Terminology

• DGEBA / BADGE: bisphenol A diglycidyl ether, the most common epoxy resin
• Hardener / curative: amine, acid, anhydride, phenol, alcohol, or thiol that cross-links the resin
• EEW: epoxy equivalent weight; higher EEW corresponds to higher Tg in some systems
• Tg: glass transition temperature
• Stoichiometric mix: hardener amount matched to resin for best physical properties
• Chip flooring: colored aggregate or chip broadcast in epoxy

History and demand

Invention

• 1934: Paul Schlack of Germany patented the condensation of epoxides and amines
• 1943: Pierre Castan claimed the bisphenol A resin, later licensed by Ciba
• 1946: Sylvan Greenlee of Devoe & Raynolds patented a resin from bisphenol A and epichlorohydrin

Sourcing

• China is the largest producer: about 29 percent of 3.1 million tons of 2024 world production by one count (IndexBox) and about 45 percent by another market report, with South Korea about 15 percent
• Asia-Pacific holds over 60 percent of capacity; China's capacity was expected to reach 3.76 million tonnes a year by the end of 2024, up 90 percent from 2017 (OilChem via Mysteel)

Demand trend

• Global market about $8 billion in 2016; Asia-Pacific about 55 percent, China almost 35 percent of resin consumption; Europe made about 323,000 tonnes in 2017
• Trends toward bio-based monomers, waterborne systems, and recycled raw materials

Composition and production

Raw materials

• Epichlorohydrin reacted with bisphenol A (or bisphenol F, for lower viscosity and better chemical resistance) using sodium hydroxide
• Hardeners: amines are the most important class; aliphatic amines are more reactive, aromatic amines give more heat-resistant networks

Manufacturing process

• Exothermic cross-linking cure; many systems cure at room temperature, many need heat up to about 150°C (300°F), specialist systems up to 200°C (390°F)
• Too little heat leaves an incompletely cross-linked network with reduced mechanical, chemical, and heat resistance
• One-component products use latent hardeners that need heat only

Properties

Mechanical

• Cured epoxies show excellent adhesion, good to excellent mechanical properties, and very good electrical insulation

Thermal and moisture

• Glass transition: cure temperature should reach the Tg of the fully cured network for maximum properties

Durability

• Chemical and heat resistance: excellent when fully cured

Uses in buildings

Building elements

• Resinous Flooring: epoxy coatings and mortars
• Terrazzo: epoxy resinous matrix, the most common terrazzo binder today
• Post-Installed Anchors: structural adhesives and rock bolt anchors
• Paint and Coatings: heavy-duty metal coatings and primers

Pros and cons

Pros

• Excellent adhesion and chemical resistance
• Cures at room temperature in many systems
• Usable as a concrete or mortar additive

Cons

• Uncured resin irritates skin and eyes and is a sensitizer
• Added cost as a concrete additive
• Improper mix ratio or low cure heat degrades properties

Sustainability

Health

• Uncured liquid resins irritate the eyes and skin; sensitization (dermatitis, occupational asthma) is the main concern, stronger with low-molecular-weight diluents
• Vapors and sanding dust from incompletely cured material add risk; solid epoxy resins are generally safer
• Bisphenol A is being replaced in some accelerators because of health concerns

Manufacturing and cost

Main manufacturers and suppliers

• Hexion
• Olin Epoxy
• Huntsman
• Sherwin-Williams
• Sika

Trade association: American Chemistry Council.

Sources

• Wikipedia: Epoxy, https://en.wikipedia.org/wiki/Epoxy
• Wikimedia Commons: FiveMinEpoxy.jpg, photo by Taktoa (CC BY-SA 3.0), https://commons.wikimedia.org/wiki/File:FiveMinEpoxy.jpg
• Mysteel: China's epoxy resin industry, shift from oversupply to global reach, https://www.mysteel.net/analysis/5057737-chinas-epoxy-resin-industry-shift-from-oversupply-to-global-reach
• IndexBox: epoxide resin world market overview 2024, https://www.indexbox.io/blog/epoxide-resin-world-market-overview-2024-2/