MAIN TECHNICAL QUESTIONS

They are basically:

• Film formers (latex, resins, and hardeners)
• Volatile components (solvents and coalescents)
• Insoluble components (pigments and fillers)
• Additives

There is also a distinction between water-based,solvent-based and 100% solids paints and coatings. Water-based use water as a solvent, meaning film formers are diluted in water. Solvent-based use organic solvents to dilute film formers. There are no volatile components in 100% solids paints and coatings.

Additives improve specific attributes in formulations or aid in paint/coating manufacturing processes. They are used in small dosages and can aid properties such as viscosity, leveling, color development, foam reduction, coverage, etc.

The main additives are wetting and dispersing agents, defoamers, and rheological modifiers.

Paint and coating performance is very complex, making additives essential.

The starting point is to understand the final application of the coating, as well as the final attributes and properties desired. This makes it essential to select the additives that will provide the expected benefits and use them in the appropriate dosage.

Automotive paints are the ones automakers apply, and those used in refinishing a vehicle. Industrial paints are usually applied when the item is manufactured such as household appliances, metal structures or equipment. They can be have specific properties such asas anti-corrosion or abrasion resistance. Architectural paints are decorative paints, applied on both internal and external building surfaces. These types of paint are formulated very differentlybased on:

• In the substrate that will be coated: wood, metal, masonry or polymers. etc.
• In the form of application: spray, roller, brush or dip.
• In the curing mode: ambiant temperature, elevated temperature (baking), UV or radiation, or two component cure.
• In the final properties required: physical properties, chemical resistance, gloss, color, exterior durability or other specific required properties., etc.

Ecological paints are those that are less harmful to the environment and human health, such as those based on sustainable content, with low VOC emissions, low odor, without the presence of toxic substances.

There is no formal classification of ecological paint. There are paints that are guaranteed to meet specifications from government and independent organizations, such as the Green Seal^®, which certifies VOC limit standards, the safety of the chemicals involved, environmentally friendly packaging and performance, ensuring safety in environmental, toxicological, and human health aspects.

The world is constantly changing, and coating technology is evolving to serve new demands and meet the challenges in a universe of applications that is already diverse and demanding. Formulations now not only need to protect and decorate surfaces but are also becoming multifunctional, adding value to consumer goods and positively impacting people’s daily lives and well-being.

In this scenario, interest in smart coatings is increasing. Their innovative proposal is to assign to coatings a functional role to be transferred to the surface or product they are applied to. Some examples of these products are utensils with non-stick surfaces, the prevention of biological contamination on floors and walls, equipment with self-cleaning surfaces, coatings that regenerate if damaged, and so on.

Choosing the best quality raw materials that meet the customers’ needs is the first step. Using them properly and with the correct dosages will ensure the quality of your final product.

Surfactants are essential components in the formulation of coatings. They are used in the composition of resin emulsion, they come in during the polymerization process and, in the final coating, during the dispersion of pigments and fillers. In these processes, they act as system stabilizers. In addition, surfactants can be used as additives to adjust specific properties of the formulation, based on one of their main characteristics, the hydrophilic-lipophilic balance (HLB), it is possible to choose the most suitable molecule for each specific application, having a huge influence on the final performance of the coating.

The pigment dispersion process can be divided into three stages: wetting, dispersion/grinding, and stabilization. In the wetting stage it is important to use an additive that reduces the surface tension of the water and allows it to penetrate the pores of the pigments, so facilitating the wettability of the pigments to be dispersed.

In the dispersion/grinding stage, pigment agglomerates are mechanically separated into smaller particles. The wetting and dispersing surfactants act synergistically to ensure that the wetting of the smaller particles generated occurs more quickly and that the particles are not re-agglomerated.  Therefore, surfactants reduce the processing time and, consequently, the energy needed.

The right wetting and dispersing surfactant decreases the interaction between pigment particles, lowering the viscosity of the medium, allowing a greater incorporation of the pigment content and ensuring the stabilization of dispersed particles over time. As the color of the pigments occurs by the absorption and scattering of light on their surface, the size of the pigment particles, in addition to the charged amount, directly interferes with the color produced.

To obtain a water based resin emulsion, the main component of paints and water-based adhesives, the main process used is polymerization in emulsion. In it, monomers are polymerized in an aqueous medium through free radical polymerization, where surfactants are necessary for the stabilization of the system during polymerization, and of dispersed polymer particles formed.

The batch polymerization process consists of adding all the inputs, among which are a surfactant solution, a mixture of monomers, and starter solution, to the reactor at the beginning of the process and maintaining polymerization in a certain condition of agitation/temperature until the conversion of the monomer into a polymer close to 100%. Learn more here: https://oxiteno.com/us/en/surfactants-emulsion-polymerization/

Pigment wetting in water-based systems is a challenging phenomenon, mainly due to the high surface tension of water, compared to other media. This great energy difference in the pigment/water interface hinders the wettability of aggregates and particle clusters and their incorporation into the grinding load. The wetting surfactant reduces the surface tension of the water and, consequently, reduces the energy difference in the pigment/water interface, favoring the penetration of water in the pigment particle clusters and facilitating the dispersion process.

Anionic and nonionic surfactants are widely used in emulsion polymerization of conventional anionic latices. Usually, a single surfactant is not enough to produce latex with all the required features. Anionic surfactants promote the mechanical stability of latex through the electrostatic stabilization of particles, while nonionic surfactants promote stability to electrolytes and heating and cooling cycles through steric stabilization.

There are paints that have low volatile organic compound (VOC) content. These are compounds that have a low boiling point and evaporate easily from the surface of the film. These VOCs have high vapor pressure, so when they come into contact with the atmosphere, they quickly turn into gases that can harm human health and the environment.

The methods used for quantification and the VOC limits allowed vary by country and region.

Additives are ingredients added in small quantities (usually below 2% by weight) to modify specific properties. They can be simple molecules or polymers, organic or inorganic, soluble or insoluble in the medium. Learn more at: https://www.blucher.com.br/manual-descomplicado-de-tecnologia-de-tintas_9788521212447