Questions about the main chemical applications for the coatings market? - Asia

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FAQ – Coatings

Coatings

MAIN TECHNICAL QUESTIONS

The most frequently asked technical questions about the coatings market.

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PAINTS AND COATINGS

1- What are the basic components of paints and coatings?

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.

2- What additives can be used in 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.

3- How can coating performance be improved?

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.

4- What are the differences between automotive, industrial, and architectural paints?

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.

5- What is ecological paint?

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.

6- What are smart coatings?

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.

7- How to make a coating perform well?

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.

8- How important are surfactants in the manufacture of coatings?

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.

9- How does the pigment dispersal process work?

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.

10- What is the emulsion polymerization process for?

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.

11- How does the emulsion polymerization process work?

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/

12- How does the wetting process work?

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.

13- How do anionic and nonionic surfactants work?

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.

14- What are zero-VOC coatings?

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.

15- What are additives?

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

COALESCING AGENTS

1 - What is a coalescing agent?

Coalescing agents are solvents that plasticize the polymeric phase present in the formulations of coatings, enamels and adhesives, reducing their formation temperature and favoring particle deformation, as well as the interdiffusion of polymer chains.

2 - What role do coalescing agents play in the formulation of coatings?

In water-based architectural paint formulations, coalescing agents play a key role in the latex film formation process. These molecules mainly aid the final stage of particle coalescence.

3 - What are the benefits of coalescing agents?

Coalescing agents are responsible for ensuring that the coating makes a homogeneous/continuous film and generating a product that delivers the expected properties, such as brightness and mechanical and chemical resistance.

4 - How do coalescing agents help in coating performance?

They help to allow the polymer present in the paint to form into a film properly, while ensuring the protective and aesthetic properties of the coating.

5 - What is the film formation process by coalescing agents like?

The coalescence process occurs for water-based latex coatings, in which the drying process goes through three main steps:

Step 1: Evaporation of water from the medium, promoting the packing of polymeric particles.

Step 2: Irreversible contact occurs between polymeric particles, evaporation of residual water and deformation of polymer particles.

Step 3: In the final stage, coalescence promotes the interlacing of the polymer chains between neighboring particles, also known as coalescence, ensuring the formation of continuous and homogeneous film.

SOLVENTS

1 - What are solvents for in coatings?

Solvents provide adequate viscosity for application of coatings on the substrate, promoting resin dispersion across the surface, improving leveling, evaporation rate, and the final physical properties.

2 - What are coating solvents or solvent-based coatings?

In solvent-based coatings, the solvent plays a key role in controlling the solubility of resins and drying speed, which consequently has a strong influence on the final properties of paint or coating.

3 - What are the benefits of solvents for coatings?

Solvents, due to their excellent properties and versatility, have played an important role in formulations since the beginning of the paint industry. There are several criteria in choosing a solvent for use in paint and varnish formulations, the main ones being solvency power and evaporation rate. The choice of solvent depends on the desired characteristics, which are usually tied to the physical-chemical properties and their chemical nature.

4 - How do solvents work?

Solvents come into contact with the resin to lower viscosity, and fulfill fundamental functions in the preparation, stabilization, and application of paints and varnishes. They are present in the formulations for the most diverse segments: original automotive, automotive refinishing, can coatings, wood, industrial maintenance, printing, coil coatings, and so on. Also, solvents can adjust leveling and curing properties, besides playing a key role in the drying speed of the paint because the film is formed after evaporation of the solvent.

To know the solubility of a resin in each solvent, some models are understood, such as Hansen solubility parameters (HSP), which quantify the intermolecular forces of a compound. According to the HSP, the closer the intermolecular forces between different compounds, the greater the affinity between them. So, the combination of these properties is essential to ensuring solubility and compatibility of the solvent with the resins in each paint formulation.

EMULSIFIERS

1 - What is an emulsifier?

Emulsifying agents are surfactants added to emulsion processes to increase their stability, making them stable and homogeneous. The molecule in an emulsifier has a polar part (compatible with water) and another nonpolar part (compatible with the polymer). They are essential to the emulsion polymerization process.

2 - What is an emulsion?

It is a colloidal dispersion – that is, a mixture of two immiscible liquids, consisting of a dispersed phase and a continuous phase in which small droplets of one liquid mix or spread in the other liquid. Thera are oil in water emulsions, when the dispersed phase is oily – that is, the oil droplets are in an aqueous solution (continuous phase); or water in oil, when the water is the dispersed phase, and the oil is continuous.

3 - How do emulsifiers work in coatings?

Emulsifiers are essential components for the formulation of coatings, having numerous functions. They can be surfactants that enter the composition of latex in emulsion polymerization, and they can also act as dispersants or wetting pigments and mineral fillers. Basically, they act as system stabilizers.

4 - What types of emulsifiers are there?

The main types of emulsifiers or surfactants anionic, responsible for the electrostatic stability of particles, nonionic surfactants, responsible for steric stabilization.

BUILDING BLOCKS

1- What are building blocks?

Building blocks are functional products used in various resin and paint formulations. Due to their reactive nature, they can be incorporated into the polymeric film of paints, contributing to the final properties of paint systems, ensuring high performance, such as improving strength and durability, appearance, flexibility, stability, etc. Indovinya’s Building Block portfolio is composed of functional molecules that can be used both as monomers for the synthesis of polyester, alkyd, polyurethane and epoxy resins, and directly in the formulation of high-performance industrial paints.

In general, we classify Building Blocks as monomers, oligomers, and materials used for the synthesis of resins and polymers in general, as well as, when looking at formulations of functional paints, resins and binders, hardeners and cross-linkers, since such substances have reactive functional groups and participate in the synthesis or curing reaction of high-performance coating systems. The appropriate choice of building blocks for a system is directly linked to the set of properties that is sought in the final application of the coating.

2- How do building blocks work?

When properly formulated, taking into account functionality and the correct stoichiometry in a given polymer formulation, or bi-component painting system, Building Blocks will participate in organic reactions (polymerization or curing) that promote the formation of the polymer matrix in coatings. Polyols, one of the types of Building Blocks offered by Indovinya, are a class of materials widely explored in the coatings industry. Because they have free hydroxyls as functional groups, polyols have a broad range of applications in the synthesis of polymers (e.g. polyesters, alkyds, epoxys) and contribute to the balance of the properties of the polymer and, consequently, the final coating. Hydroxyls are also the main feature when we look at bi-component systems for coatings, and the polyurethane system (polyol reaction with polyacrylates) is one of the most used in high-performance coatings. Mechanical properties such as flexibility, adhesion, and impact resistance, as well as improved durability and chemical resistance, are examples of the properties that can be improved when using alkoxylated polyols, such as those in the ULTRATINT® line.