US2417028A - Process for the treatment of metal surfaces and product thereof - Google Patents

Description

Patented Mar. 4, 1947 PROCESS FOR THE TREATMENT OF METAL SURFACES AND PRODUCT THEREOF Franklin B. Wells, Verona, N. J., assignor to Ellis- Foster Company, a corporation of New Jersey No Drawing. Application December 1, 1942, Serial No. 467,556

2 Claims.

This invention relates to the protection of metal surfaces against corrosion. More particularly it relates to the temporary protection of metal surfaces, especially ferrous surfaces such as sheet steel, wire, etc., against corrosion and rusting due to moisture condensation during shipment and storage.

As is well known, newly manufactured surfaces, especially ferrous surfaces, corrode rapidly unless treated with corrosion inhibitors. In the past many types of materials have been used for this purpose such as various grades of wool fat (lanolin), water-insoluble greases, mineral oils, petrolatums, asphalts, etc. These materials have all been found satisfactory as corrosion inhibitors within certain limits, the chief objection having been that, for the most part, relatively thick films are required to prevent corrosion and rusting. A thick film must be removed before metal objects may be printed or lithographed, and in many cases, such as where mineral oil is used, inks or paints will not adhere properly to the metal if oil is present. Thus, metal surfaces which have been treated with mineral oil, or thick films of other corrosion and rust inhibitors, must be pretreated in order to remove such protective coatings before painting, printing, or lithographing can be carried out.

This invention has as its object the provision of a method for treating bright metal surfaces, especially ferrous surfaces, to inhibit corrosion and resting due to condensed moisture. Another object is to provide a protective treatment for a metal surface, especially a ferrous surface, which wi11 adequately protect said surface against corrosion or rusting and which will not interfere with subsequent painting, printing, or lithographing on such surface.

These objects are accomplished by depositing on a ferrous metal surface a thin continuous layer of a mixture of fatty acids, a mixture of higher fatty alcohols, and other unsaponifiable matter, or a mixture of fatty acidsand fatty alcohols and other unsaponifiablematerial. The mixture preferably should form an homogeneous, substantially non-crystalline film under ordinary conditions of temperature.

Such a mixture comprises hydrolyzed lanolin obtained by the hydrolytic splitting of the esters present in lanolin into a mixture of higher fatty acids and higher alcohols and other unsaponifiables. be separated and used alone; or the crude mixture of acids and unsaponifiable matter may be employed. Other materials may be added to the The acids and the unsaponifiablesmay hydrolyzed lanolin or the components thereof in amounts up to about 50% of the mixture. These include such substances as tall oil and tallow or cottonseed oil fatty acids, etc. Also certain nitrogenous compounds such as alphanaphthylamine or phenylnaphthylamine maybe advantageously included. The rustproofing materials are dissolved in a suitable solvent and applied to the ferrous surface as a dilute solution.

To form the corrosion-resisting material, lanolin is saponified by any known method. If the unsaponifiables are required the saponified product is extracted with a liquid which is a solvent for the unsaponifiables. When the lanolin fatty acids are required, the soap solution from which the non-soaps have been removed is acidified and the fatty acids taken up in a solvent. It is advantageous to use hydrolyzed lanolin which comprises the products obtained by saponifying lanolin and acidifying the mixture of soaps and alcohols to give a mixture of fatty acids and unsaponifiable material. The solvents used to take up thevarious lanolin components and to form the rustproofinig composition are preferably volatile coal-tar hydrocarbons, petroleum hydrocarbons containing an influential amount of aromatic hydrocarbons, or chlorinated hydrocarbons. The solutions may be applied to articles having ferrous surfaces by dipping, spraying, flowing or brushing and the necessary thickness of film to produce rustproofing and a paintable surface is substantially equal to that obtained by dipping the article in a 1 to 10% solution of the substance in xylene, allowing excess solution to drain off and the residue to dry.

As metioned above, other substances such as tall oil may be added to hydrolyzed lanolin and its saponifiable and unsaponifiable components. Also, nitrogenous antioxidants may be introduced, this being conveniently done by forming a waterinsoluble fatty acid salt thereof. For example, an amino compound such as a naphthylamine or bone oil is heated preferably with 'an excess of lanolin saponifiable matter or with acids such as tall oil or cottonseed oil acids and enough of this compound is used to introduce from about 11:0 10% of nitrogenous material into the rustproofing composition.

A series of tests to illustrate the effectiveness of hydrolyzed lanolin products in comparison with other compositions was made wherein various materials in 4% xylene solution were applied by dipping to strips of tin can base stock which had been abraded on a sanding machine. The strips with their deposited films were suspended 3 over water in a closed container and kept at about 40 C. for 96 hours. The following table shows the degree of rust protection afforded by different materials, the degree being a grading based on 100% for complete freedom from rust in this time and being complete rusting of the surface. Untreated iron and two examples where the material was smeared on as a thick film are also included for comparison, as well as certain prior art materials.

. Degree of Number Composition protection Hydrclyzed lanolin 100 Lanolin fatty acids... 99 Lanolin unsaponifiablc 95 Tall oil. 90 50% tall oil-50% hydrolyzed lanolin. 96 25% tall oil-75% hydrolyzed lanolin 98. 6 75% tall oil-25% hydrolyzed lanolin. 88 50% hydrolyzed lanolin-45% tall oil- 99.5

5% alphanaphthylamine. 50% hydrolyzed lanolin-44% tall oil- 94. 5

6% phonyl-alphanaphthylamine. 90% tall oil10% alphanaphthylamine" 93 88% tall oil-12% phenylalphanaphthyl- 96 amine. Lanolin 10 Cottonseed fatty acid. 93 80% cottonseed fatty acid-20% alpha- 97 naphthylamine. Cholesterol 53 Coconut oil acids 94 Aluminum grease (smeared on) .1 100 Lubricating oil (S.A.E. 50-Pcnna) 60 (smeared on). 19 Metal untreated 62 Degree of protection Composition Water 5% NaOl Hydrolyzcd lanolin 96 92. 5 Lanolin unsaponifiables 97 40 Lanolin fatty acids 96. 5 57 50% hydrolyzed lanolin-50% tall oil 90 50 50% hydrolyzed lanolin-45% tall oil-5% alphanaphthylamine 92. 5 65 50% hydrolyzed lanolin-44% tall oil-6% phenylnaphthylamine 94. 5 50 all oil 5 40 Coconut fatty acids 2. 5 25 The concentration of lanolin fatty acids dissolved in xylene was varied as follows and the compositions applied to iron and tested as in the first table:

Concentration Protection Per cent Per cent Also, a steel panel was coated in sections with various concentrations of hydrolyzed lanolin in xylene. To portions of each section there were applied: (a) a conventional nitrocellulose lacquer, and (b) a commercial drying oil varnish. The lacquer dried on all sections and also the varnish, except that adhesion was better over films deposited from solutions containing 10% or less of hydrolyzed lanolin. Therefore, the range of concentration for satisfactory rustproofing and paintability is from 1 to about 10% concentration.

It is known that: A film of lanolin thin enough to be painted over or printed upon satisfactorily no longer possesses adequate corrosion resistance, and from commercial operations it has been apparent that there is no film thickness of lanolin which will prove satisfactory both for prevention of corrosion and for direct application of adherent paint coatings or ink compositions. Therefore, it is entirely unexpected that completely hydrolyzed lanolin or the separate ingradients thereof (acids and unsaponifiable matter) show rust preventing properties in such an enhanced degree. It may be remarked that crude or rancid lanolin may contain varying amounts of free fatty acid and may have been used for rustproofing. However, the hydrolyzed lanolin which I use has an acid content of entirely different magnitude. Also it may be noted that the unsaponifiable material from lanolin contains cholesterol in mixture with other compounds and that a film of pure cholesterol shows poor rustproofing qualities whereas the crude cholesterol-containing material is very effective,

I claim:

1. An article of manufacture having a ferrous surface and, in order to render said surface corrosion-resistant and at the same time capable of being subsequently coated directly, a continuous thin film superposed on said ferrous surface and comprising completely hydrolyzed lanolin ob"- tained by hydrolyzing lanolin to a mixture of higher fatty acids and higher alcohols, said film being of a thickness such as is obtained by dipping the article in a 1 to 10% solution of said material in xylene and allowing same to drain and dry.

2. The process of rendering a ferrous surface corrosion-resistant and at the same time capable of being subsequently coated directly, which comprises depositing on said surface a continuous thin film comprising completely hydrolyzed lanolin obtained by hydrolyzing lanolin to a mixture of higher fatty acids and higher alcohols, said film being of a thickness such as is obtained by dipping an article having a ferrous surface in a 1 to 10% solution of said material in xylene and allowing same to drain and dry.

FRANKLIN B. WELLS.

REFERENCE S CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,624,938 Fowler et a1 Apr. 19, 1927 1,996,392 Torrence et al. Apr. 2, 1935 2,151,353 Montgomery Mar, 21, 1939 2,153,811 Montgomery Apr. 11, 1939 FOREIGN PATENTS Number Country Date 163,474 British 1921