US3247120A - Composition and process for cleaning metal surfaces - Google Patents

Description

United States Patent'O 3,247,120 COMPOSITION AND PROCESS FOR CLEANING METAL SURFACES James A. Von Pless, Syracuse, N.Y., assignor to Cowles Chemical Company, Siraneateles Falls, N.Y., a corporation of Ohio N Drawing. Filed Apr. 30, 1962, Ser. No. 191,251

11 Claims. (Cl. 252114) I Additional objects of the invention are to provide improvements in the cleaning of the metal surface over present methods and compositions.

Many processes for the fabrication of zinc-base die castings involve an operation in which a coating is applied to the surface of the metal, either for protective or decorative purposes. Thus zinc-base die castings are electroplated, chromated, painted and otherwise treated to provide a finished article. In connection with the fabrication, it is essential that the surface of the article to be subjected to the application of the coating be free from soils of all kinds which would tend to interfere with the uniform adherence of the coating to the surface of the metal. Buffing compounds used in buffing zinc castings are particularly difficult to remove. Poorly cleaned castings result in inferior plating. This leads to the blistering which is so common on parts of many modern automo biles. Buffing compounds are compounded mixtures of abrasive and binder or carrier. The bar type consists of solid sticks of high melting fats and waxes plus abrasives. These materials are applied to a bufiing wheel like crayon and melted thereon due to temperature. The liquid type consists of pasty materials comprising a high melting lubricant and abrasive emulsified in water or kerosene in a high speed mill to suspend materials in the water or solvent system used. Abrasives used in bufling compounds are, for example, aluminum oxide, amorphous silica, tripoli, emery and chalk. Examples of binders and carriers are petroleum wax, fat, kerosene, water, vegetable waxes and emulsifiers. Fatty acids (stearic or unsaturated hydrogenated acids), glycerides, beeswax and pitch are examples of lubricants. W

A method proposed for cleaning metal surfaces to prepare them for subsequent treatment and particularly coating thereof, involves immersing the metal objects in baths containing non-aqueous solvents for greases; as for example: trichloroethylene and petroleum distillates. Such materials are toxic and require expensive systems for recovery and purification of the soiled solvents for re-use.

Another method which is more commonly used is an alkaline type bath containing fatty acid alkanolamides and amine condensates plus other surfactants. These materials tend to do a better job of soil removal than solvents; however, due to the presence of free amines in solution they tend to sequester introduced metallic ions and deposit such sequestered ions (particularly copper) on the surface of the metal to be cleaned and therefore having a deleterious effect on subsequent electroplating processes. These types of baths also are very hard to control operationally and lose their ability to clean with little or no ICC warning to the user, thereby shutting down a production line immediately. Additions of new chemical to these expired baths are of no avail and will not re-activate the baths to operating levels.

With a view to overcoming these difficulties encountered in production lines this invention provides maximum wetting of the soils in the minimum of time, high emulsification and dispersion of soils, stability of pH at elevated temperatures, anti-corrosion qualities, the ability to carry large soil loads, and the minimum amount of operational control by titration methods.

In accordance with the present invention, unusually effective results in cleaning, and especially in removing but'ring compounds from zinc die castings are obtained with the following cleaning composition:

TABLE I Percentage Ingredients: by weight (a) Hydrated borate, calculated as Na B O 10H O (b) Alkali metal soap of highly unsaturated oil, calculated as cottonseed oil sodium soap having a titer value of 29-32 C. 1020 (c) Water soluble lignosulfonate, calculated as sodium lignosulfonate 1-4 (d) Alkyl ether of polyethylene glycol 2-10 (e) Polyethylene or polymethylene glycol tertiarydodecyl thioether "075-5 (f) Alkyl phenoxy polyethoxyethanol 0.75-5 (g) Ethylene glycol monoalkyl ether 1.5-5 (h) Pine oil 0-0.5

Examples of (a) are borax (Na B O 10H O) and other hydrated borates, for instance, sodium pentaborate. Borax is preferred because it is readily available and inexpensive. If the pentahydrate is used, the Na O content is adjusted to meet the decahydrate qualities and an inert material is added to compensate for the weight differential.

Cottonseed oil sodium soap is preferred for ingredient (b) due to its high linoleic acid content. This oil also has a high content of oleic acid but the polyunsaturated acid with two double bonds has a very powerful detergency for cleaning die castings. Other'soaps of highly unsaturated fatty acid oils having an iodine value at least as high as cottonseed oil can be used, e.g., sesame oil and safilower oil. I

The water soluble lignosulfonate used as ingredient (c) is preferably sodium lignosulfonate. A preferred sodium lignosulfonate contains not more than 0.4% by weight calcium oxide, not more than 4.5% by weight reducing sugars, not more than 0.05% by weight iron, about 7.4% total sulfur and gives a 50% by weight solution in water having a pH value of 6.07.5 containing no insoluble materials. This type of substance has a dispersing action and also a partial sequestering action for metal ions.

In (d) the alkyl groups can contain one to eighteen carbon atoms (e.g., methyl, ethyl, 'butyl, decyl, dodecyl, tridecyl, tetradecyl, hexadecyl, octadecyl) and there can be two to twenty oxyethylene groups (e.g., Tergitol TMN3, TMN6 and TMNIO).

Examples of (e) are Nonic 218, 234, 260 and 261. A preferred material is decamethylene glycol tertiary dodecyl mono thioether. Other examples of thioethers in this class are those containing 6 to 18 carbon atoms in the polymethylene group.

A preferred example of (f) is Makon BXS which contains 12 moles of ethylene oxide. Compounds of this type are made by adding ethylene oxide to an alkyl phenol containing one or more alkyl groups substituted for hydrogen in the phenolic nucleus wherein the alkyl groups contain 9 to 18 carbon atoms. Mixtures of such monoand dialkyl phenols which have been oxyalkylated with 8 to 30 moles of ethylene oxide per mole of phenol can be used.

Examples of (g) are the methyl, ethyl, propyl, and butyl ethers of ethylene glycol. These substances act as solvents for the non-ionic surface active agents (d), (e) and (f). They are also solvent carriers for small amounts of trichloroethylene, chloroethane, kerosene, Stoddard solvent, and naphtha that are employed in manufacturing media.

In the following examples, the inhibitive and protective quality of the cleaning composition is supplied by the poly-unsaturated oil soap used in conjunction-with the specific quantities of mixed non-ionics. If the quantities of mixed non-ionics are removed or altered beyond the limits set forth the cleaning solution will not function as intended. Operating conditions of this invention are elevated temperatures of 88-97 C. with a stabilized pH of 8.7-8.9. The protective film provided by the polyunsaturated oil soap prevents air or water from corroding the basis metal prior to neutralization of the film.

Composite liquid alkaline solutions of the following ingredients were prepared and tested using proportions of 8-10 oz. of alkaline additive to one U.S. gallon of water under the aforementioned operating conditions.

TABLE II Ingredients: Percent by weight Na B O lH O Cottonseed soap (29-32 C. titer) -20 Sod. lingnosulfonate 1-4 Alkylether of polyethylene glycol such as Tergitol TMN (Union Carbon & Carbide) 2-10 Polyethylene glycol tertdodecyl thioether such as Nonic 218, 234, 260, 261 (Pennsalt Chemical Co.) .75-5 Alkyl phenoxy polyethoxy ethanol such as Makon (Stepan Chemical Co.) .75-5 Ethylene glycol mono alkyl ether such as Cellosolves (Union Carbon & Carbide) 1.5-5 Pine oil (odor) 0-.5

In general, these additives consist essentially of TABLE III Ingredients: Percent by Weight Hydrated borate, calculated as Na B O IOH O 68-73 Polyunsaturated oil soap, calculated as cottonseed oil sodium soap -10 Other wetting agents 12-17 Table IV gives more specifically weight percentages of the foregoing additives used in the examples.

Alkaline mixtures as described in Table IV were prepared and dissolved in the ratio of 8-10 oz. of formula per gallon (U.S.) of water.

Example I Soiled zinc die cast parts were immersed in the cleaning solution at a temperature ranging from 88-97 C. for a period of from 3-20 minutes with rapid emulsification and dispersing action on the removed soil. No corrosion or darkening of the basis metal was exhibited.

4- Example 11 Soiled zinc die cast parts were immersed in the cleaning solution at a temperature ranging from 8897 C. for a period of from 3-20 minutes with rapid emulsification and dispersing action on the removed soil. No corrosion or darkening of the basis metal was exhibited.

Example Ill Soiled zinc die cast parts were immersed in the cleaning solution at a temperature ranging from 88-97 C. for a period of from 3-20 minutes with rapid emulsification and dispersing action on the removed soil. No corrosion or darkening of the basis metal was exhibited.

Example 1V Soiled zinc die cast parts were immersed in the cleaning solution at a temperature ranging from 88-97 C. for a period of from 3-20 minutes with rapid emulsification and dispersing action on the removed soil. No corrosion or darkening of the basis metal was exhibited.

Example V Soiled zinc die cast parts were immersed in the cleaning solution at a temperature ranging from 88-97" C. for a period of from 3-20 minutes with rapid emulsification and dispersing action on the removed soil. No corrosion or darkening of the basis metal was exhibited.

Example VI Soiled zinc die cast parts were immersed in the cleaning solution at a temperature ranging from 88-97 C. for a period of from 3-20 minutes with rapid emulsification and dispersing action on the removed soil. No corrosion or darkening of the basis metal was exhibited.

The compositions and procedures of Examples I-VI can also be used in the cleaning of buffed copper and certain aluminum alloys without detrimental effect to the basis metal in the fabrication of such metals to a finished coated article.

The mixed wetting agents in the examples can be broken down further as shown in the following Table V.

TABLE V Weight percent of total additive Examples I II III IV V VI Ingredients:

Sodium lignosulionate 0.5 1. 5 2. 0 2. 0 1. 5 2. 0 'Iergitol TMN 10 5. 5 3. 5 3.0 4.0 4. 5 5.0 Nonic 260 2. 5 2. 5 2. 5 3. 5 3. 5 3. 5 Makon BXS 1. 5 2.0 2. 5 3.0 3.5 4.5 Butyl Cellosolve. 1.5 3.0 3. 5 2.0 2. 5 1.5 Pine oil (for odor 0.5 0.5 0.5 0.5 0.5 0.5

Total percent 12. 0 13.0 14. 0 15. 0 16. 0 17.0

Preparations of the ingredients listed in Table IV and performances listed under Examples I-VI used in concentrations from 8-10 oz. of formula per US. gallon of water at temperatures ranging from 88-97 C. exhibit excellent soil removal qualities. These compositions give complete protection of the basis metal and are unique in the industry, since they contain no amides, amines or phosphates, therefore eliminating the possibilities of copper deposition by immersion. The compositions of the invention are stable during operation, have tremendous soil capacity and have a stable pH.

The introduction of plating solution (specifically CrO in small amounts to the cleaning solution does not hinder its ability to clean, nor will it deposit metallic ions on the basis metal by immersion means (e.g., copper by immersion plate).

The invention also is unique in that the basis metal can be immersed for extended periods of time (up to 20 min.) without showing signs of corrosion or ionic metal deposition.

The invention is hereby claimed as follows.

I claim:

1. A composition adapted to be added to Water to produce a cleaning composition and consisting essentially of the following ingredients in weight percent based on the total Weight of the composition before addition to water:

Ingredients: Percentage by Weight (21) Hydrated sodium borate, calculated as the Na B O 1011 equivalent weight 68-73 b) Alkali metal soap of highly unsaturated fatty oil having a titer value of 29-32" C. (c) Water soluble sodium lignosulfonate (d) Alkyl ether of polyethylene glycol contain 1 to 18 carbon atoms in the alkyl groups and 2 to 20 oxyethylene groups (e) Polyalkylene glycol tertiarydodecylthioether from the group consisting of polyethylene glycol tertiarydodecylthioethers and polymethylene glycol tertiarydodecylthioethers containing 6 to 18 carbon atoms in the polyalkylene group 0.75- (f) Alkyl phenoxy polyethoxyethanol containing 9 to 18 carbon atoms in the alkyl groups and 8 to 30 moles of ethylene oxide per mole of phenol 0.75-5 (g) Ethylene glycol monoalkylether containing 1 to 4 carbon atoms in the alkyl group (b) Pine o-il 2. A liquid cleaning composition consisting essentially of the composition of claim 1 dissolved in water in the proportions of 8 to 10 ounces of the composition of claim 1 per gallon of water.

3. A composition as claimed in claim 1 in which (b) is cottonseed oil sodium soap.

4. A composition as claimed in claim 1 in which (e) is decarnethylene glycol tertiary dodecylmonothioether.

5. A composition as claimed in claim 1 in which (f) contains 12 moles of ethylene oxide.

6. A process of cleaning metals which comprises washing them with a composition as claimed in claim 1 dissolved in Water in proportions from 8 to 10 ounces of said composition per gallon of water at a temperature of 88 C. to 97 C. at a pH of 8.7 to 8.9.

7. A process as claimed in claim 6 in which the metal surface to be cleaned is a zinc base die casting.

8. A process as claimed in claim 6 in which the metal surface to be cleaned is a buffed copper surface.

9. A process as claimed in claim 6 in which the metal surface to be cleaned is an aluminum alloy surface.

10. An additive adapted to produce a liquid cleaning composition when added to water consisting essentially of the following ingredients in Weight percent based on the total Weight of the composition:

Ingredients: Percentage by weight NEIZBQOTIOHZO Cottonseed oil sodium soap having a titer value of 29-32 C Other ingredients from the class consisting of sodium lignosulfonate, alkyl ethers of polyethylene glycols containing 1 to 18 carbon atoms in the alkyl groups and 2 to 20 oxyethylene groups, polymethylene glycol containing 6 to 18 carbon atoms in the polymethylene group, alkyl phenoxy polyethoxyethanols containing 9 to 18 carbon atoms in the alkyl groups and 8 to 30 moles of ethylene oxide per mole of phenol, ethylene glycol Inonoalkyl ethers containing 1 to 4 carbon atoms in the alkyl groups, and pine oil 11. A composition adapted to be added to water to produce a cleaning composition and consisting essentially of the following ingredients:

Ingredients: Percent by weight (a) Sodium tetraborate decahydrate 67-73 (b) Sodium soap of cottonseed oil (29-32 C. titer) 10-20 (0) Sodium lignosulfonate 1-4 (d) An alkylether of a polyethylene glycol containing 1-18 carbon atoms in the alkyl groups and 2-20 oxyethylene groups 2 2-10 (e) Polymethylene glycol tertiarydodecylmonothioether containing 6-18 carbon atoms in the polymethylene groups 0.75-5

(f) Alkylphenoxy polyethoxyphenol containing 9-18 carbon atoms in the alkyl groups and 8-30 moles of ethylene oxide per mole of phenol a- 0.75-5

(g) Ethylene glycol monalkylether containing 1-4 carbon atoms in the alkyl group 1.5-5 (h) Pine oil 0-0.5

References Cited by the Examiner UNITED STATES PATENTS 2,097,737 11/1937 Pickett et al. 252-121 XR 2,595,300 5/1952 Safrin et al 252-109 2,664,399 12/1953 Kluender 252-109 XR 2,954,348 9/1960 'Schwoeppe 252-121 XR 3,048,547 8/1962 Vosbogian 252-154 XR FOREIGN PATENTS 671,358 5/1952 Great Britain.

OTHER REFERENCES Bennett: The Chemical Formulary, (vol. V), Chem. Publ. Co., Brooklyn, NY. (1941) (p. 572).

JULIUS GREENWALD, Primary Examiner.

Claims (1)

1. A COMPOSITION ADAPTED TO BE ADDED TO WATER TO PRODUCE A CLEANING COMPOSITION AND CONSISTING ESSENTIALLY OF THE FOLOWING INGREDIENTS IN WEIGHT PERCENT BASED ON THE TOTAL WEIGHT OF THE COMPOSITION BEFORE ADDITION TO WATER: INGREDIENTS: PERCENTAGE BY WEIGHT (A) HYDRATED SODIUM BORATE, CALCULATED AS THE NA2B4O7$10H2O EQUIVALENT WEIGHT 68-73 (B) ALKALI METAL SOAP OF HIGHLY UNSATURATED FATTY OIL HAVING A TITER VALUE OF 29-32*C. 10-20 (C) WATER SOLUBLE SODIUM LIGNOSULFONATE 1-4 (D) ALKYL ETHER OF POLYETHYLENE GLYCOL CONTAIN 1 TO 18 CARBON ATOMS IN THE ALKYL GROUPS AND 2 TO 20 OXYETHYLENE GROUPS 2-10 (E) POLYALKYLENE GLYCOL TERTIARYDODECYLTHIOETHER FROM THE GROUP CONSISTING OF POLYETHYLENE GLYCOL TERTIARYDODECYLTHIOETHERS AND POLYMETHYLENE GLYCOL TERTIARYDODECYLTHIOETHERS CONTAINING 6 TO 18 CARBON ATOMS IN THE POLYALKYLENE GROUP 0.75-5 (F) ALKYL PHENOXY POLYETHOXYETHANOL CONTAINING 9 TO 18 CARBON ATOMS IN THE ALKYL GROUPS AND 8 TO 30 MOLES OF ETHYLENE OXIDE PER MOLE OF PHENOL 0.75-5 (G) ETHYLENE GLYCOL MONOALKYLETHER CONTAINING 1 TO 4 CARBON ATOMS IN THE ALKYL GROUP 1.5-5 (H) PINE OIL 0-0.5