US3510440A - Corrosion preventing compositions - Google Patents

Description

United States Patent 3,510,440 CORRQSION PREVENTING COMPOSITIONS Robert Edward Campbell, Doncaster, England, assignor to British Ropes Limited, Doncaster, England, a British company No Drawing. Filed Oct. 18, 1965, Ser. No. 497,478 Claims priority, application Great Britain, Dec. 1, 1964,

48,711 Int. Cl. C09d /08 US. Cl. 260-23 27 Claims ABSTRACT OF THE DISCLOSURE Thin flakes of platelets of organic or inorganic material are first mixed with smaller sized lead or tin containing particles and milled so as to produce a thin continuous lead or tin containing film completely encapsulating the flakes. The coated flakes then are dispersed in a medium which at room temperaure is viscous and p0- lymerizable and the composition used to coat wire, wire strands or Wire ropes to protect the same against corroslon.

This invention relates to corrosion preventing compositions more especially for use for protecting wire, wire strands or wire ropes from corrosion.

The metal lead and certain of its alloys, are noteworthy for their chemical inertness over a wide range of corrosive environments. However, the employment of such materials has, in the past, been considerably limited because of the following aspects:

(a) The high intrinsic cost.

(b) High specific gravity and consequent ditficulty in maintaining particulate dispersions in a satisfactory state prior to, and during, their application.

(0) Difiiculty in finding an effective dispersive agent, embodying elastomeric qualities.

The present invention consists in a corrosion preventing composition comprising a dispersive medium and particulate material in the dispersive medium, in which the particulate material is provided with a coating of lead or a lead alloy or tin or a tin alloy.

The specific gravity of the dispersive material may be about 1.1, with a possible variation of some 25% either way.

The particulate material itself may be selected from a wide range of materials cheaper than lead and its specific gravity may be such as to ensure good suspension on the dispersive material.

Prior to adding the particulate material to the dispersive medium, it is necessary to apply simply and cheaply a thin, homogeneous film of lead or a selected alloy to the entire surface of the particles forming the particulate material.

Preferably the particulate material is in the form of thin flakes or platelets and the following are the preferred materials for these platelets:

(i) Metal: aluminium or its alloys magnesium or its alloys (ii) Organic polymer: polyvinyl chloride, polyethylene, polypropylene, nylon, or the like (iii) Inorganic material: mica, asbestos, vermiculite, or micaceous iron ore processed to a suitable condition and size that it will pass through a 200 mesh sieve.

If an uncoated particulate material from category (i) is employed, its gravity will be such that it will tend to settle in the dispersive medium. However, if a material from category (ii) is employed, the specific gravity can range from as low as 0.90 to as high as 2.20; consequently, it is possible to select a material which will remain in suspension, even when coated with a thin film of metal such as lead. Likewise, the materials listed in category (iii) permit a similar combination.

It will be seen that by careful selection of the particulate agent, it is possible to exercise a much greater control in maintaining the encapsulated particles in a state of suspension. This would prevent excessive settlement in storage containers, a normally serious problem with metallic dispersions. It can also offer advantages in use, as a better dispersion of the particulate material is obtained as the solvent content evaporates.

As a dispersive medium, there may be used any synthetic resinous material which, at room temperature, is a viscous fluid capable of controlled progressive polymerisation by blending with a suitable proportion of a reactive intermediate; specific examples of such an intermediate are (a) benzoyl peroxide, (b) an oil of vegetable origin such as linseed oil, or any oil possessing drying, or semi-drying properties.

Alternatively, materials of animal origin, which are capable of polymerisation, such as lanolin, may be employed. Such a mixture subsequently reacts to produce certain desirable physical and chemical characteristics.

A specific example of a mixture generically of this type is Grade R302, manufactured by Bakelite Limited. Grade R302 is an amber colored viscous liquid which flows slowly at 20 C. and comprises an oil modified heat hardening phenolic resin having a specific gravity at 25/25 C. of 0.98. Its viscosity at 25 C. diluted 2:1 wt./wt. with toluene is centistokes. It has an acid value of 34 mg. KOH/ g. and is soluble in benzene, toluene, xylene and drying oils.

Preferably the particulate material is milled together with the coating agent in the ratio of 2-15 of coating agent by weight per unit weight of particulate material.

A suitable particle size for the lead particles to be milled to form the surface coating is dust to 100 mesh with 0-200 mesh preferred.

The preferred metal for the coating material is lead. Small additions of tin would improve the toughness of the metallic film without destroying its smear capacity, whilst antimony could materially improve the hardness.

The minimum amount of coating metal is that which will produce a thin, but continuous, film to completely envelop the supporting agent, and this should not be less than 2% volume/ volume.

Regarding the maximum amount, there does not appear to be any technical advantage in exceeding 10% volume/volume, where a pure coating metal is involved, although alloying agents might permit the employment of a slightly higher percentage.

The optimum percentage lies in the region of 5% of coating metal to of supporting agent, volume/volume.

The actual operation of encapsulation is two-fold in that dust particles of the selected metal adhere to the surface of the supporting elastomer, or inorganic material, and, due to their small size, are capable of deformation and smearing with very light pressure; there is also the possibility of electro-static attraction. Simultaneously, the larger particles of metal are impressed into the surface of the supporting medium and, once mechanically an chored, the exposed surface irregularities are plastically deformed and smeared together by the milling operation.

The most positive method of checking is by a colourmacroscopic technique.

The colour check is achieved by employing a reagent which forms a brightly coloured, or distinctive, pigment when it reacts with the selected encapsulating metal or alloy. Then follows the macroscopic examination of a suflicient quantity of the material to ensure that encapsulation of the particles has been complete, and that the metallic agent has truly coated the supporting material, and not merely formed a dry dispersion.

For example, nylon powder has a white, almost crystalline appearance, but after milling has a grey appearance. If it is then treated with acidified Potassium Dichromate and elutriated with water, a continuous bright yellow film forms over all the particles, and proves quite readily that complete encapsulation has been achieved.

The same technique applies when aluminum is encapsulated with lead.

The milling operation may be carried out by employing a ball mill, an end runner mill, or any such device which will produce a thin, continuous coating.

The final operation-to produce the requisite protective and lubricating compound is to disperse the composite metal-flake in the preferred synthetic resin base by any appropriate means, usually in the presence of a small amount of organic solvent which facilitates the mixing operation. When the formulation is subsequently applied to a metal surface, in the presence of air, the solvent is lost by evaporation.

Protective coatings applied in the manner described will give indefinite protection to ferrous surfaces in both acid and alkaline environments. They are of particular value in the manufacture, and subsequent dressing, of steel wire where the agent required to give protection of the wires against corrosion must, at one and the same time, function as a lubricant when the rope is subjected to dynamic loading.

Furthermore, formulations of this nature are extremely stable over a wide range of temperatures, and have high adhesive powers. However, they may when necessary, be readily removed with a suitable solvent mixture, but are readily re-applied by brushing or spraying, thus permitting ready inspection and re-sealing of the underlying structure.

Tests have shown that, when the same base resin is employed as the dispersant, that lead encapsulated aluminium flake has a 2% increase in lubricating efficiency, compared with untreated aluminum flake of the same size.

Preferred sample compositions are as follows:

Percent Range Typical 4o Composition 1:

Lead coated aluminum flake 20-30 24 Resin base 25-35 30 Microcrystalline wax, melting point 140- 170 F 5-10 7 Solvent (white spirit)--. 35-45 39 Composition 2: Lead coated magnesium flake 20-30 24 Resin base 25-35 30 Microcrystalline wax, melting point 140- 170 F 5-10 7 Solvent (white spirit) 35-45 39 Composition 3:

Lead coated organic powders in the form form of polymers, e.g. polythene, polypropylene, P.V.C 20-30 24 Resin base 25-35 30 Microcrystall' 170 F 5-10 7 Solvent (White spirit) 35-45 39 Composition 4:

Lead coated inorganic flake material, e.g.

mica, micaceous iron ore, vermiculite as pigment 20-30 24 Resin base 25-35 30 Microcrystalline wax, meltlng point 140- 0 5-10 7 35-45 39 Corn osition 5:

Bead coated zinc powder 20-30 24 Resin base 25-35 30 Microcrystalline wax, melting point 140- 170 F 5-10 7 Solvent (white spirit) 35-45 39 Composition 6:

Lead coated zinc powder 82-88 87 Resin base 2. 5-4. 5 3 Microcrystalline wax, melting point F 0. 9-1. 8 0. 5 Solvent (white spirit) 5-15 9. 5

Various modifications may be made in accordance with the invention.

I claim:

1. A particulate organic material comprising thin flakes or platelets thereof which are coated with a thin homogeneous film of lead or a lead alloy or tin or a tin alloy which completely envelope the flakes or plateets.

2. A corrosion preventing composition comprising thin flakes or platelets of inorganic material coated with a thin homogeneous film of lead or lead alloy or tin or tin alloy which completely envelopes the flakes or platelets, said coated flakes or platelets being in a viscous fluid comprising oil modified phenolic resin and an evaporable organic solvent.

3. A corrosion preventing composition comprising thin flakes or platelets of organic or inorganic material other than lead or tin, said thin flakes are platelets being individually encapsulated by a thin continuous coating of lead, lead alloy, tin, or tin alloy, said encapsulated flakes or platelets being suspended in a dispersive medium comprising a polymerizable viscous fluid.

4. A corrosion preventing composition as claimed in claim 3 in which the thin flakes or platelets are metallic particles.

5. A corrosion preventing composition as claimed in claim 4 in which the thin flakes or platelets are aluminium or aluminium alloy particles.

6. A corrosion preventing composition as claimed in claim 4 in which the thin flakes or platelets are magnesium or magnesium alloy.

7. A corrosion preventing composition as claimed in claim 3 in which the thin flakes or platelets are polyvinyl chloride.

8. A corrossion preventing composition as claimed in claim 3 in which the thin flakes or platelets are polyethylene.

9. A corrosion preventing composition as claimed in claim 3 in which the thin flakes or platelets are polypropylene.

10. A corrosion preventing composition as claimed in claim 3 in which the thin flakes or platelets are particles of inorganic material.

11. A corrosion preventing composition as claimed in claim 10 in which the particles are mica.

12. A corrosion preventing composition as claimed in claim 10 in which the particles are asbestos.

13. A corrosion preventing composition as claimed in claim 10 in which the particles are vermiculite.

14. A corrosion preventing composition as claimed in claim 10 in which the particles are micaceous iron ore.

15. A corrosion preventing composition as claimed in claim 14 in which the particles are of such a size that will pass through a 200 mesh sieve.

16. A corrosion preventing composition as claimed in claim 3 wherein the dispersive medium is oil modified heat hardening phenolic resin.

17. A corrosion preventing composition as claimed in claim 3 in which the dispersive medium is a mixture of an oil of vegetable origin and a synthetic resinous material which, at room temperature, is a viscous fluid capable of controlled progressive polymerisation when mixed with the oil.

18. A corrosion preventing composition as claimed in claim 17 in which the specific gravity of the dispersive medium is l.l- -25%.

19. A corrosion preventing composition as claimed in claim 3 in which the ratio by Weight of coating agent to flakes or platelets is in the range 2-15%.

20. A corrosion preventing composition as claimed in claim 3 in which the volume ratio of coating agent to flakes or platelets is in the range 210%.

21. A corrosion preventing composition as claimed in claim 20 in which the volume ratio is 5%.

22. Ferrous materials having their surfaces protected by a coating composition as claimed in claim 3.

23. Steel wire ropes having the wire surfaces protected by coating compositions as claimed in claim 3.

24. In the process of making a corrosion preventing composition for the treatment of wire, wire strands and wire ropes, the improvement wherein thin flakes or platelets of organic or inorganic material are first encapsulated with a thin coating of lead-or tin-containing smaller sized particles which is smeared or deformed with light pressure to produce a thin continuous film completely enveloping the individual flakes or platelets and after which the encapsulated flakes or platelets are dispersed in a viscous polymerizable fluid.

25. The process claimed in claim 24 wherein the polymerizable fluid comprises lanolin.

26. The process claimed in claim 24 wherein the poly- 15 merizable fluid comprises a synthetic resin which at room temperature is a viscous fluid capable of controlled progressive polymerization with an oil of vegetable origin.

27. The process claimed in claim 24 wherein the fluid is polynieri zable by oxidation.

References Cited UNITED STATES PATENTS 3,070,469 12/1962 Jenkin 117l00 3,316,073 4/1967 Kelso 51309 3,287,142 11/1966 Russell 10614 3,244,656 4/1966 de Mejer 260-296 3,003,975 10/1961 Louis 252503 2,939,804 6/ 1960 Schossberger 11771 DONALD E. CZAJA, Prmary Examiner D. I. BARRACK, Assistant Examiner U.S. Cl. X.R.