Title: Process for reducing the rate of sludge formation in crystalline phosphatizing baths

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Claims: What is claimed is:

1. In a process for forming a crystalline zinc or manganese-based phosphate coating on a metallic surface wherein the surface is contacted with an aqueous acidic solution containing a zinc or manganese phosphate compound, and wherein insoluble sludge is formed during the contact period, the improvement comprising reducing the rate at which sludge is formed by including in the solution 0.005 to 20 g/liter of a phosphoric acid ester in which at least one hydrogen is replaced by an organic condensate radical of the formula:

-- R"O ).sub.n R'

wherein

R" = alkyl group of 2 to 3 carbon atoms;

R' = alkyl, oxoalkyl or alkyl phenol group where the alkyl group has 5 to 20 carbon atoms;

n = an integer from 3 to 15.

2. The process of claim 1 wherein at least one of the remaining hydrogens is replaced by a soluble cation selected from the group consisting of alkali metal and ammonium.

3. The process of claim 1 wherein the ester concentration is 0.02 to 5 039780499 g/liter.
Other info:

Inventors: Smadja, Dora (Paris, FR)
Decker, Marie-Therese (Gennevilliers, FR)
Derouet, Francoise (Levallois-Perret, FR)
Lorin, Guy (Enghiens-les-Bains, FR)

Application Number: 569733
Filing Date: 1975-04-21
Publication_date: 1976-08-31
Assignee: Oxy Metal Industries Corporation (Warren, MI)
Primary Class(es): 148/250
Other Classes:
US Patent Ref:

2304299	Dec, 1942	Boyle et al.	148/6.
2744555	May, 1956	Nicholson et al.	148/6.
3276916	Oct, 1966	Wurstner	148/6.

Other Refs:
Primary Examiner: Kendall, Ralph S.
Assistant Examiner:
Attorney: Kluegel; Arthur E., Mueller; Richard P., Claeboe; Bertram F.