| 摘要 |
An ester of a mercapto carboxylic acid derived from an alcohol having at least 12 carbon atoms, e.g. stearyl mercaptopropionate and stearyl, lauryl or iso-octyl thioglycollate, is used to prevent tarnishing of copper, silver or nickel. In an example, a liquid polish consists of (by weight) polishing powder (diatomaceous earth) 20%, ethyl alcohol 20%, stearyl glycollate 2.5%, phosphoric acid 0.2%, water up to 100%. Bentonite (2 to 4%) may be added and acetic or hydrochloric acid may be used instead of phosphoric acid. The polish may also be in the form of a paste, powder, block or impregnated fabric.ALSO:An ester of a mercapto carboxylic acid derived from an aliphatic alcohol having at least 12 carbon atoms, e.g. stearyl, lauryl or iso octyl thioglycollate and stearyl mercaptopropionate is used to prevent tarnishing of silver, nickel or copper. The ester may be added to a pickling, detarnishing, brightening, de-scaling or etching bath. In an example, the solution contains (by weight) 3 stearyl thioglycollate, 3 ethoxylated fatty alcohol, 0.2 phosphoric acid, 94 water. Acetic or hydrochloric acid may be used instead of phosphoric acid as a stabilizer. |
