Hydrophobic Contamination

Test specimens were prepared shown in Fig. 8, were cured at 23°С for seven days, and were installed on an outdoor exposure rack facing south, (the inclination angle of the exposure rack was 45° to the hori­zontal, the location of the rack was in Hyogo prefecture in Japan) outdoors. The contact angle data were taken every four weeks and are shown in Fig. 9. The water shedding length from the sealant is also shown in Table 5.

TABLE 3—Failure mode of UV resistant test pieces.

Initial

500 h

1000 h

2000 h

3000 h

10000 h

Failure mode

TCF

CF

CP

CF

CF

CP

Note: TCI’: thin layer cohesive failure; CF: cohesive failure.

TABLE 4—Adhesion test results after UV irradiation.

1000 h

3000 h

5000 h

7000 h

10 000 h

SR

CP

CF

CF

CF

CF

NTP

CF

CF

CF

CF

CP’

Note: CF: cohesive failure.

FIG. 8—Test piece for SCG outdoor exposure.

The contact angle close to the silicone sealant was very high, and the length of water shedding area also increased during exposure time. During the exposure period, the NTP sealant showed just 5 mm of water shedding without further increase.