Aqueous cleaning composition
An aqueous acidic cleaning composition suitable for the cleaning of metal parts is constituted by urea phosphate, a surfactant, a corrosion inhibitor, and water. The corrosion inhibitor can be a phosphatizing compound such as iron phosphate, zinc phosphate, manganese phosphate, and the like.
This application claims the benefit of U.S. Provisional Application No. 60/672,586 filed on Apr. 19, 2005, incorporated herein by reference.
FIELD OF INVENTIONThis invention relates to aqueous cleaning compositions suitable for use in agitation systems.
BACKGROUND OF INVENTIONAgitation systems that employ ultrasonic waves are often utilized in industrial cleaning operations. In such systems one or more transducers convert electrical energy to intense, high-frequency vibrations within a cleaning bath (ultrasonic cleaning).
Ultrasonic waves generate pressure gradients within a cleaning liquid contained in the bath and form bubbles within low pressure regions. The formed bubbles expand until they reach a region of pressure high enough to collapse the bubbles. As a result, small voids, usually referred to as cavitations continually grow and collapse at the surface of a part that is submerged in the bath.
The energy created by such cavitations loosens and removes contaminants that reside on the surface or surfaces of the part.
The present invention is directed to an aqueous cleaning composition that further enhances the efficacy of ultrasonic cleaning of industrial parts.
SUMMARY OF INVENTIONAn aqueous cleaning composition which comprises urea phosphate, a surfactant, a corrosion inhibitor, and water is provided. The aqueous cleaning composition is acidic, preferably has a pH value of no higher than about 2.5, more preferably no higher than about 2.2, and is useful for cleaning ferrous as well as non-ferrous metal. If the present aqueous cleaning solution includes a phosphatizing compound such as ferric phosphate, zinc phosphate, manganese phosphate, and the like, the pH value of the composition can be higher, but preferably no higher than about 5.5.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTSThe present aqueous cleaning composition is acidic, and is eminently well suited for cleaning and deoxidation of metal parts made from ferrous metal such as steel, cast iron, and the like as well as parts made from aluminum, copper, copper alloys, magnesium, and the like. The present composition can also be used as an activator for iron phosphate compounds. The pH value of the present compositions usually is in the range of about 2 to about 6, preferably no higher than about 2.5 unless a phosphatizing agent or phosphatizer is present as a corrosion inhibitor. In such cases the pH value of the composition can be in the range of about 3 to about 6, preferably no higher than about 5.5.
The cleaning composition embodying the present invention is also useful as a final rinse in an iron phosphate process for steel, galvanized steel, aluminum, aluminum alloys, and the like, as well as a final rinse prior to a coating process such as powder coating, spray painting, dip coating, flow coating, e-coating, and the like.
Urea phosphate salt suitable for present purposes is a reaction product of urea and phosphoric acid (H3PO4), and can be represented by the formula
CO(NH2)2.H3PO4
for urea monophosphate and
CO(NH2)2.2H3PO4
for urea diphosphate.
Urea-phosphate salts useful for the present purposes can be formed at varying molar ratios of urea and phosphoric acid. The molar ratio of urea to phosphoric acid can be in the range of about 1:1 to about 1:5. A molar ratio of about 1:1 is preferred.
The surfactant component of the present composition is a blend of a non-ionic surfactant and a cationic surfactant capable of removing grease and oil from the part to be cleaned, preferably a biodegradable blend. Particularly preferred such surfactant is commercially available from Akzo Nobel Surface Chemistry LLC, Chicago, Ill. 60606-9977 under the designation BEROL® 226 SA.
The corrosion inhibitor suitable for the present purposes preferably is a water-based corrosion inhibitor selected based on the composition of the metal parts to be cleaned so as to negate the effects of oxidation and acid/alkali attack. Such corrosion inhibitors include polymeric silicates, triazoles such as benzotriazole, blends of polyamines and thiourea, phosphatizers such as iron (ferric) phosphate, zinc phosphate, manganese phosphate, etc., and the like.
For ferrous metal parts a preferred corrosion inhibitor is a blend of polyamines and thiourea, such as the corrosion inhibitor commercially available from Crown Technology, Inc., Indianapolis, Ind. 46250-0426 under the designation CROWN® L 1011 NFNC.
For copper, high copper alloys, aluminum, aluminum alloys, zinc, and zinc alloys a preferred corrosion inhibitor is benzotriazole.
In use, the present aqueous cleaning composition can be further diluted with water, if desired. For effective cleaning the concentration of urea is in the range of about 0.1 to about 50 weight percent and the concentration of phosphoric acid is in the range of about 0.1 to about 50 weight percent while maintaining the aforementioned molar ratio ranges for urea and phosphoric acid.
A preferred aqueous cleaning composition is constituted by the following ingredients
to obtain an aqueous composition having a pH value of about 2.2 and containing urea phosphates, i.e., a mixture of urea monophosphate and urea diphosphate.
Optionally, a corrosion inhibitor such as benzotriazole and the like can be added to the above composition if copper, copper alloy, aluminum, or aluminum alloy parts are to be cleaned. For ferrous metal parts, a phosphatizing compound, e.g., ferric phosphate, zinc phosphate, or manganese phosphate can be added to the above composition, if desired. This is particularly desirable if the present cleaning solution is to be a final rinse after an iron phosphate treatment.
The foregoing description and the example are intended as illustrative, and are not to be taken as limiting. Variations of the foregoing are possible without departure from the spirit and scope of the present invention and will readily present themselves to those skilled in the art.
Claims
1. An acidic aqueous cleaning composition which consists essentially of a urea phosphate salt, a surfactant, a corrosion inhibitor, and water.
2. The composition in accordance with claim 1 wherein the corrosion inhibitor is benzotriazole.
3. The composition in accordance with claim 1 wherein the corrosion inhibitor is a blend of polyamines and thiourea.
4. The composition in accordance with claim 1 wherein the urea phosphate salt is a mixture of urea monophosphate and urea diphosphate.
5. The composition in accordance with claim 1 wherein pH value of the composition is no higher than about 5.5.
6. The composition in accordance with claim 1 wherein the composition has a pH value no higher than about 2.5.
7. The composition in accordance with claim 1 wherein the composition has a pH value of about 2.2.
8. The composition in accordance with claim 1 wherein the corrosion inhibitor is a phosphatizer.
9. The composition in accordance with claim 1 wherein the corrosion inhibitor includes iron phosphate.
Type: Application
Filed: Apr 19, 2006
Publication Date: Feb 12, 2009
Inventor: Lyle Carman (Mason, OH)
Application Number: 11/918,930
International Classification: C23G 1/06 (20060101);
