Alcan International Limited

Mark A Jozefowicz

Aron M Rosenfeld

Robin C Furneaux

Michael P Thomas

A process for producing a structure including an anodic film exhibiting a colored pattern, and the resulting structures. The process involves anodizing a surface of a metal substrate or article made of or coated with aluminum or an anodizable aluminum alloy to produce an anodic film preferably having pores extending from the film surface inwardly towards the underlying metal. A semi-reflective layer of a non-noble metal is then deposited on or within the pores of the film in order to generate a color by effects including light interference. Limited areas of the resulting film are then contacted with a solution of a noble metal compound (e.g. Pd, Au or Pt) by a procedure which avoids the use of an adhering mask. The noble metal from the solution at least partially replaces the non-noble metal in the contacted areas and creates a different color in these areas. The non-noble metal in the remaining areas may be fully or partially leached out, if desired, or the color in the contacted areas may be changed by carrying out further anodization of the article, in which case the non-noble metal is also partially or fully leached away. The result is a patterned anodized article in which the colors are highly resistant to fading or lack of uniformity.

Process for producing anodic films exhibiting colored patterns and

Porous membranes suitable for separation devices and other uses

A process for producing a structure including an anodic film exhibiting a colored pattern, and the resulting structures. The process involves anodizing a surface of a metal substrate or article made of or coated with aluminum or an anodizable aluminum alloy to produce an anodic film, preferably having pores extending from the film surface inwardly towards the underlying metal. A semi-reflective layer of a non-noble metal is then deposited within the pores of the film in order to generate a color by effects including light interference. Limited areas of the resulting film are then contacted with a solution of an acid or other leaching material, preferably by a maskless procedure, in order to leach the non-noble metal from the film, at least partially. The film is then contacted by a solution of a more noble metal compound (e.g. Pd, Au or Pt). The more noble metal from the solution at least partially replaces the non-noble metal remaining in or on the film and stabilizes the deposits against further leaching. A further anodization step creates different colors in the leached and unleached areas. The result is a patterned anodized article in which the colors are highly resistant to fading or lack of uniformity.

Optical interference structures incorporating porous films are disclosed. These structures are capable of exhibiting a color by interference effects caused by the interference of light reflected from various layers within the structure. Basically, the structures comprise a reflective substrate, a porous transparent dielectric film on the substrate and at least one semi-transparent layer supported by the porous dielectric film. The structure is such that there are at least two reflective surfaces separated by an optically thin porous layer of the dielectric film. These structures can be formed by several methods, but the most convenient involves the porous anodization of a substrate metal (e.g. aluminum) to form the dielectric film and the deposition of a semi-transparent metal layer within the pores or on the film surface. The structures can be made inexpensively and are capable of generating strong and, if desired, dichroic colors. The porous nature of the film can also be exploited to create color shifts. The structures can be used for decorative purposes or to create a wide range of indicators, sensors, security devices and the like.

Optical interference structures incorporating porous films

Liquid and/or temperature activated elaspsed time sensors suitable, in particular, for use as doneness indicators for foodstuffs and for other purposes. The liquid activated indicators include a porous structure which generates a first color by effects which include optical interference when pores of the structure are gas-filled, and a second contrasting color when the pores of the structure are liquid filled. The porous structure is covered with a transparent or translucent cover which is unattached in certain areas to allow for capillary movement of liquid between the cover and the porous structure. An entrance permits liquid to enter between the cover and the porous structure. When contacted with liqiuid, the liquid is drawn into the device and produces an expanding area of contrasting color which is used to indicate the elapse of time. In one form, the doneness indicator, when located on the outside of a food container, can be activated by water condensed from steam generated as the food is heated, preferably by microwaves. In an alternative form the activated elapsed time indicator may contain a meltable solid which provides the liquid to operate the liquid activated indicator described above at a predetermined temperature.

Liquid and/or temperature activated elapsed time indicators suitable, in

A process for producing a structure including an anodic film exhibiting a colored pattern, and the resulting structures. The process involves anodizing a surface of a metal substrate or article made of or coated with aluminum or an anodizable aluminum alloy to produce an anodic film preferably having pores extending from the film surface inwardly towards the underlying metal. A semi-refective layer of a non-noble metal is then deposited on or within the pores of the film in order to generate a color by effects including light interference. Limited areas of the resulting film are then contacted with a solution of a noble metal compound (e.g. Pd, Au or Pt) by a procedure which avoids the use of an adhering mask. The noble metal from the solution at least partially replaces the non-noble metal in the contacted areas and creates a different color in these areas. The non-noble metal in the remaining areas may be fully or partially leached out, if desired, or the color in the contacted areas may be changed by carrying out further anodization of the article, in which case the non-noble metal is also partially or fully leached away. The result is patterned anodized article in which the colors are highly resistant to fading or lack of uniformity.

A process for producing a two phase metal/oxide film. The process comprises forming a porous oxide film on a substrate, introducing a weakened stratum into the oxide film so that the film (or at least an outer part of the film) can be subsequently detached along the weakened stratum, depositing a metal on and/or within the pore of the film, and detaching at least the outer film part from the substrate. The detached film so produced can be used for many purposes depending on the film thickness, position of the metal deposits on or with the pores etc. Examples include optical interference devices, magnetic media, coatings for plastics and paper, etc.

Growing community of inventors

Kingston, Canada

Mark A Jozefowicz