Alcan International Limited

Paul Smits

Aron M Rosenfeld

Howard F DeFerrari

A bilayer oxide film which comprises a preferably porous layer containing aluminum oxide and a non-porous layer comprising an oxide of a valve metal, e.g. tantalum. The layers are integral. The film is produced by forming a coating of aluminium or an anodizable aluminum alloy on a valve metal (or alloy), anodizing the resulting structure in an electrolyte (preferably one capable of converting the aluminum (or alloy) to a porous oxide film) in the presence of an adhesion-reducing agent (e.g. fluoride ions) that makes the resulting anodized bilayer film easily detachable from the remaining valve metal. The bilayer film is then detached from the valve metal, e.g. by adhering a flexible plastic film to the bilayer and using the film to peel off the bilayer from the valve metal. The resulting bilayer can be used for a variety of purposes, e.g. as a vapor or oxygen barrier useful for packaging, or as a coating containing magnetic particles used to make a magnetic recording medium.

Bilayer oxide film and process for producing same

A process for producing a released film made of at least two layers, one or more of which has been formed by a vapor deposition technique. The process involves anodizing a metal substrate comprising a valve metal or valve metal alloy to form an anodic oxide layer on the substrate, the anodization being carried out in the presence of an adhesion-reducing agent (e.g. fluoride) which makes the anodic layer detachable from the valve metal, coating the anodic layer with one or more layers of desired materials by a vapor deposition technique (e.g. sputtering or vacuum evaporation, etc.) to form a film of desired structure which is releasable from the metal substrate, and then detaching the releasable film from the metal substrate. The film can, if desired, be transferred to another substrate by attaching the other substrate to the releasable film before the releasable film is detached from the metal substrate. The process makes it possible to provide free-standing vapor deposited films or heat-sensitive (or other) substrates coated with such films.

Process for producing released vapor deposited films and product

The invention relates to a laminated tamper-evident structure which exhibits an irreversible color change upon delamination. The structure includes a laminate of at least two layers capable of generating a color by a light interference and absorption phenomenon that requires direct and intimate contact between an adjacent two of the layers. The strength of attachment among the layers of the laminate is such that the laminate can be uniformly and reliably peeled apart at the interface between the adjacent two layers. An overlying flexible strip of transparent or translucent material is adhered to the laminate to facilitate the peeling operation. Upon peeling apart the laminate, the generated color is irreversibly lost, thus providing evidence that the structure has been tampered with. The structure can be incorporated into a variety of closable articles or products to provide evidence of opening or tampering.

Tamper-evident structures

A process for coating a packaging film with a transparent barrier coating. The process starts with a metal substrate made of, or having a surface coating of, a valve metal or valve metal alloy. The metal substrate is anodized to form an anodic film of the valve metal on the metal substrate. The anodic film is made readily detachable from the metal by carrying out the anodization step in the presence of an adhesion-reducing agent, e.g. a fluoride. The packaging film is then attached to the anodic film and the anodic film is detached from the metal. The transferred anodic film forms a thin dense oxide coating on the packaging film that acts as a barrier against oxygen and moisture transport. The invention can be used for making packaging films suitable for packaging foodstuffs, and the like.

Process for coating a packaging film with a transparent barrier coating

A process for coating a packaging film with a transparent barrier coating. The process starts with a metal substrate made of, or having a surface coating of, a valve metal or valve metal alloy. The metal substrate is anodized to form an anodic film of the valve metal on the metal substrate. The anodic film is made readily detachable from the metal by carrying out the anodization step in the presence of an adhesion-reducing agent, e.g. a fluoride. The packaging film is then attached to the anodic film and the anodic film is detached from the metal. The transferred anodic film forms a thin dense oxide coating on the packaging film that acts as a barrier against oxygen and moisture transparent. The invention can be used for making packaging films suitable for packaging foodstuffs, and the like.

Packaging film with a transparent barrier coating

A process for coating a polymer sheet with a transparent coating having moisture and oxygen barrier properties. The process starts with a metal substrate made of, or having a surface coating of, a valve metal or valve metal alloy. The metal substrate is anodized to form an anodic film of the valve metal on the metal substrate. The anodic film is made readily detachable from the metal by carrying out the anodization step in the presence of an adhesion-reducing agent, e.g. a fluoride. The polymer sheet, usually in the form of a thin transparent layer, is then attached to the anodic film and the anodic film is detached from the metal. The transferred anodic film forms a thin dense oxide coating on the polymer sheet that acts as a barrier against oxygen and moisture transport. The invention can be used for making packaging sheets suitable for packaging foodstuffs, and the like.

Process and apparatus for producing coated polymer sheets having oxygen

The method involves forming a laminate capable of generating a substantially non-dichroic color by a light interference and absorption phenomenon by depositing a layer of a metal of medium light reflectivity by a vapor deposition technique on a suitable substrate, anodizing a surface of the metal in the presence of fluorine ions to form a detachable film of an oxide of the metal on the surface having a thickness suitable for color generation, and adhering a flexible strip of transparent or translucent material over the oxide film in such a manner that the strength of attachment of the flexible strip to the oxide film exceeds the adhesive strength between the oxide film and said surface of said metal.

Method of making tamper-evident structures

A laminated color change device which exhibits an irreversible color change upon delamination. The device comprises two layers capable of generating a color by a light interference and absorption phenomenon that requires direct and intimate contact between the two layers. One of the layers is a color-generating metal, such as a valve metal (e.g. tantalum), and the other is an overlying light-transmitting film thin enough to cause light interference effects. The film is produced by coating the color generating metal with aluminum or an aluminum alloy and then anodizing (preferably porous anodizing) the aluminum to consumption in the presence of an adhesion-reducing agent, e.g. fluoride, that reduces the strength of attachment between the layers so that the laminate can be uniformly and reliably separated at the interface between the adjacent two layers. An overlying layer of transparent or translucent material is normally adhered to the laminate to facilitate the separation of the layers. When the thin film is detached from the color-generating metal, the generated color is lost, thus providing a color change that is in effect irreversible. The device can be incorporated into a variety of closable articles or products to provide evidence of opening or tampering, or can be used for other purposes.

Growing community of inventors

Kingston, Canada

Paul Smits