Title of Invention

"A FILM FOR PACKAGING AND A PROCESS FOR PREPARING THE SAME"

Abstract The present invention relates to a film for packaging comprising layers of biaxially oriented material, low density polymer and composite film, said film having superior barrier properties and the process of preparation thereof. (Fig 1)
Full Text FIELD OF THE INVENTION:
The present invention relates to a film for packaging having superior barrier properties. A process for preparing such a film is also provided. The invention also provides a pouch prepared employing the film of the invention.
BACKGROUND OF THE INVENTION:
The packaging industry utilizes polymeric packages for packaging and transporting of various products such as, liquid food, snacks, drugs and the like. Most of such flexible packaging are laminates comprising two or more different layers, each of different materials. In order to benefit from respective advantageous properties of various materials, they are often laminated together into a packaging laminate. The aim is often to provide the best possible protection to the product to be packed, at the same time the package is made sufficiently mechanically strong to allow for convenient handling.
To store food and pharmaceutical products over a long period of time, it is necessary to provide for packaging with excellent barrier properties, that is to say — one which is capable of preventing entry of oxygen and water vapor which accelerate deterioration and putrefaction. Further, it also helps to maintain the inner atmosphere inert, preventing the transmission of nitrogen from inside of the package to outside. In addition, the package is also required to be dimensionally stable to facilitate easy handling at the time of transport and distribution and prevent leakage at different altitudes.
Today, in the packaging industry, there is yet no 'ideal polymer barrier material. Moisture susceptibility, high cost, difficulties in recycling or disposal, inadequate barrier protection are some problems with current materials. herefore, efforts are on to provide low cost but high barrier polymeric material. Towards this end, the present invention provides a film having superior barrier properties and a process for producing the same.
OBJECTS OF THE INVENTION:
The main object of the invention is to provide an improved film having superior barrier properties and useful in packaging.
Another object is to provide a process for the preparation of a film with superior barrier properties.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
The accompanying drawings represent a preferred embodiment of the
invention wherein:
Figure 1: depicts a film of the invention. Wherein,
1 = a inner three layered sealant film- metallocene based PE,
2 = dry lamination (solvent less)
3= inner barrier plasma treated met PET 4= outer film printable, non barrier BOPP
STATEMENT OF INVENTION
Accordingly, the present invention relates to a film for packaging comprising,
i. a first layer composed of a polymer selected from biaxial ly oriented polypropylene, polyethylene terephthalate and polyethylene naphthylene terephtlalate and polyethylene naphthalate, the layer optionally coated with nitrocellulose and optionally adapted for printing and ink anchorage;ii. a second layer composed of a polymer selected from low density polyethylene or polypropylene;
iii. a third layer of film selected from a polymer selected from polyethylene terephthalate, biaxially oriented polypropylene or cast polypropylene, and metallised on one side employing plasma atmosphere; and
iv. a fourth layer composed of a composite film comprising two or three layers and made of a polymer selected from linear low density polyethylene.
Also the present invention relates to a process for preparing an improved film for packaging, said process comprising the steps of:
i. preparing a first layer composed of a polymer selected from biaxially oriented polypropylene, polyethylene terephthalate and polyethylene naphthalate, the layer optionally coated with nitro-cellulose;
ii. optionally subjecting one side of the film to corona treatment whereby the film is adapted for polyurethane based ink anchorage and the other side thereof is non-sealable and non-treated;
iii. providing a core layer of polyethylene by way of extrusion;
iv. preparing a third layer composed of a polymer selected from polyethylene terephthalate (PET) or biaxially oriented polypropylene (BOPP) or cast polypropylene (CPP) and subjecting it to the step of corona treatment and plasma metallization,
v. joining together the outer layer of step (i) with the third layer step (iii) with the layer of step (ii) there between by performing a step selected from co-extrusion, extrusion lamination or lamination using a water or solvent based primer coat;
vi. generating two to three layered film composed of 85-90& linear low density polyethylene (of metallocene grade) or case polypropylene and 10-15% low density polyethylene; and
vii. laminating the layer generated in step (vi) with the film prepared in step (v) by performing solvent-less lamination and obtaining the film of the invention
DETAILED DESCRIPTION OF THE INVENTION:
Accordingly, in one aspect, the invention provides a novel film comprising:
i) a first layer composed of a polymer selected from biaxially oriented polypropylene, polyethylene terephthalate and polyethylene naphthalate, the layer optionally coated with nitrocellulose and optionally adapted for printing and ink anchorage;
ii) a second layer composed of a polymer selected from low density polyethylene or polypropylene; and

iii) a third layer of a film selected from a polymer selected from polyethylene terephthalate, biaxially oriented polypropylene or cast polypropylene, the and metallised on one side employing plasma atmosphere; and
iv) a fourth layer composed of a composite film comprising two or three layers and made of a polymer selected from linear low density polyethylene or low density polyethylene or medium density polyethylene.
Thus, the film of the invention comprises four layers. The outermost layer is composed of a polymer selected from biaxially oriented polypropylene (BOPP), polyethylene terephthalate (PET) and polyethylene naphthalate (PEN). The said layer may optionally comprise a layer of a polymer as aforesaid and may be coated with nitrocellulose.

The thickness of this outermost layer may be about 10 to 35 microns. The thickness of the layer would vary with the kind of film used. For instance, if the film is BOPP, the thickness may be 15 to 25 microns; if nitrocellulose coated, it may be 12 to 18 microns and may range from 10 to 25 microns if the film is polyethylene terphthalate or naphthalate. The said layer may be adapted for ink anchorage and printing and is made so by corona treatment whereby at least one side thereof is rendered printable.

The second layer is composed of low density polyethylene or polypropylene. Preferably, the layer

is composed of extrusion grade PE. The said layer acts as an adhesive/binding layer. In addition, it adds to the barrier properties of the film and acts as a protective layer to metallization. The thickness of this layer may vary from 10 to 20 microns.
The third layer is an inner barrier layer composed of a polymer selected from polyester or polyethylene terephthalate, biaxially oriented polypropylene or cast polypropylene. This layer is metallised on its inner side. Metallisation in the case of the film of the invention is effected by plasma atmosphere. On account of such treatment, the layer provides consistent and excellent barrier properties. The film of the invention exhibits a water vapour transmission rate of less than 0.3 gms/sqm per 24 hours @38°C 90%RH and an oxygen transmission rate of less than Ice per sqm per 24 hours @23°C 0%RH which is not found in the currently existing films. Thus, such metallization enables the film of the invention to acts as a barrier for moisture and oxygen. As a result a package made employing the film of the invention can better store food and other edible items than conventional packages.
The thickness of this third layer may vary from 10 to 40 microns, depending on the material used; preferably 12 to 30 microns. This layer by its very presence ensures excellent dimensional stability and consistent barrier property.

The fourth layer is a composite film which may be composed of at least two layers: an outer layer, and a core layer. Preferably, the said layers of the fourth layer may be made of linear low density or low density polyethylene. The outermost layer acts as a sealant layer and the inner layer assists in lamination binding when bound to the other layers of the film of the invention.
Most preferably, the aforesaid fourth layer may be a three-layered film comprising an inner layer, core layer and an outer layer, composed of linear low density or low density polyethylene or cast polypropylene.
The said film may be made of metallocene polyethylene having 85-90% linear low density polyethylene and 10-15% low density polyethylene. A film so prepared exhibits good hot tack and is capable of being used over a broad sealing temperature range.
Preferably, the ratio of thickness : "15 : 12 : 12 .-25" of BOPP :Extr. PE :Met. PET : PE. The ratio of grammage : " 0.03 : 0.04 :0.06 :0.02" of BOPP :Extr. PE .-Met. PET : PE
The film of the invention may be prepared by co-extrusion or lamination or extrusion-lamination: however, irrespective of the process followed, the preparation of the film requires no solvent. As a result, the film prepared does not carry the odour of the solvent (no odour entrapment). This is important in case of food materials and other edible products

since the consumer is interested in the aroma and flavour of the product and if solvent is used, it may interferes with the aroma and flavour of the product contained. This problem has been effectively overcome in the present invention.
Since solvents and similar adhesives are not used, the cost of manufacture is also substantially cut down. The shelf-life of this film is also longer as compared to other prior art films.
Yet another advantage of the film of the invention is that the overall grammage of the package is substantially reduced for a particular thickness of film. The individual layers are so selected that the overall thickness of the film does not exceed 60-65 micron as compared to prior art films. An example of a film made according to the invention is shown in figure 1.
The film of the invention has not been derived out of known combinations of existing films and layers nor is it a mere re-arrangement of known films. This is for the reason that all polymers are not always compatible with each other. And, further, a combination such as to confer superior barrier properties without the use of any solvent is to be achieved. The inventors did try to perform lamination with the help of solvents: but they found that the system did not work and the final film did not provide the desired properties. Hence, the inventors developed the present film of the invention.

In another aspect, the invention provides a method for
preparation of the film of the invention, comprising
the steps of:
i) preparing a first layer composed of a polymer selected from biaxially oriented polypropylene, polyethylene terephthalate and polyethylene naphthalate, the layer optionally coated with nitrocellulose;
ii) optionally subjecting one side of the film to corona treatment whereby the film is adapted for polyurethane based ink anchorage and the other side thereof is non-sealable and non-treated;
iii) providing a core layer of polyethylene by way of extrusion;
iv) preparing a third layer composed of a polymer selected from polyethylene terephthalate (PET) or biaxially oriented polypropylene (BOPP) or cast polypropylene (CPP) and subjecting it to the step of corona treatment and plasma metallization at OD (optical density) of 2.4 - 2.7;
v) joining together the outer layer of step (i) with
the third layer step (iii) with the layer of step
(ii) therebetween by performing a step selected from
co-extrusion, extrusion lamination or lamination
using a water or solvent based primer coat;
vi) generating two or three layered film composed of 85-90% linear low density polyethylene (of metallocene grade) and 10-15% low density polyethylene; and
vii) laminating the layer generated in step (vi) with the film prepared in step (v) by performing solvent-

less lamination and obtaining the film of the invention.
In yet another embodiment, the invention provides a package constructed, employing the film made according to the invention.
The invention is now illustrated by the following examples and drawings which are not meant to limit the scope of the invention in any manner:
Example 1: Preparation of film of invention:
1) Printing- of the top substrate : 15 micron BOPP
15 micron transparent Biaxially oriented Polypropylene film with GSM of 13.5 , one side modified for better ink anchorage with minimum treatment level of 38 dynes and other side non heat sealable and untreated is printed on a standard gravure press at a speed of 140 m/min under drying temperature of 50 - 60degC at an air volume of 2800 - 3000 cfm ensuring no dimensional changes of the substrate. The Polyurethane based ink system is used for better adherence and solvent retention less than 3 mg/sqm.
To remove the stresses developed , retained solvent during printing operation , curing is carried out for 24 hours at 40degC.
2) Plasma Metallization of 12 micron PET film
Vacuum metallization of 12 micron Polyethylene Terephthalate (PET) film is carried out in a vacuum chamber , with pressure 5 x 1/100000 under plasma environment using 99.8% pure Aluminum at a speed of 400 - 500 m/min. . The film is unwound at a tension of


350 N and is subjected to the plasma atmosphere generated through a mixture of inert gases for surface polarization . The film with modified surface morphology is subjected to Aluminum vapors generated at a temperature of 1500deg C and immediately passed over a chilled drum at a temperature of - 20degC. The OD of film produced is in range of 2.4 - 2.7.
3) Extrusion lamination
Extrusion lamination of reverse printed BOPP film and plasma metallized PET film is carried out using LDPE of density 0.92 gm/cc and MFI 7 gm/lOmin on a standard extrusion lamination machine with extrusion temperature of 225- 305 degC and Die temperature varying from 320 - 330 degC at a speed of 120 m/min. For interlayer bond strength of 100g/25mm ,.0.1 gsm primer coating is given in dilution of 1:01 with water at a temperature of 50 - 65 degC immediately before lamination.
4) Solventless lamination
2 component PU based solventless adhesive in 100:45 ratio is used for lamination of BOPP/Extr. PE / Plasma met PET and 25 micron three layer PE film on a standard solventless lamination machine at a speed of 250 m/min. The nip temperature is maintained at 40degC with adhesive deposition of 2.2 -2.5 gsm. The 1st and 2nd unwinder tension is maintained at 1-6 Kgs and rewinder tension at 8-10 Kgs with laminating pressure of 3-6 Kg/sqcm for proper lamination and roll winding .To avoid any odour entrapment and stress

relieving , 48 hour curing is carried out before slitting.
Example 2:
As per the procedure described in example 1 above, the following different types of films were prepared. Table 1 compares the films prepared and their properties.
Conventional film structure:
12 mic.reverse printed PET /Solvent based Adhesive / 12 mic. Vacuum metallized PET / Solventless adhesive / 35 micron PE
Improved film structure :
15 mic reverse printed BOPP / 12 mic Extruded PE / 12 mic. Plasma metallized PET / Solventless adhesive / 25 micron PE

S.NO. PARAMETER CONVENTIONAL FILM STRUCTURE IMPROVED FILM STRUCTURE
1 Water vapour t ransmi s s i on rate (g/sqm/24hrs at 3 8degC,90%RH) 2 Oxygen transmission rate (cc/sqm24hrs at 2 3degC,0%RH 3 COF 0.2 -0.35 0.2 - 0.35
4 Thickness (microns) 60 65
5 GSM 63.4 68.64
6 Yield (gm/cm) 1.056 1.056
7 Shelf life (for snack foods) 14-16 weeks 16-18 weeks
8 Cost (Rs./sqm) If Rs X 2% lower than X

As may be seen from table 1, the water vapour transmission rate and oxygen transmission rate of the films prepared as per the process of the invention are less than the existing films.
Example 3:Preparation of package using film
The film of invention is mounted on vertical form fill seal machine and converted into a tube using a collar former and vertical " fin" seal at a temperature band of 150 degC - 170degC , followed by horizontal crimp seal at a temperature band of 145 deg C - 165 degC, thereby a three side sealed pouch is formed on a vertical form fill seal machine using the film of the invention. Both the horizontal seals are crimp seal and the vertical seal is fin seal. With the COF of the film varying between 0.2 - 0.35 and the sealant layer having a broad sealing temperature window, it can be used on high speed packing machines at 100 bags per minute.
The film of the invention gives superior barrier properties in terms of moisture and oxygen, and helps to increase the shelf life of the food products packed in. Secondly, since this is done using extrusion lamination, no solvents are used making it much more environment friendly compared to the current films available in the market. This structure is also all Olefin based and so easier to recycle.
The film of the invention exhibits a water vapour transmission rate of less than 0.3 gms/sqm per 24

hours @38°C 90%RH and an oxygen transmission rate of less than 1 cc per sqm per 24 hours @23°C 0%RH.
Advantages:
The film of the invention differs from, conventional
films in the following aspects:
- Better aesthetics [pliability, gloss) and option
of converting it into a paper look alike; matt
finish through addition of additives in the skin
layer of the reverse printed film.
- Printed substrate (BOPP) with low density
(0.910gm/cc) and modulus of elasticity ranging
between 18000-20000 Kg/sqcm backed with low density extrusion PE layer resulting in less memory retention of the top substrate , thereby less wrinkling / crumpling appearance.
- No possibility of solvent retention ( no odour
entrapment) , because of lamination between
printed 15 micron BOPP (Biaxially oriented
Polypropylene) and 12 micron plasma metallized
PET (Polyethylene Terephthalate) is carried out
with extrusion lamination using 12 micron LDPE
(Low Density Polyethylene)
- The individual layers of the film are so selected
that it delivers low gsm ( 68.64) for a film of
thickness of 65 micron in comparison to
conventional film structures providing yield
benefit.
- Coefficient of friction (COF) ranging from 0.2 -
0.35, leading to ease of processing on different
kind of packaging machines / operation.

The structure uses film from different polymer family viz . one side treated ; non heat sealable Biaxially oriented polypropylene (BOPP) , Low density polyethylene (LDPE ) and Poly ethylene terephthalate (PET ), employing unique cost effective process like :
Using Plasma technology for generating barrier
layer.
Using cost effective extrusion lamination process
for binding two substrates (Reverse printed BOPP
and Plasma metallized PET)
Usage of extrusion process with water based
primer for anchorage between different polymeric
families
Possibility of using white master batch in PE
extrusion to eliminate high cost white ink in
printing.



WE CLAIM:
1. A film comprising:
i) a first layer of biaxially oriented polypropylene, the layer optionally coated with nitrocellulose and optionally adapted for printing and ink anchorage;
ii) a second layer low density polyethylene;
iii) a third layer of a film made up of polyethylene terephthalate, and metallised on one side employing plasma atmosphere; and
iv) a fourth layer composed of a composite film comprising two or three layers and composed of 85-90% linear low density polyethylene of metallocene grade and 10-15% low density polyethylene.
2. A film as claimed in claim 1, wherein the thickness of the first layer ranges from 15 micron to 25 micron.
3. A film as claimed in claim 1, wherein the thickness of the second or core layer ranges from 10 micron to 2 0 micron.
4. A film as claimed in claim 1, wherein the thickness of the third layer ranges from 10 micron to 4 0 micron.
5. A film as claimed in claim 1, wherein the thickness of the fourth layer ranges from 20 micron to 4 0 micron.
6. A film as claimed in claim 1, wherein the water vapour transmission rate is less than 0.3 gms/sqm per 24 hours @38°C 90% RH. and oxygen transmission rate is less than 1 cc./sqm per 24 hours @23°C, 0% RH

7. A package comprising the film of claims 1 to 6.
8. A process for preparing a film as claimed in claims 1 to 7, said process comprising the steps of:
i) preparing a first layer composed of biaxially oriented polypropylene, the layer is optionally coated with nitrocellulose;
ii) optionally subjecting one side of the film to corona treatment whereby, the film is adapted for polyurethane based ink anchorage and the other side thereof is non-sealable and non-treated;
iii) providing a second or core layer of low density polyethylene by way of extrusion;
iv) preparing a third layer of polyethylene terephthalate (PET) and subjecting it to corona treatment and plasma metallization at OD of 2.4 to 2.7;
v) joining together the first layer of step (i) with the third layer of step (iv) , with the second layer of step (iii) therebetween by performing a step selected from co-extrusion, extrusion lamination using a water based primer coat;
vi) generating a tow or three layered film composed of 85-90% linear low density polyethylene of metallocene grade and 10-15% low density polyethylene; and
vii) laminating the layer generated in step (vi) with the film prepared in step (v) by performing solvent-less lamination and obtaining the film of the invention.

9. A film and a process for preparing the film substantially as hereindescribed and illustrated.

Documents:

691-DEL-2004-Abstract-(10-10-2008).pdf

691-del-2004-abstract.pdf

691-DEL-2004-Claims-(10-10-2008).pdf

691-DEL-2004-Claims-(19-08-2009).pdf

691-del-2004-claims.pdf

691-DEL-2004-Correspondence-Others-(10-10-2008).pdf

691-del-2004-correspondence-others.pdf

691-del-2004-correspondence-po.pdf

691-DEL-2004-Description (Complete)-(10-10-2008).pdf

691-del-2004-description (complete).pdf

691-DEL-2004-Drawings-(10-10-2008).pdf

691-del-2004-drawings.pdf

691-DEL-2004-Form-1-(10-10-2008).pdf

691-del-2004-form-1.pdf

691-del-2004-form-13-(12-06-2008).pdf

691-del-2004-form-18.pdf

691-DEL-2004-Form-2-(10-10-2008).pdf

691-del-2004-form-2.pdf

691-DEL-2004-Form-26-(10-10-2008).pdf

691-DEL-2004-Form-3-(10-10-2008).pdf

691-del-2004-form-3.pdf

691-DEL-2004-Form-5-(10-10-2008).pdf

691-del-2004-form-5.pdf

691-del-2004-form-6.pdf

691-del-2004-form-9.pdf

691-DEL-2004-Hearing Document-(19-08-2009).pdf

691-DEL-2004-Petition-137-(10-10-2008).pdf

691-DEL-2004-Petition-138-(10-10-2008).pdf

691-DEL-2004-Pre-Grant-Opposition-(07-02-2011).pdf


Patent Number 236008
Indian Patent Application Number 691/DEL/2004
PG Journal Number 38/2009
Publication Date 18-Sep-2009
Grant Date 14-Sep-2009
Date of Filing 08-Apr-2004
Name of Patentee PEPSICO INDIA HOLDINGS PVT LTD
Applicant Address 3B, DLF, Corporate Park, S Block, Qutab Enclave-III, Gurgaon
Inventors:
# Inventor's Name Inventor's Address
1 BIMAL LAKHOTIA 3B, DLF, Corporate Park, S Block, Qutab Enclave-III, Gurgaon
2 THATAI SREENIVAS RAMSUNDER MURALI 3B, DLF, Corporate Park, S Block, Qutab Enclave-III, Gurgaon
PCT International Classification Number B32 B27/32
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA