JEC COMPOSITES MAGAZINE - Issue #77 - December 2012 - 18

epoxy

Epoxy: the second-most-used
thermoset resin for matrices
Epoxy resins are discreetly present in the daily life of each and everyone. They also play a crucial role in high-performance composites. There would be no Airbus A380 XWB or Boeing B787 without them. The market for them as a composite matrix is large, but difficult to get a handle on. Here, we try to shed some light on this market.
dation of multifunctional structures derived from phenols and formaldehyde or from aromatic amines and aminophenols. Epoxy resins are thermo setting. They cure (polymerization and cross-linkage) in an irreversible exothermic reaction once they are mixed with a catalyst or hardener. The four main categories of cross-linking agent are: 1) amines and amine derivatives, 2) acid anhydrides, 3) catalysts, and 4) the melamine-, urea- and phenol-aldehyde resins. sectors for epoxy resins are protective coatings, adhesives, tool manufacturing, and composites (reinforced plastics). Epoxy resins are a part of everyday life. For example, the inside of all metal beverage cans are coated with a film of epoxy resin to protect the metal from the contents, and most computer equipment containing a printed circuit uses a laminate with an epoxy matrix. Composite applications include (by decreasing order of volume): copper clad laminates for printed circuit boards (PCB), wind energy, civil and military aerospace, sports & leisure (bicycles, golf shafts, tennis racquets, fishing rods, etc.), building & construction, and industry. Millions of square meters of PCBs are produced every year. Wind energy is a large consumer of epoxy: about 75% of the composite matrices it uses are made with epoxy resins. A single blade for a 1.5 MW wind turbine requires about 10 metric tons (MT) of epoxy resin. This market was recently affected by the decline in wind energy in the United States and China after state subsidies in those two countries were called into question.

Producers
Some producers of epoxy resins for composite matrices are particularly active, e.g. 3M, BASF, Bayer MaterialScience, Dow Chemical, Huntsman, Momentive, Sika, and Kukdo Chemical (see more players in Table 1). Where high performance is required, niche markets exist. Note that there are large numbers of formulators specializing in epoxy resins. For our market overview, we chose to focus only on actual epoxy producers, even if some of these are also formulators. The specialty chemists who develop the hardeners and catalysts also play an important role in the quality of the finished resin.

poxy resins cover a range of organic polymer materials that contain the epoxide or oxirane group (see Figure 1).

Fig. 1: The oxirane group, building block for epoxy resins

Consumption
Composites accounted for only 700,000 metric tons (PCB included) out of the 2 million MT consumed in 2011, all epoxy resin uses lumped together (publisher’s own data in Figure 2). This estimate is based only on epoxies used as matrices, i.e. excluding adhesives, coatings and tooling boards. That figure can also be compared to the 3.3 million MT of thermoset resins consu-

The most common epoxy resins are produced by reaction between epichlorhydrin and bisphenol A in the presence of sodium hydroxide, forming epoxyterminated liquid polymers. Solid resins can be obtained by adding more bisphenol A to these liquid forms to induce chain extension. These diglycidyl ethers of bisphenol A account for 8085% of global epoxy-resin consumption. Other epoxies are based on the epoxi-

Properties
Epoxy resins are highly adhesive, and highly chemical and heat resistant. They also have excellent mechanical and dielectric properties. Epoxies go hand and hand with high performance in the composite materials sector; however, they are more expensive than polyester or vinylester resins.

Application sectors
The main application

18 jec composites magazine / No77 December 2012

JEC COMPOSITES MAGAZINE - Issue #77 - December 2012

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #77 - December 2012