Bonded films antimony trioxide

Fillers. Fillers are not commonly added to CR adhesives. Calcium carbonate or clay can be primarily added to reduce cost in high-solids CR mastics. Maximum bond strength is obtained using fillers with low particle size (lower than 5 [jim) and intermediate oil absorption (30 g/100 g filler). In general, fillers reduce the specific adhesion and cohesion strength of adhesive films. Although polychloroprene is inherently flame retardant, aluminium trihydrate, zinc borate, antimony trioxide or... 

Probably the most important additive is antimony trioxide, which has been widely used in commerciai formulations. Calhoun et al studied a number of different substances as additives for bonded molybdenum disulphide films, but the only one which was effective in increasing wear life was antimony trioxide. Kinner carried out a detailed study of the influence of antimony trioxide. He found that the improvement in wear life was particularly marked at high temperatures, and could be as great as 1000% at 200°C. The improvement was sometimes at the expense of some loss in room temperature performance. 

The mechanism of action of antimony trioxide has been discussed in some detail in Chapter 7. It has been widely used in bonded film formulations since the mid-nineteen-sixties to improve the wear life of coatings. The greatest improvement is obtained at higher temperatures, and Kinner found a small deterioration in performance at low temperatures when antimony trioxide was used. He also found that the use of lead oxide, PbO, together with antimony trioxide gave markedly improved performance at both high and low temperatures. 

Lavik et al ° reported up to 400% improvement in wear life, and lower friction at high or low temperature, when antimony trioxide was used in polyimide or polybenzothiazole-bonded films. Lower improvements, up to 270%, were obtained with antimony trisulphide, while Bartz reported that the addition of both graphite and antimony tetrasulphide (or antimony thio-antimonate Sb(SbS4)) gave a much greater improvement in the life of a polybutyltitanate-bonded molybdenum disulphide film than either of the additives separately. 

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