Aging Properties And Mechanism Of New Camouflage Coatings

Camouflage painting technology is the foundation of camouflage technology. Camouflage coatings can reduce the probability of being recognized, detected and attacked by precise guide weapon of enemy for military targets, which can enhance military targets'viability in war field greatly. However, camouflage coatings exist aging phenomenon, such as chapping, chalking, peeling and even desquamating, until lose camouflage function at last.In this paper, the aging properties of polyurethane resin and camouflage coatings were studied through two experiments: nature weathering aging and artificial accelerated aging. After 90d nature weathering aging, the chromatism of polyurethane resin was 34.76, the average molecular weight reduced by 77%; after 800h UV accelerated aging, the chromatism of polyurethane resin was 51.81, the average molecular weight reduced by 54%. After 90d nature weathering aging, the chromatism of camouflage coating was 22.57, the residual weight increased by 13% at 400℃, the peel strength decreased by 56%; after 800h UV accelerated aging, the chromatism of camouflage coating was 8.26, the residual weight increased by 2.8% at 400℃, the peel strength decreased by 38%.The content of cross-linking agent had great impact on the aging properties of the coatings, and it can improve the anti-aging properties of camouflage coatings. It was shown that anti-aging properties of polyurethane resin and camouflage coatings with 3%(wt.%) cross-linking agent were best. After 90d nature weathering aging, the chromatism of polyurethane resin with 3%(wt.%) cross-linking agent decreased by 36%, and the average molecular weight increased by 3.4 times, compared to the pure resin; after 800h UV accelerated aging, the chromatism of polyurethane resin with 3%(wt.%) cross-linking agent decreased by 73%, and the average molecular weight increased by 1.4 times, compared to the pure resin. Compared to the camouflage coating without cross-linking agent, the chromatism of camouflage coatings containing 3%(wt.%) cross-linking agent decreased by 23%, the peel strength increased by 110%, and the residual weight increased by 9% at 400℃, after 90d nature weathering aging; after 800h UV accelerated aging, the chromatism of camouflage coating containing 3%(wt.%) cross-linking agent decreased by 48%, the peel strength increased by 85%, and the residual weight increased by 9% at 400℃, compared to the camouflage coating without cross-linking agent.The content of stabilizer had effects on the aging properties of the coatings. The anti-aging properties of coatings was improved after adding stabilizer. The anti-aging properties of polyurethane resin and camouflage coatings with 2%(wt.%) stabilizer was best. After 90d nature weathering aging, the chromatism of polyurethane resin with 2%(wt.%) stabilizer decreased by 46% compared to the pure resin, and the average molecular weight increased by 63%; after 800h UV accelerated aging, the chromatism of polyurethane resin with 2%(wt.%) stabilizer decreased by 45% compared to the pure resin, and the average molecular weight increased by 47%. Compared to the camouflage coating without stabilizer, the chromatism of camouflage coating containing 2%(wt.%) stabilizer decreased by 45%, and the peel strength increased by 45% after 90d nature weathering aging; after 800h UV accelerated aging, the chromatism of camouflage coating containing 2%(wt.%) stabilizer decreased by 77%, and the peel strength increased by 36% compared to the camouflage coating without stabilizer.Curing process also perform significant effect on the peel strength of camouflage coatings. At last, the temperature 130~140℃and time 8~10min were chosen as the curing conditions.