By Santiago Jaramillo H.
Solvent-based paint formulators are making more and more efforts to achieve greater harmony with the environment. In the same way, local legislation in Latin American countries seeks to harden so that in the medium and long term the consequences of pollution are less.
Currently in the area of Latin America many of the laws that seek to control the emissions of VOCs and polluting materials in solvent-based paints have raised concerns, since the permissiveness of the same is still very high compared to world standards so the paint sector, together with environmental groups, has expressed its concern and, prior to updating the levels of requirement of the laws, they have advanced to produce less polluting compounds.
"The regulations for the manufacture of solvent-based paints and coatings are subject to constant updating through European directives, all member countries must submit to these directives within the deadlines set in each of them. The regulations include both the limitations or prohibitions of the use of certain raw materials and the labeling of paints according to their composition," said Jordi Calvo Carbonell, who is a Chemical Technical Engineer and author of the book "Paints and coatings introduction to their technology".
Meanwhile, Gerardo Gurrola, director of research and development in Mexico of the company Sherwin Williams S.A., indicated that in this country "there is a legislation of volatile organic material, which is an official Mexican standard, but this is being reviewed through the National Association of Manufacturers of Paints and Inks (Anafapyt), because at present it is too high, is 450 grams per liter. In both architectural and industrial paintings there is no differentiation in terms of VOC content, so it is being sought to lower it to 200 grams per liter at an initial stage and later up to 100, but this is hardly in the revision stage. "
On the other hand, our experts when asked why components could be the most advisable in the formulation of solvent-based paints, stressed that although it is difficult to accurately indicate any particular component, since each company has its own formulation, what should be sought is to maintain, to a greater extent, a good relationship with the environment.
"No specific recommendations can be made since each paint or coating has a different formulation scheme that in one way or another involves the use of certain components. In general, it can be said that taking into account the regulations of each country, the products with the lowest environmental impact and least dangerous are for the health of the people who come into contact with the product should be used; we can give as an example the substitution of lead, chromium and molybdate pigments for organic pigments, in terms of solvents whenever it is possible to replace aromatics with aliphatics, glycols with ethers, etc.", said Calvo Carbonell.
Meanwhile, Gurrola ponders that "there are several types of solvent-based paints, those for architectural and industrial use, and the most harmful components are the unsubstituted aromatic ones such as benzene, also toluene that is already coming out of use and eventually is trying to use aliphatic naphthas and xylene".
In the same sense, this representative of the Mexican industry clarifies that "all components can be replaced, but a differentiation has to be made between architectural alkalic enamels and industrial coatings. Architectural alkalic enamels can be substituted in solvents by a proportion of water up to 25%. While in the industrial sector it is difficult to replace them, what is done in these is to use products with a higher content of solids so that it goes less solvent to the environment". Environmental vocation
Large companies in the paint sector are aware of the serious damage they can cause to the environment by having among their compounds to produce solvent-based paints elements with high levels of pollutants, so for a considerable time they have been advancing initiatives that are for environmental conservation, seeking in passing to correct the legislative gaps that exist.
Our guest of Sherwin Williams S.A., relates some processes that they do from the company he represents to contribute in this matter "the first thing we do in alkydálicos that are for architectural use is to replace solvent with emulsified water. In the industrial, on the other hand, what we do is raise the content of solids and in many cases get to use coatings that are 100% solid, that is, free of solvents. On the other hand, also in the industrial sectors we are launching new products that are emulsified in water".
Likewise, Gerardo Gurrola highlights that "in terms of production we have solvent captor filters that are made from activated carbon and are changed every month or month and a half depending on how saturated they are according to the production".
Meanwhile, Calvo Carbonell warns that the most important thing is "to control the VOC from the moment the formulation of the product begins in order that in its commercialization phase it complies with the requirements of the legislation in each geographical area, but it is very important to control the manufacture and each of its phases, since VOC emissions are initiated in this process. During the dispersion and grinding of the paints the temperature of the product increases and can easily reach 40-50ºC which facilitates the evaporation of solvents and therefore the emission of VOC; these emissions can be measured with appropriate instruments and put the means to reduce emissions by means of properly placed extractor hoods and specific filters for the solvents being processed."
Solvents, their advantages and disadvantages
Each type of paint has certain solvents suitable for solubilizing the binder of the same. If we talk in a general way, the most used are White Spirit or Mineral Spirit and Xylene, then, on a smaller scale, esters, ketones and alcohols.
As our guest Jordi Calvo Carbonell had already mentioned, "we cannot talk about the advantages or disadvantages of each of them since the solvents must be adapted to the binder during the entire time that the evaporation of these lasts. What can be optimized is the proportion of solvent mixtures, for example in a solvent for nitrocellulosic lacquers esters and ketones can be minimized in favor of aromatic solvents such as xylene and toluene, but taking into account that the solvent capacity of the mixture during evaporation must be maintained so that insolubilizations do not occur. "
As for replacing products with others of lower toxicity, Calvo Carbonell, indicates that "certain glycols are susceptible to be replaced by ethers and aromatic solvents by aliphatic whenever possible, however, the path to the reduction of VOC depends on the sector of application, in decorative paints the substitution of solvents by water or the replacement of conventional binders by others modified to be water-soluble or hydrodispersible it is one of the paths that can also be opted for the formulation in high solids although this leads to an increase in the cost of raw materials parallel to a greater efficiency of the product which is not always easy to bring to the market. In industrial paint the way forward is similar to the exposed one while in anticorrosive paint the tendency is to work with high solid or solvent-free paints, that is, 100% solid". Evolution of the segment
Solvent-based paints are experiencing an increasing tendency to lose presence in the market, since formulations with a greater presence of water and more environmentally friendly elements are gaining greater strength.
This was shown by our guest staff when asked about it: "Depending on the sector of application there is a decrease in the group of products with solvent such is the case of architectural and decorative paints, where enamels tend to a change of orientation in their design, paints for facades, already mostly formulated in aqueous base, they give way in the niches of consolidants historically in solvent base to aqueous products, the paints for walls of high quality also in solvent base are moving to aqueous systems, "says Calvo Carbonell.
As for the paint factories, "more or less 80% of their sale is water-based products for architectural coatings and 20% solvent-based," says Gerardo Gurrola.
With regard to high solids paints, as Calvo Carbonell clarifies, "these have had a strong increase in industrial maintenance paints, where the client is able to understand that more solid means a higher performance and therefore the price can be increased, however, this philosophy is difficult to apply to what we could call DIY paint. All this has led to the use of high solid or 100% solid paints in a very specific sector that is that of industrial or anticorrosive protection always to the detriment of paints with solvents".
Finally, a group of paints strongly affected are the intumescent paints that are increasingly used in the protection of structures against fire, "today 90% of these paints are manufactured in aqueous base", concluded Calvo Carbonell.
Leave your comment