US2418075A - Rust-preventive composition - Google Patents

Description

Patented Mar. 25, 1947 RUST-PREVENTIVE COMPOSITION Myron H. Kellen, Ferndale, Mich., and Marcellus T. Flaxman, Whittier. Calii'., assignors to Union Oil Company of California, Los Angeles, Calif., a corporation of California No Drawing. Application November 5, 1945, Serial No. 626,884

18 Claims. 1 This invention relates especially to compositions having high degrees 01' eiilciency for the prevention of rusting of ferrous and other metallic articles and is a continuation-in-part of patent application, Serial No. 470,640, filed Decemhe: 30, 1942.

Important objects of the invention are to protect metals, especially iron and steel surfaces, against corrosion under severe conditions when applied only in thin iilms, particularly where the films oi the protective material are to be subjected to prolonged exposure to the atmosphere. These objects include the preparation of rust preventive compositions which will be readilyremovable with ordinary solvents. Also, compositions are preferred which dry readily within a reasonable period of time, for example, within four to six hours after application, to the extent of yielding a non-tacky, preferably transparent film which is tough and will resist shock; and will also adhere tenaciously to the metal surface even under wide extremes of temperature variations.

In its broadest aspects the invention comprises oil-soluble polyvalent metal soaps of organic fats and acids capable of adhering tenaciously to metal articles in the presence of moisture and varying temperature conditions, after such soap ha" been appl ed as a solution in a thinner, for example, in a light mineral solvent. Such a polyvalent metal soap may be a polyvalent metal soap of wool grease (degras), or a. polyvalent metal soap of refined tall oil. For best results both of these types of soap are employed. Roughly, about one-half the composition when applied will be the soap or soap mixture and the other half will be thinner. For the purpose of promoting greater water resistance a few percent of a low-melting parafiinwax may be employed, e. g., from about 2% to perhaps 6%. Similarly, a small percentage of a parafflnic-type lubricating oil may be added, e. g., from 2% to about 6% for the purpose of plasticizing the product and avoiding objectionable brittleness. The term oil-soluble" is meant to include good dispersibility or colloidal distribution in oil, and not necessarily true solution.

In order to secure an important object of the invention, that is, drying to a non-tacky condition in a comparatively short time, a small proportion of an active drier is used. The most effective drier found for this purpose has been a cobalt salt sufliciently compatible with the composition, or sufliciently oil-soluble or solvent-soluble, e. g., cobalt naphthenate or linoleate or tall oil soap or the like. For practical purposes the composition should contain in the order of 0.01%

of cobalt calculated as metal, where about onehalf the composition is thinner.

One very desirable composition contained the following:

The proportions of the various components of the composition may be modified, or various constituents may be entirely omitted, according to characteristics required in a given product for any given use or according to which of the indicated characteristics may be permissibly elimlnated for an given use. Thus, if the composition consisted wholly of thinner and the lead tall oil soap, the product would be too hard and brittle when dried and moreover would not be removable by any ordinary solvent within a few months after application. Similarly, if the proportion of the tall oil soap with respect to other constituents is too great, the composition becomes too brittle. Again, if the lead wool grease soap were the only constituent employed with the thinner the composition would be too soft, and its viscosity and pour point would be too high, but if from. 5% to 30% of lead soap of wool grease, based on the non-volatile constituents, is used the product becomes readily removable long after application, merely by employing ordinary solvent such as the various volatile, mineral solvents. Around 5% to 10% of the wool grease soap (based on the nonvolatile constituents) appears to be the minimum necessary to insure sufliciently ready removal several weeks or months after application. The paraffin wax is employed to render the composition more water-resistant. In the example above given, wax amounting to 4% of the total composition was employed because it gave a dull finish which eliminated reflections, this being due apparently to a slight incompatibility. When 2% or 3% of the total is paraflln wax, the product is still very desirable but the finish when dry tends to be shiny. If appreciably greater proportions than 4% of parafiin wax were employed the pour point would be raised objectionably. In other words, in the specific composition given, 4% paraflin wax 3 approaches the critical. Similarly, the 15% of wool grease soap in said example approaches the critical because of objectionable increase in viscosityand pour point if much larger proportions are used. The lubricating oil is employed to plasticize the composition and make it less brittle. Preferably, the lubricating oil should be a rather heavy lubricating oil such as one having a viscosity of 150 seconds Saybolt Universal at 210 F., corresponding with '70 S. A. E. grade. Here again, the 4% of oil based on the total composition above given approaches the critical, inasmuch as larger proportions of lubricating oil tend to retard the drying excessively and to make the dried film too soft.

The range of the cobalt drier previously given represents the practical limits. If much less drier is used its effectiveness is inconsequential, and if greater proportions than about 0.1% (metal content in thinned product) are employedno additional benefits appear to be obtained. The presence of the drier speeds up the drying of the applied film so that good drying may be obtained in as little as six to eight hours. If the time of drying is of no particular consequence so that a drying period of 30 to 50 hours or more is no hindrance, the drier may be eliminated, Ii. drying within two or three hour is required the cobalt may be increased two or three times the indicated .01

From the foregoing it is apparent that the paraflln wax, the lubricating oil and the drier may be reduced or eliminated according as speed of drying. or freedom from brittleness, or water-resistance may be reduced or eliminated. Thus, it is possible for varying purposes to vary the components of the anti-rust composition within the approximate limits given below. However, for purposes of the principal invention those limits given in the column headed Practical Range will be-ordinarily controlling, except in so far as the drier or the lubricating oil or the parafiin wax may be eliminated: I

Without Thinner Over-All Practical Range Range Per cent Per cent50 Lead tall oil soap 5 to 05 85 to Lead wool grease soap. 5 to 85 5 to 80 Parafln wax None to 12 5 to Lubricating oil hjonc to 12 5 to 10 Cobalt drier (as metal) L\ one to 0.2 0.01 to 0.1

The thinner added to the above normally will be roughly one-half the finished product, but may vary from about 30% to about 70% of the total composition. Smaller proportions of thinner make the composition too heavy to apply and larger proportions make it too thin to be practical. The thinner may be any readily volatile mineral oil fraction such as mineral spirits, or naphtha, or equivalent thinner.

The wool grease employed is the commercial degras of crude wool grease. Degras is the grease-like material which protects the wool while on sheep or on other animals, and is extractable from the fleece with a detergent, or with a hydrocarbon or other solvent. Degras comprises high molecular weight alcohol esters of fatty acids as well as free fatty acids. The tall oilis an article of commerce obtained as a byproduct from the Swedish process for cellulose pulp making. Waste liquor from the process separates into two layers, the upper of which is the crude tall oil which may be purified by distillation to yield a product containing both fatty acids and rosin-type acids.

In practicing the invention, the oil-soluble polyvalent metal soaps of tall oil and. of degras or degras fatty acids are prepared by methods given below following which the two soaps are commingled with the parafiin wax, lubricating oil and cobalt drier at suitable temperatures. The methods outlined below are specific to the prep-. aration of the lead soaps, however, they are applicable to the preparation of other polyvalent metal soaps with modifications which will be apparent to those skilled in the art.

The lead tall oil soap is prepared by heating the tall oil with the theoretical quantity of litharge, the proportions varying with the acid number of the tall oil and the purity of the litharge. The tall oil is heated in a steam jacketed kettle equipped with an agitator, and when the temperature of the batch reaches 250" F. the litharge is slowly added. The rate of addition of the litharge is such that excessive foaming due to liberation of water is avoided. The temperature of the batch is slowly increased during the course of the reaction so that when all of the litharge has been incorporated the batch is at a temperature of 310 F. to 340 F., and this temperature should be held until foaming has entirely ceased. This will generally require from 1 to 2 hours after the final addition of litharge. The batch in the kettle should then be cooled to 250 F. and thinned by the gradual addition of the indicated thinner until it consists of a solution of soap in the thinner containing approximately 50% by weight of soap. The finished batch is then held ata temperature of F. to F. for 18 to,-24 hours to permit settling, of the unreacted litharge or impurities, and then drained off into storage, taking care not to disturb material that has settled out.

- The lead tall oil soap may alsobe prepared by first reacting tall oil with sodium hydroxide to form the sodium soap and then metathesizing the sodium soap with a water soluble lead salt, such as lead acetate, to form the lead tall oil soap. In forming the tall oil soap of some of the polyvalent metals disclosed hereinbelow this would be the degra fatty acids it is necessary first to prepare the sodium soap by saponification of the fatty acid esters present in the lead soap by metathesis f the sodium soap. The required quantity of wool grease is charged to a. steam jacketed kettle equipped with an agitator and the theoretical quantity of caustic soda indicated by the saponification number is added in the form of a 50% water solution. With the agitator in motion the batch is heated slowly, with care to avoid excessive foaming, to 300 F. to 320 F., and heldat this temperature untilan analysis indicates that the reaction is complete and all of the caustic soda has been utilizedsg u-if necessary, small additions of water may bemade during the course of the saponification. No free caustic shall be present when saponification has been completed, and if necessary, a small addition of wool grease is made to neutralize any free caustic soda present. When saponification is degras and then the i complete, the soap in the kettle is diluted with water to yield a soap content of %.to by weight. To the diluted soap, which should be at a temperature of 180 F. to 200 F., the theoretical quantity of lead acetate based on the'methyl orange soap number of the wool grease soap is added to the batch as a solution in water.

The lead acetate solution shall be added as rapidly as it will be taken up by the batch, and with the agitator in motion. The batch is then maintained at a temperature of 180 F. to 200 F. for one hour, at which time formation of the lead soap should be complete and no more than a small amount of free lead 'ion present as indicated by'a test with potassium dichromate solution.

The agitator is then stopped and the lead wool grease allowed to separate from the water phase, the temperature being maintained at 180 F. to 200 F. The separted water is then drained of! and the batch washed with hot water until free from lead ion. The batch is then dehydrated by heating to 325 F. to 340 F., drawing of]? separated water when possible, and held at this temperature with continued agitation for four hours. At the end of this time the soap is reduced in the thinner at the lowest practical temperature to yield a gel containing approximately'55% of soap. 1

The tall oil soap and the degras fatty acid soap may be prepared simultaneously. In this case the degras fatty acids are obtained by saponification of degras with sodium hydroxide followed by acidification of the resulting sodium soaps to liberate the free degras fatty acids. These fatty acids are washed with water, dried, and mixed with the desired proportion of tall oil. The mixed tall oil and degras fatty acid soap may be prepared by either inethod described for the preparation of tall oil soaps.

The finished rust-preventive compound is then prepared by blending the two described lead soap products with other specified ingredients. This is accomplished by charging the required amount of the lead wool grease soap gel to a steamjacketed kettle equipped with an agitator and adding the paraffin wax and the lubricating oil. The batch is then heated to 130 F. to 150 F. with agitation and it is held at this temperature with agitation until the paraffin is melted and the batch has become uniform. The lead tall oil soap solution and the cobalt drier are then added and the batch agitated at from 90 F. to 110 F. until it is again uniform. Thereafter, volatile thinner of petroleum origin or other type heretofore indicated is added in the required amount yielding a product possessing the properties heretofore described.

Although the specific description of our invention relates to the preparation of a lead soap composition other polyvalent metal soaps may be used in place of a part or all of the lead soap. Polyvalent metals apparently must be employed in order to produce soaps having suflicient oilsolubility and water insolubility to produce the desired anti-rust compositions. Thus the monovalent metals and particularly the alkali metals produce soaps which are not sufficiently oil soluble to be soluble or dispersible in the thinner employed in thefinished rust preventive composition and which are sufiiciently water-soluble in that they are too readily leached by water from surfaces to which they have been applied.

Polyvalent metals which we may employ in the preparation of oil-soluble metal tall oil or degras or degras fatty acid soaps are preferably the amphoteric metals, zinc, tin, aluminum, manganese, iron, cobalt, nickel, copper, vanadium, chromium and especially lead, although the alkaline earth metals, calcium, strontium, barium and magnesium may be employed. The amphoteric metals are those metals whichform at least one oxide which has both acidic and basic properties as is well understood in the art.

One or more of the polyvalent metals'may be employed in the preparation of either the tall oil soap or the degras soap or both so that the finished anti-rust composition may contain soaps of one or more metals. In general it'is desirable to include at least some lead soapin the composition together with one or more of the other polyvalent metal soaps disclosed althoughsatisfactory anti-rust compositions have been prepared with metals other than lead which were entirely satisfactory.

Specific examples of anti-rust compositions \giich are illustrative of our invention are given low: i

25 Example I Approximate 7 by Weight 0 I With 1 Without Thinner Thinner Manganese soap of tall oil. 29 52. 7 Lead soap of wool grease 18 32.7 Paraffin wax 4 7. 3 Lubricating oil 4 7. 3 Petroleum thinner 45 None Example II Approximate 7 by Weight 0 With Without Thinner Thinner Lead soap of tall oil. 35 65 Iron soap of wool grease 12 22 Paraffin Wax 7" l3 Drier. cobalt content 0. Oil 0.02 Petroleum thinner 46 None Ewample III Approximate 7 by Weight With Without Thinner- Thinner Lead soaps of tall oil 36 72 Calcium soap of degree fatty acid.... 8 16 Parafiin wax 3 6 Lubricating oil 3 6 Petroleum thinner 50 None Example IV Approximate 7 by Weight 0 With Without Thinner Thinner Chromium soap of tall oil. :27 54 Manganese soap of wool grease. 18 36 Paralfin wax 2 4 Lubricating oil 3 6 Petroleum thinner.. 50 None tween 30% and 70% Example V Approximate 7 by Weight With Without Thinner Thinner Manganese soup of tail oil 10 20 Load soup of tail oil. 18 36 iron soup of wool grease 18 36 lnitaiiln wax 4 8 60 N one 'lhinncr In addition to modifications herein suggested, others will be apparent to those skilled in the art and come within the scope of the appended claims.

We claim:

1. An anti-rust composition comprising between about 5% and 95% of oil-soluble polyvalent metal tall oil soap and between about 5% and 85% of oil-soluble polyvalent metal degras soap;

2. An anti-rust composition according to claim '1 to which has been added a substantialproportion of a volatile hydrocarbon solvent, said solvent amounting to between 30% and 70% of the total composition.

3. An anti-rust composition according to claim 1 wherein said oil-soluble polyvalent metal tall oil soap is an amphoteric metal soap.

4. An anti-rust composition according toclaim 1 wherein said oil-soluble polyvalent metal degras soap is an amphoteric metal soap.

5. An anti-rust composition according to claim 1 wherein said oil-soluble polyvalent metal soaps are amphoteric metal soaps.

6. An anti-rust composition according to claim 1 wherein at least one of said polyvalent metal 508.138 i8 a manganese SOa-D.

7. An anti-rust composition according to claim 1 wherein said oil-soluble polyvalent metal soaps are alkaline earth metal soaps.

8. An anti-rust composition according to claim 1 wherein said oil-soluble polyvalent metal soaps are calcium soaps.

9. An anti-rust composition comprising 50% to 85% oil-soluble polyvalent tall oil soap, 5% to 30% oil-soluble polyvalent metal wool grease soap, 5% to paraflin wax, 5% to 10% lubrieating oil and 0.0% to 0.1% of cobalt in the form of an oil-s0luble salt.

10. An anti-rust composition according to claim 9 to which has been added a volatile hydrocarbon solvent, said solvent amounting to beof the total composition. 11. An anti-rust composition comprising between about 5% and 95% of oil-soluble polyvalent metal tall oil soap and between about 5% and 85% of oil-soluble polyvalent metal degras fatty acid soap. Y

12..An anti-rust composition comprising between about 5% and 95% of lead tall oil soap and between about 5% and 85% of lead degras soap.

13. An anti-rust composition according to claim 12 containing cobalt drier having between about 0.1% and 0.2% soaps.

14. An anti-rust composition according to claim 12 containing between about 5% and 10% of paraflin waxbased on the soaps.

15. An anti-rust composition according to claim 12 to which has been added a substantial proportion of a volatile hydrocarbon solvent, said.

solvent amounting to between 30% and or the total composition.

16. An anti-rust composition according to claim 12 containing 0.01% to 0.2% of cobalt in the form of cobalt drier and wherein the composition is diluted with a substantial proportion of a volatile hydrocarbon thinner, said thinner amounting to between 30 and 70%01 the total composition.

17. An anti-rust composition according to claim 12 containing between about 5% and 10% of paraflin wax based on the soaps and wherein the composition is diluted with a substantial proportion of a volatile hydrocarbon solvent, said solvent amounting to between 30% and 70% of the total composition.

18. An. anti-rust composition comprising 50% to lead tall oil soap, 5% to 30% lead wool grease soap, 5% to 10% paraflin wax, 5% to 10% lubricating oil and 0.01% to 0.1% of cobalt in the form of an oil-insoluble salt.

MYRON H. KOLLEN. MARCELLUS T. FLAXMAN.

REFERENCES orrEn UNITED STATES PATENTS metal content based on the