US 3923539 A
Alkaline concentrate and aqueous solution for removing lubricant carrier and residue from iron containing surfaces. The alkaline solution contains phosphate ions and either cobalt or nickel ions or a mixture of the two. Use of the solution helps prevent inter stage rusting and the problems resulting therefrom.
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Description (OCR text may contain errors)
United States Patent Jorns 1 1 Dec. 2, 1975 1 1 METHOD CONCENTRATE AND SOLUTION  References Cited FOR SIMULTANEOUS CLEANING, UNITED STATES PATENTS DEGREASING AND REMOVAL OF THE 2.499.261 2/1950 Roscnhloom 1 17/127 LUBRICANT CARRIER LAYER FR M IR N 2.813.075 11/1957 Brooke 252/855 AND STEEL WORKPIECES 2.916.459 12/1959 Arnold 252/152 3.015.630 l 1962 Th 252 101 [751 lnventor: Peter Jorns, Frankfurt am Main. 3J5 087 911964 2521387 Germany 3.668.132 6/1972 Finder 134/2  Assigneel y Meta] Industries Corporationq 3.723.334 3/1973 Maurer 21/27 R Warren, Mich. Primary E.\'aminerBarry S. Richman 1 1 "led? 1973 Assistant E.\umincrDale Lovercheck  AppL NO; 332,055 Attorney. Agent. or Firm-Arthur E. Kluegel; Richard P. Mueller; B. F. Claeboe  Foreign Application Priority Data  ABSTRACT 1972 Germany 2207848 Alkaline concentrate and aqueous solution for removing lubricant carrier and residue from iron containing 134/2 134/40 3 0 surfaces. The alkaline solution contains phosphate ions and either cobalt or nickel ions or a mixture of  Int. Cl. ..C23g 1/16;C11d7/16;C23g1/20 th t U fth hl I t  Field of Search 252/146, 147, 387. 79.1, e be 0 e so u e p5 preen m m 5 age rusting and the problems resulting therefrom.
4 Claims. N0 Drawings METHOD CONCENTRATE AND SOLUTION FOR SIMULTANEOUS CLEANING, DEGREASING AND REMOVAL OF THE LUBRICANT CARRIER LAYER FROM IRON AND STEEL WORKPIECES BACKGROUND OF THE INVENTION Prior to the forming of metal workpieces, it is customary to apply chemical coatings, particularly phosphate layers, to their surfaces, and to carry out the forming in the presence of lubricants. The residues located on the surface after the forming may interfere with the further processing or use of the workpieces, so that their removal is necessary.
Aqueous alkaline solutions based on soluble phosphates are often used for simultaneous removal (cleaning) of the lubricant carrier layers and the lubricant residues. Salts of orthophosphoric acid and/or salts of condensed phosphates come into consideration as phosphates. However, it has been found that the treated workpieces are subject to considerable danger of rusting upon leaving the removal zone, and the rust occurs particularly in the transition zones between processing stages. The susceptibility to rust is also at least partially due to the deformation of the workpiece, and thus the change in the surface structure of the material. In automatically timed systems, long carry-over times can sometimes intervene between the cleaning bath and the rinsing baths. The parts cleaned with the phosphate solution rust slightly during this time. However, this is undesirable and greatly interferes with subsequent treatments, especially for subsequent phosphation.
THE INVENTION It has not been found that this disadvantageous susceptibility to rust can be avoided by adding to the cleaning solution soluble metal compounds of nickel and/or cobalt, preferably cobalt.
The rust-inhibiting effect is attained upon the addition of at least 0.05 g/l of the metal compound, calculated as cobalt and/or nickel. Quantities of more than g/l offer no additional advantage. Preferably, 0.1 to 2 g/l of the metal or metals is added.
Suitable cobalt salts include cobalt nitrate, cobalt sulfate, cobalt acetate, cobalt chloride. Suitable nickel compounds include nickel nitrate, nickel sulfate, nickel chloride, nickel acetate.
The phosphates used in the cleaner in accordance with the invention primarily include those of condensed phosphoric acids, especially pyrophosphoric acid. The phosphate content advantageously amounts to 5 to 80 g/l, preferably to 50 g/l, calculated as P 0 The aqueous cleaning solution normally has a pH of 8-13, and preferably the pH is kept in the range of 9-12. In order to increase the cleansing effect of the aqueous solution, surface-active substances and/or solvents may be included. Suitable surfactants include anionic surfactants such as alkybenzencsulfonates, fatty alcohol sulfates, etc., or nonionic surfactants, such as ethylene oxide addition products to alkylphenols or fatty alcohols. When nonionic surfactants are used, it is necessary to make sure that these surfactants possess sufficient solubility at the concentration and temperature used. Preferably, anionic surfactants are used. It is advantageous to add O.l3 g/l wetting agent. Organic solvents, such as higherboiling hydrocarbons (kero- 2 sene, petroleum), glycols, or polyglycols are advantageously used in quantities of 0.510 g/l.
The cleansing solution in accordance with the inven tion can advantageously be prepared from a solid cleanser concentrate. Such a concentrate preferably has the following composition:
907: NzuP o,
O 1071 Na;,P O
0 20% solvent The use of the cleanser in accordance with the invention will be explained in greater detail on the basis of the following examples:
EXAMPLE I Intermediate stages from shock-absorber piping manufacture, which were covered with a residual phosphate and lubricant layer, were cleaned in a cleanser solution containing 46 g/l Na,P,O calc.
2 g/l Na P O caIc. 1 g/l polyethylene glycol (molecular weight ca. 4000) for 10 min. at C. After this time, the phosphate and lubricant residues were completely removed from the surface of the workpiece. Following the cleaning, the parts were slowly introduced into a water rinsing bath within 60 sec, and rinsed vigorously there.
During the transport of the workpieces from the cleansing bath to the water rinsing bath, a very thick layer of rust was formed.
In a parallel experiment, 1.24 g/l Co(NO 6 H O (corresponding to 0.25 g/l Co) were added to the cleaning solution. In this experiment, no formation of heavy rust on the workpieces occurred.
During the subsequently performed phosphation, when the Co-free cleaner bath was used, phosphate layers flecked irregularly with rust were formed, and led to substantial disturbances during the subsequent defor mation stage. When the Co-containing cleaner bath was used, no difficulties of this type occurred in the phosphation and shaping processes.
EXAMPLE II In order to determine the influence of the Co concentration on the prevention of heavy rust formation, 0-5 g/l of Co in the form of cobalt nitrate were added to the cleaning bath according to Example I. In the various cleaning baths, drawing blanks covered with residual phosphate and lubricant layers were cleaned for 10 min at 95C. The cleaned parts were then kept in the vapor atmosphere of the cleaning bath up to the beginning of heavy rust formation. The experimental results thus obtained are presented in the following table.
TABLE Addition. g/l Co Beginning of heavy rust formation after ca.... minutes TABLE-continued Addition g/l Co Beginning of heavy rust formation after ca... minutes EXAMPLE lll l. A method for the simultaneous cleaning, degreasing and removal of a cold-forming lubricant carrier layer from workpieces containing iron comprising con- 4 taeting said workpiece with an aqueous alkaline solution comprising 5-80 g/l phosphate ion and at least 0.05 g/l of a metal ion selected from the group consisting of cobalt. nickel and mixtures thereof. and having a pH adjusted to a value between 8 and 13 for at least one minute.
2. The method of claim 1 wherein said metal ion is present in a concentration of from 0.1 to 2.0 g/l.
3. An alkaline phosphate-containing aqueous solution for the simultaneous cleaning. degreasing and removal of a cold forming lubricant carrier layer from workpieces containing iron, comprising 5-80 g/l phosphate ion and at least 0.05 g/l of cobalt ion and having a pH adjusted to a value between 8 and 13.
4. The solution according to claim 3 wherein the cobalt ion is present in a concentration of aboutOrl to 2.0 g/l.