Rapid sealing of anodised coatings - using dilute tri:ethanolamine soln. pref. at b.pt.

摘要

Anodised coatings are sealed using a soln. contg. 0.1-1.0 (pref. about 0.5) g/l triethanolamine, pref. at 95-100 degrees C, the soln. being periodically regenerated by passage over an anionic resin. Compared with prior processes using a more conc. (5120 g/l) triethanolamine soln., the treatment time is reduced from >=2 min./mu to 1 min./mu for a 15-20 mu thick coating and formation of powdery deposits is minimal. The soln. is less sensitive to impurities (e.g. 400 mg/l on a dry basis can be tolerated) so that it can be used for >6 months and the frequency of regeneration of the soln. is reduced considerably. By using a hot soln., a final drying step can be omitted.