Epoxy resins types

Aliphatic epoxy resins generally have higher color stability and reactivity than aromatic epoxy resins, but their resistance to aqueous acid solutions is much lower. 

Glycidyl Esters. Glycidyl ester resins were originally developed for electrical applications. Glycidyl esters of phthalic acid, hexahydro phthalic acid, terephthalic acid or trimellitic acid (e.g. Araldite PY 284, PT 910) cured with carboxy functional polyesters or polyacrylates at elevated temperatures give coating with both excellent colour stability and outdoor resistance. 

Heterocyclic Epoxy Compounds. The technically most important heterocyclic epoxy resin is triglycidyl isocyanurate, obtained by reacting cyanuric acid with epichlorohydrin (Araldite PT 810, Ciba-Geigy Tepic, Nissan). This trifunctional epoxy resin is combined with carboxy-terminated polyesters to give weather-resistant powder coatings [2.122]-[2.124]. 

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Figure 9.1 Cross-sections of a typical inert or redox electrode, embedded (a) within glass, and (b) within epoxy resin. Type (b) is preferred if the metal is liable to melt or react when very hot.

Epoxy Resin Type Examples Resin/Snpplier Viscosity (poise 25 °C, (unless indicated) Epoxy Equivalent Weight (gm)... 

The solubility characteristics of two common epoxy resin types are given in Table 3.3. 

Abraham and co-workers [32] described measurements of the tensile shear lap strength of bonded specimens of an epoxy imide resin derived from N-(4-carboxyphenyl) trimellitimide bonded to stainless steel. The effect of epoxy resin type on adhesive strength of the Pl-aluminium bond, are also discussed. 

Approximately 75% of the epoxy resins currently used worldwide are derived from DGEBA. This market dominance of bisphenol Abased epoxy resins is a result of a combination of their relatively low cost and adequate-to-superior performance in many applications. Figure 1 shows U.S. consumption of major epoxy resin types for the year 2000. 

Powders used for fluidized-bed painting [248, 249] include low- and high-pressure polyethylene, polyvinyl butyral (Butvar), polystyrene emulsion, polyamide resin type AK-7, polyoxymethyl-ene, polyvinyl chloride, a copolymer of styrene with methylmeta-crylate, epoxy resin type E-41, phenolformaldehyde resin No. 108, In addition to the main components, pigments and dyes imparting heat resistance and other qualities to the coating are introduced. 

The epoxy resins mainly used are based on bisphenol A or F they are manufactured by conversion of the corresponding bisphenols with epichlorohydrin. Such conventional epoxy resin types may still contain traces of hydrolyzable chlorine and inorganic salts (ash). The presence of aromatic rings in these resins increases UV absorption and facilitates degradation processes by forming conjugated structures [706], [707],... 

General-purpose isotactic PP homopolymer (type F401, melting flow index (MI) = 8.5 g/10 min and 6.7 g/10 min, respectively) was provided by Guangzhou Petroleum Chemical Co., China. It should be noted that this is a rather brittle PP, compared to other PP types available on the world market. In addition, a bisphenol-A epoxy resin (type E-51) and 4,4 -diaminodiphenylsulfone (DDS) were provided by Guangzhou Dongfeng Chemical Co., China, as matrix materials. 

Epoxy grouting is one of the most commonly used techniques for the repair of cracked structural elements. For the successful application of this technique, the surface of the damaged or cracked section needs to be properly prepared (Fig. la). Depending on the type of damage, different epoxy resin types and installation procedures can be used (Fig. lb). 

Phenohc resins are the oldest form of synthetic stmctural adhesives. Usage ranges from bonding automobile and other types of brake linings to aerospace apphcations. These adhesives have a reputation for providing the most durable stmctural bonds to aluminum. Because of volatiles, however, and the need for high pressures, the phenohc resins are used less as adhesives than the epoxy resins. 

Composites. Various composite materials have evolved over the years as a significant class of high performance textile products. The prototype composite is carbon fiber with an epoxy resin matrix for stmctural akcraft components and other aerospace and military appHcations. Carbon fiber composites ate also used in various leisure and spotting items such as golf clubs, tennis rackets, and lightweight bicycle frames. However, other types of appHcations and composites ate also entering the marketplace. For example, short ceUulose fiber/mbbet composites ate used for hoses, belting, and pneumatic tire components. 

A second type of uv curing chemistry is used, employing cationic curing as opposed to free-radical polymerization. This technology uses vinyl ethers and epoxy resins for the oligomers, reactive resins, and monomers. The initiators form Lewis acids upon absorption of the uv energy and the acid causes cationic polymerization. Although this chemistry has improved adhesion and flexibility and offers lower viscosity compared to the typical acrylate system, the cationic chemistry is very sensitive to humidity conditions and amine contamination. Both chemistries are used commercially. 

The rate of stripping or the stripabiUty on cataly2ed urethane and epoxy resin finishes can be increased by adding formic acid, acetic acid, and phenol. Sodium hydroxide, potassium hydroxide, and trisodium phosphate [10101-89-0] may be added to the formula to increase the stripabiUty on enamel and latex paints. Other activators include oleic acid [112-80-17, trichloroacetic acid [76-85-9], ammonia, triethanolamine [102-71-6], and monoethyl amine. Methylene chloride-type removers are unique in their abiUty to accept cosolvents and activators that allow the solution to be neutral, alkaline, or acidic. This abihty gready expands the number of coatings that can be removed with methylene chloride removers. 

The distribution of powder coating sales by resin type for various geographical areas is given in Table 5. The polyester—epoxy hybrids account for 50% of the European market, yet have only market share <25% in the rest of the world. Similarly, the polyester urethanes, which account for only a small market share in Europe, find significant usage in the United States andjapan. AcryUcs hold a significant share only in the Japanese market. 

For some years, this type of vehicle was used in anionic electro deposition primers. However for automobiles cationic electro deposition primers are now preferred. The vehicles for cationic primers are proprietary but probably consist of the reaction product of epoxy resins and polyfunctional amines solubilized by the conversion of amine groups into salts using an acid such as lactic acid (2-hydroxypropanoic acid) [50-21-5] Alcohol-blocked... 

Other Coatings Resins. A wide variety of other resin types are used in coatings. PhenoHc resins, ie, resins based on reaction of phenols and formaldehyde, have been used in coatings for many years. Use has been declining but there are stUl significant appHcations, particularly with epoxy resins in interior can coatings. 

The cycloahphatic products are generally Hquids of lower viscosity than the standard glycidyl ether resins. The peroxidized resins contain no chlorine and low ash content and their ring-contained oxirane group (cyclohexene oxide type) reacts more readily with acidic curing agents than the bisphenol A-derived epoxy resins. 

SoHd epoxy resins are sometimes designated as 1-, 4-, 7-, or 9-type resins these approximate the degree of polymerization. Commercial products are designated similarly, eg, Epon 1001, 1004, 1007, and 1009 (SheU Chemical Co.). The relationship between n value, epoxy equivalent weight, and melting point is shown in Table 5. 

Figure 15.14 Typical indoor-type bar primary epoxy resin cast CTs (Courtesy Kappa Electricals)...

In planning cathodic protection, the specific resistivity of the water, the size of the surfaces to be protected and the required protection current densities have to be determined. The protection current density depends on the type and quality of the coating. Thermosetting resins (e.g., tar-epoxy resin coatings) are particularly effective and are mostly used today on coastal structures. They are chemically... 

Unless great care is taken in control of phenol/acetone ratios, reaction conditions and the use of catalysts, a number of undesirable by-products may be obtained such as the o-,p- and o-,o- isomers of bis-phenol A and certain chroman-type structures. Although tolerable when the bis-phenol A is used in epoxy resins, these have adverse effects on both physical properties and the colour of polycarbonate resins. 

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