FORM 2
THE PATENT ACT 1970 (39 of 1970)
The Patents Rules, 2003
COMPLETE SPECIFICATION
[See Section 10, and rule 13

1. TITLE OF INVENTION
2. APPLICANT(S)
a) Name
b) Nationality
c) Address
ULTRA HIGH BARRIER METALLISED FILM - BARRIMET

JHAVERI FLEXO INDIA LTD.
INDIAN Company
301/401, KUNDAN BAUG,
SAMARTH RAMDAS MARG, OPP 10TH ROAD,
J.V.P.D. SCHEME, VILE PARLE (W),
MUMBAI - 4 00 04 9
MAHARASHTRA

3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed : -


1878

-5 SEP 2008

FIELD OF INVENTION :
The present invention relates to the field of metallized plastic films which are having excellent adhesion to other film substrates especially, but not exclusively, useful for packaging materials, particularly for materials which are sensitive to light, oxygen and/or water vapours.
BACKGROUND OF THE INVENTION :
It is well known to package materials in plastic films or plastic film laminates. Where the materials are sensitive to oxygen and/or water vapours (e.g. materials such as certain foodstuffs, beverages, chemicals, pharmaceuticals, seeds, electrical components, etc.), a plastic packaging material is chosen which provides a barrier against ingress of oxygen and/or water vapours. It is also well known art that packaging of certain foodstuffs in an atmosphere of a gas contained within a plastic material is chosen for its low permeability to that gas (controlled atmosphere packaging).
One such plastic film which has the properly of low permeability to oxygen, other gases and water vapours is metallized poly ethylene glycol teraphthalate (hereafter referred as PET), a single web of which may typically provide an oxygen barrier of about 1 cc/meter2/24 hours (at 23°C, 0% RH) and a moisture barrier of about 1 gram/meter2/24 hours (at 38°C, 90% RH). Metallized PET can be further laminated to a heat sealable film such as a polyolefin (e.g. polyethylene or polypropylene) to produce a material suitable for packaging oxygen or moisture-sensitive products, but gas and moisture barrier are not significantly improved by this lamination.
By laminating metallized PET to a further web of metallized film, either another ply of metallized PET or another metallized thermoplastic polymer film, further reductions in permeability can be achieved. For some other applications it is desirable to decorate the package with, for example, print, and for reasons of
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security and integrity this print is often preferably sandwiched within the laminate. This can be achieved by printing the PET, and metallizing over the print before further conversion. This procedure normally gives a material with a greater permeability than that of the film metallized directly. By careful choice of inks it is possible to keep this decoration in barrier within acceptable limits, but no instances have been disclosed of use of this technique to improve barrier.
Other plastic films which have the property of low permeability to moisture (but not oxygen) are metallized polyolefins, such as metallised oriented polypropylene (hereafter OPP) or metallized polyethylene (hereafter PE) or metallized unoriented polypropylene film, single webs of which may typically provide a moisture barrier of about 1 gram/meter2/24 hours (at 38°C, 90% RH), and laminates of such metallized polyolefin films or unmetallized films are suitable for packaging of moisture sensitive materials. Gas and moisture barrier are not significantly improved over those of the single web metallized film by this lamination, unless the clear web itself or the adhesive has good barrier properties.
By laminating a metallizsed polyolefin film to a further web of a metallized polyolefin film, further reductions in permeability can be achieved and a material with both good moisture barrier and good oxygen barrier is produced. Cast polypropylene films with metallization on one side are also known and commercially available. Such films are widely used for packaging either in single web form or laminated to another unmetallized web.
Whilst laminates as described above of metallized polyolefin films to other metallized polyolefin films or metallized cellophane films or metallized polyester films are highly advantageous in packaging moisture and/or oxygen sensitive materials, because of their excellent barrier properties, they also have some disadvantages, for example:
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(a) Cost: Relative to many other thermoplastic films and laminates used in
packaging, these laminates are expensive, so for some end uses their use is
precluded on cost grounds.
(b) If it is desired to decorate the pack with a sandwiched print, this can often only
be achieved by laminating on a further ply of reverse printed film, which both
increases costs and reduces flexibility of the laminate.
Neither of these structures described above provides adequate oxygen barrier properties for long-term packaging of foodstuffs, beverages, chemicals, pharmaceuticals, seeds, electrical components etc. There is a need in food packing applications where the oxygen barrier properties of the multilayer film should be substantially better than the barrier properties of either EVOH or aluminum metallized on an EVOH film. The applicant has devised a composition which will be able to address all the short comings experienced with the available prior art and a protection is desired for such an invention.
OBJECTIVE OF THE INVENTION ;
The objective of the invention is to develop flexible metallized plastic films useful for packaging materials, particularly for materials which are sensitive to light, oxygen and/or water vapours.
One more objective of the invention is to develop metallized plastic films which are having excellent adhesion to other film substrates.
One further more objective of the invention is to develop a co-extrusion based modified layer film for proper adhesion wherein the co-extrusion is based on modified top layer with maleic anhydride grafted copolymer and or EVOH and or Nylon 6.
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One main objective of the invention is to develop a flexible plastic film containing polyamide in the barrier film in the desired amount to provide an excellent mechanical strength/property.
One further main objective of the invention is to develop thermally stable plastic resin modified co-extrusion material other than polyvinyl chloride and polyvinylidene chloride.
SUMMARY OF THE INVENTION :
The present invented flexible metallized plastic film contains EVOH (Ethylene Vinyl Alcohol) or Polyamide (PA) on the top layer that gives high metal adhesion during metal deposition. The film gives better oxygen barrier and moisture barrier properties which find large use in packaging materials sensitive to moisture, oxygen and light. Film bonding with other films substrate like PET, BOPP etc. would be better in improving the film properties. Presence of polyamide in the barrier resin in the present invention provides an excellent mechanical strength to the film.
DETAILED DESCRIPTION OF THE INVENTION :
A polyolefin/polyalkylene is a polymer produced from a simple olefin (also called an alkene with the general formula CnH2n) as a monomer. For example, polyethylene, polypropylene are the polyolefin used in the present invention in making the flexible plastic film for packaging purposes. Biaxially oriented polypropylene abbreviated as BOPP and cast polypropylene abbreviated as CPP is chosen as the preferred polyolefin used in the invention.
Ethylene vinyl alcohol (EVOH) resin is a random copolymer of ethylene and vinyl alcohol. It is a crystalline polymer which has a molecular structure represented by the following formula:
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(CH 2 - CH 2) m (CH 2 - CH) n
OH Wherein m and n is the repeated number of functional units.
EVOH resins can be co-extruded with many types of polyolefins, polyamides, polystyrene and polyesters.
Ethylene vinyl alcohol (EVOH) has been one of the most effective barrier materials known to the flexible packaging industries, especially in providing excellent barrier for oxygen and aroma. However, the polar EVOH is not compatible with the non-polar polyolefinic film such as biaxially oriented polypropylene (BOPP). Thus, it requires an adhesion promoter or tie-layer resin such as anhydride-modified polyolefin in order to adhere to a non-polar polyolefinic substrate. Additionally, EVOH loses its barrier property if it is exposed to a high moisture environment. Therefore, it requires a moisture barrier layer for protection such as an anhydride-modified polyolefin or other non-polar layer or metallized layer.
A polyamide is a polymer containing monomers of amides joined by peptide bonds. For example, nylons, aramids, and sodium poly (aspartate) are the polyamides used in making the flexible plastic film of the present invention. Polyamide films are excellent in mechanical properties, dimensional stability, heat resistance, oil resistance, solvent resistance/ optical properties, piercing pinhole resistance and gas-barrier properties and thus have been employed in packaging foods, medicines, miscellaneous goods, etc. In recent years, however, the application range of polyamide films has been broadened and the conventional polyamide films sometimes fail to satisfy the requirements. It is therefore required to further improve each of the properties of polyamide films.
We have now found that, metallized PET films are good oxygen barrier but not high moisture barrier and metallized biaxially oriented polypropylene (BOPP) film is a good moisture barrier but not good oxygen barrier. Both Metallized PET and OPP film are also not having very high sealing property as desired for many packagings.
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Therefore, it is needed to combine or laminate sealant layer i.e. PE or cast polypropylene (CPP) film with the metallized film.
In accordance with the present invention, there is provided a flexible plastic film A and is metallized on one of polar surface. The metallized film of the proposed invention will provide both high barrier to both moisture and oxygen for controlled atmosphere packaging of foodstuffs, beverages, chemicals, pharmaceuticals, seeds, electrical components, etc. The invention also provides a film that combines barrier and sealing property to reduce packaging cost and packaging waste as well.
Film A is preferably a polyolefin with top layer consist of EVOH and or polyamide of any thickness in their weight ratios in the range of 20:80 to 80:20, preferably in the weight ratios 30:70 to 70:30 and most preferably in the weight ratios 40:60 to 60:40 which can be metallized, including composites or co-extrusions of the above materials, whether or not these other plastics have barrier properties. Presence of polyamide in the barrier film in the desired amount provide an excellent mechanical strength/property which in most cases can withstand any load associated with the amount of material to be packed.
The applicant unexpectedly found that applying an EVOH and or polyamide layer directly onto a metallized layer which in turn, is deposited on a Cast film layer provides exceptionally good barrier properties in a multilayer Cast film. This unique configuration of EVOH and or polyamide on the metallized aluminum layer unexpectedly provides a synergistic high barrier for the extrusion coated flexible structure.
One embodiment of this invention is a laminate film, comprising a biaxially oriented polypropylene film substrate; a metal-containing layer; and an EVOH and polyamide layer present in their weight ratios in the range of 20:80 to 80:20 co-extruded or laminated directly on the metal-containing layer. In one variation, the metal-containing layer is a vacuum metallized layer especially vacuum metallized
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aluminium layer of relatively desired thickness. The metal-containing layer could have an optical density of about 1.5 to 5.0. The substrate could be discharge-treated in an atmosphere of CO2 and N2.
One further embodiment of the present invention is a plastic film useful for packaging substances which material further comprises a flexible co-extruded plastic film based on 5 layer and or 3 iayer co-extrusion and having combination 0/ barrier layer as well as modified sealing layer and the film having a smooth outer surface; and a vaccum-metallized layer of metal on said smooth outer surface, the thickness of the metal layer being in the effective range that provides an optical density of 1.0 to 4.0. This addition of further layer over the basic structure happens in case of demand.
In one embodiment, the polymer film comprises a polymer selected from the group consisting of polyolefin, as described above and combinations thereof. Preferably, the polymer film comprises polyolefin. In another embodiment, the laminate film further comprises an adjacent layer of anhydride modified polyolefin on the EVOH and or polyamide layer. Preferably, the adjacent layer comprises a blend of a polyolefin resin , wherein the polyolefin resin is a low density polyethylene, a medium density polyethylene, polypropylene or combination thereof. The said film has a barrier polar resin on at least one surface with at least one thin and smooth layer of a thermally stable plastic resin co-extrusion material other than polyvinyl chloride and polyvinyhdene chloride. We have found that inclusion of material like polyvinyl chloride and polyvinylidine chloride have a deleterious effect on the overall properties of the product and are not used in the manufacturing of the flexible plastic film. The laminate film preferably has a oxygen transmission rate of 0.5cc/m2 /day or less, more preferably 0.35 cc/m2/day or less and most preferably 0.2cc/m2 /day or less.
The vacuum-metallized plastic co-extruded cast film is also available with 5 layer and or 3 layer having a low permeability to gases, moisture and light, which
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comprises (a) a film substrate made of barrier resin of EVOH and or Polyamide (Nylon), said film substrate having opposite surfaces, (b) at least n layer of a polyolefin resin on at least one of said opposite surfaces of said film substrate.
The process description for making Cast Barrier Film is described below:
1. RAW MATERIAL MIXING & FEEDING: Various grades/types pre-specified quantity of Raw materials in granules form pneumatically fed in the mixing system. After thorough mixing, the mixed is fed in the hoppers of extruders. Extruder hoppers are equipped with level sensors, which ensure minimum level of raw material in hoppers. Difference material according to type of film to be made is fed in difference extruders.
2. EXTRUSION OF MATERIAL: The mixed raw material is passed in Extruder barrel. The barrel is heated enough by electrical heaters, where first materials soften then turned into molten polymer thereafter this molten polymer is being filtered.
3. MELT PUMPS AND FEEDBLOCK: The filtered polymer fed into feedblock with the help of melt pump. Distribution of layers takes place in feedblock.
4. FLAT DIE: Molten polymer from the feedblock, comes in to flat die, where it takes flat shape. The die is equipped with auto thickness controller.
5. CASTING OF THE POLYMER: Molten polymer from the feedblock, comes into flat die, where it takes flat shape. This flat shaped molten polymer is immediately quenched on a chill roll. This chill roll is a polished chrome platted roll with chilled water circulation inside it.
6. ONLINE THICKNESS SCANNER: The Cast film produced after cooling at chill roll is passed through online thickness scanner. The scanner gives

feedback to the auto thickness controller of die and accordingly thickness is being controlled. After scanning the film is passed through set of rollers (side slip unit).
7. CORONA TREATER: After initial trimming and usage of side slip unit for randomization of gauge, the film is passed through corona theater, Corona treatment is being done in order to increase the surface tension of the film, thus enables printing/metallization.
8. MALIC ANHYDRIDE MODIFICATION: Prior to metallization/printing addition of the adjacent layer which comprises a blend of a polyolefin resin and maleic anhydride modified adhesive resin, is made in contact with the film of desirable thickness wherein the polyolefin resin is a low density polyethylene, a medium density polyethylene, polypropylene or combination thereof.
9. WINDER: After Corona treatment, film is winded on 6 inches paper or plastic cores at winder. After completion of 800 mm diameter or specified length, turreting takes place at winder and the inline core is replaced by empty core.

10. SLITTER: Rolls produced at winder that kept on roll stand for 24 hours maturation. After maturation, rolls are being slitted into desired widths and lengths. These finished rolls that packed and dispatched either to customer or in house usage is ready for lamination/metallization.
11. RECYCLING: Recycling is being done in three stages. After scanning, the film is passed through set of rollers where rough edged of the film is being trimmed and fed into trim grinder. From the grinder the pieces of trimmed film are fed directly into hopper of main extruder. Trim and/or wastage film generated in winding and slitting process are fed to recycling unit thereby around 90-95 % wastage are recycled.
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12. METALLIZATION: Final film roll goes through process of vaccum aluminium metal deposition according to known conventional process.
The summary of the method adopted for manufacturing of a laminate plastic film, comprising of extruding a biaxially oriented polymer i.e. polypropylene film substrate; applying a metal-containing layer on the substrate; applying a co-extruded or laminated EVOH and or polyamide layer in their desired ratios directly on the metal-containing layer; applying an adjacent layer of anhydride modified polyolefin on the EVOH layer and applying a second film layer on the adjacent layer, the second film layer comprising polypropylene, poly(ethylene terephthalate), or combination thereof.
Thickness of the flexible plastic film of the present invention is designed to be 25 micron to 150 micron and the film type is metallized co-extruded cast film. Its generic name for trade purpose is designed as "BARRIMET".
Special features and properties of the film:
1. The invented film contains EVOH (Ethylene Vinyl Alcohol) and or Polyamide (PA) on the top layer that gives high metal adhesion during metal deposition.
2. Also the film gives better oxygen barrier and moisture barrier properties which find large use in packaging materials sensitive to moisture, oxygen and light.
3. Film bonding with other films substrate like PET, BOPP etc. would be better in improving the film properties.
4. Presence of polyamide in the barrier resin in the present invention provides an excellent mechanical strength to the film.
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Comparison with present film structure:
1. At present in market similar kind of film is available as metallized CPP (cast polypropylene) film;Metallised PET (poly ethylene terapthalate) and Metallised BOPP (biaxially oriented polypropylene film)
2. Metallized CPP and BOPP film has poor metal bond strength and does not have EVOH and or PA on the top layer;
3. Metallised CPP film and BOPP has poor oxygen barrier but the present film of the invention have very good oxygen barrier;
4. Metallized CPP film has poor adhesion to other film substrate while being laminated to PET or BOPP but the present film of the invention gives very high and excellent bond strength.
5. Presence of polyamide in the barrier resin in the present invention provides an excellent mechanical strength to the film which is not available in the film available in the market.
These and other modifications and variations to the present invention may be practiced by those of ordinary skill in the art, without departing from the spirit and scope of the present invention, which is more particularly set forth in the appended claims. In addition, it should be understood that aspects and various embodiments may be interchanged both in whole and in part. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the invention so further described in such appended claims.
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WE CLAIM :
1. A flexible plastic film having ultra low permeability to gases, moisture and light which comprises a film substrate selected from the group consisting of polyolefin and barrier resin such as EVOH and or polyamide in a fixed weight ratios wherein the said film has a barrier polar resin on at least one surface with at least one thin and smooth layer of a thermally stable plastic resin modified co-extrusion material other than polyvinyl chloride and polyvinylidene chloride, and a vacuum metallized layer over the polar barrier resin surface having an optical density of 1.0 to 4.0.
2. A plastic film as claimed in claim 1 wherein the EVOH and or polyamide of the said barrier resin is present in the ratios of 80:20 to 20:80 parts by their weight.
3. A plastic film as claimed in claim 1 wherein the EVOH and or polyamide of the said barrier resin is preferably present in the ratios of 70:30 to 30:70 parts by their weight.
4. A plastic film as claimed in claim 1 wherein the EVOH and or polyamide of the said barrier resin is most preferably present in the ratios of 40:60 to 60:40 parts by their weight.
5. A plastic film according to claim 1, wherein the co-extrusion is based on modified top layer with maleic anhydride grafted copolymer.
6. A plastic film according to claim 1, wherein the substrate is a polyolefin selected from polyethylene or polypropylene and preferably polypropylene.
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7. A flexible plastic film as claimed in claim 1 wherein the polyamides used are selected from nylons, aramids, and sodium .poly (aspartate) and most preferably nylons.
8. A plastic film useful for packaging substances as claimed in any of the preceding claims which are moisture-and oxygen-sensitive, which material further comprises a flexible co-extruded plastic film based on 5 layer and or 3 layer co-extrusion and having combination of barrier layer as well as modified sealing layer and the film having a smooth outer surface; and a vaccum-metallized layer of metal on said smooth outer surface, the thickness of the metal layer is provided to produce an optical density in the range 1.0 to 4.0.
9. A packaging material according to claim 8, wherein the substrate is polyethylene or polypropylene film to give better sealing property.
10. A vacuum-metallised plastic co-extruded cast film with 5 layer and or 3 layer having a low permeability to gases, moisture and light, which comprises (a) a film substrate made of barrier resin of EVOH and Polyamide (Nylon), said film substrate having opposite surfaces, (b) at least n layer of a polyolefin resin on at least one of said opposite surfaces of said film substrate.
11. A plastic film having ultra low permeability to gases, moisture and light as substantially herein described with reference to the specification disclosed.

HIRAL CHANDRAKANT JOSHI AGENT FOR .
JHAVERI FLEXO INDIA LTD.
Dated this 5th day of September, 2008. /
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