Abstract
Twelve kinds of two-part polyurethanes for roof and waterproof coating for building were experimentally produced controlling the ratios of amine/polyol-equivalents in the curing agents (Table 1), and examined of their movement capability during cure. They were applied on polypropylene substrates bridging butt joints at the center of the substrates, and, at the appropriate lapses of curing time at 20℃, the joints were opened to the shape of wedge by inserting spacing pieces of 0.5mm thickness in one end of the joints. The membranes thus formed and subjected to joint-opening were removed from the substrates after being cured and inspected of their failures (Fig. 3). The polyurethanes cured by amine-rich curing agents ruptured by joint-opening after several hours of age (Fig. 4). The characteristics of the polyurethanes during cure were also investigated by the drying recorder and the T. B. A., significant information relating movement capability, however, was not obtained from the results of them (Figs. 1 and 2). Next, the polyurethanes were applied on substrates of asbestos cement board and conducted by the same procedure as mentioned above, except the joints were opened to 0.5mm width in parallel. The membranes adhering on the substrates were inspected after cured for seven days at 20℃, and those without visual failure were evaluated of their movement capability by "expanding joint" and "cyclic opening/closing joint" (Tables 2 and 3). Finally, six types of reinforcing fabrics (Fig. 5 and Tables 4 and 5) were examined of their ability to prevent failures of the polyurethane during cure which showed one of the worst results in the previous examinations. Two types of the fabrics entirely prevented failures and the others improved the membrane to a little extent (Fig. 6), and the membranes without failure were evaluated by "expanding joint" (Table 6).
