METAL CLEANING PROCESS

摘要

1321513 Cleaning metals; electrolytic degreasing UNILEVER Ltd 19 April 1971 [1 April 1970] 25824/71 Headings C7B and C7E [Also in Division C5] Metal, e.g. Al, Zn, Fe, or bronze, is cleaned by treatment in baths (1) and (2) as defined below, either consecutively or simultaneously. Bath (1) comprises (a) a non-ionic surface-active addition product of 3-15 moles of ethylene oxide with an organic compound containing active H bound to O, S, or N (b) a fatty acid and/or alkyl polyethylene oxide-carboxylic acid and (c) an alkanolamine and/or oxazine, the amount of (c) being # 1À5 times molar excess over the amount of (b). Bath (2) is mixible with water and with bath (1) and contains (d) an alkali, e.g. KOH, K 2 CO 3 , Korthophosphate, K 4 P 2 O 7 , alkanolamine (mono, di, or tri-ethanolamine) or morpholine and (e) a sequestrant for heavy metal ion such as a salt of citric, tartaric gluconic, boro-gluconic, amino polycarboxylic or ethane-1, hydroxy-1,1, diphosphonic acid, and has pH 12À4 - 13À8 and a wt ratio free alkali; total salt # 2:1; it may also contain (f) a lowfoaming detergent, e.g. C n H 2n+1 - (OCH 2 CH 2 ) 3-5 -O(CH 2 ) 1-2 -COOH, a fatty alcohol/ethylene oxide condensate, an ethylene oxide and propylene oxide block polymer, a condensate of alkyl phenol with ethylene oxide and/or propylene oxide block polymer, or a fluorinated wetting agent such as a perfluorinated alkylsulphonic acid (g) soil-suspending agents such as carboxymethylcellulose, polyvinylpyrrolidone or polyacrylate and (h) hydrotropes, e.g. K xylene sulphonate, K toluene sulphonate, polyglycol, hexylene glycol, or cumene sulphonate. The compositions are preferably free of Na ion, and are used diluted in water. Bath (2) may be used for electrolytic degreasing at current 1-2 A dm-2; baths (1) and (2) may be mixed together, when the mixture should have pH 12À4- 13À8.