US3159499A

US3159499A - Treating water-wetted surfaces with corrosion-resistant coating material

Info

Publication number: US3159499A
Application number: US139605A
Authority: US
Inventors: Robert M Jorda
Original assignee: Shell Oil Co
Current assignee: Shell USA Inc
Priority date: 1961-09-21
Filing date: 1961-09-21
Publication date: 1964-12-01
Anticipated expiration: 1981-12-01

Description

Dec. 1, 1964 R. M. JORDA 3,159,499

TREATING WATER-WETTED SURFACES WITH CORROSION-RESISTANT COATINGMATERIAL Filed Sept. 21, 1961 PO LYAMIDE POLYEPOXIDE FILLER PIGMENT PIG MENT FILLERS 5% lo 50% sroiehiomerric excess of polyomide in relation to polyepoxide Mix thoroughly at ambient temperature PUTTY- LIKE TREATING COMPOSIT|ON Application to surfaces immersed in water INVENTOR:

ROBERT M. JORDA HIS AGENT United States Patent 3,159,499 TREATXNG WATER-WETTED SURFAfiES WETH CQRRUSltlN-RESISTANT COATENG MATEREAL Robert M. .lorda, Houston, Tex., assignor to Shell Gil Company, New York, N.Y., a corporation of Delaware Filed Sept. 21, 1961, Ser. No. 139,605 14- Qlaims. (Cl. 117-4) This invention relates to a new process for treating wet surfaces and to the resulting products. More particularly, the invention relates to a new process for treating Water Wetted surfaces to apply a corrosion-resistant coating thereto and/ or repair defects in the said surfaces, and to the products prepared thereby.

Specifically, the invention. provides a new and highly efiicient process for applying a hard, tough and highly flexible resinous material to water wetted surfaces, and preferably metal surfaces, which material provides protection against corrosion and/or repairs defects so as to render the surface water tight. This process comprises applying to the water wetted surface a composition comprising a mixture of a polyepoxi'de having more than one Vic-epoxy group, and preferably a glycidyl polyether of a polyhydric phenol, and a special controlled excess amount of a polyamide of an aliphatic or cycloaliphatic polycarboxylic acid containing at least 7 carbon atoms and an aliphatic polyamine, said polyamide containing groups reactive with the epoxy groups, and allowing the composition to set hard.

As a special embodiment, the invention provides a new process for applying a hard, tough and highly flexible corrosion-resistant coating to metal surfaces of off-shore structures which are in the vicinity of the water line and may be highly corroded, such as, for example, metal supports of off-shore drilling platforms, which comprises forming a putty-like mixture of a polyepoxide, 5% to 50% stoichiometric excess of a polyamide of a polymerized unsaturated long chain fatty acid and an aliphatic polyamine, said polyamide having a plurality of free amino hydrogen, and a thixotropic material, and then applying the putty-like material to the surface while submerged below the water, and allowing the coating to set hard while under the surface of the water.

This application is a continuation-in-part of my application Serial No. 61,063, filed October 7, 1960, now abandoned.

There is a growing need in industry for a superior plastic coating material that can be applied to surfaces while wet or while submerged under water so as to repair defects therein and/ or apply a corrosion-resistant coating thereto. This includes, for example, repair of leaks in water lines without interruption of the water flow, repair of electrical conduits buried in wet soil, repair of boat hulls while the boat is still in the Water, repair of waterwetted surfaces of pressure vessels, and the like, as well as applying corrosion-resistant coatings to the aforedescribed materials.

One of the greatest problems has been the prevention of corrosion of metal members of off-shore drilling structures,particularly those parts disposed in the splash zone, i.e., disposed in the vicinity of the Water line. The corrosion of metal members in this area is particularly severe. If a metal member extends from the bottom to a point above the water level, the general pattern of its relative losses of metal due to corrosion usually has the following general characteristics; the corrosion rate is relatively low along those portions of the metal member which is within and immediately above the bottom sediments in which the member is disposed. Proceeding upwardly through the zone between the mud line and the low-tide water level, the rate of corrosion undergoes arelatively sudden and severe increase along a portion of the metal 3,159,499 Patented Dec. 1, 1964 member which is located just below the low-tide water level and is generally continuously submerged. Further up, the corrosion rate may drop off along a short section between the low-tide and high-tide water levels, and then increase to a rate which usually exceeds the corrosion rate anywhere else along the metal member, this maximum being within the zone in which the member is subject to the action of waves. Above this zone, the metal member is subjected to atmospheric corrosion in which the metal is in contact with the moist air and some spray action normally existing above a body of water. The corrosion rate is high, and corrosion protection is needed along all of the portions of such metal members which are wetted and exposed to relatively high oxygen concentrations. Such portions include those portions of the metal which are substantially continuously immersed in water which has a relatively high concentration of dissolved and/ or entrained oxygen.

It is known that those portions of metal members which are located well above the water line may be adequately protected against corrosion by the application thereto of conventional marine paints. Similarly, the use of impressed cathodic as well as of sacrificial anodic protection techniques have been found to provide adequate protection of the corrodible metal members located well below the water line. However, several factors make it exceedingly diflicult to protect those portions of corrodible metal members which are located in the vicinity of the water line. This is a zone in which waves and tides produce rather strong currents which cause rapid erosion of most non-metallic coatings normally applied to the metal surfaces. It is essential that corrosion protective materials be applied to those portions of the corrodible metal members which extend at least about a foot, or frequently even further below the low-tide level. The problem of applying such production to metal member portions which are located under water is further aggravated by the presence of cross-bracing at or very close to the water line.

It was previously demonstrated that some simple offshore structures, e.g., wellheads mounted on unbraced surface conductors, may be protected against corrosion by enclosing the underwater portions thereof which are near the Water line by means of a caisson-type structure, removing the wat'er from the caisson-type structure, and then applying a plastic coating by any of the well-known conventional marine coating application procedures. Although the cost of the materials which are used in this caisson technique is quite low, the use of this technique is rather expensive due primarily to the time necessary for effecting said corrosion inhibition technique. Also, the application 'of this technique becomes unfeasible, complex and diflicult when the structure to be thus protected has cross-bracing and the like at or near the water line, e.g., where the aforesaid corrosion protection is to be applied.

Similar disadvantages are inherent in other more recently proposed treatment processes, such as, surrounding the corrodible metal members with a corrosion-resistant sleeve, then removing the water between the member to be protected and the sleeve, and finally filling the void thus formed with a corrosion-resistant sealing material construction or coating the structural members which are to be disposed at or near the water line with corrosionresistant metals or plastics; or placing a sleeve around the metal member, which sleeve is filled with porous materials which keep the metal members continuously wetted with an electrolyte, and effecting corrosion inhibition by means of a sacrificial metal and anoicl arrangement.

It is an object of the invention therefore to provide a: new process for treating wet surfaces- It is a further object to provide a new low-cost process for applying a corrosion-resistant coating to a water wetted surface. It is a further object to provide a new process for applying a corrosion-resistant coating to already corroded metal surfaces while immersed in water. It is a further object to provide a new process for applying a coating to wet surfaces which render the surfaces resistant to corrosion by fresh or saline water. It is a further object to provide an easy method for applying a protective coating to complicated structural members of off-shore drilling platforms which are disposed in the vicinity of the water line. It is a further object to provide a new process for applying a coating which is hard and tough to wet surfaces. It is a further object to provide a new process for applying corrosion-resistant coatings which have excellent flexibility and distensibility. It is a further object to provide an economical and highly efficient process for treating surfaces which are under salt water, It is a further object to provide a new process for treating wet surfaces to repair defects therein. It is a further object to provide a new process for treating wet surfaces to make them water tight and corrosion resistant. These and other objects of the invention will be apparent from the following detailed description thereof and from the attached drawing which is a flow diagram illustrating one preferred method of preparing the new compositions and using the compositions for treating surfaces in contact with water.

It has now been discovered that these and other objects may be accomplished by the process of the invention which comprises applying to the water wetted surface a composition comprising a mixture of a polyepoxide having more than one Vic-epoxy and preferably a glycidyl polyether of a polyhydric phenol, and a special controlled excess amount of a polyamide of an aliphatic or cycloaliphatic polycarboxylic acid containing at least 7 carbon atoms and an aliphatic polyamine, said polyamide containing groups reactive with the epoxy groups, and allowing the composition to set hard. It has been found that by the use of this process one can very easily apply corrosion-resistant coatings to surfaces which are wet or even totally submerged under water. The application is particularly efficient when applied as a putty to surfaces while they are under water. The coatings have excellent adhesion to the surface even when they are under water. The coatings when cured also demonstrate outstanding resistance to corrosion by fresh water, saline water, moist air and the like. In addition, the coatings are very hard and tough and have excellent flexibility and distensibility. They thus can be subjected to considerable pressures without chipping or cracking.

It has also been surprisingly found that the process is effective for repairing defects in wet surfaces, such as holes, cracks, pits and the like. When the compositions are applied to the surfaces when wet or submerged under water, the coatings fill the holes or cracks and can be leveled to form a smooth coating. The process can thus be used both for repair and for application of corrosion resistant coatings to boat hulls, water pipes, electrical conduits, pilings and the like.

The theory which was developed for the obtaining of the above-described superior results has been confirmed by laboratory tests. The use of the controlled excess amount of the polyamide as described hereinafter brings about a displacement of the water molecules at the interface of the surface and coating composition and permits the formation at that point of the superior adhesive forces which bond the cured composition to the surface. The afiinity of the polyamide to the metal or other surface is greater than the affinity of water to such surfaces and thus, the polyamide displaces the water to provide an essentially water-free surface onto which the coating can bond. It has been shown that only if the polyamide is available as an excess over the stoichiomctric amount will the drying of the surfaces occur.

The polyepoxides used in the process of the invention comprise those organic materials possessing more than one Vic-epoxy group, i.e., more than one group. These materials may be saturated or unsaturated, aliphatic, cycloaliphatic, aromatic or heterocyclic and may be situated with substituents, such as chlorine, hydroxyl groups and ether radicals. They should not, however, possess active groups, such as isocyanate groups, which are reactive with water.

For clarity, many of the polyepoxides and particularly those of the polymeric type will be described in terms of epoxy equivalent value. The meaning of this expression is described in US. 2,633,458.

If the polyepoxide consists of a single compound and all of the epoxy groups are intact, the epoxy equivalency will be integers, such as 2, 3, 4 and the like. However, in the case of polymeric type polyepoxides many of the materials may contain some of the monomeric monoepoxides or have some of their epoxy groups hydrated or otherwise reacted and/or contain macromolecules of somewhat different molecular weight so the epoxy equivalent values may be quite low and contain fractional values. The polymeric material, may, for example, have epoxy equivalent values, such as 1.5, 1.8, 2.5 and the like.

Examples of the polyepoxides include, among others, 1,4-bis(2,3-epoxypropoxy)benzene, 1,3-bis(2,3-epoxypropoxy) benzene, 4,4'-bis(2,3-propoxy)diphenyl ether, 1,8- bis(2,3-epoxypropoxy)octane, 1,4-bis(2,3-epoxyprop%xy) cyclohexane, 4,4'-bis(2-hydroxy-3,4'-epoxybutoxy)dip enyl dirnethylmethane, 1,3-bis(4,5-epoxypentoxy) -'5-chlorobenzene, 1,4-bis(3,4-epoxybutoxy)-2-chlorocyclohexane, 1,3-bis(2-hydroxy-3,4-epoxybutoxy)benzene and 1,4-bis (2-hydroxy-4,5-ep oxypentoxy) benzene.

Other examples include the epoxy polyethers of polyhydric phenols obtained by reacting a polyhydric phenol with a halogen-containing epoxide or dihalohydrin in the presence of an alkaline medium. Polyhydric phenols that can be used for this purpose include, among others, resorcinol, catechol, hydroquinone, methyl resorcinol, or polynuclear phenols, such as 2,2-bis(4-hydroxyphenyl) propane (Bisphenol-A) 2,2-bis(4-hydroxyphenyl)butane, 4,4-dihydroxybenzophenone, bis-(4-hydroxyhpenyl)ethane, 2,2-bis(4-hydroxyphenyl)pentane, and 1,5-dihydroxynaphthalene. The halogen-containing epoxides may be further exemplified by 3-chloro-l,2-epoxybutane, 3- bromo-1,2-epoxyhexane, 3-chloro-1,2-epoxyoctane, and the like.

The monomer products produced by this method from dihydric phenols and epichlorohydrin may be represented by the general formula wherein R represents a divalent hydrocarbon radical of the dihydric phenol. The polymeric products will generally not be a single simple molecule but will be a complex mixture of glycidyl polyethers of the general formula wherein R is a divalent hydrocarbon radical of the dihydric phenol and n is an integer of the series 0, 1, 2, 3, etc. While for any single molecule of the polyether n is an integer, the fact that the obtained polyether is a mixture of compounds causes the determined value for n to be an average which is not necessarily zero or a whole number as noted above.

The aforedescribed preferred glycidyl polyethers of the dihydric phenols may be prepared by reacting the required proportions of the dihydric phenol and the epichlorohydrin in an alkaline medium. The desired alkalinity is. obtained by adding basic substances, such as sodium or potassium hydroxide, preferably in stoichiometric excess to the epichlorohydrin. The reaction is preferably accomplished at temperatures within the range of from 50 C. to 150 C. The heating is continued for several hours to effect the reaction and the product is then washed free of salt and base.

The preparation of some of the glycidyl polyethers of dihydric phenols will be illustrated below. Unless otherwise specified, parts indicated are parts by weight.

PREPARATION OF GLYCIDYL POLYETHERS OF DIHYDRIC PHENOLS Polyether A 1 mol of bis-phenol was dissolved in mols of epichlorohydrin and 1 to 2% water added to the resulting mixture. 5% by weight phenol was added to the mixture. The combined mixture was then placed in a kettle provided with heating and cooling means, agitator, distillation condenser and receiver. The mixture was brought to 80 C. and 2 mols of solid sodium hydroxide added in small portions. .Sufiicient cooling is applied during the addition so that the temperature is maintained at about 95-97 C. and there is a gentle distillation of epichlorohydrin and water. After the last addition of sodium hydroxide with the completion of the reaction, the excess epichlorohydrin is removed by vacuum distillation. After completion of the distillation, the residue is cooled to about 90 C. and about 300 parts of benzene added. Cooling drops the temperature of the mixture to about 40 C. with precipitation of salt from the solution. The 0 salt is removed by filtration and the removed salt carefully washed with about an additional 300 par-ts of benzene to remove polyether therefrom. The two benzene solutions were combined and distilled to separate the benzene. When the kettle temperatures reached 125 C., vacuum is applied and distillation. The resulting product is a liquid composition containing glycidyl polyether of bis-phenol having the following properties: Epoxy Value of 0.541 eq./'100 g., color 6 (Gardner), chlorine (percent W.) 0.24, viscosity 70 poises.

Polyether B A solution consisting of 11.7 parts of water, 1.22 parts of sodium hydroxide, and 13.38 parts of 2,2-bis(4-hydroxyphenyl) propane was prepared by heating the mixture of ingredients to 70 C. and then cooling to 46 C. at which temperature 14.06 parts of epichlorohydrin was added While agitating the mixture. After 25 minutes had elapsed, there was added during an additional minutes time a solution consisting of 5.62 parts of sodium hydroxide in 11.7 parts of water. This caused the temperature. to rise to 63 C. Washing with water at a temperature of C. to C. was started 30 minutes later and continued for 4 /2 hours. The product was dried by heating to a final temperature of 140 C. in =80 minutes and cooled rapidly. At room temperature, the product was an extremely viscous semi-solid having a melting point of 27 C. by Durrans Mercury Method and a molecular weight of 483. The product had an epoxy value eq./ 100 Q g. of 0.40. For convenience, this product will be referred to as Polyether B.

Preferred members of the above-described group of polyepoxides are the glycidyl polyethers of the dihydric phenols, and especially 2,2-bis(4-hydroxyphenyl)propane, having'an epoxy equivalency between 1.0 and 2.0

and a molecular weight between 250 and 900. Particularly preferred are those having Durrans Mercur See Chemical Week, vol. 69, page 27, for' novalac resins which resins are obtained by condensing an aldehyde with a polyhydric phenol. A typical member of this class is the epoxy resin from formaldehyde 2,2- bis(4-hydroxyphenyl)propane novalac resin.

The polyamides used in the process of the invention comprise the reaction product of an aliphatic or cycloaliphatic polycarboxylic acidcontaining at least 7 carbon atoms and preferably those containing at least seven carbon atoms between the acidic groups, and an aliphatic polyamine, the resulting product possessing a group reactive with epoxy groups, such as, for example, free amino groups or free carboxyl groups.

Examples of polybasic acid materials used in making these polyamides include, among others, 1,10-decanedioic acid, 1,12-dodecadienedioic acid, 1,20-eicosadienedioic acid, 1,14-tetradecanedioic acid, 1,18-octadecanedioic acid and dimerized and trimerized unsaturated fatty acids obtained by heating polymerizing drying oil fatty acids under known conditions. Normally, this is effected by utilizing the lower aliphatic esters of drying oil esters so as to prevent decarboxylation during the heating period. During the heating period, dimers and trimers are usually obtained. The process is illustrated in the Industrial and Engineering Chemistry, vol. 38, page 1139 (1946). The structures of the products so obtained are believed to be those given in industrial Engineering Chemistry, vol. 33, page 89 (1941). Numerous drying oil acids can be used in preparing the polymerized acids, but the preferred acids are those containing from 16 to 24 carbon atoms, such as, for example, linoleic acid, linolenic acid, eleostearic acid, and licannic acid, such as may be derived from oils, such as soybean oil, linseed oil, tung oil, perilla, oiticia, cottonseed, corn, tall, sunflower, dehydrated castor oil and the like. The expression polymerized unsaturated fatty acids as used herein in a generic sense is intended to include the polymerized mixture of dimerized acids, trimerized acids, higher polymerized acids as well as small portions of residual monomer.

The aliphatic polyamines used in preparing the polyamides may be any di-, trior polyamine such as, for example, ethylene diamine, diethylene triamine, triethylene tetramine, tetraethylene pentamine, 1,4-diaminobutane, 1,3 diaminobutane, hexamethylene diamine, 3 (N isopropylamino)propylamine, and the like. Particularly preferred polyamines are those containing from 2 to 12 carbon atoms, and especially those of the formula wherein x is an integer of 0 to 10 and R is a bivalent hydrocarbon radical containing from 1 to 10 carbon atoms. Coming under special consideration are those polyamines having at least 3 atoms intervening between the amine groups principally involved in the amidification reaction. These three atoms may be carbon atoms or hetero atoms, such as nitrogen atoms.

Especially preferred polyamides are those derived from the aliphatic polyarnides containing no more than 12 carbon atoms and polymeric fatty acids obtained by dimerizing and trimerizing ethylenically unsaturated fatty acids containing upv to 24 carbon atoms. These preferred polyarnides have a viscosity between 10 and 1750 poises at 40 C., and preferably 20 to 250 poises at 40 C. Preferred polyamides also have amine values between 50 and 450. Amine number is number of milligrams of KOH equivalent to the free amino groups present in one gram of the polyamide.

Corning under special'consideration are the fluid poly- .amides produced by the condensation of polymerized linoleic acid with an aliphatic polyamine, e.g., diethyl- Another group of polyepoxidesthat may be used in I preparing the emulsions comprises the glycidyl ethers of value 210-230, a viscosity of 500450 poises at 40 C., specific gravity of 0.99 and Weighing about 8.3 pounds per gram.

The polyamides used in the process of the invention preferably possess at least one and more preferably two or more hydrogen attached to amino nitrogen atoms or carboxyl hydrogen atoms. Such products are obtained by controlling the proportion of reactants so that there is always at least one amino hydrogen or carboxyl group, such as, for example, by using an excess of the polyamine reactant. A process for making such polyamides (to obtain free amino groups) or an excess of acid (to obtain carboxyl groups) is illustrated in US. 2,450,940 and US. 2,695,908 and so much of these patents relative to the preparation of the polyamides is incorporated herein by reference.

Other materials may also be included in the compositions of the present invention. Materials which are particularly desirable for use, especially when the coatings are to be applied while the surface is immersed under water, are those which impart thixotropic properties to the composition. Examples of these include, among others, silieas, silicates, non-fibrous asbestos, silica aerogels, montmorillonite clay minerals as hentonite and the like. These materials are preferably finely divided and preferably have particles of up to 50 microns in size. Particularly preferred materials to be utilized include the finely divided colloidal materials which swell in the presence of Water, and especially those having a heat of interaction with the polyepoxide of less than 300 ergs/sq./cm. These thixotropic materials are preferably utilized in amounts up to about 10% by weight of the combined mixture, and still more preferably in amounts varying from about 0.1% to by weight.

Other materials to be added also include inert fillers, such as sand, crushed shells, rocks, aluminum powder, iron particles and the like.

Gther materials that may be used in the composition include those which tend to extend the polyepoxide but do not seriously affect the properties of the cured product, such as, for example, coal tars, asphalts, road oils, extracts and distillates, middle oil, refined coal tars, pine tars and oil, and the like as well as other types of resins as phenol-aldehyde resins, phenol-urea resins, polythiopolymercaptans, vinyl resins, polyolefins, synthetic rubbers, and the like and mixtures thereof. Particles of solid resins as particles of nylons, rayons, dacrons, and the like may also be added for strength. These other materials are preferably employed in amounts less than 60% by weight of the polyepoxide, and more preferably not more than 40% by weight of the polyepoxide.

Other materials that may be used include pigments, plasticizers, stabilizers, fungicides, insecticides, activators for the cure of the epoxy resins, such as, for example, phenols, amines, acids, salts, thiols, sulfides, and the like, and mixtures thereof. Other types of curing agents for the polyepoxides may also be used in combination with the above-noted polyamides as long as the polyamides make up at least 50% by weight of the combined curing agent.

The proportions of the polyepoxide and the polyamide to be used in the compositions of the invention should be maintained Within controlled ranges in order to obtain the above-noted superior results. The amount of the polyamide employed so as to be freely available to dry the surface, for example, should be at least a 5% stoichiometric excess and not more than 50% stoichiometric excess in relation to the polyepoxide. As used herein as in the appended claims stoichiometric amount refers to that amount needed to furnish one amino hydrogen or COOH hydrogen for every epoxy group to be reacted. Particularly superior results are obtained when the polyamide is employed in from to 40% stoichiometric excess.

The compositions may be prepared by any suitable method. They may be prepared, for example, by merely mixing the polyepoxide and poiyainide together in the above-noted proportions along with any of the abovcdescribed materials, such as tillers, thixotropic agents, pi

ments and the like. It is sometimes desirable to prepare the polyepoxide along with fillers, thixotropic agents, pigments and the like in a separate composition and the polyamide in a separate composition along with desired fillers, thixotropic materials and pigments, and then mix the two compositions together just before application is needed. This is preferred as it gives more time to work with the composition before it sets up to the hard insoluble material.

A preferred method of preparing the compositions is illustrated in the attached drawing and in Example I. In this case, the polyamide curing agent, filler and pigment are combined as Composition A and Composition B is prepared by mixing the polyepoxide, pigment and filler. Compositions A and B are then mixed in such proportions as to give a 5% to 50% stoichiometric excess of polyamide in relation to the polyepoxide. The mixing is accomplished at ambient temperature. The resulting putty-like composition is then applied to the wet surface.

The viscosity of the compositions used in the process of the invention will depend upon the viscosities of the polyepoxide and polyamide used in the mixture and the amount of added fillers and the like added. If thicker more putty-like compositions are needed, they may be prepared by the addition of more fillers or thixotropic agents. In general, putty-like compositions are obtained by adding from 20% to 150% by weight of the polyepoxide and polyamide of the filler materials. On the other hand, if more fluid compositions are needed as for brushing, etc. one may add more fluid polyepoxides, such as, for example, glycidyl ethers of polyhydric alcohols, diglycidyl ether, polyglycidyl esters of lower acids and the like, until the desired fluidity is obtained.

The above-noted compositions are applied to the waterwetted surface when the surface is in contact with any amount of water, e.g., the surface may just have a layer of water say several molecules thick, or the surface may be totally immersed in fresh or saline water. When the surface is in contact with only a small amount of water, the composition may be applied by simply brushing, spraying or otherwise applying the composition. However, when the surface is under water and exposed to considerable movement of the water, a putty-like material is prepared and applied to the surface as by hand or other suitable techniques so as to force the composition on the surface to be coated and form a continuous layer thereon.

The thickness of the coating on the surface will depend on the desired need of the application. The coating may, for example, vary from just a few mils thickness up to as high or higher than one inch thickness. The edges of the coatings are preferably feathered down so as to make a secure seal on the surface.

If the surface to be coated has already been corroded or is coated with oils and the like, it is preferred to clean the surface before application of the coatings of the invention. This may be accomplished by any suitable means, such as steel brushing, sandblasting, etching with acids, cleaning with organic solvents and the like.

After the material has been coated With the desired coating, the coating is then allowed to set until it has become cured to the insoluble infusible state, e.g., is insoluble in acetone and does not soften when heated say to C. The curing takes place at normal temperatures so no external steps need be taken to effect cure. Heat, of course, will speed the cure, and if possible applications, such as heat lamps and the like, might be utilized to speed the setting up of the coating. Under ordinary application conditions, the coating will generally harden by being allowed to set say in from 4 to 24 hours after mixing.

The process of the invention is particularly adapted for use in the protection of metal structures disposed offshore and subjected to the action of an electrolyte, such as sea water, this process including the steps of mixing a polyepoxide and fil er material which proportions are selected to form a putty-like composition which preferentially wets treatment of ferruginous metal surfaces.

metal surfaces and becomes substantially rigid in from about 4 to 24 hours after mixing, and applying a coating of said putty-like composition on surfaces of metal members to be protected, which surfaces are located between the upper level reached by waves and a level at least one foot below the low-tide water line, by forcing said puttylike composition to contact said metal surfaces and form into a continuous layer along which there is substantially continuous composition-to-metal contact.

In treating a vertical metal member which extends through the Water line of an offshore structure, the surfaces of the member to be protected are cleaned from a level as high as the anticipated lapping of the waves, or splashing of the water, to a level which is at least about a foot below the low-tide water line, said cleaned surface being then coated with a layer of the aforesaid selfhardening mixture.

One of the preferred methods of applying the mixture to the structural member is to first form a ring of the material or mixture on the structural member at a point somewhat above the highest point to which Water may splash, then smearing the material downwardly and uniformly a foot or so below the low-tide water level with the bottom edge of the plastic feathered to the metal member to be protected. The composition used for this protection of metal structural members is readily molded in place by-the use of the applicators hands, particularly when the latter are wet. The application of the subject compositions to complex geometric structures is easy and readily accomplished by the use of techniques similar to those employed in applying putty.

As noted, the process of the invention is also particularly adapted for use in the repairing of defects in surfaces, such as holes, cracks and the like and optionally placing of a corrosion resistant coating on such surfaces at the same time. This is accomplished by preparing the composition as noted above and then applying the composition to the defective surface. If the defects are very fine cracks, and the wet surfaces are not exposed to -much action of the Water, the composition may be of the fluid type so as to fill the cracks and defects. If the cracks are very large and/ or if the action of the water is very strong it may be necessary to employ the composition in the form of a thick putty as described above. After the composition has been applied to the defect so as to eifect the repair, the surface may then be coated to effect the direct corrosion prevention. In some cases, in repairing the defects in the presence of water, it may be desirable to speed cure of the composition so as to more efficiently close the crack or hole. This may be accomplished by the addition of cure accelerators noted above, such as phenols, thiols and the like. 7

The process of the invention may be used for the coating and/0r repair of any surface. Such surfaces include, among others, wood, cement, plaster, metal, glass and the like. The process is particularly suited for use in treating metal surfaces, such as, for example, copper, aluminum, brass and iron surfaces. The process has shown especially superior results when used for the The'surfaces may be in any type of structure, such as, for example, pipes, boats, pilings, reactionvessels, structural members of oil well drilling platforms, well jackets, collection platforms and the like.

To illustrate the manner in which the invention may be carried out, the following examples are given. .It is to be understood, however, that the examples arefor the purpose of illustration and the invention is not to be regarded as limited to any of the specific materials or conditions recited therein.

components together in' the proportions indicated:

1 use of this composition for treatment of off-shore drilling structures disposed in the splash zone.

Composition A was prepared by mixing the following components together in the proportions shown:

Composition B was prepared by mixing the following components together in the proportions shown:

Parts Polyether A 18 Talc 18 Pigment 1 Triphenyl phosphite 1.8

The compositions were mixed together in substantially equal parts by volume. The resulting composition was a putty-like composition which could be easily formed by hand and when allowed to stand set up to a hard tough flexible insoluble infusible material. 7

The above uncured composition was applied by hand to the steel legs of the well jacket and the flow line of an offshore drilling platform located in ocean water where severe splash zone corrosion was taking place. The surfaces had been previously scraped and wire brushed to remove most of the rust. The coating was applied to cover the area in the spray zone, at the splash zone and about one foot below low tide water level. The composition was applied under the water line by applying pressure to squeeze the water away from the member and establish a substantially continuous composition-to-metal contact under the layer of the coating material. No difliculty was encountered in having the coating adhere to the members and the plastic coating was fully set about 24 hours to form a hard tough and highly distensible coating. The wave action was particularly severe during a storm justafter the application, but this did not disrupt or remove the coating.

, The coatings on the Well jacket and fiow line were inspected 20 months after application and were found to be in excellent condition. The coatings had withstood considerable pressures and because of its great distensibility had not chipped or pealed off. The adhesion was excellent and the coatings were providing complete corroslon protection to the members.

EXAMPLE II (A). This example further illustrates the preparation of a coating composition containing Polyether A and a polyamide of dimerized linoleic acid and diethylene, triamine, and the superior properties of the composition as a coating for steel pipes in splash zones.

Composition A was, prepared by mixing the following components together in the proportions indicated:

. Parts Polyether A 40.4 Triphenyl phosphite 3.7 Cab-O-Sil (thixotropic agent) 47.5 Chrome yellow pigment 3.4

Composition B was prepared by mixing the following Parts Polyamide of dimerized'linoleic acid and diethylene triamine having anamine value of 306 (versamid 125) 42.3 Silica filler 12.7 Cab-O-Sil (thixotropic agent) 44.8 Lamp black .2

I 1 Compositions A and B were then mixed together in a weight ratio of 1: 1.1. The resulting mixture was a puttylike composition which could be easily formed by hand. When allowed to set, the mixture set up in 4 to 10 hours to form a hard tough flexible insoluble infusible material.

The above uncured composition was applied by hand to a steel pipe disposed in an accelerated splash zone corrosion test apparatus. The pipe had been previously cleaned by sandblasting and the coating was applied by hand under 3% brine solution. The coating remained intact with no slumping or running and set to form hard tough flexible coating in 12 to 18 hours. The pipe was retained in the apparatus where it was exposed to the brine solution under accelerated splash zone conditions for seven days. The water was kept at 70 F. for 24 hours and then the temperature raised to 150 F. to accelerate the test. At the end of7 days, the coating demonstrated excellent adhesion, toughness and distensibility and excellent corrosion protection.

(B) The above experiment was repeated with the exception that the amount of polyamide employed was reduced to the stoichiometric amount. In this case, the composition applied to the steel pipe in the accelerated splash zone corrosion test had poor adhesion to the pipe and gave little protection against corrosion.

(C) The above experiment was also repeated with the exception that the amount of polyamide was changed to 130% excess. In this case also, the composition applied to the steel pipe in the accelerated splash zone corrosion test had poor adhesion to the pipe and gave little protection against corrosion.

EXAMPLE III Example II was repeated with the exception that the amount of polyamide in the coating composition was changed from 16% excess to 50% excess. Related results are obtained.

EXAMPLE IV Example II was repeated with the exception that the amount of poly-amide in the coating composition was changed to 10% excess. Related results are also obtained.

EXAMPLE V Example II is repeated with the exception that the amount of polyamide in the coating composition is changed to 40% excess. Related results are also obtained.

EXAMPLE v1 Example 11 was repeated with the exception that Polyether A was replaced with an 85-15 mixture of Polyether A and butyl glycidyl ether. Related results are obtained.

EXAMPLE VII Example II is also repeated with the exception that Polyether A is replaced with diglycidyl ether of resorcinol. Related results are also obtained.

EXAMPLE VIII EXAMPLE IX Example II is repeated with the exception that the polyamide is replaced by a polyamide of eicosanedioic acid and ethylene diamine. Related results are obtained.

. EXAMPLE X Composition A was prepared by mixing the following components in the proportions indicated:

Percent 8515 mixture of Polyether A and butyl glycidyl ether 30 Triphenyl phosphite 6 Asbestos 12 Aluminum powder 1O Phythalox amine blue 3 Composition B was prepared by mixing the following components in the proportions indicated:

Percent Polyamide of dimerized linoleic acid and diethylene triamine having an amine value of 306 15 Polyamide of climerized linoleic acid and diethylene triamine having an amine value of 216 15 Aluminum powder 10 Yellow pigment 1.7

The two compositions above were mixed together in substantially two parts of B to 1 part A by volume. The resulting composition was a putty-like composition which could be easily formed by hand and when allowed to stand set up to a hard tough distensible composition.

The above composition was applied to the steel legs of offshore production platform as shown in Example I. The coating did not slump or run and set hard under the water to form a hard tough distensible coating. Examination of the coating after 14 months indicated the coating was in excellent condition, had not chipped or marred and had given complete protection against corrosion.

EXAMPLE XI The coating compositions shown in Examples I, II and X are applied to iron and copper water piping which have water leaking through small holes. The coatings set up in a few hours to seal the holes and furnish a hard tough flexible corrosion-resistant coating for the pipes.

EXAMPLE XII The coating compositions shown in Examples I, II and X are also applied to the side of a metal hull of a boat while in the water so as to effect a repair of a small hole therein. A successful patching and coating of the hole is obtained.

It has also been unexpectedly found that the new compositions are excellent materials for treating heat exchange tubes, heat exchange tube sheets, heads and the like. The compositions form a strong corrosion resistant coating when applied according to the process of the invention, In addition, it was surprisingly found that the resulting coatings inhibit the formation of mineral scale depositions during operation of the heat exchanger.

The above is illustrated by the following: A coating composition prepared as in Example II was applied to wet surfaces of heat exchanger tube sheets of a heat exchanger which had been opened for repairs. The composition was applied so as to form a thick coating on the wet metal surfaces, and the coating allowed to cure. The heat exchanger was then put back into service. After 18 months of service, the heat exchanger was again opened for examination. It was noted that the abovenoted coating had given excellent corrosion resistance to the surfaces treated. In addition, it was noted that a mineral scale deposition had occurred on all water-wetted surfaces except the surfaces coated with the above material. The coating had thus given unexpected resistance to mineral scale deposition. Compositions containing the above-described polyepoxides and certain polythiols possess certain of the abovedescribed properties. Such compositions will be covered in continuation-in-part applications.

I claim as my invention:

1. process for treating water-wetted surfaces which comprises applying to the wet surface while immersed in watera mixture of a liquid polyepoxide having more than one vie-epoxy group and from 5% to 50% stoichiometric excess of a polyamide of apolycarboxylic acid containing at least 7 carbon atoms and an aliphatic polyamine, said poly-amide having groups reactive with epoxy groups, and allowing the coating to set hard while the coated surface is immersed in water.

2. A process for forming a corrosion-resistant coating on a metal surface while the surface is immersed in water which comprises applying to the surface while immersed in water a putty-like mixture of a liquid polyepoxide containing only carbon, hydrogen and oxygen and having more than one vie-epoxy group and from to 50% stoichiometric excess of a polyamide of a polycarboxylic acid containing at least 7 carbon atoms and an aliphatic polyamine, said polyamide possessing hydrogen attached to amino nitrogen, and said polyamide having greater affinity to the metal surface than the Water and functioning so as to displace the water from the surface of the metal and cure the polyepoxide, and then allowing the mixture to harden under the water.

3. A process as in claim 2 wherein the polyepoxide is a glycidyl polyether of a polyhydric phenol having an epoxy equivalency of more than 1.0 and a molecular weight between 250 and 900.

4, A process as in claim 2 wherein the polyamide is a reaction product of a polymerized unsaturated fatty acid and an aliphatic polyamine.

5. A process as in claim 2 wherein the putty-like mixture is applied to a steel metal surface.

6. A process as in claim 2 wherein the polyarnide is employed in a stoichiometric excess of 5% to 25%.

7. A process as in claim 2 wherein the putty-like mixture contains a finely-divided colloidal silicon-containing material.

8. A process for the protection against corrosion of a corrodible metal structure disposed off-shore partly below and partly above the water level, which comprises mixing into a putty like resinous composition a liquid glycidyl polyether of a polyhydric phenol having an epoxy equivalency greater than 1.0 and from 5% to 50% stoichiometric excess of a polyamide of a polymerized unsaturated fatty acid and an aliphatic polyamine, said polyami-de containing unreacted groups selected from the group consisting of amine and carboxyl groups, applying the said putty-like composition onto the metal surfaces exposed above and below the water level by forcing said putty-like composition against the wet metal surfaces, thereby disposing a layer of the composition in contact with said surfaces, and causing the formation on the surfaces of a solid corrosion-protecting coating of the cured, hardened resinous composition while the coated surface remains immersed in water.

9. A process as in claim 8 wherein the polyamide is a reaction product of a polymerized linoleic acid and diethylene triamine.

10. A process as in claim 9 wherein the glycidyl polyether is a glycidyl polyether of 2,2-bis(4-hydroxyphenyl)- propane.

11. A process as in claim 8 wherein the metal surface is a steel surface. 1

12. A process for the protection'of a structure which is disposed off-shore in saline water and has generally tubular ferruginous metal structural members located within a zone partly below and partly above the water level, which comprises forming a mixture (1) of a liquid polyepoxide having more than one Vic-epoxy group, (2) from 5% to 50% stoichiometric excess of a polyamide of a polymerized unsaturated fatty acid and an aliphatic polyamine, said polyamide possessing hydrogen attached to amine nitrogen, and said polyamide having greater affinity to the metal surface than the water and fumetioning so as to displace the water from the surface of the metal and cure the polyepoxide, and (3) thixotropic material, applying the resulting mixture to the aforedescribed structural members from above to below the water level while the structure immersed in water, and allowing the coating to set to a hard tough flexible insoluble infusible coating while immersed in the said water. I

13. A process for repairing a defect in a wetted metal surface which comprises applying to the surface while immersed in the water a composition comprising a mixture of (1) a liquid polyepoxide having more than one Vic-epoxy group, (2) from 5% to 50% stoichiometric excess of a polyamide of a polycarboxylic acid containing at least 7 carbon atoms and an aliphatic polyamine, said polyamide having groups reactive with epoxy groups, and said polyamide having greater aflinity to the metal surface than the water and functioning so as to displace the water from the surface of the metal and cure the polyepoxide and (3) a thixotropic agent, and then allowing the composition to set to a hard tough flexible plastic material while the coating surface remains immersed in water.

14. A process for forming a corrosion resistance coating on a surface which is located in a body of water and extends above and below the water line, the portion above the water line being subjected to frequent splashing of water by Wave action, which comprises applying to the wet surface above and below the water line a mixture of a liquid polyepoxide having more than one Vic-epoxy group and from 5% to 5 0% stoichiometric excess of a po'lyamide of a polycarboxylic acid containing at least 7 carbon atoms and an aliphatic polyamine, said polyamide having groups reactive with epoxy groups, and allowing the coating to set hard.

References Cited in the file of this patent UNITED STATES PATENTS 2,522,469 Sweeney Sept. 12, 1950 2,705,223 Renfrew et al Mar. 29, 1955 2,829,984 Yaeger Apr. 8, 1958 2,944,036 Floyd et al. July 5, 1960 2,986,539 Schniepp et a1 May 30, 1961 2,987,492 P-inder June 6, 1961 OTHER REFERENCES Proceedings of the International Patent Ofiice Workshop on Information Retrieved, US. Dept. of Commerce, pp. 147 to 154, T223 P204.

Lee et al.: Epoxy Resins, McGraw-Hill, 1957, pages 166-172, 148, 204, 274-279, TP 986. E6 L4.

Glaser et al.: Coatings Based on Blends of Polyamide arsrd Epoxy Resins, Ofiicial Digest, February 1957, pages 1 9-169.

Claims

1. A PROCESS FOR TREATING WATER-WETTED SURFACES WHICH COMPRISES APPLYING TO THE WET SURFACE WHILE IMMERSED IN WATER A MIXTURE OF A LIQUID POLYEPOXIDE HAVING MORE THAN ONE VIC-EPOXY GROUP AND FROM 5% TO 50% STOICHIOMETRIC EXCESS OF A POLYAMIDE OF A POLYCARBOXYLIC ACID CONTAINING AT LEAST 7 CARBON ATOMS AND AN ALIPHATIC POLYAMINE, SAID POLYAMIDE HAVING GROUPS REACTIVE WITH EPOXY GROUPS, AND ALLOWING THE COATING TO SET HARD WHILE THE COATED SURFACE IS IMMERSED IN WATER.