The present invention relates to the field of Packaging and Printing Films.
More particularly the present invention relates to the field of biaxially oriented polyethylene (BOPE) films.
Even more particularly the present invention relates to process for manufacturing of BOPE films.
Even more particularly the present invention relates to a highly efficient film which is manufactured through biaxial stretching of a linear low density Polyethylene resin (LLDPE).
Background and prior art of the invention:
Traditionally, the packaging and printing films comprises of Biaxially Oriented Polypropylene (BOPP). BOPP films are commonly used in packaging industry. Few examples of use of BOPP films are in candy wrappers, chips packaging, vitamin multi-packs, CDs and DVDs. BOPP has more flexibility than polyester. BOPP can be used at various processes such as metalizing, packaging, stationery products, labeling, etc. However, the BOPP packaging materials lacks few important features like high heat seal strength, high shrinkage, tear-resistance, and puncture resistance. Therefore, the present invention aims to provide a film in combination of both the BOPP and BOPE for better and efficient product which may overcome the above mentioned problems.
Reference may be made to WO/1997/022470, BIAXIALLY ORIENTED POLYETHYLENE FILMS 26.06.1997 by EXXON CHEMICAL PATENTS INC. In this invention, there are provided articles and films from ethylene-based polymers made using a metallocene catalyst system. Biaxial orientation dramatically improves clarity, stiffness, dart drop impact, puncture resistance, and shrink. Tensile strength at yield and ultimate tensile are also improved. Film stiffness, as measured by secant modulus, is increased by 300 % over an unoriented film of the same ethylene polymer. These
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articles and films are useful as shrink wrap, overwrap, and for dry packaging applications such as snacks and cereals as well as non-packaging applications such as photograph and document holders.
Reference may be made to EP0450088 BIAXIALLY ORIENTED POLYETHYLENE by KOHJIN CO ISOZAKI HIDEO. A biaxially oriented film mainly composed of a linear low-density polyethylene having a temp. difference between Tmb and Tma of at least 3 deg.C, wherein Tma is a main peak temp. of a melting curve obtained in the m.pt. measurement with a differential scanning calorimeter by holding a sample at 190 deg C for 30 mins., lowering the temperature to 20 deg.C at a rate of 100 deg.C/min., and elevating the temp. at a rate of 10 deg.C/min., the Tma being 118 +/- 5 deg.C, and Tmb is a main peak temp. of another melting curve obtained. Similarly, by holding a sample at 190 deg.C for 30 mins., lowering the temp. to 20 deg.C at a rate of 10 deg.C/min., and elevating the temp. at a rate of 10 deg.C. Since this resin is excellent in stretching stability, it can be stretched with a low tensile strength stably, thereby giving an oriented film excellent in not only stretchability and shrinkage but also elastic recovery.
Reference may be made to KR 1020000064446 BIAXIALLY ORIENTED POLYETHYLENE FILMS by EMPIRE FILMS DEVELOPMENT COMPANY. Articles and films are provided from ethylene-based polymers made using a metallocene catalyst system. Biaxial orientation dramatically improves clarity, stiffness, dart drop impact, puncture resistance, and shrink. Tensile strength at yield and ultimate tensile are also improved. Film stiffness, as measured by secant modulus, is increased by 300 % over an un-oriented film of the same ethylene polymer. These articles and films are useful as shrink wrap, overwrap, and for dry packaging applications such as snacks and cereals as well as non-packaging applications such as photograph and document holders.
Reference may be made to JP 2006181831 BIAXIALLY ORIENTED MULTI-LAYER POLYETHYLENE FILM by PRIME POLYMER. This invention provides a biaxially oriented multi-layer polyethylene film which can be torn both longitudinally and laterally and is excellent in transparency, shrinkability, heat sealability, and bending resistance. In the biaxially oriented multi-layer polyethylene film, a heat fusion layer obtained from an ethylene--olefin random copolymer (B) of 890-910 kg/m3 density is laminated on at least one side of a biaxially oriented polyethylene film substrate layer obtained from polyethylene (A) having a density of 915-938 kg/m3, a fusion heating value (HT)
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obtained by a differential scanning calorimeter (DSC) of 100-140 J/g, a fusion heating value (HL) in a range of a fusion starting temperature -110C of 50-80 J/g, a fusion heating value (HH) in a range of a fusion finishing temperature 110C- of 35-80 J/g, and a ratio (HH)/(HL) of 0.5-1.5.
Reference may be made to JP 2004238543 POLYETHYLENE-BASED RESIN COMPOSITION FOR BIAXIAL ORIENTATION AND ORIENTED FILM by IDEMITSU PETROCHEM CO LTD. This invention provides a polyethylene-based resin for biaxial orientation, having a wide temperature range enabling orientation, enabling stable molding and capable of providing a film excellent in physical properties such as haze, impact strength and tear strength, a polyethylene resin composition for biaxial orientation containing the polyethylene-based resin and an oriented film. In the polyethylene resin for biaxial orientation, the melt index is 0.5-2.0 g/10 min and the density is 0.905-0.920 g/cm3 and inclination (elution amount/temperature) of melted component amount in 40-70% melted component amount by a temperature-raising and fractionating method is 2.0-3.3%/C and a high-density polyethylene component amount in TREF elution curve of the temperature-raising and fractionating method is 8-25%. The polyethylene-based resin composition for biaxial orientation comprises the polyethylene-based resin. The film is obtained bi-axially orienting the polyethylene-based resin or the polyethylene-based resin composition.
Reference may be made to WO/2000/038843 BIAXIALLY ORIENTED POLYETHYLENE FILM WITH IMPROVED OPTICS AND SEALABILITY PROPERTIES by MOBIL OIL CORPORATION. Methods of preparing bi-axially oriented polyethylene films with improved optics and sealability properties are provided. The methods include stretching in the machine direction a multi-layer base sheet having a core layer with a first and a second side, at least one skin layer and outer surfaces; then coating at least one of the outer surfaces with a resin selected from the group consisting of low density polyethylene, very low density polyethylene, linear low density polyethylene and blends thereof; and finally, stretching the base sheet in a direction transverse to the machine direction.
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Reference may be made to EP 1156887 BIAXIALLY ORIENTED POLYETHYLENE FILM WITH IMPROVED OPTICS AND SEALABILITY PROPERTIES by EXXONMOBIL OIL CORP. Methods of preparing bi-axially oriented polyethylene films with improved optics and seal-ability properties are provided. The methods include stretching in the machine direction a multi-layer base sheet having a core layer with a first and a second side, at least one skin layer and outer surfaces; then coating at least one of the outer surfaces with a resin selected from the group consisting of low density polyethylene, very low density polyethylene, linear low density polyethylene and blends thereof; and finally, stretching the base sheet in a direction transverse to the machine direction.
Reference may be made to CA 2353447 BIAXIALLY ORIENTED POLYETHYLENE FILM WITH IMPROVED OPTICS AND SEALABILITY PROPERTIES by MOBIL OIL CORPORATION. Methods of preparing bi-axially oriented polyethylene films with improved optics and seal-ability properties are provided. The methods include stretching in the machine direction a multi-layer base sheet having a core layer with a first and a second side, at least one skin layer and outer surfaces; then coating at least one of the outer surfaces with a resin selected from the group consisting of low density polyethylene, very low density polyethylene, linear low density polyethylene and blends thereof; and finally, stretching the base sheet in a direction transverse to the machine direction.
Reference may be made to CN 102774110 Bi-axially-oriented polyethylene shrink film and production technique thereof by Hangzhou Deya Packaging Co., Ltd. The invention discloses a biaxially-oriented polyethylene shrink film which is prepared from the following components in percentage by mass: 40-60% of low-density polyethylene, 10-20% of high-density polyethylene, 10-20% of metallocene polyethylene, 10-20% of linear low-density polyethylene, 0-2% of antistatic agent, 0-1% of anti-blocking agent and 0-2% of lubricant. The mass ratio of outer surface layer material to middle layer material and inner surface layer material is 1:1:1-1:3:1. The biaxially-oriented polyethylene has the advantage of small thickness, and can reduce the consumption of the raw material when being used for composite plastic flexible packaging, thereby lowering the cost; and meanwhile, the biaxially-oriented polyethylene shrink film has the advantages of high deflection, high strength and high
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heat sealing temperature, the lateral shrinkage is greater than 35%, and the longitudinal shrinkage is greater than 35%.
Reference may be made to WO/2015/138096 IMPROVED BIAXIALLY ORIENTED METALLOCENE LINEAR LOW DENSITY POLYETHYLENE FILM, METHOD AND RESIN COMPOSITION FOR SAME by JINDAL FILMS AMERICAS LLC. Embodiments provide extruded oriented low density polyethylene (LDPE) films. Embodiments provide methods for making extruded oriented low density polyethylene (LDPE) films. Embodiments provide resin compositions for extruded oriented low density polyethylene (LDPE) films.
Reference may be made to US 20150258756 BIAXIALLY ORIENTED METALLOCENE LINEAR LOW DENSITY POLYETHYLENE FILM, METHOD AND RESIN COMPOSITION FOR SAME by Jindal Films Americas LLC. Embodiments provide extruded oriented low density polyethylene (LDPE) films. Embodiments provide methods for making extruded oriented low density polyethylene (LDPE) films. Embodiments provide resin compositions for extruded oriented low density polyethylene (LDPE) films.
However, none of the inventions discussed above comprises novel and innovative features as discussed in present invention. The present invention is capable of providing high stiffness, better oxygen & water vapor barrier, puncture resistance, pinhole resistance and impact strength in comparison to any other film known in the prior art.
Objects of the invention:
The main objective of the invention is to provide a Packaging and Printing Films.
Another objective of the invention is to provide a Packaging film in combination of various properties of Biaxially Oriented Polypropylene (BOPP), Cast Polypropylene (CPP) and Biaxially Oriented Polyethylene (BOPE) combined together.
Another main objective of the invention is to provide a Packaging and Printing Film which comprises high stiffness, better oxygen & water vapor barrier, puncture resistance, pinhole resistance and impact strength in comparison to BOPP.
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Another objective of the invention is to provide a Packaging and Printing Film which comprises of High seal strength with excellent hot-tack and good seal integrity.
Another objective of the invention is to provide a process to manufacture the BOPE film which can be used in various industries for the purpose of packaging and printing.
Summary of the invention:
This invention provides a Packaging film in combination of various properties of Biaxially Oriented Polypropylene (BOPP), Cast Polypropylene (CPP) and Biaxially Oriented Polyethylene (BOPE) combined together.
The film comprises high stiffness, puncture resistance, pinhole resistance and impact strength in comparison to BOPP, and also comprises of High seal strength with excellent hot-tack and good seal integrity. There is also provided a process to manufacture the BOPE film which can be used in various industries for the purpose of packaging and printing
The said film is a multilayer bi-axially oriented polyethylene film, having improved formulation and properties, and a process for manufacturing the same, said film having a thickness in the range of 10 to 60 um, said film prepared using plurality of polymers including but not limited to polyethylene, metallocene LLDPE with or without LDPE, and an anti-block agent in the percentage range of 1 to 10%.
The process provided in the present invention to manufacture the multilayer bi-axially oriented polyethylene film comprises biaxial stretching of a Linear low density Polyethylene resin (LLDPE) which so far could not be oriented on Standard BOPP Lines.
Brief desccription of the diagram:
Figure 1 provides a BOPE flow chart diagram explaining the steps of manufacturing said film of the present invention.
Bi-Oriented Polyethylene (BOPE) films are manufactured using a tenter frame sequential process in which a polyethylene (PE) film is oriented in two directions (machine and transverse directions).
The production of biaxially-oriented BOPE film is a continuous process. It is a co-extrusion process, where up to 5 single and/or twin screw extruders are involved. Usually the base BOPE polymer and additives are fed via a continuously operating loss-
7
in-weight feeder into the single/twin screw extruder. The melt that passes directly inline via the usual process for cast film, then transfers to longitudinal and transverse stretching elements.
Sequential lines first stretch the cast film along the direction of the machine through a system of rollers; the stretching is achieved by increasing the speeds between groups of rollers. Then the MD-stretched film enters the tenter, an oven-like device which uses a chain to grip and stretch the web in a transverse direction on diverting rails. Then the film is pulled by Pull Rollers where the film can be corona treated before it finally goes to the winder where it is wound on rollers.
Detailed Description of the invention:
It should be noted that the particular description 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 may be 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 provides a unique Biaxially Oriented Polyethylene (BOPE) film and process for manufacturing the same. The present invention provides biaxial stretching of a Linear low density Polyethylene resin (LLDPE) which so far could not be oriented on Standard BOPP Lines. Under the present invention the recently developed polymers (LLDPE resin and blends) and unique recipe are used where, M-PE, LDPE may be blended/mixed/coextruded to make it processable on a BOPP stenter line (biaxial orientation).
The BOPE film manufactured under the present invention comprises of high heat seal strength, high shrinkage, tear-resistance and metallizable surface for imparting oxygen and moisture barrier. The film under the present invention also has very high stiffness,
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puncture resistance, pin hole resistance and impact strength in comparison to BOPP. The film under the present invention is a combination of various properties of BOPP, CPP and BOPE combined together for better performance.
Further the film of the present invention can be used for high metal adhesion. It can also be used for High seal strength with excellent hot-tack and good seal integrity. The film can be used for collation or bundling of objects due to high shrinkage in both the directions. Under the present invention the orientation of LLDPE is carried on a stenter facility, in the three layers in a multilayer structure, which is not a normally used in the industry and is a novel and unique feature of the present invention. The process under the present invention uses the polymers which results into a highly efficient films. The Stentor process of the present invention provides better gauge control and superior barrier. The present invention further comprises of novel process for manufacturing the BOPE films. Firstly, the formulation is done with respect to the design; secondly the co-extrusion process of LLDPE with M-PE and their mixtures with LDPE by using manifold die is carried on. Once the formulation of design and co-extrusion process is complete then the next step starts with orientation of the BOPP and ends with Corona treatment and winding of the films. The formulation under the present invention comprises of the Stretching of LLDPE of high density on a conventional BOPP line of 3-5 layers without any modification of the BOPP film Line. During the formulation the thickness of the film ranges from 10 to 60 microns preferably 30 microns, where this thickness mentioned is total thickness of the film. The formulation comprises of using a blend of metallocene based LLDPE with or without LDPE in one of the layers preferably core layer. The percentage of LDPE varies from 5-30 % preferably 15 %. Further, M-PE (Evolue 1540) in one or both the skin layers is may be used. The thickness of the skin layer may vary from 1 micron to 5 microns preferably 2 microns. In the Skin layer, Copolymers of PP-PE or other copolymers of PE are also used where the PE content varies from 3-40 %. Further the LDPE used for blending in core layer can have MFI from 1.0 to 7.0. The OPP line used is having capability to stretch in MD from 2-6 times preferably 5 times. The line has capability to stretch film above its crystallite melting point in TD of 7-10 times. The variation in annealing temp will decide the shrinkage of the film both in MD and TD.
Under the process the film is stretched 3 – 6 times with or without LDPE in the core layer. MDO typical temperature ranges from 80 – 120 Degree Celsius. The pre-heat
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temperature requirement is 110 – 145 Degree Celsius and stretching temperature ranges from 100 – 118 Degree Celsius. Further the film is stretched in cross direction at temperature 120 – 135 Degree Celsius and typical temperature in pre-heat was 120 – 130 Degree Celsius, Annealing Temperature is maintained in the range of 120 – 125 Degree Celsius. Further the film is cooled in the cooling zone and temp of cooling zone ranges in 25 – 60 Degree Celsius after that film is finally corona treated. The above novel and unique process under the present invention results into a novel and unique BOPE films for the purposes of packaging and printing, the films also comprises of high heat seal strength, high shrinkage, tear-resistance and metallizable surface for imparting oxygen and moisture barrier. The film also has very high stiffness and impact strength in comparison to BOPP. In the manufacturing of Bi-Oriented Polyethylene (BOPE) films, there is used a tenter frame sequential process in which a polyethylene (PE) film is oriented in two directions (machine and transverse directions). The production of biaxially-oriented BOPE film is a continuous process. It is a co-extrusion process, where up to 5 single and/or twin screw extruders are involved. Usually the base BOPE polymer and additives are fed via a continuously operating loss-in-weight feeder into the single/twin screw extruder. The melt that passes directly inline via the usual process for cast film, then transfers to longitudinal and transverse stretching elements. Sequential lines first stretch the cast film along the direction of the machine through a system of rollers; the stretching is achieved by increasing the speeds between groups of rollers. Then the MD-stretched film enters the tenter, an oven-like device which uses a chain to grip and stretch the web in a transverse direction on diverting rails. Then the film is pulled by Pull Rollers where the film can be corona treated before it finally goes to the winder where it is wound on rollers.
The major advantages of BOPE over BOPP in terms of properties are given below:
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Following are the advantages of BOPE over regular PE sealant film -
Differences from regular PE sealant film
 higher tensile strength
 higher dart impact
 higher clarity and gloss
 higher stiffness (Young modulus)
 Higher puncture strength
 Higher pinhole resistance
 Easy tear
Major Modifications over BOPP process: The main extruder mesh was changed to 40/80/80 against 40/80/200 used in previous trial.
BOPE requires higher melting energy over BOPP due to higher enthalpy, which would be achieved by using twin screw extruders and employing shearing elements on the screw profile like maddock mixing element.
S. No.
Properties
Unit
BOPE Grade
BOPP Grade
11
MFR
g/10min
1.6(190°C)
3.0(230°c)
1
Density
gm/cc
0.927
0.91
2
Melt Tension
mN
65
36
3
Main Tm
°C
127
160
4
⊿Hm
j/g
131
95
Examples:
The following examples are for the purposes of illustration only and therefore should not be construed to limit the scope of the invention:
Description:
Materials used:
BOPE: 1011404 (Evolue SP 3022)
Antiblock Agent: 1013322 (NC Block 44)
Recipe:
The following recipe was used during the trials: Layer configuration RM-1 % dosing RM-2 % dosing Layer Thickness Treatment Required Skin (Untreated) 1011404 5% 1013322 2.0μ NA Core 1011404 RGG %: Nil Skin (TREATED) 1011404 2% 1013322 2.0μ 44±2
Process Parameters:
The following process parameters were used: Extrsn temp (Mention section) MDO temp (Mention section) TDO temp Chill Roll temp Water bath temp MDSR TDSR Output (Kg/Hr) Line Speed (MPM) (°C) (°C) (°C) (°C) (°C) Skin Inside- Preheat - 110,110, 110 Preheat - 120*2 30 32 4.8 9 330 60
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170, 245, 250*6 Stretching - 100, 105 Annealing - 110 Stretching - 105*2 Annealing - 110*2
Core- 225, 265, 270*7
Skin Outside- 80, 245, 250*6
Following are the properties achieved with the above trial:
The major advantages of BOPE over regular BOPP & regular PE:
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- Down gauging by 50% of film thickness
- Superior Heat Seal Properties
- High Impact Strength & Pinhole properties at Very low temperature
- Excellent Ant blocking property
- Excellent Mechanical properties
- Excellent OTR and WVTR after metallization vis a vis PE
So accordingly, the present invention provides a multilayer bi-axially oriented polyethylene film, having improved formulation and properties, and a process for manufacturing the same, said film having a thickness in the range of 10 to 60 um, said film prepared using plurality of polymers including but not limited to polyethylene, metallocene LLDPE with or without LDPE, and an anti-block agent in the percentage range of 1 to 10%.
In an embodiment, said process for manufacturing said film comprises biaxial stretching of a Linear low density Polyethylene resin (LLDPE) which so far could not be oriented on Standard BOPP Lines
In another embodiment, said film comprises preferably five layers.
In another embodiment, said film comprises preferably three layers, i.e. one core layer, one middle layer and one skin layer.
In another embodiment, said formulation comprises of using a blend of metallocene LLDPE with or without LDPE in one of the layers; preferably the core layer.
In another embodiment, said orientation of LLDPE is carried on a stenter facility, in the three layers in a multilayer structure, thus providing better gauge control and superior barrier.
In another embodiment, said formulation comprises recently developed polymers (LLDPE resin and blends) and a unique recipe where, M-PE, LDPE may be blended/mixed/coextruded to make it processable on a BOPP stenter line (biaxial orientation). In another embodiment, said formulation comprises stretching the LLDPE of high density on a conventional BOPP line of 3-5 layers without any modification of the BOPP film Line.
In another embodiment, the thickness of the film ranges from 10 to 60 microns and preferably 30 microns, wherein this thickness mentioned is total thickness of the film.
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In another embodiment, the percentage of LDPE varies from 5-30 %, preferably 15 % and M-PE (Evolue 1540) in one or both the skin layers is used.
In another embodiment, the thickness of the skin layer may vary from 1 micron to 5 microns, preferably 2 microns.
In another embodiment, in the skin layer, copolymers of PP-PE or other copolymers of PE are also used where the PE content varies from 3-40 %.
In another embodiment, the LDPE used for blending in core layer can have MFI from 1.0 to 7.0.
In another embodiment, the OPP line used is having capability to stretch in MD from 2-6 times, preferably 5 times.
In another embodiment, the line has capability to stretch film above its crystallite melting point in TD of 7-10 times.
In another embodiment, under the process the film is stretched 3 – 6 times with or without LDPE in the core layer and MDO typical temperature ranges from 80 – 120 Degree Celsius.
In another embodiment, the pre-heat temperature requirement is 110 – 145 Degree Celsius and stretching temperature ranges from 100 – 118 Degree Celsius.
In another embodiment, the film is stretched in cross direction at temperature 120 – 135 Degree Celsius and typical temperature in pre-heat was 120 – 130 Degree Celsius, Annealing Temperature is maintained in the range of 120 – 125 Degree Celsius.
In another embodiment, the film is cooled in the cooling zone and temperature of cooling zone ranges in 25 – 60 Degree Celsius after that film is finally corona treated.
In another embodiment, said film is having improved gloss in the range of 120 to 140 percent.
In another embodiment, said film is having tensile strength in the range of 60 to 100MPa in md and 100 to 140Mpa in td.
In another embodiment, said film is having Young's modulus in the range of 500 to 800MPa in md and 800 to 1800Mpa in td. In another embodiment, said process for manufacturing said film comprises the steps of: the formulation is done with respect to the design; the co-extrusion process of LLDPE with M-PE and their mixtures with LDPE by using manifold die is carried on; once the formulation of design and co-extrusion process is complete,
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then the next step starts with orientation of the BOPP and ends with Corona treatment and winding of the films.
The novel and unique feature of the present invention makes it eligible for different applications, few of the applications are:
1) Good stiffness and heat sealability.
2) Inner sealant layer due to high seal strength.
3) Shrink sleeves due to high shrinkage in TD.
4) Replacement of POF shrink-film like Cryovac due to high shrinkage in both the directions.
5) Barrier PE film for packaging of Fragile items.
6) High barrier metallised film with excellent seal.
7) Top printable layer due to excellent optical and thinner gauge.
8) Film for meat packaging.
Key advantages of the invention:
 The Stentor process under the present invention provides better gauge control and superior barrier.
 The invention comprises various properties of BOPP and BOPE combined together.
 The film can be used for different applications in the packaging and printing industry.
 The invention comprises of high heat seal strength.
 The invention comprises of high shrinkage.
 The invention comprises of tear-resistance and metallizable surface for imparting oxygen and moisture barrier.
 The film also has better puncture resistance, pin hole resistance and impact strength in comparison to BOPP.
 The invention comprises of printable layer due to excellent optical and thinner gauge.
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We claim:
1. A multilayer bi-axially oriented polyethylene film, having improved formulation and properties, and a process for manufacturing the same, said film having a thickness in the range of 10 to 60 um, said film prepared using plurality of polymers including but not limited to polyethylene, metallocene LLDPE with or without LDPE, and an anti-block agent in the percentage range of 1 to 10%.
2. A multilayer bi-axially oriented polyethylene film as claimed in claim 1, wherein said process comprises biaxial stretching of a Linear low density Polyethylene resin (LLDPE) which so far could not be oriented on Standard BOPP Lines
3. A multilayer bi-axially oriented polyethylene film as claimed in claim 1, wherein said film comprises preferably five layers.
4. A multilayer bi-axially oriented polyethylene film as claimed in claim 1, wherein said film comprises preferably three layers, i.e. one core layer, one middle layer and one skin layer.
5. A multilayer bi-axially oriented polyethylene film as claimed in claim 1, wherein said formulation comprises of using a blend of metallocene LLDPE with or without LDPE in one of the layers; preferably the core layer.
6. A multilayer bi-axially oriented polyethylene film as claimed in claim 1, wherein orientation of LLDPE is carried on a stenter facility, in the three layers in a multilayer structure, thus providing better gauge control and superior barrier.
7. A multilayer bi-axially oriented polyethylene film as claimed in claim 1, wherein said formulation comprises recently developed polymers (LLDPE resin and blends) and a unique recipe where, M-PE, LDPE may be blended/mixed/coextruded to make it processable on a BOPP stenter line (biaxial orientation).
8. A multilayer bi-axially oriented polyethylene film as claimed in claim 1, wherein said formulation comprises stretching the LLDPE of high density on a conventional BOPP line of 3-5 layers without any modification of the BOPP film Line.
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9. A multilayer bi-axially oriented polyethylene film as claimed in claim 1, wherein the thickness of the film ranges from 10 to 60 microns and preferably 30 microns, wherein this thickness mentioned is total thickness of the film.
10. A multilayer bi-axially oriented polyethylene film as claimed in claim 1, wherein the percentage of LDPE varies from 5-30 %, preferably 15 % and M-PE (Evolue 1540) in one or both the skin layers is used.
11. A multilayer bi-axially oriented polyethylene film as claimed in claim 1, wherein the thickness of the skin layer may vary from 1 micron to 5 microns, preferably 2 microns.
12. A multilayer bi-axially oriented polyethylene film as claimed in claim 1, wherein in the skin layer, copolymers of PP-PE or other copolymers of PE are also used where the PE content varies from 3-40 %.
13. A multilayer bi-axially oriented polyethylene film as claimed in claim 1, wherein the LDPE used for blending in core layer can have MFI from 1.0 to 7.0.
14. A multilayer bi-axially oriented polyethylene film as claimed in claim 1, wherein the OPP line used is having capability to stretch in MD from 2-6 times, preferably 5 times.
15. A multilayer bi-axially oriented polyethylene film as claimed in claim 1, wherein the line has capability to stretch film above its crystallite melting point in TD of 7-10 times.
16. A multilayer bi-axially oriented polyethylene film as claimed in claim 1, wherein under the process the film is stretched 3 – 6 times with or without LDPE in the core layer and MDO typical temperature ranges from 80 – 120 Degree Celsius.
17. A multilayer bi-axially oriented polyethylene film as claimed in claim 1, wherein the pre-heat temperature requirement is 110 – 145 Degree Celsius and stretching temperature ranges from 100 – 118 Degree Celsius.
18. A multilayer bi-axially oriented polyethylene film as claimed in claim 1, wherein the film is stretched in cross direction at temperature 120 – 135 Degree Celsius and typical temperature in pre-heat was 120 – 130 Degree Celsius, Annealing Temperature is maintained in the range of 120 – 125 Degree Celsius.
19. A multilayer bi-axially oriented polyethylene film as claimed in claim 1, wherein the film is cooled in the cooling zone and temperature of cooling zone ranges in 25 – 60 Degree Celsius after that film is finally corona treated.
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20. A multilayer bi-axially oriented polyethylene film as claimed in claim 1, wherein said film is having improved gloss in the range of 120 to 140 percent. 21. A multilayer bi-axially oriented polyethylene film as claimed in claim 1, wherein said film is having tensile strength in the range of 60 to 100MPa in machine direction (MD) and 100 to 140Mpa in transverse direction (TD).
22. A multilayer bi-axially oriented polyethylene film as claimed in claim 1, wherein said film is having Young's modulus in the range of 500 to 800MPa in MD and 800 to 1800Mpa in TD.
23. A multilayer bi-axially oriented polyethylene film as claimed in claim 1, wherein said process for manufacturing said film comprises the steps of: a. the formulation is done with respect to the design; b. the co-extrusion process of LLDPE with M-PE and their mixtures with LDPE by using manifold die is carried on; c. once the formulation of design and co-extrusion process is complete, then the next step starts with orientation of the BOPP and ends with Corona treatment and winding of the films.