Description:Field of the Invention:
This patent application along with its accompanying documents is being filed as a Patent of Addition to the pending patent application number: 202111016603, titled “An improved multilayer high barrier extrusion grade metalized cast propylene film and a method of manufacturing thereof” dated 08/04/2021. The applicant for the aforementioned application is Aditya Flexipack Pvt. Ltd.
The present invention relates to preparation of high barrier film. More particularly, the invention relates to preparation of multilayer metalized cast polypropylene film. Even more particularly, the invention relates to the preparation of multilayer metalized cast polypropylene which is extrusion coatable, recyclable, laminated using BOPP and PET having high binding force.
Background of the Invention:
There are many commercially available metallized packaging films made from cast polyethylene (CPP) face issues of poor metal adhesion and bond strengths limiting their end use application. Most of the film available in the market provides poor barrier to the moisture or air hence to leads to damaging of the products. Following prior art discusses about many multilayer products invented earlier.

Reference has been made to US patent no. US20160144603A1 by Western Clinical Engineering Ltd dated 2002-01-18 titled “Metallized polyethylene film with improved metal adhesion”. The present invention relates to a multi-layer structure comprising: (a) a skin layer comprising at least 50% by weight of an ethylene/a- olefin interpolymer composition (LLDPE) having a Comonomer Distribution Constant (CDC) in the range of from 45 to 400, and wherein the skin layer does not contain any migratory additive; (b) a metal layer disposed on the skin layer to form a metalized film; and (c) at least one substrate layer laminated onto the metallized film; wherein the ethylene/a-olefin interpolymer composition comprises (i) less than or equal to 100 percent by weight of the units derived from ethylene; and (ii) less than 30 percent by weight of units derived from one or more a-olefin comonomers is provided.

Another reference has been made to US patent no. US5591520A by ExxonMobil Oil Corp dated 1991-12-11 titled “Metallized polyethylene film with improved metal adhesion”. The present invention relates to an oriented film combination of:
(a) a base layer of polypropylene at least one surface of which comprises a maleic acid anhydride modified polypropylene; and (b) on at least one surface, a skin layer of an amorphous polyamide or a blend of an amorphous polyamide and a semicrystalline polyamide.

Another reference has been made to patent no. WO2020234890A1 by Cosmo Films Limited dated 2019-05-21 titled “Metallized polyethylene film with improved metal adhesion”. The present disclosure relates to a multilayer film comprising:
a) a metallizable skin layer comprising a polyolefin and an antiblock; b) a middle core layer comprising a homopolymer PP resin and a stiffener; and c) a sealant layer comprising a copolymer and an antiblock. Said a multilayer film has high metal bond and high barrier properties and can be used in packaging of foods requiring very high metal bond and high barrier to oxygen and moisture.

Another reference has been made to US patent no. US8569411B2 by Earth First Industries Inc Smart Planet Tech Inc dated 2019-05-21 titled “Flexible packaging composites”. The present discloses flexible packaging composites include one or more mineral-containing layers with a thermoplastic bonding agent. In addition to the mineral-containing layer, the composite can contain one or more non-mineral containing layers, including various combinations of extruded resins, cast or blown films, and fibers. The mineral-containing layer is substantially and continuously bonded to the other layers. The polymer, fiber, and mineral containing layers can be shaped, sized and manufactured such that composite structure formed is subsequently machined to form a storage article. The composite structure has advantages including a high degree of pliability and flexibility, a minimum 37 dyne level on the surface of the mineral-containing layer; a mineral-containing layer that is highly 86 opaque, and has a bright, white printing surface that readily accepts coating and inks, therefore, rendering it highly attractive to consumers.

Another reference has been made to patent no. CA2822446C by Frito Lay North America Inc dated 2007-08-31 titled “Environmentally-friendly multi-layer flexible film having barrier properties”. The present invention discloses multi-layer film with barrier properties having one or more layers made from a bio-based film is disclosed. In one aspect, the print web comprises a bio-based film. In one aspect, the barrier web comprises a bio-based film. In one aspect, a bio-based adhesive adheres the print web to the barrier web. The bio-based film can include paper, PCR, polylactide or polyhydroxy-alkanoate. Unlike prior art petroleum-based films, the bio-based film of the present invention is made from a renewable resource and is biodegradable.

Another reference has been made to patent no. JP6211517B2 by E.I. Dupont Doe Nemours and Company dated 2011-07-27 titled “Multi-layer film for reclosable packaging”. The present invention a multilayer structure comprising in this arrangement a heat-sealable layer, a pressure sensitive adhesive layer, a tie layer and a structural layer, The heat-sealable layer comprises amorphous polyethylene terephthalate having a melting temperature higher than 200 ° C; The tie layer comprises a polymer composition having a melting temperature of 80-120 ° C., one surface of the tie layer is in direct contact with the pressure sensitive adhesive layer, and the other surface of the tie layer is In direct contact with the structural layer, The structural layer is an ethylene homopolymer, ethylene a-olefin copolymer, propylene homopolymer, propylene a-olefin copolymer, polyethylene terephthalate, metallized polyethylene terephthalate, oriented polypropylene, oriented polyamide, polyvinyl chloride, polyacrylonitrile, paper, foil, And comprising at least one of the heat-sealable layer or the composition of the structural layer has a melting point higher than the decomposition temperature of the pressure-sensitive adhesive.

Another reference has been made to US patent no. US8734933B2 by Toray Plastics America Inc dated 2009-09-25 titled “Multi-layer high moisture barrier polylactic acid film”. The present invention relates to a laminate film including a first core polylactic acid layer, a coating receiving-layer of polylactic acid, and coated on one side of the coating receiving-layer with PVOH, EVOH, a blend of crosslinked EVOH/PVOH, vinyl alcohol-vinylamine (PVAm) copolymer, anionic carboxylated styrene-butadiene copolymer (SBR) emulsion, or blends thereof. This coating may be applied after the machine-direction orientation step and dried and oriented in a transverse direction orientation oven if in-line coating is desired; or applied to the film in an off-line coating method and dried in an air flotation oven. The dried coating layer can be metallized. This laminate film exhibits excellent gas and moisture barrier properties, appearance, and metal adhesion. It may also optionally include a heat sealable or winding improving layer on the side opposite the coating receiving-layer of the core layer.

Another reference has been made to US patent no. US20170361993A1 by Transcontinental Us LLC Coveris Holding Corp dated 2005-08-19 titled “Bags having composite structures and related methods”. The present invention relates A bag can include walls formed of a material having multiple layers, which can include a paper layer located between an outer layer and an inner layer. The outer layer can be formed from a nylon material and the inner layer can be formed from a polyolefin material, and the bag can exhibit grease-resistant properties. The bag can be formed into a variety of configurations, such as a sewn-open-mouth configuration in which a stitching element extends through a wall of the bag or a variety of pinch-type closure configurations.

Another reference has been made to US patent no. US9969150B2 by Transcontinental Us LLC Coveris Holding Corp dated 2012-12-20 titled “Multilayer films of FDCA-based polyesters”. The present invention relates to a multilayer film comprising (a) a biaxially-oriented polyethylene furanoate (BO-PEF) polymer layer, (b) an optional ink layer, (c) a bonding layer, and (d) a sealant layer, wherein the BO-PEF polymer has an O2 gas permeability of less than 0.25 cc- mil/100 in.2 24 hrs atm at 80% relative humidity, or a moisture permeability of less than 0.5 g-mil/100 in.2 24 hrs atm at 38° C., or both. The film may be formed from microlayers of BO-PEF-based polymer and polymer with a melting point of at least 5° C. greater than the melting point of the BO-PEF-based polymer. A multilayer film comprising (a) a biaxially-oriented polyethylene furanoate (BO- PEF) polymer layer, (b) an optional ink layer, (c) a bonding layer, and (d) a sealant layer, wherein the BO-PEF polymer has an O2 gas permeability of less than 0.25 cc-mil/100 in.2 24 hrs atm at 80% relative humidity, or a moisture permeability of less than 0.5 g-mil/100 in.2 24 hrs atm at 38° C., or both. The film may be formed from microlayers of BO-PEF-based polymer and polymer with a melting point of at least 5° C. greater than the melting point of the BO-PEF-based polymer.

Another reference has been made to Indian patent no. 202147001511 by TOYOBO CO., LTD. dated 19/06/2018 titled “polypropylene-based multilayer film”. The present invention provides a polypropylene-based multilayer film having high heat resistance and high rigidity. The polypropylene-based multilayer film comprises a base layer (A) which is constituted of a polypropylene-based resin satisfying the following requirements 1) to 4) and contains an antifogging agent and, disposed
on one or both surfaces of the base layer (A), a heat-sealing layer (B) constituted of a polyolefin-based resin. The polypropylene-based multilayer film has a lower- limit coefficient of planar orientation of 0.0125. 1) To have a lower-limit mesopentad content of 96%. 2) To have an upper-limit content of comonomers other than propylene of 0.1 mol%. 3) To have a [mass-average molecular weight (Mw)]/[number-average molecular weight (Mn)] of 3.0-5.4. 4) To have a melt flow rate (MFR), as determined at 230°C and 2.16 kgf, of 6.2-9.0 g/10 min.

Metallized CPP film due to its inherent weaknesses of poor WVTR properties, extremely poor OTR Properties, Poor Bond between the bare and the metal layer, high seal initiation temperature and inferior hot tack values meant that the use of metallized CPP film has been extremely limited when compared to even the general grade metallized BOPP film.
Due to the above-mentioned limitations, in spite of the fact metallized CPP in general has a better seal strength and also tensile strength as compared to BOPP film, yet the use of CPP was restricted to large pack and for smaller packs the preferred sealant layer was always Met BOPP.

However, none of the above discussed inventions discloses an improved multilayer high barrier extrusion grade metalized cast poly propylene film and a method of manufacturing thereof. The present invention has overcome the above discussed problems in the prior art. The present invention provides a CPP film which is much superior to any CPP film ever made and even superior to the general grade Metallized Bopp films in most of the functional properties. The metallized CPP of present invention ensures high speed machinability of food packaging material or other substances being packed, increased shelf life due to increased metal bond, excellent OTR and WVTR parameters and eliminates the use of metallized Polyester or metallized BOPP as a sandwich or middle layer in processed food packaging, thereby ensuring a fully recyclable and sustainable structure.

Objectives of the Invention:
The main objective of the present invention is to provide an improved multilayer high barrier metalized cast polypropylene film.
Another objective of the present invention is to provide high barrier metalized cast polypropylene extrusion grade film.
Another objective of the present invention is to provide multilayer metalized cast poly propylene film having strong metal bonds.
Another objective of the present invention is to provide multilayer metalized cast poly propylene having recyclable laminated film.
Another objective of the present invention is to provide extrusion grade metallized film which can be laminated by extrusion process to printed film.
Another objective of the present invention is to provide film high barrier like oxygen and water vapor (OTR & WVTR) for any packaged food.
Summary of the Invention:
The present invention is provided an improved multilayer metalized cast polypropylene (CPP) film consisting of thickness ranging from 15 microns to 50 microns. The film provides high barrier to oxygen transmission rate and water vapor transmission rate thus preserving the packaged food. The metalized cast polypropylene film layer consists of 3 to 7 layers. The top layer / Outer layer is a metallizable layer. The middle layer or layers, which can be 1 to 5 in number, depending on the machine configuration typically use Homo Polymers. Polypropylene and Polyethylene based CO-polymers are used in the inner or sealant layer. The multilayer metalized cast polypropylene film having strong metal bond ranging from 150 to 900 gmf. The disclosure reveals about recyclable, laminated, high binding force metalized film having special additives. The metallized CPP of present invention can be perfectly laminated even at a dyne value of 34 dynes by any adhesive lamination method be it solvent base or solvent less adhesive against the normal dyne requirement of 38 dynes for Lamination purposes. The film of present invention is a combination of Machine Processability, Recipe and use of Oxygen treatment of the film during metallization, which is a unique process of enhancing metal bond and barrier properties.
Statement of the Invention:
The present invention provides an improved multilayer high barrier extrusion grade metalized cast polypropylene film and a method of manufacturing thereof; the film provides high barrier to oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) thus preserving the packaged food; the metalized cast polypropylene film layer consists of 3 to 7 layers; the extrusion coated laminates made from the use of film of present invention are superior in quality due to the metal bond in excess of 150 gmf – 900 gmf and a film which has a low WVTR of 0.30 and below and an OTR of less than or equal 40.
Brief Description of the Drawing:
Figure 1: The figure/flow chart given describes the overall process flow for preparing the film of present invention.
Detailed Description of the Invention:
It should be noted that the particular description with features, designs, components, construction, working and embodiments set forth in the specification below are merely exemplary of the wide variety and arrangement of instructions which can be employed with the present invention. The present invention maybe embodied in other specific forms without departing from the spirit or essential characteristics thereof. All the features disclosed in this specification may be replaced by similar other or alternative features performing similar or same or equivalent purposes. Thus, unless expressly stated otherwise, they all are within the scope of present invention. Various modifications or substitutions are also possible without departing from the scope or spirit of the present invention. Therefore, it is to be understood that this specification has been described by way of the most preferred embodiments and for the purposes of illustration and not limitation.

The present invention relates to a metallized cast polypropylene film (CPP), which is improved in many properties than such films in prior art and is recyclable.

The Metallized CPP or Metallized Cast polypropylene film of present invention has a very high metal bond, much superior water vapor transmission ratios and oxygen transmission ratios when compared to other Metallized CPP films available in the market or being produced. The metallized CPP of present invention can be perfectly laminated even at a dyne value of 34 dynes by any adhesive lamination method be it solvent base or solvent less adhesive against the normal dyne requirement of 38 dynes for Lamination purposes.
The film has applications in multiple laminate structures. The extrusion coated laminates made from the use of film of present invention are superior in quality due to the metal bond in excess of 150 gmf – 900 gmf and a film which has a low WVTR of 0.30 and below and an OTR of less than or equal 40.
The metalized CPP film of present invention, when used in Extrusion process has the capability to withhold Nitrogen flushing.

A comparative table has been provided below with features of films known in the art as compared to the features of the present invention, which proves how much improved and better is the film of present invention:

Property Metallized BOPP normal grade Metallized CPP normal Grade Metallized CPP of present invention
SIT Range in Degree Celsius 110-115 115-120 80- 115
Seal Strength Max 450 gms 1200 gms More than 1500 gms
Hot tack Poor Moderate Very High
WVTR
Less than 1gm Less than 1gm 0.30 and below
OTR Less than 100 Less than 125 40 and below

Metal bond Approx. 100-150 gms 30-150 gms 150 gms to 900 gms

Treatment 38 dynes 38 dynes 34 dynes - can be perfectly laminated even at 34 dynes

Lamination type suitable- adhesive
Suitable Suitable Suitable
Lamination type suitable- Extrusion Not suitable- Metal failure observed Not suitable- Metal failure observed Suitable
Packaging Speed suitability Normal Normal Very high to high speed

The film of present invention is a combination of Machine Processability, Recipe and use of Oxygen treatment of the film during metallization, which is a unique process of enhancing metal bond and barrier properties.

Further alteration of regular standard process is being done, by doing slitting before the step of metallizing, which provides a significant impact on metal bond and barrier properties.

The film in combination with BOPP is a highly Sustainable laminate and will have a very positive impact on sustainable packaging.

The metallized CPP of present invention ensures high speed machinability of food packaging material or other substances being packed, increased shelf life due to increased metal bond, excellent OTR and WVTR parameters and eliminates the use of metallized Polyester or metallized BOPP as a sandwich or middle layer in processed food packaging, thereby ensuring a fully recyclable and sustainable structure.

With the properties of high metal bond, both with the printed Ink as well as with the bare CPP film, the high metal bond between metal layer and bare film has an additional advantage on the printed film to metal bond, the adherence improves significantly which results in better functional performance of the pack.

Along with Low WVTR and OTR parameters as a result the film of present invention provides high Barrier properties along with high-speed machinability.
Due to these features, the film can be easily used in combination with transparent Biaxially oriented polypropylene (BOPP), Machine direction oriented Poly ethylene (MDO-PE) or Machine direction-oriented Poly propylene (MDO-PP) easily, after extrusion process / Adhesive process.
This results in a laminate having an OTR less than or equal to 40 depending upon the requirement, a WVTR of 0.30 and below, along with Nitrogen and air retention properties, excellent machinability, and all these properties without the fear of metal failure or barrier issues and above all a laminate which is fully recyclable and supports sustainability.

PROCESS and FILM DETAILS:

OUTER LAYER/TOP LAYER: The Cast Poly Propylene film of present invention can be made on a 3 layer to 7-layer CPP or CPE film line. All layers apart from the Top/ Outer Layer and Bottom layer / Inner layer can be termed as Middle layers.

The Top layer / Outer layer is a metallizable layer. A combination of Random co-polymers of Polyolefin are being used, which belong to Poly-propylene and Poly-ethylene family along with Ethylene 1- Hexane Copolymers and metallocene grade Polymers. These polymers have a density 0f 0.90 to 9.0 g/cm3 and Melt Flow Index (190 degree C /2 .16 kg) of 3.0g – 10.5 /10 Min (ASTM D1238, ISO 1133). The properties of the Outer layer or Top layer are further enhanced by use of MET Block granules which imparts good anti block properties as well as maintains the desired level of COF (Co-efficient of friction) in the film, we also use HO block granules in the outer layer – this prevents the blocking of the film onto the roll creating bumps on the film surface allowing the air to be trapped. The synthetic silica used in HO BLOCK is specially formulated for CPP plain film.

The Superior quality metallisable CPP FILM is further supported by another Superior process – Metallization process is done with a unique metallizer comprising of latest and novel features wherein a special gas is used in the metallization chamber which results in increasing the metal bond and barrier values, and results in exceptionally high strong bond of metal (preferably aluminum) in the metalized film, and increases adhesion, surface energy and barrier properties. The high dyne retention as a result of this system results in improved wettability and enhanced structure stability during lamination.
Thus, a combination of innovative polymer combination, state of art metallization process and innovative process results in Metal bonds in Cast Poly Propylene film in excess of 150 grams - 150 GMS TO 900 GMS when measured with a 25 mm strip. WVTR Readings of 0.30 and below (depending on requirements) and an OTR reading less than or equal to 40 (depending on the requirement) along with high Dyne retention.

MIDDLE LAYER: The middle layer or layers, which can be 1 to 5 in number (1), depending on the machine configuration typically use Homo Polymers having a Density (23 degree C, Method D) of 0.88 - .092 and Melt Flow Index (230-degree C/2.16kgs) of 3.0 to 10.0 – Test Method ISO 1133 and also the outer trim / edge width is grinded inline and used along with the Homo polymer film Resins to save on wastages. The combination of granules is subjective to the requirements of stiffness and molecular weight distribution required in the CPP film and also subjective to the requirement of a seal range and the broader Hot tack window, and improved metallisable barrier requirements in the metallized Cast Poly Propylene film.

INNER LAYER: Polypropylene and Polyethylene based CO-polymers are used in the inner or sealant layer. The Polyolefin polymers used are a combination of PP Co-Polymers, Ethylene based polymers blended with Performance polymers which are crystalline copolymers with tunable amorphous content and are compatible with other Polyolefinic materials, a percentage of MET block is further added to ensure enhanced performance. Terpolymers with low SIT for skin layer of CPP are also used.

COATING: Once a bare CPP film is made, it can go through a special coating process (barrier and other properties enhancers), which is determined by the requirements of the final product. This coating can be applied either before or after metallization.

METALLISATION: The Cast poly Propylene film is used for metallization by use with or without Plasma treatment depending on the levels of WVTR requirements in the end product and as a result of various permutations and we can achieve the WVTR values of 0.30 and below and OTR Values of less than or equal to 40 in the Metallized CPP film of present invention, depending upon the end product requirements. The metal bond is exceptionally high and the range is a minimum 150 gmf to a maximum of 900 gmf when measured on a 25 mm strip. The metallization Optical Density is in the range between 1.9 to 3.1 depending on the OTR and WVTR requirement. Metallization process is done with a unique metallizer comprising of latest and novel features wherein a special gas is used in the metallization chamber which results in increasing the metal bond and barrier values, and results in exceptionally high strong bond of metal (preferably aluminum) in the metalized film, and increases adhesion, surface energy and barrier properties. The high dyne retention as a result of this system results in improved wettability and enhanced structure stability during lamination.

The present invention provides an improved multilayer high barrier metallized cast polypropylene film. It discloses about recyclable, laminated, high binding force metallized film having special additives.
The metallized cast polypropylene film’s thickness ranges from 15 microns to 50 microns containing 3 to 7 layers. The film incorporate laminate made up of Biaxially Oriented Polypropylene (BOPP) having thickness 10 to 40 microns and Polyethylene Terephthalate (PET) having thickness 8 to 18 microns.
The disclosure reveals that WVTR barrier is 0.3 grams/m2 and below, OTR barrier of 40 cc/m2 and below, and the metal bond strength ranges from 150 to 900 gmf.
The disclosure is to provide an extrusion coated printed film on which barrier coating is done that results in high barrier to OTR and WVTR. The multilayer film is recyclable and laminated by using BOPP and PET material.
The properties of the metallized cast polypropylene film have been mentioned in the table 1 below:
Table 1:

Properties Values
Film thickness 15 to 50 in microns
CPP 5 layer 3 to 7 layers
WVTR 0.3 grams/ m2
OTR 40 cc/m2
Metal Bond range 150-900 gmf
Laminate BOPP 12, 15, or 18 microns
PET 10 or 12 microns

The present invention provides a multilayer metallized cast polypropylene (CPP) film prepared and then slit into the required sizes, the process of slitting is done before metallization to avoid the friction caused by the slitter and avoid a process known as Metal Erosion due to friction of metal-to-metal contact in slitting machine, this results in better OTR and WVTR parameters.

Examples:
The following examples are given by way of illustration of the present invention and should not be construed to limit the scope of present disclosure:
Example 1:
The multilayer metallized cast polypropylene film may comprise of components and range as mentioned in the table below.
Properties Values
Film thickness 22 in microns
CPP layer 5
WVTR 0.30 grams/ m2
OTR 24 cc/m2
Metal Bond 500 + gmf
Laminate
PET 10 microns

Example 2:
In another example of the metallized cast polypropylene film may contains the composition:
Properties Values
Film thickness 25 in microns
CPP layer 5
WVTR 0.25 grams/ m2
OTR 20 cc/m2
Metal Bond 650 gmf
Laminate BOPP 15 microns

The testing of various parameters is being done by the below mentioned testing methods:

1. SIT (Seal initiation temperature) ASTM -F 2029-2000.
2. Seal Strength- ASTM – F88-99- machine speed should be 200-300mm/min.
3. Hot tack -ASTM- F1921.
4. WVTR – ASTM- F 1249- gms/ per meter sq/ per 24hrs at 38 degree Celsius and 90% Relative Humidity.
5. OTR- ASTM- F3985 – CC / per meter sq / per 24 hrs at 23 degree Celsius and 0% relative humidity.
6. Metal Bond – test method is Amical test kit.
All of the above-mentioned parameters are specified and used in the present invention and are not repeated for the sake of brevity.
Referring to figure 1 is an overall process flow for preparing the film of present invention. After quality control approval, the raw material is released from the store, which imparts good anti block properties as well as maintains the desired level of COF (co-efficient of friction) in the film granules. The CPP machine include four-hopper loader, which is used to hold materials before they are transferred into the CPP machine and further forms inner five layer. The further process includes a seeding/outer layer formation, a core layer formation, and a corona treatment formation, all of which pass through the die lip. The CPP film formation start either 3 layer or 5 layers. Further, the process involves corona treatment, which increases the surface energy of the plastic films and their wettability, coating, and adhesives. Thickness monitoring scanner; monitor the thickness of the film. The jumbo roll exits the machine and is processed further in a slitter machine, where it is slit to the desired width and now film is ready to use. Following the slitting process, the natural CPP is reprocessed in one of three ways to make the film ready for use: (a) natural CPP reprocessed to metalised CPP with metalisation process. (b) natural CPP reprocessed with special coating and then put to metalisation process to get metalised CPP. (c) natural CPP reprocessed to metalised CPP with metalisation process and then special coating applied.
In an embodiment, said an improved, environment friendly, recyclable, Metallized Cast Poly Propylene film (CPP) film, with a very high metal bond, Lower water vapor transmission ratios and oxygen transmission ratios when compared to other metallized CPP films available in the market or being produced, said film is able to be perfectly laminated even at a dyne value of 34 dynes by any adhesive lamination method be it solvent base or solvent less adhesive against the normal dyne requirement of 38 dynes for Lamination purposes, once a bare CPP film is made, it can go through a special coating process; said film having 3 to 7 layers as defined herein, such that said film is cut or slit before being metalized, so as to avoid the friction caused by the slitter and avoid a process known as Metal Erosion due to friction of metal to metal contact in slitting machine, thus resulting in better OTR and WVTR parameters; said film ensuring high speed machinability of food packaging material or other substances being packed, increased shelf life due to increased metal bond, and eliminates the use of metallized Polyester or metalized BOPP as a middle layer in processed food packaging, thereby ensuring a fully recyclable and sustainable structure film.
In another embodiment, said film is comprising 3 to 7 layers, which are: one top layer, one or plurality of middle layers and one bottom or sealant layer.
In another embodiment, said top layer is comprising of polypropylene Co-polymers, High metal adhesion polymers, a combination of HDPE and PE granules to enable high metal bond retention.
In another embodiment, said top layer is a Metallisable layer, said layer comprising of a combination of Random Co Polymers of Polyolefin which belong to Poly Propylene and Poly Ethylene Family along with Ethylene 1- Hexane Copolymers and Metallocene grade Polymers, having a density 0f 0.90 to 9.0 g/cm3 and Melt Flow Index (190 degree C /2 .16 kg) of 3.0g – 10.5 /10 Min (ASTM D1238, ISO 1133).
In another embodiment, said middle layers or layers are comprising homo-polymers having a Density (23 degree C, Method D) of 0.88 - .092 and Melt Flow Index (230-degree C/2.16kgs) of 3.0 to 10.0 – Test Method ISO 1133 and also the outer trim / edge width is grinded inline and used along with the Homo polymer film Resins to save on wastages as per the requirements of stiffness and molecular weight distribution required in the CPP film.
In another embodiment, said inner or sealant layer is comprising Poly Propylene based Co-polymers, Polyolefin polymers, a combination of PP Co- Polymers, Ethylene based polymers blended with Performance polymers which are crystalline copolymers with tunable amorphous content and are compatible with other Polyolefin materials, a percentage of MET block is further added to ensure enhanced performance.
In another embodiment, said film is used for metallization by use with or without Plasma treatment depending on the levels of WVTR requirements in the end product and as a result of various permutations and we can achieve the WVTR values of less than or equal to 0.30 and an OTR Values of less than or equal to 40 in our Metallized CPP film depending upon the end product requirements.
In another embodiment, after making the bare CPP film, coating it through a special coating process (barrier and other properties enhancers), as per the requirements of the final product; such that this coating is applied either before or after metallization process.
In another embodiment, said film has a Seal Initiation Temperature (SIT) is in the range of 80- 115 degree Celsius.
In another embodiment, said film has a seal strength of more than 1500 gram.
In another embodiment, said middle layers are having a surface adhered to each other and the base surface of middle layer is adhered to the Bottom or the sealant layer (layer 5), on which barrier coating is done for providing high barrier properties to oxygen transmission rate (OTR) and water vapor transmission rate (WVTR); said middle layers comprising combination of PP homo polymers; said multilayer metallized cast polypropylene film having strong metal bond ranging from 150 gmf to 900 gmf has very good machinability attributes, ensuring Low SIT, low and broad Hot tack window, and excellent seal strengths, so as not to adversely affect the oxygen and water vapor barrier properties of said film.
In another embodiment, said film’s total thickness is in the range of 15 microns to 50 microns.
In another embodiment, said film has an oxygen transmission rate (OTR) barrier of 40 cc/m2 and below, and water vapor transmission rate (WVTR) barrier of 0.3 grams/m2 and below.
In another embodiment, said film has a Metal bond strength in the range of 150 to 900 gmf.
In another embodiment, said film is treatable and is perfectly laminated even at 34 dynes.
In another embodiment, said film is recyclable and is laminated by using BOPP and PET material.
In another embodiment, said a method of preparing multilayer metallized cast polypropylene film comprised of following steps (1): selection of raw materials as per the total number of layers in film, transporting raw materials to the machines by separate hopper loaders to load and extrude to form said multilayer cast polypropylene film, after formation said film is passed through rolls and slitters to cut in desired size and finally the slit pieces are metallized to result in the final multilayer metallized cast polypropylene film product.
In another embodiment, said film prepared is then slit into the required sizes before metallization, so as to avoid the friction caused by the slitter and avoid a process known as Metal Erosion due to friction of metal-to-metal contact in slitting machine, thus resulting in better OTR and WVTR parameters.
In another embodiment, said the film produced and then slit after a specific relaxation time, and then the metallization layer is applied.
In another embodiment, said the metallization is done with a unique metallizer comprising of latest and novel features wherein a special gas is used in the metallization chamber which results in increasing the metal bond and barrier values, and results in exceptionally high strong bond of metal (preferably aluminum) in the metalized film, and increases adhesion, surface energy and barrier properties. The high dyne retention as a result of this system results in improved wettability and enhanced structure stability during lamination.
While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects and, therefore, the aim in the present invention is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

Advantages of the invention:

1. The film of present invention has reduced consumption as it is replacing thicker layers of polymers being currently used.
2. The film is completely recyclable and hence is 100% sustainable.
3. With better barrier properties, it has higher shelf life, resulting in protecting foods for a longer period of time.
4. Enhancement in speed of packing will increase efficiency at brand level and result in reduced cost.
5. Lower SIT will result in lower power consumption which has direct impact on cost saving as well as environmental sustainability.
6. It results in overall reduction in packaging material consumption.
, Claims:We Claim:
1. An improved, environment friendly, recyclable, Metallized Cast Poly Propylene film (CPP) film, with a very high metal bond, Lower water vapor transmission ratios and oxygen transmission ratios when compared to other metallized CPP films available in the market or being produced, said film is able to be perfectly laminated even at a dyne value of 34 dynes by any adhesive lamination method be it solvent base or solvent less adhesive against the normal dyne requirement of 38 dynes for Lamination purposes, coating the bare CPP film after making with a special coating process; said film having 3 to 7 layers as defined herein, such that said film is cut or slit before being metalized, so as to avoid the friction caused by the slitter and avoid a process known as Metal Erosion due to friction of metal to metal contact in slitting machine, thus resulting in better OTR and WVTR parameters; said film ensuring high speed machinability of food packaging material or other substances being packed, increased shelf life due to increased metal bond, and eliminated use of metallized Polyester or metalized BOPP as a middle layer in processed food packaging, thereby ensuring a fully recyclable and sustainable structure film.
2. The improved, environment friendly, recyclable, Metallized Cast Poly Propylene film (CPP) film as claimed in claim 1, wherein said film is comprising 3 to 7 layers, which are: one top layer, one or plurality of middle layers and one bottom or sealant layer.
3. The improved, environment friendly, recyclable, Metallized Cast Poly Propylene film (CPP) film as claimed in claim 1, wherein said top layer is comprising of polypropylene Co-polymers, High metal adhesion polymers, a combination of HDPE and PE granules to enable high metal bond retention.
4. The improved, environment friendly, recyclable, Metallized Cast Poly Propylene film (CPP) film as claimed in claim 1, wherein said top layer is a Metallisable layer, said layer comprising of a combination of Random Co Polymers of Polyolefin which belong to Poly Propylene and Poly Ethylene Family along with Ethylene 1- Hexane Copolymers and Metallocene grade Polymers , having a density 0f 0.90 to 9.0 g/cm3 and Melt Flow Index ( 190 degree C /2 .16 kg) of 3.0g – 10.5 /10 Min ( ASTM D1238, ISO 1133).
5. The improved, environment friendly, recyclable, Metallized Cast Poly Propylene film (CPP) film as claimed in claim 1, wherein said middle layers or layers are comprising homo-polymers having a Density( 23 degree C, Method D) of 0.88 - .092 and Melt Flow Index (230 degree C/2.16kgs) of 3.0 to 10.0 – Test Method ISO 1133 and also the outer trim / edge width is grinded inline and used along with the Homo polymer film Resins to save on wastages as per the requirements of stiffness and molecular weight distribution required in the CPP film.
6. The improved, environment friendly, recyclable, Metallized Cast Poly Propylene film (CPP) film as claimed in claim 1, wherein said inner or sealant layer is comprising Poly Propylene based Co-polymers , Polyolefin polymers, a combination of PP Co- Polymers, Ethylene based polymers blended with Performance polymers which are crystalline copolymers with tunable amorphous content and are compatible with other Polyolefin materials, a percentage of MET block is further added to ensure enhanced performance.
7. The improved, environment friendly, recyclable, Metallized Cast Poly Propylene film (CPP) film as claimed in claim 1, wherein said film is used for metallization by use with or without Plasma treatment depending on the levels of WVTR requirements in the end product and as a result of various permutations and we can achieve the WVTR values of less than or equal to 0.30 and OTR Values of less than 40 in our Metallized CPP film depending upon the end product requirements.
8. The improved, environment friendly, recyclable, Metallized Cast Poly Propylene film (CPP) film as claimed in claim 1, wherein after making the bare CPP film, coating it through a special coating process (barrier and other properties enhancers), as per the requirements of the final product; such that this coating is applied either before or after metallization process.
9. The improved, environment friendly, recyclable, Metallized Cast Poly Propylene film (CPP) film as claimed in claim 1, wherein said film has a Seal Initiation Temperature (SIT) is in the range of 80- 115 degree Celsius.
10. The improved, environment friendly, recyclable, Metallized Cast Poly Propylene film (CPP) film as claimed in claim 1, wherein said film has a seal strength of more than 1500 gram.
11. The improved, environment friendly, recyclable, Metallized Cast Poly Propylene film (CPP) film as claimed in claim 1, wherein said middle layers are having a surface adhered to each other and the base surface of middle layer is adhered to the bottom or the sealant layer (layer 5), on which barrier coating is done for providing high barrier properties to oxygen transmission rate (OTR) and water vapor transmission rate (WVTR); said middle layers comprising combination of PP homo polymers; said multilayer metallized cast polypropylene film having strong metal bond ranging from 150 gmf to 900 gmf has very good machinability attributes, ensuring Low SIT, low and broad Hot tack window, and excellent seal strengths, so as not to adversely affect the oxygen and water vapor barrier properties of said film.
12. The improved, environment friendly, recyclable, Metallized Cast Poly Propylene film (CPP) film as claimed in claim 1, wherein said film’s total thickness is in the range of 15 microns to 50 microns.
13. The improved, environment friendly, recyclable, Metallized Cast Poly Propylene film (CPP) film as claimed in claim 1, wherein said film has an oxygen transmission rate (OTR) barrier of 40 cc/m2 and below, and water vapor transmission rate (WVTR) barrier of 0.30 grams/m2 and below.
14. The improved, environment friendly, recyclable, Metallized Cast Poly Propylene film (CPP) film as claimed in claim 1, wherein said film has a Metal bond strength in the range of 150 to 900 gmf.
15. The improved, environment friendly, recyclable, Metallized Cast Poly Propylene film (CPP) film as claimed in claim 1, wherein said film is treatable and is perfectly laminated even at 34 dynes.
16. The improved, environment friendly, recyclable, Metallized Cast Poly Propylene film (CPP) film as claimed in claim 1, wherein said film is recyclable and is laminated by using BOPP and PET material.
17. The improved, environment friendly, recyclable, Metallized Cast Poly Propylene film (CPP) film as claimed in claim 1, wherein said method of preparing multilayer metallized cast polypropylene film comprised of following steps (1): selection of raw materials as per the total number of layers in film, transporting raw materials to the machines by separate hopper loaders to load and extrude to form said multilayer cast polypropylene film, after formation said film is passed through rolls and slitters to cut in desired size and finally the slit pieces are metallized to result in the final multilayer metallized cast polypropylene film product.
18. The method of preparing multilayer metallized cast polypropylene film as claimed in claim 17, wherein said the film prepared is then slit into the required sizes before metallization, so as to avoid the friction caused by the slitter and avoid a process known as Metal Erosion due to friction of metal-to-metal contact in slitting machine, thus resulting in better OTR and WVTR parameters.
19. A method of preparing multilayer metallized cast polypropylene film as claimed in claim 17, wherein said the film produced and then slit after a specific relaxation time, and then the metallization layer is applied.
20. A method of preparing multilayer metallized cast polypropylene film as claimed in claim 17, wherein said the metallization is done with a unique metallizer comprising of latest and novel features wherein a special gas is used in the metallization chamber which results in increasing the metal bond and barrier values, and results in exceptionally high strong bond of metal (preferably aluminum) in the metalized film, and increases adhesion, surface energy and barrier properties; the high dyne retention as a result of this system results in improved wettability and enhanced structure stability during lamination.