# US 10,246,593 B2 · Sol-gel coating compositions including corrosion inhibitor-encapsulated layered double hydroxide and related processes

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- Number: US 10,246,593 B2
- Document ID: US10246593B2
- Status: Granted
- Kind: B2
- Application number: 15/231,654
- Filed: 2016-08-08
- Published: 2018-01-25
- Granted: 2019-04-02
- Earliest claimed: 2016-07-20
- Assignees: The Boeing Company
- Applicants: The Boeing Company
- Inventors: Vijaykumar S. Ijeri; Om Prakash; Stephen P. Gaydos; Raghavan Subasri; Kalidindi Ramachandra Soma Raju; Dendi Sreenivas Reddy
- Web page: https://patentgrep.com/patent/US10246593B2

## CPC

- C09D 5/086: {Organic or non-macromolecular compounds}
- B05D 1/02: performed by spraying
- B05D 1/18: performed by dipping
- B05D 3/067: {Curing or cross-linking the coating}
- B05D 5/00: Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures
- B05D 7/14: to metal, e.g. car bodies (involving a chemical reaction between the metal and the coating C23)
- C09D 5/00: Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced {(electrically insulating plastics, resins or waxes H01B3/30)}; Filling pastes
- C09D 5/084: {Inorganic compounds}
- C23C 26/00: Coating not provided for in groups C23C2/00 - C23C24/00
- C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D)
- B05D: PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL (conveying articles or workpieces through baths of liquid B65G, e.g. B65G49/02)
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)

## Abstract

A Zn—Al layered double hydroxide (LDH) composition is added to a solution including a corrosion inhibitor and stirred, and a precipitate of the solution is collected, washed, and dried to form a corrosion inhibiting material (CIM), in which the LDH composition is intercalated with the corrosion inhibitor. An inorganic CIM and/or an organic CIM may be formed. The organic CIM may be added to a sol-gel composition to form an organic CIM-containing sol-gel composition, and the inorganic CIM may be added to a sol-gel composition to form an inorganic CIM-containing sol-gel composition. Further, the organic CIM-containing sol-gel composition may be applied on a substrate (e.g., an aluminum alloy substrate) to form an organic CIM-containing sol-gel layer and cured by ultraviolet (UV) radiation, the inorganic CIM-containing sol-gel composition may be applied on the substrate to form an inorganic CIM-containing sol-gel layer and cured by UV radiation, and the sol-gel layers may be thermally cured.

## Claims

### Claim 1

A method comprising:
adding a Zn—Al layered double hydroxide (LDH) composition to a first solution comprising a first corrosion inhibiting compound and stirring;
collecting a precipitate of the first solution; and
washing and drying the precipitate of the first solution to form a first corrosion inhibiting material (CIM), the first CIM comprising the first corrosion inhibiting compound intercalated in the Zn—Al LDH composition.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
mixing a zinc nitrate solution and an aluminum nitrate solution and stirring under nitrogen purging to form a mixture;
adding a sodium nitrate solution to the mixture while maintaining a pH ranging from about 8 to about 12 and stirring under nitrogen purging;
collecting a precipitate of the mixture; and
washing and drying the precipitate of the mixture to form the Zn—Al LDH composition.

### Claim 3 (depends on 1)

The method of claim 1, further comprising:
adding the first CIM to a sol-gel composition to form a CIM-containing sol-gel composition.

### Claim 4 (depends on 3)

The method of claim 3, further comprising:
contacting a first alkoxysilane with water and an inorganic acid to form a first composition;
contacting a zirconium alkoxide with a first organic acid to form a second composition;
contacting the first composition with the second composition to form a mixture;
contacting one or more second alkoxysilanes and a second organic acid with the mixture to form the sol-gel composition, the sol-gel composition having a ratio of a number of moles of silicon to a number of moles of zirconium (nSi/nZr) ranging from about 2 to about 10;
adding a photoinitiator to the sol-gel composition; and
diluting the sol-gel composition with a solvent.

### Claim 5 (depends on 4)

The method of claim 4, wherein the contacting to form the first composition comprises mixing the first alkoxysilane having the formula RA—Si—(RB)3 with the water and the inorganic acid, wherein the RA is methacryloxyalkyl or glycidyloxyalkyl, and wherein the RB is a methoxy or ethoxy.

### Claim 6 (depends on 4)

The method of claim 4, wherein the contacting to form the second composition comprises mixing a zirconium alkoxide having the formula Zr—(RC)4 with methacrylic acid (MAA), and wherein the RC is ethoxy, n-propoxy, isopropoxy, n-butyloxy, or tert-butyloxy.

### Claim 7 (depends on 4)

The method of claim 4, wherein the contacting to form the sol-gel composition comprises:
adding one or more second alkoxysilanes each having the formula RD—Si—(RE)3 to the mixture, wherein the RD is aryl, aminoalkyl, or glycidoxyalkyl, and wherein the RE is methoxy or ethoxy; and
adding MAA and stirring.

### Claim 8 (depends on 3)

The method of claim 3, wherein the adding the CIM comprises adding the CIM in an amount ranging from about 1 to about 10 parts by weight per 100 parts by weight of the sol-gel composition or ranging from about 1 to about 10 parts by weight per 100 parts by weight of a solid content of the sol-gel composition.

### Claim 9 (depends on 3)

The CIM-containing sol-gel composition formed by the method of claim 3.

### Claim 10 (depends on 1)

The method of claim 1, further comprising:
adding the first CIM to a first sol-gel composition to form an organic CIM-containing sol-gel composition, wherein the first corrosion inhibiting compound is an organic corrosion inhibiting compound, and wherein the first CIM is an organic CIM;
adding the Zn—Al LDH composition to a second solution comprising an inorganic corrosion inhibiting compound and stirring;
collecting a precipitate of the second solution;
washing and drying the precipitate of the second solution to form an inorganic CIM, the inorganic CIM comprising the inorganic corrosion inhibiting compound intercalated in the Zn—Al LDH composition; and
adding the inorganic CIM to a second sol-gel composition to form an inorganic CIM-containing sol-gel composition.

### Claim 11 (depends on 10)

The method of claim 10, further comprising:
dispersing the organic corrosion inhibiting compound comprising 1-(3-aminopropyl)imidazole, 1H-1,2,3-triazole, 4-methyl-4H-1,2,4-triazole-3-thiol, 1,2,4-triazole-3-carboxylic acid, 3-amino-1,2,4-triazole-5-thiol, 4H-1,2,4-triazol-4-amine, 3-mercapto-4-methyl-4H-1,2,4-triazole, 5-phenyl-1H-1,2,4-triazole-3-thiol, 1-methyl-1H-tetrazole-5-thiol, 1H-tetrazole-5-acetic acid, 4-methyl-1,3-thiazole-5-carboxylic acid, 1,3,4-thiadiazole-2,5-dithiol, 1H-benzimidazole-2-carboxylic acid, 1H-benzotriazole (BTA), 2-mercaptobenzothiazole (MBT), 8-hydroxyquinoline, phytic acid, an organophosphonic acid, a vegetable oil, or a combination thereof in a solvent to form the first solution.

### Claim 12 (depends on 10)

The method of claim 10, further comprising:
dissolving the inorganic corrosion inhibiting compound comprising a vanadate, a molybdate, a tungstate, a phosphate, a manganate, a permanganate, an aluminate, or a combination thereof in a solvent to form the second solution.

### Claim 13 (depends on 10)

The method of claim 10, further comprising:
applying the organic CIM-containing sol-gel composition on a substrate to form an organic CIM-containing sol-gel layer, wherein the substrate is selected from the group comprising 2024 aluminum alloy, 6061 aluminum alloy, and 7075 aluminum alloy;
curing the organic CIM-containing sol-gel layer by UV radiation;
applying the inorganic CIM-containing sol-gel composition on the substrate to form an inorganic CIM-containing sol-gel layer;
curing the inorganic CIM-containing sol-gel layer by the UV radiation; and
thermally curing a plurality of sol-gel layers comprising the organic CIM-containing sol-gel layer and the inorganic CIM-containing sol-gel layer to form a corrosion-resistant coating.

### Claim 14 (depends on 13)

The method of claim 13, wherein:
the curing the organic CIM-containing sol-gel layer and the inorganic CIM-containing sol-gel layer by the UV radiation comprises exposing a respective one of the sol-gel layers to the UV radiation having a light dose ranging from about 500 to about 1000 mJ/cm2 for a time period ranging from about 0.5 to 30 min; and
the thermally curing the plurality of sol-gel layers comprise exposing the plurality of sol-gel layers to infrared (IR) radiation, near IR radiation, microwave radiation, hot air having a temperature ranging from about 70 to about 90° C., or a combination thereof.

### Claim 15 (depends on 13)

The method of claim 13, further comprising applying primer and/or paint on the plurality of sol-gel layers on the substrate, the plurality of sol-gel layers facilitating adherence of the primer or the paint to the substrate.

### Claim 16 (depends on 13)

The corrosion-resistant coating formed by the method of claim 13.

### Claim 17

A corrosion-inhibiting material, comprising:
a Zn—Al layered double hydroxide (LDH) composition comprising nanocarriers of Zn—Al LDH; and
a corrosion inhibiting compound intercalated in the nanocarriers of Zn—Al LDH.

### Claim 18 (depends on 17)

The corrosion-inhibiting material of claim 17, wherein:
the corrosion inhibiting compound comprises an organic corrosion inhibiting compound, an inorganic corrosion inhibiting compound, or both;
the organic corrosion inhibiting compound comprises 1-(3-aminopropyl)imidazole, 1H-1,2,3-triazole, 4-methyl-4H-1,2,4-triazole-3-thiol, 1,2,4-triazole-3-carboxylic acid, 3-amino-1,2,4-triazole-5-thiol, 4H-1,2,4-triazol-4-amine, 3-mercapto-4-methyl-4H-1,2,4-triazole, 5-phenyl-1H-1,2,4-triazole-3-thiol, 1-methyl-1H-tetrazole-5-thiol, 1H-tetrazole-5-acetic acid, 4-methyl-1,3-thiazole-5-carboxylic acid, 1,3,4-thiadiazole-2,5-dithiol, 1H-benzimidazole-2-carboxylic acid, 1H-benzotriazole (BTA), 2-mercaptobenzothiazole (MBT), 8-hydroxyquinoline, phytic acid, an organophosphonic acid, a vegetable oil, or a combination thereof; and
the inorganic corrosion inhibiting compound comprises a vanadate, a molybdate, a tungstate, a phosphate, a manganate, a permanganate, an aluminate, or a combination thereof.

### Claim 19

A corrosion-resistant coated product comprising:
at least one organic corrosion inhibiting material (CIM)-containing sol-gel layer comprising an organic CIM and a polymer composite of one or more alkoxysilanes, a zirconium alkoxide, and an organic acid, the organic CIM comprising a Zn—Al layered double hydroxide (LDH) composition encapsulating an organic corrosion inhibiting compound; and
at least one inorganic CIM-containing sol-gel layer comprising an inorganic CIM and the polymer composite of the one or more alkoxysilanes, the zirconium alkoxide, and the organic acid, the inorganic CIM comprising the Zn—Al LDH composition encapsulating an inorganic corrosion inhibiting compound.

### Claim 20 (depends on 19)

The corrosion-resistant coated product of claim 19, wherein:
the one or more alkoxysilanes comprise a methacryloxyalkyl alkoxysilane, an aryl alkoxysilane, an aminoalkyl alkoxysilane, and a glycidoxyalkyl alkoxysilane;
the organic corrosion inhibiting compound comprises 1-(3-aminopropyl)imidazole, 1H-1,2,3-triazole, 4-methyl-4H-1,2,4-triazole-3-thiol, 1,2,4-triazole-3-carboxylic acid, 3-amino-1,2,4-triazole-5-thiol, 4H-1,2,4-triazol-4-amine, 3-mercapto-4-methyl-4H-1,2,4-triazole, 5-phenyl-1H-1,2,4-triazole-3-thiol, 1-methyl-1H-tetrazole-5-thiol, 1H-tetrazole-5-acetic acid, 4-methyl-1,3-thiazole-5-carboxylic acid, 1,3,4-thiadiazole-2,5-dithiol, 1H-benzimidazole-2-carboxylic acid, 1H-benzotriazole (BTA), 2-mercaptobenzothiazole (MBT), 8-hydroxyquinoline, phytic acid, an organophosphonic acid, a vegetable oil, or a combination thereof; and
the inorganic corrosion inhibiting compound comprises a vanadate, a molybdate, a tungstate, a phosphate, a manganate, a permanganate, an aluminate, or a combination thereof.