WO2016149148A1 - Solventless anti-corrosion composition and methods of using the same - Google Patents

Abstract

A curable composition comprises: a curable resin; and microcapsules comprising a polymeric shell enclosing a fill material including at least one of a corrosion inhibitor and a liquid vehicle, wherein the curable composition is liquid, and wherein the curable composition is essentially free of organic solvent other than the liquid vehicle. The curable composition can be coated on a metal surface of a substrate and cured to form a corrosion-resistant protective layer.

Description

SOLVENTLESS ANTI-CORROSION COMPOSITION

AND METHODS OF USING THE SAME TECHNICAL FIELD

The present disclosure broadly relates to compositions for inhibiting corrosion of metals and methods of using the same.

BACKGROUND

There are many situations and applications where metal structures become subject to oxidative corrosion and ultimately fail to fulfill their intended purpose. Examples of failure by metal corrosion include deterioration of heat exchanger elements, corrosion of pipeline distribution systems, and especially the gradual disintegration of steel used for reinforcing concrete structures such as bridge decks and frames which support a wide range of modern buildings.

Newly constructed metal structures typically have a protective treatment against corrosion. As the structures age, protection diminishes and corrosion processes occur. A deterrent to such processes would delay the onset of corrosion, especially if the deterrent exerted its effect later in the lifetime of the reinforced structures. Treatments to delay the onset of corrosion, as disclosed in subsequent prior art references, include application of corrosion inhibitors or protective coatings directly to the metal surface or release of protective agents into a matrix material.

U.S. Pat. No. 6,075,072 (Guilbert et al.) describes a corrosion protective coating composition, applied over a metal surface, which contains frangible microcapsules which rupture and release fluid upon impact or other stress likely to damage the coating. The fluid, from the microcapsules, contains a film forming component to cover the damaged area of the coating and a corrosion inhibitor for the metal surface.

U.S. Pat. No. 7, 192,993 (Sarangapani et al.) describes a liquid self-healing coating, incorporating microcapsules filled with tailored repair formulations, which repairs itself upon physical compromise after curing.

SUMMARY

Corrosion protection coatings are commonly applied to manufactured goods (e.g., pipes) under factory conditions. As a result, those techniques requiring specialized equipment (e.g., for powder coating and fusion bonding) and/or ventilation (e.g., for solvent-based coatings) may be readily used. The application methods described above are less desirable if practiced outside the controlled environment of a factory. For example, a pipe that has an anti-corrosion protective coating, if cut during installation or repair in the field, will have bare metal exposed at the site of the cut that needs to be protected. Specialized equipment for powder coating is typically not particularly portable, and solvent-based coatings typically present environmental and/or regulatory issues due to the presence of solvent vapor.

Advantageously, solventless liquid anti-corrosion compositions according to the present disclosure can be applied to metal surfaces under field conditions without either of the above concerns.

In one aspect, the present disclosure provides a curable composition comprising:

a curable resin; and

microcapsules comprising a polymeric shell enclosing a fill material including at least one of a corrosion inhibitor and a liquid vehicle, wherein the curable composition is liquid, and wherein the curable composition is essentially free of organic solvent other than the liquid vehicle.

In another aspect, the present disclosure provides a method of protecting a metal surface comprising, applying a curable composition to the metal surface and curing the curable composition, wherein the curable composition comprises:

a curable resin; and

microcapsules comprising a polymeric shell enclosing a fill material including at least one of a corrosion inhibitor and a liquid vehicle, wherein the curable composition is liquid, and wherein the curable composition is essentially free of organic solvent other than the liquid vehicle.

In yet another aspect, the present disclosure provides an article comprising:

a substrate having a metal surface; and

a corrosion-resistant protective layer disposed on at least a portion of the metal surface, wherein the corrosion-resistant protective layer comprises a cured reaction product of a curable composition comprising:

a curable resin; and

microcapsules comprising a polymeric shell enclosing a fill material including at least one of a corrosion inhibitor and a liquid vehicle, wherein the curable composition is liquid, and wherein the curable composition is essentially free of organic solvent other than the liquid vehicle.

As used herein: the term "curable" means permanently hardenable by a chemical crosslinking reaction (e.g., by action of a curative and/or thermal and/or radiation energy);

the term "essentially free of " means containing less than 2 percent by weight of, preferably less than 1 percent by weight of, more preferably less than 0.1 percent any weight of, more preferably less than 0.01 percent by weight of, and even more preferably free of;

the term "liquid" means freely flowable by the force of gravity;

the term "microcapsule" refers to a capsule have a size of 500 microns or less, preferably 500 microns or less, more preferably 200 microns or less, and even more preferably 150 microns or less;

the term "organic solvent" refers to an organic liquid that is not otherwise reactive with components of the curable composition under ordinary use conditions, and is present solely for the purpose of dissolving or suspending at least one component of the curable composition and/or viscosity control;

the term "urethane" encompasses curable resins containing isocyanate groups whether cured by reaction with a polyol to form a polyurethane or a polyamine to form a polyurea, or some combination thereof;

the term "thermosetting" means curable by application of energy (e.g., heat, infrared radiation, or actinic radiation).

Features and advantages of the present disclosure will be further understood upon consideration of the detailed description as well as the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic side view of an exemplary article 100 according to the present disclosure.

It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art, which fall within the scope and spirit of the principles of the disclosure. The figure may not be drawn to scale.

DETAILED DESCRIPTION

Curable compositions according to the present disclosure comprise a curable resin.

Suitable curable resins include aminoplast resins, urethane resins (e.g., 1-part and 2-part urethane resins), epoxy resins (e.g., 1-part and 2-part epoxy resins), acrylic resins, acrylated isocyanurate resins, cyanate resins, urea-formaldehyde resins, isocyanurate resins, and combinations thereof, for example. Epoxy resins and polyurethane resins are preferred. In some embodiments, the curable resin may be a one-part curable resin that is activated by heat, and/or infrared radiation, and/or actinic radiation (e.g., visible or ultraviolet light). In some embodiments, the curable resin may be a multi-part (e.g., a two-part) curable resin that is activated by mixing two or more components together and optionally heating the resultant mixture. Examples of suitable two-part curable resins include two-part epoxy resins such as those having a polyepoxide in a part A and a curative for the polyepoxide (e.g., a polyamine, a polythiol, or a catalyst) in a Part B, and include two-part urethane resins such as those having a polyisocyanate in a part A and a curative for the polyisocyanate (e.g., a polyamine, a polyol, and/or a catalyst). In general, any curative will be present in at least an amount effective to cause curing of the curable composition (i.e., an effective amount), while the effective amount will typically vary with the specific formulation chosen; e.g., as is known in the art. For example, in the case of two-part curable resin systems the curative (e.g., polyamine, polyol, or polythiol) may be present in a stoichiometric ratio of curative to curable resin in a range of from 0.8 to 1.35; for example, in a range of from 0.85 to 1.20, or in a range of from 0.90 to 0.95, although stoichiometric ratios outside these ranges may also be used.

Curable resins useful in practice of the present disclosure may comprise at least one curable epoxy resin. The epoxy resins may be monomeric, dimeric, oligomeric or polymeric epoxy materials containing at least one epoxy functional group per molecule. Such resins may be aromatic or aliphatic, cyclic or acyclic, monofunctional or poly functional. The backbone of the resin may be of any type, and substituent groups thereon can be any group not having a nucleophilic group or electrophilic group (such as an active hydrogen atom) which is reactive with an oxirane ring. Exemplary substituent groups include halogens, ester groups, ethers, sulfonate groups, siloxane groups, nitro groups, amide groups, nitrile groups, and phosphate groups.

The molecular weights of the epoxy resins may range from about 100 g/mol for monomeric or oligomeric resins to 50,000 g/mol or more for polymeric resins. Suitable epoxy resins are typically a liquid at room temperature. However, soluble solid epoxy resins may also be used as long as the overall curable composition is liquid; for example, at room temperature or the use temperature. Epoxy resins may be used alone or in combination.

Types of epoxy resins that can be used include, for example, the reaction product of bisphenol A and epichlorohydrin, the reaction product of phenol and formaldehyde (novolac resins and/or resole resins) and epichlorohydrin, peracid epoxies, glycidyl esters, glycidyl ethers, the reaction product of epichlorohydrin and p-aminophenol, the reaction product of

epichlorohydrin and glyoxal tetraphenol. Epoxy resins may be glycidyl ethers. Suitable glycidyl ether epoxy resins include, for example, glycidyl ethers of bisphenol A and F, aliphatic diols, and cycloaliphatic diols. In some embodiments, curable epoxy resins have a molecular weight in the range of from about 170 g/mol to about 10,000 g/mol. In other embodiments, curable epoxy resins have a molecular weight in the range of from about 200 g/mol to about 3,000 g/mol.

Useful glycidyl ether epoxy resins include linear polymeric epoxides having terminal epoxy groups (e.g., a diglycidyl ether of polyoxyalkylene glycol) and aromatic glycidyl ethers (e.g., those prepared by reacting a dihydric phenol with an excess of epichlorohydrin). Examples of useful dihydric phenols include resorcinol, catechol, hydroquinone, and the polynuclear phenols including ρ,ρ'-dihydroxydibenzyl, p,p'-di(hydroxyphenyl) sulfone, ρ,ρ'- dihydroxybenzophenone, 2,2'-dihydroxyphenyl sulfone, 2,2-dihydroxy-l, l-dinaphthylmethane, and the 2,2'-, 2,3-', 2,4'-, 3,3'-, 3,4'-, and 4,4'-isomers of di(hydroxyphenyl)methane,

di(hydroxyphenyl)dimethylmethane, di(hydroxyphenyl)ethylmethylmethane, di(hydroxyphenyl)- methylpropylmethane, di(hydroxyphenyl)ethylphenylmethane, di(hydroxyphenyl)propyl- phenylmethane, di(hydroxyphenyl)butylphenylmethane, di(hydroxyphenyl)tolylethane, di(hydroxyphenyl)tolylmethylmethane, di(hydroxyphenyl)dicyclohexylmethane, and

di(hydroxyphenyl)cyclohexane.

Suitable commercially available aromatic and aliphatic epoxides include di(glycidyl ether) of bisphenol A (e.g., EPON 828, EPON 872, EPON 1001, EPON 1310 and EPONEX 1510 available from Hexion Specialty Chemicals GmbH in Rosbach, Germany), DER-331, DER-332, and DER-334 (available from Dow Chemical Co. in Midland, Michigan); diglycidyl ether of bisphenol F (e.g., EPICLON 830 available from Dainippon Ink and Chemicals, Inc.); PEG.sub.1000DGE (available from Polysciences, Inc., Warrington, Pennsylvania); silicone resins containing diglycidyl epoxy functionality; flame retardant epoxy resins (e.g., DER 580, a brominated bisphenol type epoxy resin available from Dow Chemical Co. in Midland,

Michigan); l,4-di(hydroxymethyl)cyclohexane diglycidyl ether; and 1,4-butanediol diglycidyl ether. Other epoxy resins based on bisphenols are commercially available under the trade designations D.E.N., EP ALLOY, and EPILOX.

Suitable urethane resins may include a polyisocyanate and a curative for the

polyisocyanate such as, for example, a polyol, a polyamine, and/or a catalyst (e.g., dibutyltin dilaurate or l,4-diazabicyclo[2.2.2]octane (DABCO)) or latent catalyst (e.g., a photoactivated organometallic catalyst as described in U.S. Pat. No. 4,740,577 (DeVoe et al.)). In some embodiments, the polyisocyanate may be a blocked version that generates isocyanate groups upon heating, for example.

Useful polyisocyanates include, for example, aliphatic polyisocyanates (e.g.,

hexamethylene diisocyanate or trimethylhexamethylene diisocyanate); alicyclic polyisocyanates (e.g., hydrogenated xylylene diisocyanate or isophorone diisocyanate); aromatic polyisocyanates (e.g., tolylene diisocyanate or 4,4'-diphenylmethane diisocyanate); adducts of any of the foregoing polyisocyanates with a polyhydric alcohol (e.g., a diol, low molecular weight hydroxyl group-containing polyester resin, water, etc.); adducts of the foregoing polyisocyanates (e.g., isocyanurates, biurets); and mixtures thereof.

Useful commercially available polyisocyanates include, for example, those available under the trade designation ADIPRENE from Chemtura Corporation, Middlebury, Connecticut (e.g., ADIPRENE L 0311, ADIPRENE L 100, ADIPRENE L 167, ADIPRENE L 213,

ADIPRENE L 315, ADIPRENE L 680, ADIPRENE LF 1800A, ADIPRENE LF 600D,

ADIPRENE LFP 1950A, ADIPRENE LFP 2950A, ADIPRENE LFP 590D, ADIPRENE LW 520, and ADIPRENE PP 1095); polyisocyanates available under the trade designation

MONDUR from Bayer Corporation, Pittsburgh, Pennsylvania (e.g., MONDUR 1437, MONDUR MP-095, or MONDUR 448); and polyisocyanates available under the trade designations AIRTHANE and VERSATHANE from Air Products and Chemicals, Allentown, Pennsylvania (e.g., AIRTHANE APC-504, AIRTHANE PST-95A, AIRTHANE PST-85A, AIRTHANE PET- 91A, AIRTHANE PET-75D, VERSATHANE STE- 95A, VERSATHANE STE-P95,

VERSATHANE STS-55, VERSATHANE SME- 90A, and VERSATHANE MS-90A).

To lengthen pot-life, polyisocyanates such as, for example, those mentioned above may be blocked with a blocking agent according to various techniques known in the art. Exemplary blocking agents include ketoximes (e.g., 2-butanone oxime); lactams (e.g., epsilon-caprolactam); malonic esters (e.g., dimethyl malonate and diethyl malonate); pyrazoles (e.g., 3,5- dimethylpyrazole); alcohols including tertiary alcohols (e.g., t-butanol or 2,2-dimethylpentanol), phenols (e.g., alkylated phenols), and mixtures of alcohols as described. Exemplary useful commercially-available blocked polyisocyanates include those marketed by Chemtura

Corporation under the trade designations ADIPRENE BL 11, ADIPRENE BL 16, ADIPRENE BL 31, and blocked polyisocyanates marketed by Baxenden Chemicals, Ltd., Accrington,

England under the trade designation TRIXENE (e.g., TRIXENE BL 7641, TRIXENE BL 7642, TRIXENE BL 7772, and TRIXENE BL 7774).

Suitable amine curatives include aromatic, alkyl-aromatic, or alkyl polyfunctional amines, preferably primary amines. Examples of useful amine curatives include 4,4'- methylenedianiline; polymeric methylene dianilines having a functionality of 2.1 to 4.0 which include those known under the trade designations CURITHANE 103, commercially available from the Dow Chemical Company, and MDA-85 from Bayer Corporation, Pittsburgh,

Pennsylvania; l,5-diamine-2-methylpentane; tris(2-aminoethyl) amine; 3-aminomethyl-3,5,5- trimethylcyclohexylamine (i.e., isophoronediamine), trimethylene glycol di-p-aminobenzoate, bis(o-aminophenylthio)ethane, 4,4'-methylenebis(dimethyl anthranilate), bis(4-amino-3- ethylphenyl)methane (e.g., as marketed under the trade designation KAYAHARD AA by

Nippon Kayaku Company, Ltd., Tokyo, Japan), and bis(4-amino-3,5-diethylphenyl)methane

(e.g., as marketed under the trade designation LONZACURE M-DEA by Lonza, Ltd., Basel, Switzerland), and combinations thereof. If desired, polyol(s) may be added to the curable composition, for example, to modify (e.g., to retard) cure rates as required by the intended use.

In some embodiments of the present disclosure, the curable compositions comprise at least about 20 percent by weight of curable resin, in some embodiments at least about 40 percent by weight of curable resin, and in some embodiments at least about 50 percent by weight of curable resin. In some embodiments of the present disclosure, the curable compositions comprise less than about 90 percent by weight of curable resin, in some embodiments less than about 80 percent by weight of curable resin, and in some embodiments less than about 70 percent by weight of curable resin. In some embodiments, the amount of curable resin present in the curable composition ranges of from 10 to 40 percent by weight, preferably from 15 to 30 percent by weight, and more preferably from 20 to 25 percent by weight based on the total weight of the curable composition, although amounts outside of these ranges may also be used. Percent weight is based upon the total weight of the curable composition (i.e., whether it is a one part or two- part composition (Parts A and B combined)).

The curable composition includes microcapsules comprising a polymeric shell

(preferably organic) enclosing at least one of a corrosion inhibitor and a liquid vehicle. The function of the microcapsules is to rupture when mechanical damage to the cured anti-corrosion coating occurs, thereby releasing the corrosion inhibitor at the damage site. In a preferred embodiment, the microcapsules each include both the liquid vehicle and the corrosion inhibitor. In an alternate embodiment, the liquid vehicle and the corrosion inhibitor may be present in different microcapsules that mix together after rupture of the microcapsules.

When the microcapsules are ruptured, the contents of the microcapsules preferably flow readily into coating defects, such as cracks or voids produced by impact or other damaging forces. This may require control of fluid viscosity less than 100 centipoise, preferably between about 10 centipoise and about 50 centipoise.

A wide variety of processes exist by which microcapsules can be manufactured. These varied processes provide different techniques for producing microcapsules, alternative materials for the composition of the microcapsule shell, and various different functional materials within the shell. Some of these various processes are shown in U.S. Pat. Nos. 3,516,846 (Matson); 3,516,941 (Matson); 3,778,383 (Harris); 4,087,376 (Foris et al.); 4,089,802 (Foris et al.); 4, 100,103 (Foris et al.); 4,251,386; 4,493,869 (Sweeney et al.); 4,898,633(Saeki et al.);

4,976,961 (Norbury et al.); 7, 179,480 (Klassen); and British Patent Specification Nos. 1,156,725 (Ciba Limited); 2,041,319 (Kanzaki Paper Mfg. Co. Ltd.); and 2,048,206 (Fuji Photo Film Co. Ltd.). A wide variety of different materials may be used in making the capsule shells, including gelatin and synthetic polymeric materials. A popular materials for shell formation is the polymerization reaction product between urea and formaldehyde or melamine and formaldehyde, or the polycondensation products of monomeric or low molecular weight polymers of dimethylolurea or methylolated urea with aldehydes. A variety of microcapsule forming materials are disclosed, for example, in U.S. Pat. Nos. 3,516,846 (Matson) and 4,087,376 (Foris et al.), and British Patent Specification Nos. 2,006,709 (Mitsubishi Paper Mills Ltd.) and

2,062,570 (Fuji Photo Film Co. Ltd.).

Suitable materials may also include cellulosic materials, copolymers, such as those produced by reaction of isobornyl methacrylate with acrylic acid or methacrylic acid,

condensation polymers including nylon, polyurethane, polyurea, and polycarbonate polymers. A preferred capsule wall material of this type is derived from urea, formaldehyde, and melamine monomers. Use of interfacial polymerization techniques, produces continuous-wall, non-porous microcapsules comprising these monomeric species. As an alternative, a polyurethane shell material, also formed by interfacial polymerization, provides porous microcapsules which tend to gradually lose their fluid fill material. This type of microcapsule assures controlled corrosion protection until the microcapsule fill material is exhausted.

Thermoplastic polymeric materials may be used to generate the microcapsule polymeric shell; for example, as described in U.S. Pat. No. 6,506,494 (Brandys et al.). For example, polysulfone, polyurethanes-urea, poly(ethylene glycol), and aliphatic polyesters have been used as polymeric shells for microcapsules. Likewise, preparation of a poly(methyl methacrylate) polymeric shell (PMMA) microcapsules using technology adaptable to practice of the present disclosure has been accomplished using a solvent evaporation technique as described by Teeka et al. in "Preparation of Poly (methyl methacrylate) Microcapsule with Encapsulated Jasmine Oil" in Energy Procedia, 2014 , 56, pp. 181 - 186, and by in situ polymerization as described by Pan et al. in Structure and Mechanical Properties of Consumer-Friendly PMMA Microcapsules in Industrial and Engineering Chemistry Research, 2013, 52, pp. 11253-11265. Preferred materials for the polymeric shell also include copolymers of methyl methacrylate and

methacrylic acid.

Materials for forming the capsule walls preferably comprise substances maintaining structural integrity to temperatures of at least 160 °C, although this is not a requirement. Corrosion inhibitors suitable for encapsulation, either alone or in combination with film forming components and/or marker dyes, include water insoluble amines such as VERSAMINE

551 available from Henkel Inc. of Kankakee, Illinois; benzimidazole and substituted

benzimidazoles including 1-methylbenzimidazole, 1 -phenyl benzimidazole and 2- phenylbenzimidazole; substituted thiophosphates exemplified by diethylthiophosphate and dioctylthiophosphate; thiourea and substituted structures thereof, represented by allylthiourea, phenylthiourea, and 1,3-diphenylthiourea; benzothiazole, benzotriazole, and alkyl, aryl, aralkyl and other substituted versions thereof.

Some preferred corrosion inhibitors include solutions of metal sulfonate salts available as barium-containing NACORR 1151 and zinc-containing NACORR 1551 and NACORR 1552 from King Industries of Norwalk, Conn., and LUBRIZOL 219 phosphate zinc complex available from Lubrizol Inc. of Wickliffe, Ohio.

If desired, the fill material may also include a marker dye. Marker dyes for use in the disclosure are preferably soluble in phthalate esters and include hydrophobic dyes such as SUDAN YELLOW 146 or SUDAN BLUE, which are anthraquinone type dyes made by BASF of Mount Olive, New Jersey.

Suitable liquid vehicles include virtually any liquid material, preferably that is liquid at or near room temperature. Preferably, the liquid vehicle has a normal boiling point of at least 120 °C, more preferably at least 130 °C, more preferably at least 140 °C, and even more preferably at least 150 °C; however, this is not a requirement. Examples of suitable liquid vehicles may include mineral spirits, mineral oils, butyl cellosolve, phthalate esters, vegetable oils (e.g., tung oil, linseed oil, soybean oil), dipentene, amyl acetate, benzothiazole, silicone oils (e.g., D-5 SILICONE OIL available from General Electric Co., Schenectady, New York), xylene, and other hydrophobic liquids boiling at about 150 °C or higher and capable of surviving at about a pH of 2.0.

Curable compositions according to the present disclosure can be made by simple mixing of the components by any suitable technique, or in the case of a two part system it may be supplied in a form that requires mixing by the user.

Preferably, curable compositions according to the present disclosure are essentially free of volatile organic solvents (e.g., solvents falling within the definition of volatile organic compounds defined in the U.S. Code of Federal Regulations, 40: Chapter 1, Subchapter C, Part 51, Subpart F, 51.100 as of the filing date of the present application). Preferably, the curable compositions are essentially free of solvents having a normal boiling point of 100 °C or less, more preferably 150 °C or less, and more preferable 200 °C or less. In some preferred embodiments, the curable composition is essentially free of, or even free of, added solvent (i.e., solvent that is intentionally added during formulation of the curable composition as opposed to adventitious solvent that is present as a contaminant in a raw material used to make it. In some preferred embodiments, the curable composition is essentially free of water, preferably free of all but adventitious water.

To facilitate handling, the curable composition is preferably liquid at 20 °C and one atmosphere of pressure; however, it may be effectively used even if a solid as long as it can be melted at a temperature lower than its application temperature to the substrate.

Optionally, but preferably the curable composition further comprises a filler. Exemplary fillers include sodium potassium aluminum silicate, talc, titanium dioxide, magnesium oxide, calcium oxide, silica, clay, organic polymer particulate fillers, glass beads, ceramic

microspheres, and hollow glass microspheres. Filler may be present in an amount up to about 60 percent by weight, preferably 30 to 60 percent by weight, based on the total weight of the curable composition, although this is not a requirement.

Curable and/or cured compositions according to the present disclosure may include other additives or adjuvants which may change the characteristics of coating formulations without detracting from their latent repair and corrosion inhibiting performance.

Curable compositions according to the present disclosure can be applied to the metal surface of the substrate to form a corrosion-resistant protective layer; for example, as shown in FIG. 1. Referring now to FIG. 1, article 100 comprises corrosion-resistant protective layer 110 disposed on metal surface 120 of substrate 130. Corrosion-resistant protective layer 110 comprises cured resin 140 and microcapsules 150.

Curable compositions can be applied to the metal surface of the substrate and then cured to provide a corrosion-resistant protective layer on the metal surface that enhance corrosion protection. The curable composition may be applied to the substrate by any suitable method such as, for example, spray coating, brush coating, and dip coating.

Exemplary substrates have a metal surface, which may be an exterior and/or interior surface, even though the substrate itself may or may not consist of many components, some of which may not be metal and which may form a portion of the surface of the substrate. In some embodiments, the substrate is metallic. Exemplary metals for use in the substrate include ferrous metals (e.g., iron and steel) and other oxidizable metals (e.g., copper, silver, aluminum, and tin). The substrate may be in sheet, roll, or wire form, or it may be fabricated into a complex shape such as a vehicle body part, pipe, reinforcing rod, or cabinet part, for example. One preferred use of curable compositions according to the present disclosure is that of a patch that can be applied in the field to repair damaged corrosion resistant coatings and/or as a protective coating over freshly exposed metal; for example, as in the case of a reinforcing rod with a corrosion resistant coating that is cut to length during construction of a road or building, thereby creating a fresh metallic surface at the cut site.

SELECT EMBODIMENTS OF THE PRESENT DISCLOSURE

In a first embodiment, the present disclosure provides a curable composition comprising: a curable resin; and

microcapsules comprising a polymeric shell enclosing a fill material including at least one of a corrosion inhibitor and a liquid vehicle, wherein the curable composition is liquid, and wherein the curable composition is essentially free of organic solvent other than the liquid vehicle.

In a second embodiment, the present disclosure provides a curable composition according to the first embodiment, wherein the curable resin comprises an epoxy resin.

In a third embodiment, the present disclosure provides a curable composition according to the first embodiment, wherein the curable resin comprises a polyurethane resin.

In a fourth embodiment, the present disclosure provides a curable composition according to any one of the first to third embodiments, wherein the polymeric shell comprises an acrylic polymer.

In a fifth embodiment, the present disclosure provides a curable composition according to any one of the first to fourth embodiments, wherein the liquid vehicle comprises a a corrosion inhibiting oil.

In a sixth embodiment, the present disclosure provides a method of protecting a metal surface comprising, applying a curable composition to the metal surface and curing the curable composition, wherein the curable composition comprises:

a curable resin; and

microcapsules comprising a polymeric shell enclosing a fill material including at least one of a corrosion inhibitor and a liquid vehicle, wherein the curable composition is liquid, and wherein the curable composition is essentially free of organic solvent other than the liquid vehicle.

In a seventh embodiment, the present disclosure provides a method according to the sixth embodiment, wherein the curable resin comprises an epoxy resin.

In an eighth embodiment, the present disclosure provides a method according to the sixth embodiment, wherein the curable resin comprises a polyurethane resin. In a ninth embodiment, the present disclosure provides a method according to any one of the sixth to eighth embodiments, wherein the polymeric shell comprises an acrylic polymer.

In a tenth embodiment, the present disclosure provides a method according to any one of the sixth to ninth embodiments, wherein the liquid vehicle comprises a corrosion inhibiting oil.

In an eleventh embodiment, the present disclosure provides an article comprising:

a substrate having a metal surface; and

a corrosion-resistant protective layer disposed on at least a portion of the metal surface, wherein the corrosion-resistant protective layer comprises a cured reaction product of a curable composition comprising:

a curable resin; and

microcapsules comprising a polymeric shell enclosing a fill material including at least one of a corrosion inhibitor and a liquid vehicle, wherein the curable composition is liquid, and wherein the curable composition is essentially free of organic solvent other than the liquid vehicle.

In a twelfth embodiment, the present disclosure provides an article according to the eleventh embodiment, wherein the curable resin comprises an epoxy resin.

In a thirteenth embodiment, the present disclosure provides an article according to the eleventh embodiment, wherein the curable resin comprises a polyurethane resin.

In a fourteenth embodiment, the present disclosure provides an article according to any one of the eleventh to thirteenth embodiments, wherein the polymeric shell comprises an acrylic polymer.

In a fifteenth embodiment, the present disclosure provides an article according to any one of the eleventh to fourteenth embodiments, wherein the liquid vehicle comprises an oil.

Objects and advantages of this disclosure are further illustrated by the following non- limiting examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this disclosure.

EXAMPLES

Unless otherwise noted, all parts, percentages, ratios, etc. in the Examples and the rest of the specification are by weight. The abbreviation "wt.%" means weight percent. The abbreviation "in-lb ' means inch-pound force, which is a unit of energy.

Table 1, below, lists materials used in the Examples. TABLE 1

DESIGNATION DESCRIPTION

L219 an organic phosphate zinc complex corrosion inhibitor available as

LUBRIZOL 219 PHOSPHATE ZINC COMPLEX from The Lubrizol Corporation, Wickliffe, Ohio

PMMA-co- Poly(methyl methacrylate-co-methacrylic acid) from Sigma Aldrich, MAA St. Louis, Missouri, having a weight average molecular weight of

34,000 g/mol and number average molecular weight of 15,000 g/mol, weight ratio of methyl methacrylate/methacrylic acid = 1/0.016

XAF 20 wt.% active, food-grade, silicone emulsion available as

XIAMETER AFE-1520 antifoam emulsion from Dow Corning, Midland, Michigan

SURF! branched secondary alcohol ethoxylate available as TERGITOL

TMN-100X (90 wt.%) Surfactant from the Dow Chemical, Midland, Michigan.

SK328 two-part epoxy resin available as 3M SCOTCHKOTE 328

ABRASIVE RESISTANT EPOXY COATING from 3M Company, St. Paul, Minnesota

C2043 linear polyester diol derived from caprolactone monomer and

terminated by primary hydroxyl groups, weight average molecular weight of 400 grams/mole, available as CAPA 2043 from Perstorp Holding AB, Malmo, Sweden

C3031 trifunctional caprolactone polyol terminated by primary hydroxyl groups with a weight average molecular weight of 300 grams/mole available as CAPA 3031 from Perstorp Holding AB

DBTDL dibutyltin dilaurate from Sigma Aldrich, St. Louis, Missouri

DESW dicyclohexylmethane diisocyanate available as DESMODUR W

POLYISOCYANATE from Bayer Material Science AG,

Brunsbuettel, Germany

TLV solvent-free low viscosity aliphatic polyisocyanate, TOLONATE

HDT-LV ALIPHATIC ISOCYANATE from Vencorex US, Inc., Freeport, Texas Particle Size Measurements

Microcapsule size and distribution was analyzed using a Horiba LA-950 Laser Scattering Particle Size Distribution Analyzer from Horiba, Kyoto, Japan according to the manufacturer's directions. Samples were analyzed in triplicate. Thermal gravimetric analysis (TGA) experiments were performed on a TGA2950 thermogravimetric analyzer with a heating rate of 10 °C/min under nitrogen atmosphere. Scanning electron microscopy (SEM) was performed using an XL30 ESEM FEG scanning electron miocroscope from FEI Co., Hillsboro, Oregon.

PREPARATIVE EXAMPLE 1 (PE1)

PE1 describes the synthesis of L219-containing PMMA-co-MAA microcapsules.

A glass jar was charged with 200 g of acetone and 20 g of PMMA-co-MAA . The mixture was heated (ca. 60 °C) in order to effect dissolution of the polymer. After 30 minutes, the polymer was completely dissolved; and the solution was then allowed to cool down to room temperature. L219 (80 g) was then added, and the mixture was stirred to yield a homogeneous solution. A 5-gallon pail was charged with 9 L of distilled water and agitated at 150 rpm with a Labmaster stirrer equipped with a 2-inch (5-cm) turbine blade.

In order to reduce agglomeration of microcapsules, 4.5 g of SURFl and 0.45g of XAF were also added to the water phase. The acetone solution was then sprayed through a 3M

ACCUSPRAY SPRAY GUN MODEL HG09 (3M Company) spray gun (20 psi) into the water. Immediately, a white precipitate began to form. Once all of the solution had been sprayed, the mixture was allowed to stir for another 30 minutes. The microcapsules were then collected by filtration (Buchner), washed with a small amount of water and allowed to air dry overnight (ca. 14 h), whereby 75 grams of discreet non-agglomerated microcapsules were recovered.

The size and size distribution of the microcapsules was characterized by laser diffraction (LA-950 laser particle size analyzer, Horiba). A typical mean size of the microcapsules was 50 ± 10 micrometers in diameter. The core-shell structure of the microcapsules was confirmed by analysis of crushed microcapsules, wherein the PMMA-co-MAA shell showed a thickness of 3 micrometers. Weight fractions of L219 and PMMA-co-MAA shell were measured by thermal gravimetric analysis (TGA). TGA results indicated that the capsules had an uptake of 75 wt.% of L219.

EXAMPLES 1-2 AND COMPARATIVE EXAMPLE A Microcapsules from PE1 were added to SK328 at various concentrations (as indicated in Table 2) and mixed with a DAC 150 SPEEDMIXER dual asymmetric centrifuge from FlackTek Corp., Landrum, South Carolina (2000 rpm) resulting in a curable epoxy composite resin.

Comparative samples with no microcapsules were carried out for comparison.

To evaluate corrosion resistance properties, an accelerated corrosion test was performed.

CECR1 was coated on cold-rolled steel bars (1/8 inch (0.32 cm) x 1 inch (2.5 cm) x 8 inches

(20.3 cm) at a thickness of 20 mils (508 micrometers)) on both sides with the edges touched up with a paintbrush. Coatings were allowed to stand at room temperature for 7 days. The resulting coated steel bars were bent on the edge of a lab bench to an angle of 90°, which introduced a degree of damage to the coatings. The corrosion test was done by salt spray exposure. Bent bars were added to an aqueous 5 wt.% sodium chloride solution, supplied with an air-sparging system, at 40°C for 4 days. After 4 days, samples were removed and the degree of rust was evaluated. Results are presented in Table 2, below, wherein corrosion was evaluated by visual inspection, and was rated as follows: 1 = no corrosion evident, 2 = mild corrosion evident, 3 = moderate corrosion evident, 4 = heavy corrosion evident, 5= severe corrosion evident.

TABLE 2

EXAMPLES 3-6 and COMPARATIVE EXAMPLE B

To evaluate impact and corrosion resistance, CECR1 was coated on grit blasted steel plates (4 inches x 4 inches, (10 cm x 10 cm)), at a thickness of 0.8 mm, on one side with the other side and edges touched up with a paintbrush. Coatings were allowed to stand at room temperature for 7 days. The resulting coated steel plates were impacted at variety of impact energies (70 in-lbf, 80 in-lbf, 90 in-lbf, 100 in-lbf (7.9 J, 9.0 J, 10.1 J, 11.3 J)) with a drop weight tester (model 9310) from Instron Corp., Norwood, Massachusetts. The accelerated corrosion test (above) was repeated on these samples.

The degree of corrosion was rated from 1 (mildest corrosion) to 5 (severest corrosion). The results was summarized at Table 3. As seen from Table 3, COMPARATIVE EXAMPLE B was badly corroded, while in the case of coatings with 7.0-9.1 wt.%> of microcapsules, less corrosion was evident. In Table 3, below, corrosion was evaluated by visual inspection, and was rated as follows: 1 = no corrosion evident, 2 = mild corrosion evident, 3 = moderate corrosion evident, 4 = heavy corrosion evident, 5= severe corrosion evident.

TABLE 3

COMPARATIVE EXAMPLE C

In order to test whether the microencapsulation was necessary, a comparative

experiments were done by adding 6.8 wt.% of L219 (equivalent to the L219 content in microcapsules at a 9.1 wt.% loading) into the SK328 resin (CERl). When the CERl was applied the steel surface, it did not wet out into a cohesive coating , and after standing as above, the resultant coating was not cured and wrinkled.

COMPARATIVE EXAMPLE D

Comparative Example C was repeated, except using CECR1 with 9.1 wt.% of the microcapsules, the coating was essentially the same in cure quality as compared to SK328 that was applied and cured in the same manner. EXAMPLE 7 and COMPARATIVE EXAMPLE E

Microcapsules from PE1 were added to a mixed two-part urethane coating according to the following formulation: 20 g of PE1 microcapsules, 100 g of Part A (50 g of DESW and 50 g of TLV), 100 g of Part B (70 g of C2043, 30 g of C3031, and 0.02 g of DBTDL) (EXAMPLE 7).

A control sample with no microcapsules was carried out for comparison

(COMPARATIVE EXAMPLE E).

The samples were evaluated by the impact and accelerated corrosion test as in

EXAMPLE 3, except using higher impact energies (120 in-lbf, 140 in-lbf, 160 in-lbf (13.6 J, 15.8 N, 18.1 J). Results was summarized in Table 4, below, wherein corrosion was evaluated by visual inspection, and was rated as follows: 1 = no corrosion evident, 2 = mild corrosion evident, 3 = moderate corrosion evident, 4 = heavy corrosion evident, 5= severe corrosion evident.

TABLE 3

All cited references, patents, and patent applications in the above application for letters patent are herein incorporated by reference in their entirety in a consistent manner. In the event of inconsistencies or contradictions between portions of the incorporated references and this application, the information in the preceding description shall control. The preceding

description, given in order to enable one of ordinary skill in the art to practice the claimed disclosure, is not to be construed as limiting the scope of the disclosure, which is defined by the claims and all equivalents thereto.

Claims

What is claimed is:

1. A curable composition comprising:

a curable resin; and

microcapsules comprising a polymeric shell enclosing a fill material including at least one of a corrosion inhibitor and a liquid vehicle, wherein the curable composition is liquid, and wherein the curable composition is essentially free of organic solvent other than the liquid vehicle.

2. The curable composition of claim 1, wherein the curable resin comprises an epoxy resin.

3. The curable composition of claim 1, wherein the curable resin comprises a polyurethane resin.

4. The curable composition of any one of claims 1 to 3, wherein the polymeric shell comprises an acrylic polymer.

5. The curable composition of any one of claims 1 to 4, wherein the liquid vehicle comprises a corrosion inhibiting oil.

6. A method of protecting a metal surface comprising, applying a curable composition to the metal surface and curing the curable composition, wherein the curable composition comprises:

a curable resin; and

microcapsules comprising a polymeric shell enclosing a fill material including at least one of a corrosion inhibitor and a liquid vehicle, wherein the curable composition is liquid, and wherein the curable composition is essentially free of organic solvent other than the liquid vehicle.

7. The method of claim 6, wherein the curable resin comprises an epoxy resin.

8. The method of claim 6 or 7, wherein the curable resin comprises a polyurethane resin.

9. The method of any one of claims 6 to 8, wherein the polymeric shell comprises an acrylic polymer.

10. The method of any one of claims 6 to 9, wherein the liquid vehicle comprises a corrosion inhibiting oil.

11. An article comprising:

a substrate having a metal surface; and

a corrosion-resistant protective layer disposed on at least a portion of the metal surface, wherein the corrosion-resistant protective layer comprises a cured reaction product of a curable composition comprising:

a curable resin; and

microcapsules comprising a polymeric shell enclosing a fill material including at least one of a corrosion inhibitor and a liquid vehicle, wherein the curable composition is liquid, and wherein the curable composition is essentially free of organic solvent other than the liquid vehicle.

12. The article of claim 11, wherein the curable resin comprises an epoxy resin.

13. The article of claim 11, wherein the curable resin comprises a polyurethane resin.

14. The article of any one of claims 11 to 13, wherein the polymeric shell comprises an acrylic polymer.

15. The article of any one of claims 11 to 14, wherein the liquid vehicle comprises an oil.