Self-healing coating and microcapsules to make same

• US 7,192,993 B1
• Filed: 03/04/2003
• Issued: 03/20/2007
• Est. Priority Date: 03/04/2003
• Status: Expired due to Fees

• Current Assignee: United States Secretary of the Army
• Original Assignee: The United States Of America As Represented By The Secretary Of The Army
• Inventors: Kumar, Ashok, Sarangapani, Srinivasan, Thies, Curtis, Stephenson, Larry D.
• Primary Examiner(s): NILAND, PATRICK DENNIS
• Application Number:
  US10/377,642
• Time in Patent Office: 1,477 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: B05D 5/005 Repairing damaged coatings
• CPC Class Codes: C08K 9/10 Encapsulated ingredients
• CPC Class Codes: C09D 5/086 Organic or non-macromolecular compounds
• CPC Class Codes: C09D 7/48 Stabilisers against degradation by oxygen, light or heat
• CPC Class Codes: C09D 7/69 Particle size larger than 1000 nm
• CPC Class Codes: C09D 7/70 characterised by shape, e.g. fibres, flakes or microspheres
• CPC Class Codes: Y10T 428/2984 Microcapsule with fluid core [includes liposome]
• CPC Class Codes: Y10T 428/2985 Solid-walled microcapsule from synthetic polymer

Abstract

A liquid self-healing coating, incorporating microcapsules filled with tailored repair formulations, repairs itself upon physical compromise after curing. In one embodiment, a commercially available paint primer is mixed with a pre-specified amount of these microcapsules. After the coating has cured on the substrate to which it is applied, any physical compromise of the cured coating results in the microcapsules bursting to release a liquid that fills and seals the compromised volume of the coating. In applications where paint is used to provide corrosion protection, the liquid contains anti-corrosion material as well as suitable diluents and film-forming compounds. In another embodiment, the microcapsules may be provided separately to enhance commercially available products. For example, if a paint formulation is known a priori, specifically configured microcapsules packaged separately from the paint and designed for use with the paint formulation, may be added to the commercially available product just prior to application.

Claims

1. A self-healing coating that repairs itself upon physical compromise of an application of said self-healing coating that was cured at ambient temperature, comprising:

at least one liquid COTS coating; and

microcapsules, having a shell defining a volume of a sphere with an outer diameter of approximately 150μ

, said volume containing at least one repair substance, said microcapsules wet mixed into said liquid COTS coating just prior to application of said self-healing coating,

wherein said shell is resistant to degradation by said repair substance; and

wherein prior to application of said self-healing coating and after addition of said microcapsules to said liquid COTS coating, said microcapsules are resistant to short term degradation by said liquid COTS coating; and

wherein said microcapsules in the area of a physical compromise of said applied and cured self-healing coating burst, releasing said at least one repair substance to fill and seal the compromised volume within said self-healing coating.

2. A microcapsule suitable for wet mixing in a liquid COTS coating to produce a self-healing coating cured at ambient temperature, said microcapsule comprising:

a repair substance; and

a shell enclosing a volume containing said repair substance, in which said shell is a sphere with an outer diameter of approximately 150μ

,

whereupon application of said self-healing coating to a substrate and curing of said self-healing coating thereon, physical compromise of said self-healing coating results in rupture of said shells near said physical compromise and deployment of said repair substance to fill and seal the compromised volume within said self-healing coating.