摘要 |
<p>Aluminium containers are cleaned using an alkaline cleaning soln., followed by rinsing at least once with an aq. soln. whose pH is not more than 2.5. The use of the process as a pretreatment for aluminium containers before the application of coatings is also claimed. Pref. the aluminium containers are rinsed with an acid aq. soln. of pH about 2, whose temp. is less than 65.6 deg.C, esp. 32.2-54.4 deg.C, before and/or after treatment with the alkaline cleaning soln. After the alkaline treatment, the containers are rinsed in several steps, in which the second step involves rinsing with an aq. soln. whose pH is not more than 2.5. Pref. the rinsing with the aq. soln. is with a spray, the aq. acid soln. contains fluoride ions, and rinsing with water takes place after the rinsing with aq. acid. Pref. after treatment with the alkaline cleaning soln. and rinsing, the aluminium containers are dried.</p> |