DE1419980A1 - Protection of metal surfaces - Google Patents

Description

The JOre'stal Land, Timber & Railways Company, Limited, London / England.

"Protection of metal surfaces". "■

: _ ■ i

Priority: January 6, 1956 / Great Britain \

The invention relates to the protection of metal surfaces.

It is be.kannt that vegetable tannin extracts with iron and steel surfaces to form a Tannatfilmes react, which reduces the tendency of such surfaces to the corrosion under the \ action of atmospheric influences.

The formation of a tannate protective film on metals is a property inherent in all vegetable tannin extracts; however, the level of protection achieved varies between the different Tannins

The effectiveness of the tannate film formed by one or the other extract can be increased by changing the p ^ value of the Extract solution can be changed, with the most beneficial protection with an acidic p "is achieved.

909831/1229

The "best tannate complex formed on iron and steel surfaces has the same or "better anti-corrosion properties as a phosphate coating when used in combination with a well-known paint, however, is wide more resistant to corrosion when applied without subsequent painting.

It is known that when latex paints are applied to iron or steel surfaces, they favor extremely rapid rusting W , which normally makes them unsuitable for use on such surfaces.

As used herein, the term "latex paints" refers to aqueous ones Emulsions of thermoplastic resins such as polystyrene and polyvinyl acetate, natural or synthetic rubber, chlorinated Rubber, mineral, animal or vegetable oils, e.g. linseed oil, or sulfonated castor oils, which also contain pigments, plasticizers or may contain other additives.

It has been found according to the present invention, 'That the addition of vegetable tannin extracts to latex paints or to aqueous emulsions of organopolysiloxanes normally does that prevents rusting and enables the application of the colors on iron and steel surfaces, whereby these mixtures are made Tannins and latex paints form a rust-proof coating that is many times more effective than the tannins alone.

The anti-rust effect. Is not specific to one .Tannin limited but is a general property Vegetable tannins, with only differences in the degree of effectiveness.

909831/1229

Accordingly, it is the subject of the present invention a mixture for the protection of metal surfaces, which is a latex paint (in the sense explained above) or an aqueous Emulsion of an organopolysiloxane and a vegetable tannin extract contains, the mixture having a p ^ -value below 7.

The corrosion-preventing effect of the mixtures according to the invention is not limited to iron and steel, but shows also with non-ferrous metals. *

The present invention also relates to a method to protect metals, especially iron or Steel, according to which the metal according to the invention composite mixture is coated.

The invention also includes a method of protecting of metals, especially iron and steel, according to which the metal first with a vegetable tannin extract and then is coated with a latex paint (as described above) or with an aqueous emulsion of an organopolysiloxane. "

A method also falls within the scope of the invention ziürn protecting metals, especially iron and steel, according to which the metal first with a vegetable oil extract and then with a drying oil, preferably linseed oil, or with a solution of a drying oil in a solvent is covered.

90 9831/1229

H19980

The metal surface to be treated with the mixtures according to the invention need not be rust-free. If loosely lying rust is removed (e.g. by brushing), the subsequent treatment with the mixture prevents further rust formation and effectively protects the surface for at least as long ^as: like a similar film that has been used on a clean surface.

The following examples illustrate the invention and its Advantages even closer. · '\

Example 1.

Two equal pieces of mild steel from adjacent sections of the same tape have been mined and degreased. One piece was coated with a 50 # solution of Myrabolam extract diluted with an equal volume of water was provided, while the other piece was coated with the same 50% strength by weight solution of a myrabolam extract received that plasticize with an equal part of the room Polyvinyl acetate latex was mixed. The treated samples were dried and then exposed to the action of the atmosphere outdoors under the same conditions. The rust preventive The effect of the tannate film lasted 6 times longer in the sample treated with the tannin-latex mixture than in the sample treated with tannin alone treated sample.

Example 2.

Two pieces of steel, similar to those used in Example 1, were exposed to the. Exposed to atmospheric lilies until they

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U1998O

Evenly coated with rust ". They then became light brushed with a wire brush to remove the loose rust from the surface. The two samples were with an aqueous solution of tannin and a mixture of tannin solution and latex in the manner described in Example 1 treated. The sample treated with the tannin latex ^ -G-emically had more than twice the life compared to the sample treated with tannin alone before exposure to weathering Rust formed. ·

Example 3 «

Two pieces of steel similar to those used in Example 2 were brushed lightly with a wire brush Exposed to the weather. Both pieces were treated with a 30% aqueous solution of myrabolam extract, laughs upon drying, a pattern became weak with the above solution Sprinkled with boiled linseed oil. The two samples were exposed to the atmosphere with the oiled panel remained corrosion-free at least twice as long as the |

not oiled plate.

Example 4. ■ ^f

Example 3 was repeated, but using one Chestnut extract instead of Myrabolam. The resistance of the oiled plate to corrosion was about 5 times as great like that of the non-oiled record.

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Example 5.

Two identical plates made of cast steel were cleaned and degreased. Each plate was provided with a coating of a 25 fol gene aqueous solution of a mimosa extract which was adjusted to a ρττ value of 2 by adding phosphoric acid. The tannate film thus obtained was dried. After drying, a plate was sprayed with a silicone emulsion and the two samples were exposed to the weather. The sample treated with silicone emulsion in addition to tannin remained rust-free approximately 6 times as long as the sample treated with tannin alone.

Example 6.

Two identical plates made of mild steel were cleaned and degreased with a wire brush. Each plate came with a JO ^ igen aqueous solution of a mixture of equal parts Myrabolam and Valonia extract treated. After drying, a plate was coated with a plasticized polyvinyl acetate latex emulsion, which was mixed with an equal volume of water, treated. The two panels were weathered. The plate, which had been treated with latex in addition to tannin remained rust free for about 5 times as long as the plate treated with tannin alone.

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Claims (4)

Pat e n t ansp lie he ι 1. Mixture for the protection of metal surfaces, characterized by a content of latex paint or an aqueous one Emulsion of an organopolysiloxane and vegetable tannin extract, the mixture having a p-g value below 7. 2. Process for protecting metals, especially iron and steel, characterized in that the metal with a Mixture according to claim 1 is coated. 3. A method for protecting metals, in particular iron and steel, characterized in that the metal initially with a vegetable tannin extract and then with a latex paint or with an aqueous emulsion of an organopolysiloxane is covered .. 4. Process for protecting metals, in particular Iron and steel, characterized in that the metal is first made with a vegetable tannin extract and then with a drying oil, preferably linseed oil, or with a solution of a drying oil in a solvent. 9098 31/12 2 9