Acrylic Resin vs Epoxy Resin

5th January 2024

What is acrylic resin?

Acrylic resin (C3H4O2) is copolymerized from acrylic esters or methyl methacrylate and other olefinic monomers. By selecting different types of acrylic resins, pigments, additives, solvents, and crosslinking agents, a diverse range of acrylic coatings with various properties and widespread applications can be synthesized.

chemical structure of acrylic resin

Chemical Structure of Acrylic Resin

Features of acrylic resin

Acrylic monomers, due to their unique structure with carbon chain double bonds and acyl groups, copolymerize to form acrylic resins. The main absorption peaks of these acrylic resins lie outside the range of the solar spectrum, imparting excellent light resistance and weathering performance to acrylic coatings. Acrylic coatings exhibit the following significant characteristics:

  1. Colorless and transparent.
  2. Weather resistance: High durability under outdoor exposure, resistance to ultraviolet radiation, minimal decomposition or yellowing, maintaining original gloss and color for an extended period.
  3. Heat resistance: No decomposition or discoloration at temperatures up to 170°C, and maintain stable even at around 230°C or higher.
  4. Chemical resistance: Excellent resistance to chemicals such as acids, bases, salts, oils, and detergents, preventing staining and corrosion.
  5. Excellent application properties: The presence of ester groups prevents crystallization of acrylic coatings. The versatile ester groups also improve solubility in different media and compatibility with various resins.

Due to its outstanding light resistance, acrylic coatings find the most significant market in automotive paints. Additionally, they are widely used in industries such as household appliances, metal furniture, aluminum products, sheet metal, instruments, building construction, textiles, plastics, wood products, paper, and more.

acrylic resin

Applications of acrylic resin

There is a wide variety of acrylic coatings, typically categorized into solvent-based acrylic coatings, waterborne acrylic coatings, and solvent-free acrylic coatings. Applications os these acrylic coatings are as follows:

Type Application
Solvent-based Acrylic Coating Thermoplastic Acrylic Coating Plastic Coatings, Automotive Repair Paints, Exterior Wall Coatings
Thermosetting Acrylic Coating Depending on the curing agents used
Hydroxy Acrylic Coating Amino resin as curing agent for baking crosslinking. Primarily used in automotive topcoats, household appliances, and hardware tools.

Polyisocyanate as curing agent. Mainly applied in automotive topcoats and touch-up paints, as well as coatings for plastics, exteriors, and machinery.

Epoxy Acrylic Coating Polyacid and polyamine as curing agents. Mainly used in can coatings.
Carboxylic Acrylic Coating Epoxy or amino resins as curing agents for crosslinking. Mainly used in can coatings.
N-Hydroxymethyl Acrylic Coating Amino resin as curing agent with baking crosslinking. Mainly used for metal substrates.
Water-based Acrylic Coating Waterborne Acrylic Coating Automotive Electrophoretic Coating, Household Appliance Coating, Leather Coating
Emulsion Acrylic Coating Interior and Exterior Architectural Coating, Wood Coating
Solvent Free Acrylic Coating UV-Curable Acrylic Coating Wood Coating, Paper Coating, Fiber Optic Coating
Acrylic Powder Coating Household Appliance Coating, Aluminum Wheel Coating

Thermoplastic acrylic resin does not undergo further crosslinking during the film-forming process. As a result, it has a relatively high molecular weight, exhibiting good light and color retention, water and chemical resistance, fast drying, and easy application. It is convenient for construction, re-coating, and rework. When preparing aluminum powder paint, the resin ensures the brightness and good positioning of the aluminum powder. Thermoplastic acrylic resin finds widespread applications in fields such as automotive, electrical appliances, machinery, and construction.

Thermosetting acrylic resin refers to a structure containing specific functional groups that, during paint formulation, react with functional groups in added amino resins, epoxy resins, polyurethanes, etc., forming a network structure. Thermosetting resins generally have a relatively low molecular weight. Thermosetting acrylic coatings exhibit excellent fullness, gloss, hardness, solvent resistance, weather resistance, and do not discolor or yellow during high-temperature baking. One of its most important applications is in combination with amino resins to produce amino-acrylic baked coatings, widely used on products such as automobiles, motorcycles, bicycles, and coated steel.

Acrylic vs Epoxy Resin

1. Chemical Structure

  • Acrylic Resin: As an α,β-unsaturated carboxylic acid, acrylic acid encompasses a carbon-carbon double bond and a carboxyl group. Acrylic resins, derived from acrylic acid, are commonly employed in coatings.
  • Epoxy Resin: Epoxy resins feature epoxy groups (oxirane rings) in their structure, endowing them with high reactivity. This reactivity allows epoxy resins to form robust three-dimensional networks through epoxy ring-opening reactions with other compounds.

2. Curing Mechanism

  • Acrylic Resin cured through the polymerization reaction when exposed to UV light.
  • Epoxy resin cured through the reaction with curing agents to formulate adhesive, coating, or casting material.