Common Materials Used in Coatings

PCI’s online Materials Directory has just launched. The Directory features suppliers and distributors of the multitude of additives, resins and pigments used to formulate and manufacture coatings. Below is a selection of some common products featured in our Directory, along with a few of the suppliers of these products.

Click on the material headings below to link to that section in our Directory. And click on the company logos to view those specific listings.

Acrylic Resins, Styrene Acrylic Emulsions

An acrylic resin is a polymeric material (in solution, dispersion or solid) containing acrylic monomers. These monomers are usually esters of acrylic, methacrylic acids or their derivatives, and can be functionalized by introducing different chemical groups (R groups). Other monomers can also be incorporated in the polymer chains in order to obtain resins with different properties or lower cost.

In general, acrylic resins show good chemical and photochemical resistance. They are commonly used in many different applications, from solvent-based and water-based industrial coatings to architectural coatings.

Key parameters of an acrylic resin are: Tg (glass transition temperature), average molecular weight of the polymers, and polymer molecular weight distribution. These parameters have an impact on the resin properties (viscosity, dispersion, etc.) and on the final film/coating obtained (flexibility/hardness, etc.).

Styrene monomers are probably the most used, and the resulting resins are known as styrene-acrylic. Styrene monomers are significantly less expensive than the acrylic monomers. They are known to increase water resistance and to lead to both alkali resistance and improved hardness. However styrene-acrylic resins are often subject to yellowing and chalking, which can reduce their potential applications.(Source: SpecialChem, https://coatings.specialchem.com/selection-guide/acrylic-resins-for-coatings)

Additives for Water-Based Systems

Waterborne coatings use water as a solvent to disperse the resin and other ingredients, thus making these coatings more environmentally friendly than their solvent-based counterparts. As the world pushes for more eco-friendly products, waterborne coatings are being increasingly used in all segments of the coatings industry. The task for coatings manufacturers is to develop water-based coatings that meet the same performance parameters as solvent-based coatings do, as water performs differently and introduces unique challenges. There are a multitude of additives designed specifically for all types of water-based coatings that can help formulators address these challenges and introduce performance attributes that meet or exceed solvent-based products. (Source: PCI Magazine)

Carbon Black

Carbon black is a black special chemical that is available as powder or beads. It is manufactured through highly controlled processes and contains more than 95 percent pure carbon and other components including oxygen, hydrogen and nitrogen. The black particles are 10 nm to approx. 500 nm big, and fuse into chain-like aggregates that define the structure of individual carbon black grades. Depending on the production process, carbon black types differ in size, surface chemistry, porosity and many other characteristics. During the aftertreatment process, the oxygen percentage within the carbon black can be changed according to the required needs.

Carbon black is used in a multitude of industries. It can be blended with additives, elastomers or binding agents and integrated into the customers' existing formulas, or it can be pre-processed in a form called a "preparation". A preparation is a mixture of carbon black and other additives, and streamlines production. (Source: Orion Engineered Carbons, https://www.orioncarbons.com/what_is_carbon_black)

Corrosion Inhibitors

Corrosion inhibitors are compounds that improve a coating’s ability to protect aluminum, brass, copper and steel. The term refers to a variety of materials used to prevent the oxidation of metals, including surface treatments, undercoats, and additives or elements alloyed to the surface of the metal. Corrosion poses a major potential problem for metal surfaces that are typically protected through the use of zinc-rich coatings, the use of anti-corrosive pigments and the application of a barrier coat.

Flash rust inhibitors are often used to prevent in-can corrosion during the storage of waterborne coatings. Inhibitors also may prevent the corrosion of ferrous metals during the drying time of waterborne coatings. Sodium nitrite typically has been used in the past. Other types of materials include the following: organic zinc complexes, salts of dodecylnaphthalenesulfonic acid, ammonium benzoate, 2-aminomethoxypropanol and amine neutralized thiosuccinic acid. (Source: 2013 Additives Handbook, By Dr. Joseph V. Koleske, Robert Springate and Dr. Darlene Brezinski)

Defoamers, Misc. Defoamers

Defoamers, deaerators and antifoaming agents are all additives used to prevent, reduce or eliminate foam in a coating, whether in-can, during application or in the final film. While these terms are used interchangeably, they are different. Defoamers are designed to work at the surface to break bubbles already created. Deaerators are designed to work in the bulk liquid to move air bubbles to the surface so defoamers can break them. Antifoaming agents are designed to prevent foam from forming. While an additive is designed to do one, they will all tend to do all three, but with varying efficiency. (Source: Mike Praw, Indorama Ventures) 

Defoamers, Non-Silicone

Non-silicone defoamers are designed to be used in systems where the presence of silicone is not allowed, such as in automotive coatings. Non-silicone defoamers have limits on the incompatibility due to the nature of the chemistry. (Source: Mike Praw, Indorama Ventures)

Defoamers, Silicone

These are based on silicone chemistry for higher incompatibility and greater efficiency. The higher the incompatibility of the additive, the greater the defoaming but the higher the chance of surface defects. (Source: Mike Praw, Indorama Ventures)

Distributors, Additives

Additives distributors are an integral part of a supplier’s business. They act as an extension of the supplier’s technical sales and marketing groups by providing sales and operational support in a specified territory. From a logistical standpoint, the distributor maintains local inventory to supply the customers’ requirements, which are often on a just-in-time basis. Distributors service customers of all sizes equally well, with support tailored to each account. This can include product coding and/or re-palletizing to customer specification, handling credit issues as well as providing both technical and logistical support. Distributors routinely provide their suppliers with sales trends and marketing opportunities, and tailor sales reports to meet supplier requirements.

Distributors today are involved in technical problem solving and are being treated as an extension of both the customer and the supplier technical teams. These technical support roles are highly trained, well-educated industry professionals. They play a significant role in the customer innovation process by leveraging the resources available to them. These resources include testing, benchmarking and formulation development. (Source: PCI Magazine, October 2014 issue, https://www.pcimag.com/articles/99684-paint-and-coating-distributor-focus)  

Distributors, Resins/Polymers

Resin/polymer distributors are an integral part of a supplier’s business. They act as an extension of the supplier’s technical sales and marketing groups by providing sales and operational support in a specified territory. From a logistical standpoint, the distributor maintains local inventory to supply the customers’ requirements, which are often on a just-in-time basis. Distributors service customers of all sizes equally well, with support tailored to each account. This can include product coding and/or re-palletizing to customer specification, handling credit issues as well as providing both technical and logistical support. Distributors routinely provide their suppliers with sales trends and marketing opportunities, and tailor sales reports to meet supplier requirements.

Distributors today are involved in technical problem solving and are being treated as an extension of both the customer and the supplier technical teams. These technical support roles are highly trained, well-educated industry professionals. They play a significant role in the customer innovation process by leveraging the resources available to them. These resources include testing, benchmarking and formulation development. (Source: PCI Magazine, October 2014 issue, https://www.pcimag.com/articles/99684-paint-and-coating-distributor-focus)  

Driers, Waterborne

A drier is a compound that catalyzes or accelerates the drying (curing, hardening) of oil, paint, printing ink or varnish, or the crosslinking of polymers or drying oils. Driers are not the same as curing agents, which chemically react with functional groups in the polymer. Driers are catalytic in nature and do not chemically react with the polymeric material. Driers promote or accelerate the drying, curing or hardening of oxidizable coatings vehicles.  

Cobalt is the most active drier and a strong oxidizer, however cobalt driers have been identified by the European Union as having high toxicological potential, which has created a market need to formulate with a cobalt-free alternative. Both cobalt-free and cobalt-based driers help paint, coatings and inks dry faster and more evenly, which create more durable and resistant coatings and allows coatings applicators more efficient production. (Sources: 2013 Additives Handbook, By Dr. Joseph V. Koleske, Robert Springate and Dr. Darlene Brezinski; and allnex website, https://allnex.com/en/technologies/additives/cobalt-free-cobalt-based-driers)  

Lampblack

Lampblack is soot produced by burning oil or other combustible organic materials. Soot is basically pure carbon, sometimes containing small amounts of unburned material or other combustion products. The pigment is very stable, as are all carbon blacks. It is lightfast and compatible with all other pigments. Lampblack is used as a tinting carbon black with high stability to pigment separation. (Sources: ColourLex, https://colourlex.com/project/lampblack/#:~:text=Lampblack is soot produced by,compatible with all other pigments.; The Cary Company, https://www.thecarycompany.com/media/pdf/specs/24W212.pdf)

Pigment Dispersions (Color Concentrates)

Pigment dispersions are dry pigments dispersed in liquid material that are stabilized using resins or surfactants/additives to minimize reagglomeration, a phenomenon where the pigments come back together to form “lumps”. They can contain water, solvent or based on a resin that is liquid at room temperature. Pigment dispersions often have relatively high pigment concentrations and are used in additive quantities to impart color in a wide variety of products. The term “pigment dispersions” is often used synonymously with colorants, color concentrates, and pigment preparations. (Source: Chromaflo, https://chromaflo.com/pigment-dispersion-faqs/#:~:text=Pigment dispersions are dry pigments,is liquid at room temperature.)

Solvents, Custom Solvent Blending

The term “solvents” refers to a class of chemical compounds described by function – the term derives from Latin, meaning roughly to “loosen.” In chemistry, solvents – which are generally in liquid form – are used to dissolve, suspend or extract other materials, usually without chemically changing either the solvents or the other materials. In paints, solvents dissolve or disperse the components used in the paint formulation, to make paint the desired consistency for application and to avoid clumps or globs.

The chemical classification of a solvent is based on its chemical structure.

• Hydrocarbon solvents are classified into three sub-groups based on the type of “carbon skeleton” of their molecules, giving us the aliphatic, aromatic and paraffinic solvents families. Paint thinner is a common example of a hydrocarbon solvent.
• Oxygenated solvents are produced through chemical reactions from olefins (derived from oil or natural gas), giving us the following sub-groups: alcohols, ketones, esters, ethers, glycol ethers and glycol ether esters.  
• Halogenated solvents are solvents that contain a halogen such as chlorine, bromine or iodine. (Source: ChemicalSafetyFacts.org, https://www.chemicalsafetyfacts.org/solvents/)  

Phthalocyanine Blue

Copper phthalocyanine, also called phthalocyanine blue, phthalo blue and many other names, is a bright, crystalline, synthetic blue pigment from the group of phthalocyanine dyes. Its brilliant blue is frequently used in paints and dyes. It is highly valued for its superior properties such as light fastness, tinting strength, covering power, and resistance to the effects of alkalis and acids. It has the appearance of a blue powder and is insoluble in most solvents including water. (Source: Wikipedia, https://en.wikipedia.org/wiki/Copper_phthalocyanine)

Surface Modifiers

A surface modifier is an additive intended to modify a particular surface property. Typical functions of surface modifiers are to:

• reduce the effect of friction/surface tension of the film;
• improve abrasion resistance;
• alter a coating’s “feel”;
• modify surface appearance; and
• enhance other performance properties.

(Source: 2013 Additives Handbook, By Dr. Joseph V. Koleske, Robert Springate and Dr. Darlene Brezinski)https://www.orioncarbons.com/what_is_carbon_black)

Thickening Agents and Rheology Modifiers, Clays

A material used to thicken (increase the viscosity of) a liquid. Thickening agents provide the proper consistency to coatings, aid in applying an adequate thickness of coating to a substrate, and inhibit phase separation and prevent pigment settling. Basically, thickening agents increase the viscosity at moderate shear rates and thereby increase the coating’s resistance to flow during mixing, pouring and stirring. They are important to all phases of the manufacturing process, storage and application.

Rheology modifiers are chemicals that alter the deformation and flow characteristics of matter when it is under the influence of stress. A basic understanding of coatings rheology is essential to the development of acceptable flow properties in a coating. In coatings formulations and manufacturing, rheological additives control rheology.

The rheology (viscosity as a function of applied shear) of a coating determines many of the properties such as in-can appearance, anti-settling of pigments, color stability, application performance (including sag and spatter resistance), brush or roller loading, brush drag, film build, and flow and leveling. (Source: 2013 Additives Handbook, By Dr. Joseph V. Koleske, Robert Springate and Dr. Darlene Brezinski)

Waxes

The term ‘wax’ encompasses a large range of naturally occurring and synthetic material made from high-fatty-acid esters (typically C36 – C50) or from polymeric compounds (700 < molecular weight < 10,000) that differ from fats in being harder and less greasy. It is, however, important to realize that the chemical composition alone does not determine a wax. The term wax is basically a generic term for materials that have the following physical characteristics:

• solid at 20 °C, varying in consistency from soft and plastic to brittle and hard;
• a melting point of at least 40 °C without decomposing, which distinguishes waxes from oils and natural resins; and
• a relatively low viscosity at temperature slightly above the melting point; non-stringing but producing droplets. Droplet formation will exclude most low molecular weight polymers.

With the wax layer or wax particles at the surface of the coating, the coefficient of friction has been altered (decreased) and the desired slip effect has been imparted to the film. This explains why waxes are often classified as ‘surface conditioner additives.’ Wax properties that have the greatest impact on formulation performance include the chemical composition, molecular weight, melting point, hardness and, in the case of emulsions or dispersions, the particle size. When selecting a wax it is important to consider the melting point, particle size and particle size distribution, pH, type of surfactant and order of component addition. (Source: 2013 Additives Handbook, By Dr. Joseph V. Koleske, Robert Springate and Dr. Darlene Brezinski)