Dupont developed Hypalon, which is a Dupont Company trademark for chlorosulphanated polyethylene for the automotive industry. Its heat, oil and chemical, and abrasion resistance are still today unsurpassed with the exception of some of the new and exotic silicone and fluoroelastomers.

It was these properties that prompted fire hose manufacturers to develop this material for hose. It exhibited all the properties that fire hoses were lacking at the time. The only problem was Hypalon’s high and prohibitive price. But like all good rubber compounders knew, the polymer could be mixed with clays, oil extenders and various other fillers and low and behold, the price per pound was in an acceptable range. It also could be compounded with any number of pigments to give any color under the sun.

Now the problem was to find a way to apply it to the hose jacket. Well, this was accomplished by dissolving roughly 5% compounded rubber into 95% solvent. The jacket was then in turn dipped in the mixture and the solvent driven off. Well, as you can see, the original Hypalon rubber was now diluted beyond the point where it could hope to be very effective. It did however provide a limited degree of penetration and hence some binding of the fibers. It performs best on air-entangled nylon. Because of all the air pockets in this yarn, the mixture does penetrate and bind the yarns together. Without it, the nylon would not stand a chance (could you imagine if we were to put ENCAP® on this nylon). The degree of increase in heat resistance was zero and abrasion and chemical resistance was minimal at that. It was clearly time that Hypalon more over to make way for a more sophisticated encapsulation process, Niedner ENCAP®.

The degree of increase in heat resistance was zero and abrasion and chemical resistance was minimal at that. It was clearly time that Hypalon move over to make way for a more sophisticated encapsulation process, Niedner ENCAP®.

ENCAP® is a spin off of polyurethane emulsion that was primarily developed for the rope and cable industry for use in marine applications. It was intended to act as a binder to keep the rope together as well as protecting it from the harsh marine environment. Now, compounded specifically for fire hose, it is performing the same duties.

Because ENCAP® is a polyurethane resin, its melting point is roughly the same as polyester yarn. It therefore does not offer any significant increase in heat resistance. It does however, encapsulate all the fibers of an already very tightly woven jacket and bind these to the point whereby the abrasion resistance is increased 500% over the untreated version, and 400% over Hypalon impregnated products. The chemical resistance of ENCAP® is phenomenal. Gasoline and solvents, that would strip Hypalon from a hose, do not have any effect on ENCAP® at all.

In the past, some problems were encountered in that some colors were fading prematurely. This was a problem with the pigment only. Even with the color completely dissipated, the ENCAP® resin still remains intact and functional.

The main reason for Hypalon’s poor performance was that it was too highly diluted. As compounded, the ENCAP® emulsion contains roughly 40% solids (2.5% for Hypalon), this is why more resin is being imparted to the hose jacket. This increased amount of resin as well as its natural ability to resist most disruptive elements is why ENCAP® is favored among end users.