US2933400A

US2933400A - Rust-preventing agent

Info

Publication number: US2933400A
Application number: US639622A
Authority: US
Inventors: Wurbs Anna; Wurbs Ulrike
Original assignee: Individual
Current assignee: Individual
Priority date: 1957-02-12
Filing date: 1957-02-12
Publication date: 1960-04-19
Anticipated expiration: 1977-04-19

Description

:agents is already known. agents based on this principle is due to the different bejhavior of metals which have a distant position with re- :spect to one another in the electromotive series. The

RUST-PREVENTING AGENT No Drawing. Application February 12, 1957 Serial No. 639,622

Claims. (Cl. 106-14) The present invention relates to a rust-preventing agent, more particularly an agent of the kind consisting of pow- ,ders of metals having diiferent positions in the electro- ,motive series of the elements.

The use of metal powders for making rust-preventing The eifect of the anti-rust rust-preventing agent constitutes, as it were, a galvanic cell, by whose reducing action the metal to be protected is guarded against oxidation. One condition for bringing about this eflect is the alkaline adjustment of the agent, in order to accomplish a reversal of the metals as regards their position in the electromotive series. In this man ner, iron becomes the cathode and the other metals become the anode, so that the potential causing corrosion does not become active on the iron, but on the metal powder, and is thereby made harmless.

Metal components of a coating of paint are protected by the addition of charcoal against moisture, vapors, acids and the like, since charcoal absorbs the oxygen and gives off alkalies. Furthermore, charcoal aids in the even suspension of the metal powders in a binder. Another purpose of the addition is its role as a pigment for obtaining a grey or black colored coat.

For alkaline adjustment, rust-preventing paints have already been made with charcoal, which had previously been impregnated with alkali, e.g. potash or gaseous am monia. However, it has been discovered that the impregnation with alkali often has certain disadvantages for anti-rust paints. One of them is the occurrence of a certain saponification of the binder, a second one the difficulty of maintaining a definite alkalinity, which depends on uncertain factors. If the degree of alkalinity is changed, this may sometimes lead to a reversal in the po larity of the metals, so that the anti-rust paint would on the contrary act as a rust-promoing agent.

It is the object of the present invention to provide an anti-rust agent or paint, which is free of the above mentioned drawbacks and will provide a safe protection of lasting effect. The necessary alkalinity is constantly maintained by the chosen ingredients and, if necessary, re-adjusted.

For this purpose, a conventional binder, e.g. varnish, is compounded with powdered metals, on the one hand with iron, on the other hand with a second metal of the group consisting of magnesium, lead and zinc. To this mixture, powder of active carbon, having a large surface, is added, which has not been impregnated. The active carbon will therefore retain its absorptive capacity and will be capable of forming a buffer in the system, in which it will absorb the hydrogen which will be evolved.

In addition to the above mentionedingredients, the system contains a metal oxide of the second metal, in an amount ranging from 1 or 2, up to 4% of the metal used.

The metal oxide is slightly alkaline, but the alkalinity does not become effective on the binder; however, it is sufiicient to maintain the required polarity.

Instead of using one other metal in addition to iron, a mixture of such metals may be used and, accordingly, a mixture of their oxides. Themetal oxide or oxides are continually regenerated by the oxygen evolved and the metal present. The oxide or oxides act similar to a cataiyst. The system formed is stable and resists washing out by water or moisture. The hydrogen absorbed by the active carbon is a reducing component which also acts as a protective agent for the iron.

The rust-resistive paint constitutes a system which automatically re-adjusts itself.

One definite advantage is the safety against reversal of the polarity, since the alkalinity is maintained as long as there is some metal present. It is impossible that the rust-resisting paint at one time becomes a rust-promoting agent.

Paints as described above are particularly useful as marine paints for use on hulls, decks, or bottoms of ships. A rinsing out of the alkaline components by sea water cannot take place, as it was often experienced with paints hitherto in use, which were made with charcoal having alkali absorbed therein.

When using the paint for ship bottoms, it is advantageous to add copper as second metal or in addition to a second metal, such as lead, magnesium or zinc mentioned before. Copper and its oxide have the added advantage of preventing deposits of animal or vegetable matter.

The invention will now be more fully described in a number of examples, but it should be understood that these are given by way of illustration and not of limitation and that many changes in the details can be made without departing from the spirit of the invention.

Example 1 The following components are mixed together:

120 kgs. linseed oil varnish kgs. powdered magnesium 30 kgs. powdered iron 30 kgs. active charcoal, and

8 kgs. magnesium oxide As contrasted to methods used heretofore, heating is not necessary, it should, on the contrary, be avoided. The mixture is ready for use.

Example 2 The components mixed together are:

kgs. varnish acting as a binder 80 kgs. lead powder 32 kgs. iron powder 40 kgs. charcoal, also as powder 4 kgs. PhD

7 Example 3 The following ingredients are mixed together:

100 kgs. varnish 62 kgs. lead powder 36 kgs. copper powder 32 kgs. iron powder 40 kgs. active carbon 4 kgs. lead oxide 12 kgs. copper oxide What I claim is:

l. A coating composition having rust-preventing properties due to its content of metal powders having differing positions in the electromotive series of the elements, consisting of 100 to kg. of a varnish, 30 to 32 kg. iron powder, 62 to 80 kg. of asecond polyvalent metal selected from the group consisting of magnesium, zinc, lead and a mixture of the same, as Well as 4 to 8 kg. of an oxide of the second metal, and containing 30 to 40 kg. activated carbon. i i

2. The rust-preventive coating composition according to claim 1, for use as a shi p-bottom paint, containing, in addition to the ingredients named, 36 kg. copper and 12 kg. copper oxide.

' 3. Arust-preventing composition according to claim 1, consisting of 120 kgs. linseed oil varnish, 80 kgs. magnesium powder, 30 k gs. iron powder, 30 kgs. activated carbon and 8 kgs. magnesium oxide.

4. A rust-preventing composition according to claim 1, consisting of 100 kgs. varnish, 80 kgs. lead powder, 32

References Cited in the file of this patent FOREIGN PATENTS 435,003 Great Britain Sept. 12, 1935 431,641 Great Britain July 10, 1935 563,653 Great Britain Aug. 24, 1944

Claims

1. A COATING COMPOSITION HAVING RUST-PREVENTING PROPERTIES DUE TO ITS CONTENT OF METAL POWDERS HAVING DIFFERING POSITIONS IN THE ELECTROMOTIVE SERIES OF THE ELEMENTS, CONSISTING OF 100 TO 120 KG. OF A VARNISH, 30 TO 32 KG. IRON POWDER, 62 TO 80 KG. OF A SECOND POLYVALENT METAL SELECTED FROM THE GROUP CONSISTING OF MAGNESIUM, ZINC, LEAD AND A MIXTURE OF THE SAME, AS WELL AS 4 TO 8 KG. OF AN OXIDE OF THE SECOND METAL, AND CONTAINING 30 TO 40 KG. ACTIVATED CARBON.