that they continue to use even when their harmful effects are already known.
The idea is to replicate the success obtained in the segment of architectural paints, in which solvents disappeared almost completely, from the moment in which the damage to the health of children produced by elements and compounds such as lead was made public. After end users became aware of the effects to which they were exposed, they began to demand less harmful products but with equal performance, which pushed the development of new paints that met these requirements.
Additionally, some investment is required between contractors and applicators, because although it is not strictly necessary to replace the guns, cabins and application pumps; if it is necessary to train the staff in the use and handling of the new paints, either based on water, dust or high solids. This is because the mixtures are different, as well as the drying times, viscosity, among other elements.
Main types of solvents
In order to enlighten readers, we have reviewed information regarding the most common types of solvents in the paint industry. In their order, they are:
* Water. It is the most common solvent that exists and is used for paints, especially plastic and some types of epoxy and acrylic enamels, etc. It is increasingly present in the market, given the greater ecological awareness and the regulations that limit the use of VOCs.
* Turpentine. It refers to a volatile and colorless liquid that is obtained by distilling from the resin of pine trees. Its composition varies according to the plant species from which it is extracted. It is used as a raw material and solvent for all types of oil paints, enamels, among others.
* Nitro or nitrocellulosic solvent. It is a mixture of hydrocarbons, esters, ketones and alcohols obtained by synthesis or distillation, suitable for the dissolution of all types of nitrocellulosic products (paints, varnishes, etc.). It is also used as a diluent of some synthetic paints when applied with a gun and a very rapid evaporation of the solvent is desired.
* Polyurethane solvent. It is a mixture of hydrocarbons, esters and ketones obtained by synthesis or distillation, suitable for the dissolution of polyurethane-based products. It is also useful for nitrocellulosics and synthetics, but it is advisable to test the compatibility beforehand.
* Special solvents. They are used in certain types of paints of less use, such as solvents for chlorinated rubber paints or solvents for epoxy. There are also solvents for special applications, for example in chemical pretreatments, to remove grease and oil from metal surfaces.
