Binder and Resin for Paint – The Film-Forming Component   
Paint or coating is a combination of a pigment, a binder, a solvent, and additives. The binder or resin typically gives the coating its name, such as polyurethane or acrylic. While the pigment provides the color, additives give it additional desired properties, and the solvent provides the consistency needed for application. The binder is what, as the name suggests, binds everything together. It is the film-forming component of the paint layer, the vehicle that carries the pigment and then dries or cures, holding it in place. The binder is also responsible for adhesion, durability, flexibility, gloss, and other physical properties. Binders and resins for paint are among the most important elements of a coating. 
 
 Thermoplastic and Thermosetting Resins for Paint   
While there are various types of resins used for paint, two main methods are used to classify synthetic resins: thermosetting and thermoplastic.
 
-  Thermoplastic Resins   
  Resins that are thermoplastic remain plastic after setting. They do not cure irreversibly and can soften with heat. Film formation occurs through the evaporation of solvent or water. Thermoplastic resins for paint provide excellent protection against chemicals and corrosive environments.
 
-  Thermosetting Resins   
  These resins irreversibly cure when exposed to the right conditions, such as extreme heat, chemical reaction, or radiation in the case of UV-cured resins. Thermosetting resins are sticky and liquid in their uncured state. During the curing process, the molecules form cross-links, creating long, interconnected polymers that permanently bond. Due to these cross-links, thermosetting resins provide excellent adhesion, as well as heat, chemical, and water resistance.
 
 5 Types of Paint Resins with Unique Properties   
 
Resin is a solid or highly viscous substance of plant or synthetic origin. In the coating industry, natural resins (like plant-based resins) have been almost entirely replaced by synthetic ones. Below are the top resins for paint across the industry, their applications, and the companies that provide them.
 
1.  Epoxy (Thermoset)   
   -  Applications : Epoxy is an industrial and protective coating for many markets. Common applications include flooring, can coatings, waterproofing cement, steel, tanks, pipes, transport elements, marine, oil and gas, automotive coatings, and industrial coatings. 
   -  Description : Epoxy resins, like polyurethanes, are thermosetting polymers that form a hard layer through cross-linking. Various formulations include Bisphenol A epoxy, Bisphenol F epoxy (with lower viscosity than Bisphenol A), epoxy novolac, and aliphatic epoxy. Each provides slightly different strengths. Epoxy resin curing is an exothermic reaction and can be achieved through mixing with curing agents or heat application. Epoxy resins are commonly two-component, though single-component formulations exist, and they can be water-based or solvent-based. 
   -  Advantages : Epoxy resins offer a wide range of desirable qualities, including water resistance, chemical and solvent resistance, heat resistance, excellent adhesion, and durability, making them an easy choice for many industries.
 
2.  Polyester and Vinyl Ester Resins (Thermoset)   
   -  Applications : Polyester and vinyl ester coatings are used in highly chemically demanding environments and are widely applied in coil coatings. 
   -  Description : Polyester resin is formed through the polymerization of an alcohol and an acid. Vinyl ester is a subset of polyester resins, modified by an epoxy base, typically Bisphenol A epoxy or epoxy novolac. Both polyester and vinyl ester resins are thermosetting and are often dissolved in a monomer like styrene to reduce viscosity. The curing process involves reaction with a catalyst, often methyl ethyl ketone peroxide (MEKP). 
   -  Advantages : Polyester and vinyl ester resins provide high chemical and temperature resistance, wear resistance, fast curing, and long-term corrosion protection, which is why they are used in marine coatings. Vinyl esters offer better water and chemical resistance and more flexibility than polyester resins.
 
3.  Acrylic Resins (Thermoset and Thermoplastic)   
   -  Applications : Solvent-based acrylic coatings (lacquers and enamels) are used for industrial flooring, coil coatings, metal furniture, household appliances, and automotive coatings. With stricter VOC emission limits, the industry is shifting towards water-based acrylic coatings. Other applications include architectural coatings, especially for exterior use. 
   -  Description : Acrylic resins account for nearly 30% of the coating resin market. They are derived from the polymerization of acrylate and methacrylate monomers (like methyl methacrylate or MMA) and can be thermoset or thermoplastic. Acrylic resins are used in both water- and solvent-based coatings and as lacquers (lower solids), enamels (higher solids), and powder coatings (100% solids). They can also modify other types of coatings, such as polyurethanes or epoxies, to improve their appearance. 
   -  Advantages : Acrylic resins are known for their excellent color and gloss retention, as well as their outstanding weather and UV resistance.
 
4.  Polyurethane Resins (Thermoset)   
   -  Applications : Polyurethanes are high-performance coatings for metal, concrete, wood, plastic, and more, used across a wide range of markets, including architectural, automotive, industrial, marine, and protective coatings. 
   -  Description : Polyurethanes are reactive polymers formed by the reaction of an isocyanate with a polyol. The types of isocyanates and polyols determine the resulting polyurethane's properties. Polyurethane coatings are available in one-component or two-component formulations and can be water- or solvent-based. 
   -  Advantages : Polyurethanes offer excellent chemical and solvent resistance, corrosion resistance, weather resistance, UV stability, abrasion resistance, gloss retention, hardness, and flexibility. They are also highly versatile due to the wide range of properties achievable through different formulations.
 
5.  Alkyd Resins (Thermoset and Thermoplastic)   
   -  Applications : Alkyd resins are used on a variety of substrates, from metal and wood to plastics, and in industries such as architectural coatings (especially decorative gloss paints), furniture coatings, automotive coatings, insulation enamels, and coil coatings. 
   -  Description : An alkyd is the result of the polymerization between an alcohol (like glycerol) and an acid, modified by adding oils. They are also known as oil-modified polyesters. Alkyd formulations vary in oil content, ranging from short oil (less than 40% fatty acid by weight), medium oil (40-60%), to long oil (60-70%). Long oil alkyds are the slowest to dry and most flexible, while short oil alkyds dry quickly and form the hardest films. 
   -  Advantages : Alkyd resins offer good adhesion, hardness, flexibility, corrosion resistance, and gloss retention.
 
Looking to the Future of Coating Resins   
The resin market has grown in recent years and is expected to continue on this upward trend. Major companies in the coating resin market include Allnex, Arkema, BASF, Dow Chemical, DSM, Evonik, Helios, Momentive, and Valspar. The market has shown a clear trend towards eco-friendly and sustainable coatings, as evidenced by the declining popularity of previously dominant alkyds. Resins that produce solvent-free or low/zero VOC emissions are preferred. Regulations concerning these pollutants are also becoming stricter, pushing manufacturers to focus on products aligned with this trend.
 
Newer coating technologies are also making their mark, such as fluoropolymers, UV-curable coatings, silicone-modified coatings, super polyesters for coil coatings, polyurea coatings, and more. Whether your project requires traditional binders or newer resins, we can help you find the right supplier. For more information or to request pricing, contact us via email or by clicking the button at the bottom of this page. 
 
Using Hardeners in Paint   
Paint hardeners, also known as catalysts, are used to speed up drying and increase the durability of the paint after it dries. They are mostly used with two-component paints (such as epoxy or polyurethane paints), where the base paint is mixed with a hardener before application. The hardener chemically reacts with the paint, making it harder than it would be if the paint dried on its own. This increases the paint's resistance to scratches, chemical damage, UV damage, and general wear and tear.
 
Not all paints require hardeners. For example, most latex and oil-based paints for household use do not need a hardener and dry through the evaporation of their solvents. Two-component paints always require a hardener. If unsure, it's best to consult a paint specialist. 
Consider the intended use. Even when not explicitly required, a hardener can be beneficial if you're looking for a durable and hard finish. However, using a hardener might reduce the paint's flexibility, which could be an issue if the painted object is subject to movement or temperature changes.
 
In summary, both thinners and hardeners are used to modify paint properties to match specific applications. Thinners adjust paint viscosity to facilitate application, while hardeners speed up drying and improve the final paint's durability. Whether you need one depends on the type of paint and the requirements of your project.