The combination of high-performance capabilities and good processing characteristics has led to the use of epoxy resins in a broad array of applications, including coatings, adhesives, matrix resins for composites and circuit boards, encapsulation, and aircraft/aerospace components, to name a few. Epoxy resins are a highly versatile class of multifunctional reactive intermediates that are crosslinked into three-dimensional networks with curing agents or “hardeners.” When cured, the resulting thermoset material is formed without the generation of volatile by-products, resulting in void-free cured parts.
There are many types of epoxy resin intermediates. Commercially, the glycidyl ether epoxy resins dominates, and accounts for over 90% of the market.
Major performance attributes of epoxy resins include outstanding high-temperature properties, high strength, excellent chemical and water resistance, good adhesion to multiple surfaces, toughness, and durability. The many options for processing epoxy resins allows utilization in a myriad of applications.
The workhorse epoxy resins are the bisphenol A diglycidyl ethers (BADGEs), offered in both liquid and solid forms; Liquid forms represent about 65% of the volume of BADGE consumption. They are available in low, medium, and high viscosity grades, varying in MW. BADGE represents approximately 67% of the total epoxy volumes.
Bisphenol F resins have most of the attributes of BADGE but offer lower viscosities, better processing characteristics based on the lower viscosities, and better chemical resistance. Bisphenol F resins are used in chemical-resistant coatings, adhesives, composites, and electrical/electronic applications.
Epoxy novolac resins offer excellent heat, fire and chemical resistance, and hardness. This category includes phenol-novolac resins, o-cresol-novolac resins, and bisphenol A-novolac epoxy resins. They have multi-functional backbone structures. Major applications take advantage of the heat, fire, and chemical resistance, such as the automotive sector, high-temperature composites, and adhesives.
The aliphatic epoxy resins category includes hydrogenated bisphenol A epoxy resins, cycloaliphatic epoxy resins and diglycidyl ethers of diols such as butanediol, hexanediol, etc. The latter category of diol epoxy resins are primarily employed as reactive diluents for viscosity reduction. The cycloaliphatic epoxy resins are a special class of non-glycidyl epoxy resins marketed by the Daicel Corporation. All aliphatic epoxy resins offer UV weathering resistance and transparency, and low viscosities. The cycloaliphatic epoxy resins have very low chloride contents and excellent electrical/electronic insulating properties.
The total market size for epoxy resins is approximately 3,100,000 MT in 2022 with a CAGR of about 5.5%. An estimated distribution of global market shares by the epoxy resin type are shown in the chart below.
The epoxy resins above are available in 220 Kg. drums, 17.6 MT per FCL; 1 MT IBC totes, and 20 MT ISO Tanks, delivered heated.
The types of hardeners that can be used for epoxy resins include aromatic amines, aliphatic amines, cycloalipathic amines, novolacs, anhydrides, polyamides, polyamido-amines, and polymercaptans (thiols). An indication of the market shares for the various type of hardeners is provided below.
The Gantrade blog on Epoxy Resins provides additional details on the attributes of the various hardener types available.
The epoxy resin and the hardener or curing agent should be mixed and reacted at approximately equivalent (1:1) stochiometric levels with the epoxy resin to obtain optimum properties. Weight ratios are usually expressed in parts of hardener per 100 parts of resin. To calculate the required ratio of hardener to epoxy resin, first calculate the hardener equivalent weight.
The amount of amine hardener required is calculated by from the EEW (epoxy equivalent weight) of the epoxy resin(s) and the hardener equivalent. For amines hardeners, AEW is related to the number of active hydroxy atoms on the primary amine moieties. Standard diamine hardeners have functionalities of four (4).
Thereafter, apply the equation below to determine the weight of amine hardener to use with 100 parts of the reactive epoxy resin(s) component.
Adding too much of either resin or hardener will alter the cure time and chemical reaction, and the mixture will not properly cure.
The major market segment for epoxy resins is paint and coating for heavy-duty service, representing approximately 40% of the end-use volume. This is followed by adhesives, composites (including wind turbine blades), electrical/electronics, and construction. The global epoxy resin market volume is estimated to be about 3,100,000 MTs in 2022, with a CAGR projected at 5.5% in the next five-year period. The chart below shows the breakdown of the epoxy resin market by application.
For more information on epoxy resins and critical selection criteria, please contact Gantrade today.
