Flexible intumescent coating composition.

摘要

Disclosed is an intumescent curable composition which contains as a resinous binder a flexible polyepoxide resin. The polyepoxide is cured with an appropriate curing agent adapted for the particular resin. An additive component is present which contains a mixture of materials which provide a source of (i) zinc, (ii) boron, (iii) phosphorus, and (iv) an expansion gas upon thermal decomposition. The composition is capable of forming a carbonaceous char upon exposure to heat or flame, with the proviso that the cured, unburned composition has sufficient flexibility that it passes at least 10 continuous cycles of a cold cycle test without cracking. The cold cycle test involves the following steps: the composition is applied at a thickness of 0.5 inch (12.7 millimeters) to a 10 inch (0.254 meter) section of a 4W13 I-beam having two thermocouples attached to the surface, allowed to cure at ambient temperature for 16 hours, force cured for 5 days at about 60 DEG C and subjected to the cold cycle test. For one cycle, the beam is placed in a freezer operating at a temperature between about 0 DEG F (-18 DEG C) and about -10 DEG F (-23 DEG C) for sufficient time for the steel to reach a temperature between about 0 DEG F (-18 DEG C) and about (-10 DEG F) -23 DEG C as determined by the two thermocouples attached to the surface of the beam beneath the coating, removed from the freezer and a 50 square inch area (0.0323 square meter) of the surface warmed as shown in FIGS 1 and 2 by passing a heat gun (Model No. HG 50146, Alpha Division of Loral Corp, 14 amp: minimum temperature at tip 500 DEG F (260 DEG C)) a distance of 0.5 inch (12.7 millimeter) from the surface, uniformly over the surface until the surface temperature reaches 110 DEG F (43 DEG C) within a 3 minute period, as determined by a thermocouple moved about the surface and allowed to stand for at least 2 hours at ambient temperature.