Latent coating for metal surface repair

• US 6,075,072 A
• Filed: 03/13/1998
• Issued: 06/13/2000
• Est. Priority Date: 03/13/1998
• Status: Expired due to Term

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Boyer, Charles E. III, Guilbert, Curtis R., Enos, David G.
• Primary Examiner(s): NILAND, PATRICK DENNIS
• Application Number:
  US09/042,263
• Time in Patent Office: 823 Days
• Field of Search: 523/200, 523/202, 523/205, 524/86, 524/91, 524/137, 524/211, 428/402.21, 427/213
• US Class Current: 523/200
• CPC Class Codes: B29C 73/163 Sealing compositions or agents, e.g. combined with propellant agents
• CPC Class Codes: B29C 73/22 the article containing elements including a sealing composition, e.g. powder being liberated when the article is damaged
• CPC Class Codes: C08K 5/3462 Six-membered rings
• CPC Class Codes: C08K 5/5398 Phosphorus bound to sulfur
• CPC Class Codes: C08K 9/10 Encapsulated ingredients
• CPC Class Codes: C08L 2207/53 Core-shell polymer
• CPC Class Codes: C09D 5/08 Anti-corrosive paints
• CPC Class Codes: C09D 7/00 Features of coating compositions, not provided for in group C09D5/00 driers C09F9/00; Processes for incorporating ingredients in coating compositions
• CPC Class Codes: C09D 7/48 Stabilisers against degradation by oxygen, light or heat
• CPC Class Codes: C09D 7/70 characterised by shape, e.g. fibres, flakes or microspheres
• CPC Class Codes: Y10T 428/2985 Solid-walled microcapsule from synthetic polymer

Abstract

A corrosion protective coating composition, applied over a metal surface, 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.

Claims

1. A corrosion protective coating composition, comprising:

a) a film forming binder, and

b) a plurality of microcapsules, mixed with said binder, said microcapsules containing a latent repair fluid comprising a film forming component and a corrosion inhibitor.

2. The corrosion protective coating composition of claim 1 wherein said film forming binder is in powdered form.

3. The corrosion protective coating composition of claim 1 further comprising a marker dye contained in said latent repair fluid.

4. The corrosion protective coating composition of claim 1 wherein said corrosion inhibitor is selected form the group consisting of benzimidazole, 1-methylbenzimidazole, 1-phenylbenzimidazole, 2-phenylbenzimidazole, diethylthiophosphate, dioctylthiophosphate, thiourea, allylthiourea, phenylthiourea, 1,3-diphenylthiourea, benzotriazole, benzothiazole metal phosphates, and organophosphates metal phosphonates, metal sulfates and metal sulfonates and mixtures thereof.

5. The corrosion protective coating composition of claim 1 wherein said film forming binder is selected from the group consisting of epoxy resins, polyester resins, polyurethane resins, polyvinylfluorodiene resins, alkyd resins, acrylic resins and nylon.

6. The corrosion protective coating composition of claim 1 wherein said plurality of microcapsules includes shell walls comprising a frangible material having structural integrity at temperatures of least about 160°

C.

7. The corrosion protective coating composition of claim 6 wherein said frangible material is selected from the group consisting of cellulosic materials, copolymers of isobornyl methacrylate with (meth) acrylic acid, nylon, polyurethane, polyurea, polycarbonate, and polymers formed from urea, formaldehyde and melamine monomers.

8. The corrosion protective coating composition of claim 1 wherein said microcapsules have a diameter of less than about 75 μ

m.

9. The corrosion protective coating composition of claim 8 wherein said microcapsules have a diameter of from about 10 μ

m to about 40 μ

m.

10. A corrosion protective coating composition, comprising:

(a) a film forming binder;

(b) a first plurality of microcapsules containing a corrosion inhibitor, and

(c) a second plurality of microcapsules containing a film forming component, said first and said second plurality of microcapsules being substantially uniformly distributed throughout said binder.

11. The corrosion protective coating composition of claim 10 further comprising a plurality of microcapsules containing a marker dye.

12. The corrosion protective coating composition of claim 10 wherein said corrosion inhibitor is selected form the group consisting of benzimidazole, 1-methylbenzimidazole, 1-phenylbenzimidazole, 2-phenylbenzimidazole, diethylthiophosphate, dioctylthiophosphate, thiourea, allylthiourea, phenylthiourea, 1,3-diphenylthiourea, benzotriazole, benzothiazole metal phosphates, and organophosphates metal phosphonates, metal sulfates and metal sulfonates and mixtures thereof.

13. The corrosion protective coating composition of claim 10 wherein said film forming binder is selected from the group consisting of epoxy resins, polyester resins, polyurethane resins, polyvinylfluorodiene resins, alkyd resins, acrylic resins and nylon.

14. The corrosion protective coating of claim 10 wherein said plurality of microcapsules includes shell walls comprising a frangible material having structural integrity at temperatures of at least about 160°

C.

15. The corrosion protective coating composition of claim 14 wherein said frangible material is selected from the group consisting of cellulosic materials, copolymers of isobornyl methacrylate with (meth) acrylic acid, nylon, polyurethane, polyurea, polycarbonate, and polymers formed from urea, formaldehyde and melamine monomers.

16. The corrosion protective coating composition of claim 10 wherein said microcapsules have a diameter of less than about 75 micrometers.

17. A corrosion protective layer, comprising:

(a) a continuous resin phase, and

(b) a plurality of frangible microcapsules, substantially uniformly dispersed in said resin phase, said microcapsules containing a fluid composition to effect repair of said layer when damaged.

18. The corrosion protective layer of claim 17 wherein said fluid composition comprises a corrosion inhibitor and a film forming component.

19. A method for forming the corrosion protective layer of claim 17, comprising the steps of:

(a) providing a fluid bed comprising a coating powder having an encapsulated corrosion inhibitor;

(b) heating a substrate to a temperature above the melting point of said coating powder;

(c) submerging at least a portion of said substrate in said coating powder form a corrosion protective layer over said substrate; and

(d) withdrawing said substrate from said fluid bed.