Method of manufacturing metal with biocidal properties
Inventors
Agg, Philip James • Shawcross, James Timothy • Pickford, Martin Edward Lee • Turner, Andrew Derek • Lewis, David Richard
Assignees
Interested in licensing this patent?
MTEC can help explore whether this patent might be available for licensing for your application.
Publication Number
US-8858775-B2
Publication Date
2014-10-14
Expiration Date
Abstract
Metal objects are treated by anodising the metal object in contact with an acidic solution, and then subjecting the anodised metal object to a reversed voltage (compared to the anodising voltage). The thus-treated metal object is then contacted with a biocidal metal-containing solution. Biocidal metal is deposited on the surface of the metal object, resulting in improved biocidal properties.
Core Innovation
The invention relates to a method treating a metal object to form thereon a surface layer which is integral with the metal object and includes a biocidal material. The method immerses the metal object in an anodising electrolyte containing a solvent and anodises the metal object by applying a positive voltage between 15 and 200 V to passivate it by forming an anodised integral surface layer on the metal object.
After passivation, anodising is continued by applying a positive voltage to produce pits through the integral surface layer and into the substrate. Then, after anodising during the positive-voltage steps, a hydrous metal oxide or phosphate is produced by applying a negative voltage which is insufficient to cause electrolysis of the solvent to the metal object, while in contact with the anodising electrolyte, or by contacting the metal object with an electrolyte solution containing a reducible soluble salt of titanium or the substrate metal and another solvent and applying a negative voltage which is insufficient to cause electrolysis of the other solvent.
The anodised metal object resulting from the hydrous metal oxide or phosphate step is removed or separated from the anodising electrolyte or the electrolyte solution, and is then contacted with a solution containing a biocidal material so as to incorporate the biocidal material into the surface layer. The pits and the produced hydrous metal oxide or phosphate provide a matrix for ion exchange and adsorption of biocidal material, such as silver ions, leading to improved, consistent silver loading and inhibition of biofilm and microorganisms.
Claims Coverage
The provided independent claim content identifies five core inventive features covering passivation by positive-voltage anodising, pit formation, hydrous metal oxide or phosphate production using a negative-voltage route, removal or separation from the electrolyte, and incorporation of a biocidal material into the resulting integral surface layer.
Integral anodised surface layer with biocidal material
A method treating a metal object to form thereon a surface layer integral with the metal object and including a biocidal material.
Passivation by positive voltage anodising
Immersing the metal object in an anodising electrolyte containing a solvent and anodising the metal object to passivate it by forming an anodised integral surface layer on the metal object by applying a positive voltage between 15 and 200 V.
Pit formation through the integral surface layer
Continuing anodising by the application of a positive voltage to produce pits through the integral surface layer and into the substrate.
Hydrous metal oxide or phosphate formation using negative voltage insufficiency
After anodising during the steps producing pits, producing a hydrous metal oxide or phosphate by applying a negative voltage which is insufficient to cause electrolysis of the solvent to the metal object while in contact with the anodising electrolyte, or by contacting with an electrolyte solution containing a reducible soluble salt of titanium or the substrate metal and another solvent and applying a negative voltage which is insufficient to cause electrolysis of the other solvent.
Biocidal incorporation into the surface layer
Removing or separating the anodised metal object resulting from the hydrous metal oxide or phosphate step from the anodising electrolyte or the electrolyte solution, and then contacting the anodised metal object with a solution containing a biocidal material so as to incorporate said biocidal material into the surface layer.
The inventive features combine integral anodised layer formation, pit generation, negative-voltage production of a hydrous metal oxide or phosphate, and subsequent incorporation of biocidal material into the surface layer.
Stated Advantages
Improved and consistent silver loading, as described by increased silver loading and consistency versus omission of the reversed/negative-voltage step.
Inhibition of biofilm formation and microorganisms.
Documented Applications
Medical implants using titanium and alloys.
Jewellery using titanium and alloys.
Interested in licensing this patent?