Curing phenalkamine

As a new family of curing agents, the phenalkamines offer a unique combination of properties making them particularly well suited for ambient temperature cured high solids epoxy coatings. Studies on the reactivity of these curing agents and on the properties of certain cured formulations are presented. Experimental... 

Curing Agent Properties. Table I gives some specific properties on the three commercial phenalkamines, namely "CARDOLITE" Brand NC-540, NC-541 and NC-542. The three products have gel times ranging from 40 minutes up to 2 hours with a variation in mixing ratio from 40-100 parts per hundred parts resin. Viscosities cover the range from 2500 cps to 40,000 cps. 

Phenalkamine properties are positioned roughly between those of the polyamines and polyamides. They combine the best properties of each of these familiar types of curing agents. The phenal kamines have an intermediate viscosity, the chemical and hydrolytic resistance of the polyamines, and the low toxicity of the polyamides. They have the fast cure and ability to cure at reduced temperatures of the polyamines while exhibiting better compatibility than either the polyamines or the polyamides. The phenalkamines also provide flexibility comparable to the polyamides with similar easy-to-use, relatively non-critical mix ratios. 

Table II also rates the properties of amidoamines and cycloaliphatic amines. None of these curing agents appear to satisfy all of the desired properties. There are clearly some unfulfilled needs here however, the particular combination of properties of the presently commercial phenalkamines comes closest to satisfying the requirements. They are quite suitable for high solids systems.

By spot-tests on coatings and immersion-tests on castings the excellent chemical-resistance of phenalkamine-cured epoxy systems has been demonstrated. In addition, near-infrared cure studies have documented the rapid complete cure of epoxies at room temperature and also satisfactory cure at reduced temperatures when phenalkamines are used as the curing agents. 

This unique combination of properties of the phenalkamines suggests they should be the curing agents of choice not only for high solids field applied industrial coatings, but also for heat-cured factory applied industrial finishes... 

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