FORM - 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
PROVISIONAL
Specification
(See section 10 and rule 13)
PINTABLE ALU-ALU LAMINATES
BILCARE LIMITED
an Indian Company
of 1028, Village Shiroli, Taluka Khed, Rajguranagar,
Pune 410 505, Maharashtra, India,
THE FOLLOWING SPEC IFICATION DESCRIBES THE INVENTION.

This invention relates to laminates.
Particularly, this invention relates to laminates for use in the pharmaceutical industry.
A significant fraction of healthcare products are packaged in blisters. Amongst many other advantages, blister packaging offers convenience in terms of portability and also helps protect a drug over a long shelf life.
One way to form blisters is by thermoforming a polymer film, and foil. However a simple blister obtained by thermoforming a polymer may not be adequate in meeting key requirements, particularly in the area of pharmaceutical packaging, such as improved impact strength and barrier properties.
A variety of packaging solutions are being developed to meet expanding regulatory and customer requirements including new kinds of film, new foil-to-foil packages, and new methods of forming such as cold-forming.
Blisters made out of special materials offer higher levels of barrier for moisture, light, and oxygen. Of those, moisture currently seems to be the highest priority because many new drugs, especially ones developed through biotechnology, are highly sensitive to water. A typical example of such new packaging materials include multi-layered laminates such as those comprising a metallized layer and two polymers layers.
For example a laminate comprising aluminium metal layer sandwiched between a polyvinyl chloride plastic and a nylon layer, often known as, and hereinafter referred to as, alu-alu laminate. The PVC side is in direct contact with the packaged article and is also called the sealing side. The nylon side is the outer side. The alu-alu laminates are cold-formed to obtain blisters. The cold-forming process doesn't use heat; rather, the foil is shaped and molded around a plug to form a cavity.
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However, the use of alu-alu laminates has a few intrinsic problems that hinder their prolific commercial exploitation. For example, it is highly desired that the nylon side, that directly faces the customers is modified to accommodate several functional features such as colors or graphic print. However, because of the inherent properties, it is very difficult to add or apply color coats or print on the nylon side. Yet another problem is faced during the cold forming of such laminates. During a typical cold-forming process the laminate is subjected to an impact punch that often dislodges the contents on the nylon layer such as applied color, coat or ink.
The present invention comprehensively and successfully addresses the possibilities of developing such nylon based high-barrier laminates capable of retaining any applied color, ink or coat during cold forming without any damage to the print definition & quality.
Accordingly, the present invention provides nylon based high barrier laminates suitable for use in packaging, such that in use, any color, ink or coat applied on the nylon layer is deform during the cold-forming process and yet successfully withstands the cold-forming process.
According to one of the preferred embodiments, the nylon layer of high-barrier nylon based laminates is printed with a special ink composition.
According another preferred embodiment, the special ink composition comprises pigment or dye of a desired color and a cross-linkable polymer additive.
A wide variety of pigment or dyes may be employed. The cross-linkable polymer additive in accordance with this invention is such that it undergoes cross-linking polymerization reaction under certain conditions such as at a particular temperature or in presence of a suitable initiator. A typical example of such cross-linkable polymers include, but are not limited to , epoxy resins.
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The special ink composition may further comprise other components if desired, such as for examples stabilizers, enhancers and a like.
The nylon layer is first printed as desired with the special ink composition. Then the cross-linking polymerization of the cross-linkable polymer in the ink composition is initiated by a suitable means such as elevated temperature or through use of a radical polymerization initiator. The cross-linking polymerization reaction is continued until a desired amount of cross-linking occurs.
The thus printed nylon based laminates is then subjected to cold-forming process to obtain blisters. The cross-linking of the resin results in the formation of a rubber like elastic film material having high rupture strength and capable of withstanding high impact during a typical cold-forming process. The cross-linking polymer also protects and ensures excellent adhesion of print with the nylon layer.
In a typical non limiting example, a commercially available alu-alu laminate having total thickness of about 135 micron was used as a base material and contained an aluminium layer (about 50 microns) sandwiched between a PVC layer (about 60 microns) and a nylon layer (about 25 microns). The nylon side of this laminate was corona treated at Lamination machine and printed with the desired text using an ink composition comprising a polyurethane and an epoxy based resin. During a typical Corona treatment procedure, or any other suitable subbing process, the surface tension of the material is increased to improve the printability of the surface. In the 2nd pass operation; the printed laminate obtained in the 1st pass operation was coated over the print surface, with an overcoat medium. The material obtained from the 2nd pass operation was subjected to heat treatment at about 80°C & passed through 5 drying tunnels. This heat treatment induced cross-linking polymerization of the epoxy resins present in the overcoat applied during 2nd pass operation. The final material obtained by curing and drying had the following characteristics.
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Color & Appearance: No Visual defects
Scotch Tape test: Good Bonding
Adhesion Bond Strength: Min. 0.45 kg/cm
The film also withstood cold forming process without any rupture.
The laminate so obtained also withstood a typical cold forming operation (at an air pressure of 6 bars, using plug assists tools for forming) without showing any deformation or in the ink lifting in the printed matter.
While considerable emphasis has been placed herein on the specific structure of the preferred embodiment, it will be appreciated that many modifications can be made in the preferred embodiment without departing from the principle of invention. These and other changes in the preferred embodiment as well as other embodiments of the present invention will be apparent to those skilled in the art from the discloser herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as an illustrative of the invention and not as a limitation.
Date^this 11th day of December, 2006.
Mohan Dewan of R. K. Dewan & Co Applicants' Patent Attorneys
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