DESC:FIELD OF THE INVENTION
The present invention relates to the field of BOPP film. More particularly, the present invention relates to a bi-axially oriented multi-layered low microns (i.e., 6-7 microns) metallized BOPP (biaxially oriented polypropylene) film for barrier application.

BACKGROUND OF THE INVENTION
Biaxial orientation is a process whereby a plastic film or sheet is stretched in such a way that the polymeric chains are oriented parallel to the plane of the film. Bi-axially oriented polypropylene, also known as BOPP film, is a thin thermoplastic polymer that has been stretched mechanically. Biaxially oriented polypropylene (BOPP) film is most popular flexible packaging film. Biaxially oriented polypropylene film is stretched in the machine direction (MD) and transverse direction (TD). In this process, the molecular chain orientation is performed in both the directions. This film is utilized in many day-to-day products and is ideal for packaging, labelling and graphic applications. It is commonly used for applications that require moisture resistance, optical clarity and high tensile strength such as food and beverage packaging, medical packaging, personal care product packaging and tamper evident films. The wide applicability of BOPP film is attributed to its advantages such as light-weight, environment-friendly nature, preventing damages in transit, and also protection from wet weather, as it has a high tendency to keep products dry. Not only that, in comparison to other polyester films, bi-axially oriented polypropylene protects against air pollution and toxic chemicals. It is also resistant to oils and grease. Furthermore, this film has an excellent gloss and high transparency that gives it a stunning finish.
Mueller et al., in Packaging Technology and Science 2012; 25:137–148, discloses thin laminate films for barrier packaging application influence of down gauging and substrate surface properties on the permeation properties. However, the lamination does not show a significant effect on the oxygen permeability as the oxygen barrier of combinations of polyolefin films with ethylene vinyl alcohol (EVOH) barrier layer is dominated by the intrinsic barrier properties.
IN202011047634A discloses a transparent BOPP film with high oxygen barrier and hot slip properties. The BOPP film shows enhanced high oxygen barrier and hot slip properties, comprising of, an upper skin layer having a layer thickness ranging between 1 to 1.5 microns, an upper tie layer having a thickness ranging between 1.0 to 2.0 microns, a core layer having a thickness ranging between 8 to 21.5 micron and more particularly, in the range of 11 to 14.5 micron, a lower tie layer having a thickness ranging between 0.5 to 2.0 microns, and a lower skin layer having a thickness ranging between 1.0 to 1.5 microns, wherein the BOPP film having an oxygen transmission rate (OTR) in the range of 20-150 cc/m2/day, and coefficient of friction with metal at higher temperature up to 90°C is in the range between 0.15 to 0.20. The major drawback of the invention is that the film is significantly thicker without any considerable improvement in the barrier properties such as OTR.
US10718046B2 discloses about compositions and methods for a film, which may include a base film and a coating layer on the base film, wherein the coating layer has a surface energy of at least 30 dynes/cm and further, the film may include a metal oxide layer on the coating layer, wherein the metal oxide layer has an optical density of equal to or less than 0.5 and a thickness from 0.1 nm through 100 nm. The film has an oxygen transmission rate of less than 4 cm3/m²/day at 23°C and 0% relative humidity, a water vapour transmission rate of less than 4 g/m²/day at 38°C and 90% relative humidity, and a thickness of 5 µm through 50 µm. The limitation of this disclosure is the failure to provide significant gauge reduction.
US8734933 discloses a multi-layer high moisture barrier polylactic acid film. A laminate film comprising: a multi-layer bi-axially oriented polylactic acid film; a coating layer formed from a coating solution comprising an anionic carboxylated styrene-butadiene copolymer; and a non-contiguous primer metal layer on a surface of the coating layer and a metal layer applied by vacuum deposition on the primer metal layer, wherein the primer layer comprises copper or titanium. Although the invention provides improved moisture barrier properties, however the film is costly and does not shows significant gauge reduction.
US20110135916 discloses multilayer films having improved sealing properties, their methods of manufacture, and articles made therefrom, which include at least a core layer and a sealant skin layer, and optionally a first tie layer intermediate the core layer and the sealant skin layer. The sealant skin layer includes a first polymer component having a heat of fusion of less than 75 J/g and a second polymer component. The multilayer film preferably has a seal strength greater than about 200 g/2.54 cm for a seal formed on a crimp sealer at a temperature of at least 93.3°C. The core layer may include a nucleating agent and a hydrocarbon resin. The major disadvantages associated with BOPP films include poor sealing, high range of crystallinity which alters the aesthetics making it hazy, low surface energy, which means even though it is used for printing on, it does not hold ink very well, making the print result of poor quality. Generally, more than ten microns thickness film is available and reduction in thickness of barrier laminated film systems leads to a quality decrease of the resulting packaging materials functional properties. Especially for food packaging applications, adequate oxygen and water barrier properties are indispensable.
US7252878B2 discloses about high oxygen barrier, multi-layer flexible packaging structure having a vacuum metallized, biaxially oriented polypropylene (met-BOPP) or metallized polyester (met-PET) film substrate; a high barrier EVOH layer coextruded or laminated directly on the metal-containing layer; and optionally an adjacent layer of anhydride modified polyolefin such as blend of LDPE, or MDPE, or PP and maleic anhydride modified adhesive resin on the EVOH layer.
In light of the above drawbacks, there exists a need to develop multilayer metallized film having lesser thickness, and having low oxygen and water vapour transmission properties. The present invention is an endeavour in this direction.

OBJECT OF THE INVENTION
The main object of the present invention is to provide a multi-layered metallized BOPP film for barrier application.
Another object of the present invention is to provide a low micron (i.e., 6-7 micron) with good barrier BOPP film.
Yet another object of the present invention is to provide a process to develop a low micron BOPP film that reduces cost for final laminate into the sandwich layer.
Yet another object of the present invention is to provide a multi-layered metallized BOPP film materials having OTR (oxygen transmission rate) of 0.14-0.20 cc/m2/day and WVTR (water vapour transmission rate) of 0.1- 0.2 g/m2/day.
Yet another object of the present invention is to provide a multi-layered metallized BOPP film having thickness of 6-7 microns with copolymer combination that reduces cloudy appearance for metallized BOPP film.
Still another object of the present invention is to provide a multi-layered metallized BOPP film for barrier applications that is economic and more efficient.

SUMMARY OF THE INVENTION
The present invention relates to a multi-layered metallized BOPP film for barrier applications that exhibits gauge reduction with a thickness in a range of 6-7 microns to provide barrier for air, water or moisture.
In an embodiment, the present invention provides a multi-layered metallized biaxially oriented polypropylene (BOPP) film (10, 20, 30), comprising of an inner layer (11, 21, 31); a plurality of tie layer (12, 22, 32, 14, 24, 34); a core layer (13, 23, 33); a treated layer (15, 25, 35); and an outer layer (16, 26, 36).
Here, the plurality of tie layer is having an intermediate layer (12, 22, 32) and an adhesive layer or tie layer (14, 24, 34). Further, the BOPP film (10, 20, 30) exhibits gauge reduction with a thickness in a range of 6-7 microns to provide barrier for air, water or moisture; and the BOPP film (10, 20, 30) exhibits haze in a range of 1.8-3.2% and gloss in a range of 89-91 GU.
The present invention relates to BOPP films prepared with EVOH materials that reduces cloudy appearance to achieve ultra-high barrier metallized BOPP film.
The above objects and advantages of the present invention will become apparent from the hereinafter set forth brief description of the drawings, detailed description of the invention, and claims appended herewith

BRIEF DESCRIPTION OF THE DRAWINGS
An understanding of the multi-layered metallized BOPP film for barrier applications of the present invention may be obtained by reference to the following drawings:
Figure 1 is a schematic representation of the layers of the metallized BOPP film (10), according to an embodiment of the present invention.
Figure 2 is a schematic representation of the layers of the metallized BOPP film (20), according to the present invention.
Figure 3 is a schematic representation of the layers of the metallized BOPP film (30), according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION
The present invention will now be described hereinafter with reference to the accompanying drawings in which a preferred embodiment of the invention is shown. This invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiment set forth herein. Rather, the embodiment is provided so that this disclosure will be thorough, and will fully convey the scope of the invention to those skilled in the art.
The present invention now will be described hereinafter with reference to the detailed description, in which some, but not all embodiments of the invention are indicated. Indeed, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout. The present invention is described fully herein with non-limiting embodiments and exemplary experimentation.
The present invention provides a multi-layered metallized BOPP film for barrier applications that exhibits gauge reduction with a thickness in a range of 6-7 microns to provide barrier for air, water or moisture.
In a preferred embodiment, the present invention provides a multi-layered metallized biaxially oriented polypropylene (BOPP) film (10, 20, 30), comprising of an inner layer (11, 21, 31); a plurality of tie layer (12, 22, 32, 14, 24, 34); a core layer (13, 23, 33); a treated layer (15, 25, 35); and an outer layer (16, 26, 36); wherein, the plurality of tie layer is having an intermediate layer (12, 22, 32) and an adhesive layer (14, 24, 34). Further, the BOPP film (10, 20, 30) exhibits gauge reduction with a thickness in a range of 6-7 microns to provide barrier for air, water or moisture; and the BOPP film (10, 20, 30) exhibits haze in a range of 1.8-3.2% and gloss in a range of 89-91 GU.
Here, said inner layer (11, 21, 31) is a heat seal layer having a thickness ranging from 0.7-0.9 microns is made up of 90-98% copolymer and 2-10% additive. Further, said plurality of tie layer (12, 22, 32, 14, 24, 34) having a thickness ranging from 0.7-0.9 microns is made up of 100% of homopolymer or additive or compatibilizer. Said core layer (13, 23, 33) having a thickness ranging from 3-5 microns is made up of homopolymer or additive. Said treated layer (15, 25, 35) having thickness ranging from 0.7 to 1.5 microns is made up of 90-100% of terpolymer or 90-100% of copolymer and 0-10% of additive or ethylene vinyl alcohol (EVOH) or homopolymer. Said outer layer (16, 26, 36) is a metallized layer having a metal deposited with optical density (OD) ranging from 2.6 to 2.8.
Further, the BOPP film (10, 20, 30) exhibits barrier against air having oxygen transmission rate (OTR) ranging from 0.14-0.2 cc/m2/day, exhibits barrier against moisture or water having water vapour transmission rate (WVTR) ranging from 0.1 to 0.2 g/m2/day, exhibits tensile strength in a range of 1186-1300 kg/cm2 for machine direction (MD) and a range of 2323 to 2500 kg/cm2 for transverse direction (TD). In addition, the BOPP film exhibits % elongation of 145-232 for MD and 38-46 for TD.
Moreover, said multi-layered metallized BOPP film (10, 20, 30) exhibits % shrinkage of 3-4.5 for MD and 2.0 for TD at a temperature of 120°C for a time period of 5 minutes. Further, said homopolymer is selected from Homopoly.1030 FG or Moplen HP525J or HC402BF or PP Resin-Luban HP3104K; said copolymer is Cosmoplene-FS5711 or PKS 357 or PKS 607 or FL 7540 or RC 213M; said additive is selected from High Add block 2C01A, AVBT 22NSC, ABO , Antiblock 2C01A or admer QF 500T; and said terpolymer is EVAL G 156B.
Referring to Figure 1, a multi-layered structure of the metallized BOPP film (10) having plurality of layers, is depicted. The multilayered structure of the BOPP film (10) comprises of a sealing layer (11); a tie layer (12); a main layer (or core layer) (13); a tie layer (or adhesive layer) (14); a treated layer (15) comprising of homopolymer; and a metal deposited layer (16), according to the present invention.
Referring to Figure 2, a multi-layered structure of the metallized BOPP film (20) having plurality of layers, is depicted. The multilayered structure of the BOPP film (10) comprises of a sealing layer (21); a tie layer (22); a main layer (or core layer) (23); a tie layer (or adhesive layer) (24); a treated layer (25) comprising of copolymer; and a metal deposited layer (26), according to the present invention.
Referring to Figure 3, a multi-layered structure of the metallized BOPP film (30) having plurality of layers, is depicted. The multilayered structure of the BOPP film (30) comprises of a sealing layer (31); a tie layer (32); a main layer (or core layer) (33); a tie layer (or adhesive layer) (34); a treated layer (35) comprising of EVOH or terpolymer; and a metal deposited layer (36), according to the present invention.

EXAMPLE 1
For Experimentation Data
Materials and Methods
Biaxially oriented polypropylene (BOPP) film is a type of flexible packaging film. Biaxially oriented polypropylene is stretched in machine and transverse directions that results in a molecular chain orientation in both directions. The flexible BOPP packaging film is created by a tubular production process. A tube-shaped film bubble is inflated and heated to up to softening point (different from the melting point) and is stretched with machinery. The film stretches between 300%-400%. Alternatively, the film is stretched by a process known as tenter-frame film manufacturing. With the tenter-frame technique, the polymers are extruded onto a cooled cast roll (also known as a base sheet) and drawn along the machine direction. Tenter-frame film manufacturing employs several sets of rolls to create film. The tenter-frame process generally stretches the film 4.5:1 in the machine direction and 8.0:1 in the transverse direction. The ratios are fully adjustable. The tenter-frame process is more common than the tubular variant. The tenter-frame process produces a highly glossy, clear film. Biaxial orientation increases strength and results in superior stiffness, enhanced transparency, and high resistance to oil and grease.
Materials
High add 2C01A, Hoblock 10, FW4BM, Homopoly.1030 FG, Moplen HP525J, HC402BF, HP525J, HC402BF, PP Resin-Luban HP3104K, FL7540L, FS 5711, RC 213, Adsyl 3C 30 and ABVT 22 NSC were taken as raw material for composition of different layers of the BOPP film.

EXPERIMENT 1
Composition of layers in Experiment 1 for preparation of BOPP film (10)
Inner Layer (11):
The inner layer (11) is a sealing layer (heat seal layer). The thickness of sealing layer is in a range of 0.7-0.9 µ and comprises of copolymer and antiblock. The copolymer is in a range of 85-98% and is selected from EW4BM or Cosmoplane 5711 FL (TPC) or Adsyl 5C 30F (basell); and antiblock is in a range of 2-10% and is selected from High Add 2C01A (High grade) or ABO504CP (Blend Additive), ABVT 22NSC A Schulman or ABNG 50 MB Bankim Plast.
Tie Layer or Intermediate Layer (12):
The thickness of tie layer (12) is in a range of 0.7-0.9 µ. The tie layer (12) is made of 100% homopolymer. The homopolymer is selected from Homopoly.1030 FG (Indian Oil), Moplen HP525J or HC402BF or PP Resin-Luban HP3104K.
Core Layer or Main Layer (13):
The thickness of core layer (13) is in a range of 3-5 µ. The core layer (13) is made of 100% homopolymer. The homopolymer is selected from Homopoly. 1030 FG (Indian Oil), Moplen HP525J or HC402BF or PP Resin-Luban HP3104K.
Tie Layer or Adhesive Layer (14):
The thickness of tie layer (14) is in a range of 0.7-0.9 µ. The tie layer (14) is made of 100% homopolymer. The homopolymer is selected from Homopoly. 1030 FG (Indian Oil), Moplen HP525J or HC402BF or PP Resin-Luban HP3104K.
Treated Layer (15):
The thickness of the treated layer (15) is in a range of 0.7-1.00 µ and comprises of homopolymer and antiblock. The ABVT 22SC, ABVT 22NSC, High add 2C01A is in a range of 1-10% and homopolymer is in a range of 90-100 % and is selected from PKS 607 or FL 7540 or RC 213M.
Outer Layer (16)
The outer layer (16) is a metallized layer deposited with metal having optical density (OD) of 2.6 to 2.8. The metal Aluminum (Al) is deposited by physical vapour deposition.
Method 1
The prepared BOPP film (10) having (a) a sealing layer (11) comprises of 96% co-polymer (Cosmoplene-FS5711 or PKS 357) and 4% antiblock (High Add block 2C01A/AVBT 22NSC/ABO); (b) a tie layer (12) of 100% homopolymer (Homopoly.1030 FG, Moplen HP525J or Homo-Polymer: HC402BF or PP Resin-Luban HP3104K); (c) a main or core layer (13) of 100% homopolymer (Homopoly. 1030 FG, Moplen HP525J or Homo-Polymer: HC402BF or PP Resin-Luban HP3104K); (d) a tie layer (or intermediate layer, 14) of 100% homopolymer (Homopoly. 1030 FG, Moplen HP525J or Homo-Polymer: HC402BF or PP Resin-Luban HP3104K); (e) a treated layer (15) comprising of 98% homopolymer (PKS 607 or FL 7540 or RC 213M) and 2% of antiblock (Antiblock 2C01A or AVBT 22NSC); and (f) a metallized layer (16). Figure 1 shows a schematic representation of the layers of the metallized BOPP film (10). Table 1 shows the test results of Experiment 1 for BOPP film (10).

Table 1: Test results of Experiment 1 for BOPP film (10)
Property UOM Test method Experiment 1
Density gm/cc JPFTM 0.91
Haze % ASTM D 1003 3-4
Gloss 45° ASTM D 2457 88-91
Treatment Inside
Dyne/cm
ASTM-D2578
Outside 44
Coef. of friction (One side - other side) In/In

Kinetic

ASTM-D1894 0.58
In/Metal 0.35
In/Out 0.55
Out/Out 0.52
Out/Metal 0.29
Tensile strength MD kg/cm² ASTM D 882 1186
TD 2323
Elongation MD % ASTM D 882 145
TD 38
SIT 2 bar/sec ( 200gm load) Treated °C JPFTM -
Untreated -
HSS (120°C@ 2 bar , 1 sec ) Treated gm/25mm JPFTM -
Untreated -
Shrinkage (120°C@, 5 min ) MD % JPFTM 4.5.0/4.5/4.5
TD 2.0/2.0/2.0

Table 1 shows the properties of the prepared film having thickness in a range of 7-7.3 microns, haze in a range of 3-3.25, measured as per ASTM D 1003, gloss in a range of 89-91 GU, measured as per ASTM D 2457. Further, the treatment result was shown to be 45 dyne/cm for outside, measured as per ASTM-D2587, coefficient of friction in a range of 0.34-0.39 (one side-other side) as per ASTM-D1894, tensile strength in a range of 1186-1300 kg/cm2 for MD and 2323-2500 kg/cm2 for TD, measured as per ASTM-D882. In addition, the elongation is shown to be 145% at MD and 38% for TD, measured as per ASTM-D882, shrinkage (120°C@5 min.) is shown to be 3-4.5% for MD and 2% for TD, measured as per JPFTM; Oxygen transmission rate is measured in a range of 50-60 cc/m2/day as per ASTM D 3985 and Water transmission rate is measured in a range of 0.7-1.0 g/m2/day as per ASTME398.

EXPERIMENT 2
Composition of layers in Experiment 2 for preparation of BOPP film (20)
Inner Layer (20):
The inner layer (20) is a sealing layer (heat seal layer). The thickness of sealing layer is in a range of 0.7-0.9 µ and comprises of copolymer and antiblock and is selected from FL7540 85-94% and High Add 2C01A High grade or ABO504CP (Blend Additive), ABVT 22NSC A Schulman, ABNG 50 MB Bankim Plast about 2-10%.
Tie Layer or Intermediate Layer (22):
The thickness of tie layer (22) is in a range of 0.7-0.9 µ. The tie layer (22) is made of 100% homopolymer. The homopolymer is selected from Homopoly.1030 FG, Moplen HP525J or HC402BF or PP Resin-Luban HP3104K.
Core Layer or Main Layer (23):
Main layer (23) is selected from homopolymer Homopoly.1030 FG, Moplen HP525J or Homo Polymer: HC402BF or PP Resin-Luban HP3104K is taken 100% and the layer thickness is adjusted in a range of (3.00-4.00 µ) as per total microns of the films.
Tie Layer or Adhesive Layer (24):
Admer QF 500 T Mitsui chemicals or Orevec OE825 from SK functional polymer is taken 100% and the layer thickness is adjusted from 0.7-1.00 micron as per total microns of the films.
Treated Layer (25):
The thickness of the treated layer (25) is in a range of 0.7-1.00 µ and comprises of copolymer and antiblock. The antiblock is in a range of 1-5% and is selected from Antiblock 2C01A, AVBT 22NSC. The copolymer is in a range of 90-100 % and is selected from Eltex PKS 607 or FL 7540 or RC 213M, RD 265.
Outer Layer (26):
The outer layer (26) is a metallized layer deposited with metal having optical density (OD) of 2.6 to 2.8. The metal Aluminum (Al) is deposited by physical vapour deposition.
Method 2
The prepared BOPP film (20) having (a) a sealing layer (21) comprises of 90-98% co-polymer (Cosmoplene-FS5711 or PKS 357) and 4% antiblock (High Add block 2C01A/AVBT 22NSC/ABO); (b) a tie layer (22) of 100% homopolymer (Homopoly.1030 FG, Moplen HP525J or Homo-Polymer: HC402BF or PP Resin-Luban HP3104K); (c) a main or core layer (23) of 100% homopolymer (Homopoly.1030 FG, Moplen HP525J or Homo-Polymer: HC402BF or PP Resin-Luban HP3104K); (d) a tie layer (or adhesive layer, (24)) of 100% Admer QF 500T; (e) a treated layer (25) comprising of 98% copolymer (PKS 607 or FL 7540 or RC 213M) and 2% of antiblock (Antiblock 2C01A or AVBT 22NSC); and (f) a metallized layer (26). Figure 2 shows a schematic representation of the layers of the metallized BOPP film (20). Table 2 shows the test results of Experiment 2 for BOPP film (20).

Table 2: The test results of Experiment 2 for BOPP film (20)
Property UOM Test method Experiment 2
Density gms/cc JPFTM 0.91
Haze % ASTM D 1003 3.5-4
Gloss 45° ASTM D 2457 89-91
Treatment Inside dyne/cm ASTM-D2578
Outside 45
Coef. of friction (One side - other side) In/In Kinetic ASTM-D1894 0.57
In/Metal 0.35
In/Out 0.51
Out/Out 0.52
Out/Metal 0.3
Tensile strength MD kg/cm² ASTM D 882 1156
TD 2386
Elongation MD % ASTM D 882 147
TD 41
SIT 2 bar/1sec (200 gm load) Treated °C JPFTM -
Untreated -
HSS (120°C@2 bar, sec ) Treated gm/25mm JPFTM -
Untreated -
Shrinkage (120°C@5 mins ) MD % JPFTM 4.5.0/4.5/4.5
TD 2.0/2.0/2.0

Table 2 shows the thickness of prepared film in a range of 7-7.3 Microns, haze is measured in a range of 3-3.2% as per ASTM D 1003, gloss in a range of 89-91 GU measured as per ASTM D 2457, treatment is shown to be 45 dyne/cm measured as per ASTM-D2578, coefficient of friction (one side-other side) in a range of 0.3-0.39 measured as per ASTM-D1894, tensile strength in a range of 1186-1300 kg/cm2 for MD and 2323-2500 kg/cm2 for TD measured as per ASTM-D882. Further, the elongation is shown to be 145% at MD and 38% for TD measured as per ASTM-D882, shrinkage (120°C@5 min) is shown to be 3-4.5% for MD and 2.0% for TD measured as per JPFTM. In addition, the oxygen transmission rate is in a range of 40-50 cc/m2/day as per ASTM D 3985 and water transmission rate is measured in a range of 1-2 g/m2/day as per ASTME398.

EXPERIMENT 3
Composition of layers in Experiment 3 for preparation of BOPP film (30)
Inner Layer (31):
The inner layer (31) is a sealing layer (heat seal layer) and is selected from Cosmoplane 5711, PKS 359 TPC, PKS 359, ADSYL 6064 (85-94%) and High Add 2C01A High grade or ABO504CP (Blend Additive), ABVT 22NSC A Schulman, ABNG 50MB Bankim Plast (2-10%). The skin layer thickness of sealing layer is maintained in a range of 0.8-1.10 µ.
Tie Layer or Intermediate Layer (32):
The tie layer (32) is made of Homopolymer selected from HC402BF, PP Resin-Luban HP3104K is taken 100% and layer thickness of tie layer (32) is adjusted in a range of 0.7-0.9 micron as per total microns of the film.
Core Layer or Main Layer (33):
The main layer (33) is made of homopolymer selected from Repol 1030 FG, Moplen HP525J or Homo Polymer: HC402BF or PP Resin-Luban HP3104K is taken 100% and layer thickness of core layer (33) is adjusted in a range of 3.00-4.00 microns as per total microns of the film.
Tie Layer or Adhesive Layer (34):
The tie layer (34) is made of Admer QF 500 T Mitsui chemicals, Orevec OE825 from SK functional polymer (taken 100%) and layer thickness of tie layer (34) is adjusted in a range of 0.7-0.9 micron as per total microns of the film.
Treated Layer (35):
The treated layer (35) is made of terpolymer or an EVOH layer. The terpolymer is selected from (EVALG156B from Kuraray and is taken in a range of 90-100% by maintaining skin layer thickness in a range of 0.8-1.2 µ.
Outer Layer (36)
The outer layer (36) is a metallized layer deposited with metal having optical density (OD) of 2.6 to 2.8. The metal Aluminum (Al) is deposited by physical vapour deposition.
Method 3
The prepared BOPP film (30) having (a) a sealing layer (31) comprises of 90-98% co-polymer (Cosmoplene-FS5711 or PKS 357) and 4-6% anti block (High Add block 2C01A/AVBT 22NSC/ABO); (b) a tie layer (32) of 100% homopolymer (Homopoly.1030 FG, Moplen HP525J or Homo-Polymer: HC402BF or PP Resin- Luban HP3104K); (c) a main or core layer (33) of 100% homopolymer (Homopoly.1030 FG, Moplen HP525J or Homo-Polymer: HC402BF or PP Resin-Luban HP3104K); (d) a tie layer (34) of 100% Admer QF 500T; (e) a treated layer (35) comprising of 98-100% terpolymer (EVAL G 156B) or an EVOH layer; and (f) a metallized layer (36). Figure 3 shows a schematic representation of the layers of the metallized BOPP film (30). Table 3 shows the test results of Experiment 3 for BOPP film (30).

Table 3: Test results of Experiment 3 for BOPP film (30)
Sr. No. Property UOM Test method Experiment 3
1 Nominal thickness Micron ASTM E 252 24.6
2 GSM gms/m² JPFTM 22.38
3 Density gms/cc JPFTM 0.91
4 Haze % ASTM D 1003 4.1-4.2
5 Gloss 45° ASTM D 2457 81-85
6 Treatment Inside (G) dyne/cm ASTM-D2578 40
Outside (M) -
7 Coef. of friction (One side - other side) Unt/Unt Kinetic ASTM-D1894 0.3
Unt/Metal 0.22
Unt/Tr 0.26
Tr/Tr 0.3
Tr/Metal 0.21
8 Tensile strength MD kg/cm² ASTM D 882 785
TD 2352
9 Elongation MD % ASTM D 882 232
TD 46
10 OTR 23°C & 0 %RH cc/m2/day ASTM E 398 1-1.2
11 WVTR 38°C& 90 %RH g/m2/day ASTMD 3985 0.8-1
Remark: CT variation in full width
Table 3 shows the thickness of prepared film ranging from 7-7.5 microns, haze is measured in a range of 1.8- 2.15% as per ASTM D 1003 gloss is measured in a range of 89-91 GU as per ASTM D 2457, gloss in a range of 89-91 GU as per ASTM D 2457, treatment is shown to be 45 dyne/cm as per ASTM-D2578, coefficient of friction (One side-other side) is measured in a range of 0.28-0.29 as per ASTM-D1894, tensile strength is shown to be in a range of 1186-1300 kg/cm² for MD and 2323-2500 kg/cm² for TD measured as per ASTM-D882, elongation is shown to be 145% at MD and 38% for TD measured as per ASTM-D882, shrinkage (120°C for 5 mins) is shown to be 3-4.5 % for MD and 2 % for TD measured as per JPFTM. Further, the oxygen transmission rate is measured in a range of 0.14-0.2 cc/m2/day as per ASTM D 3985 and water transmission rate is measured in a range of 0.1-0.2 g/m2/day.
Therefore, the present invention provides a seven-micron metallized BOPP film that is cost effective and sustainable and a method to provide ultra-high barrier BOPP film with special properties that reduced the cost for final lamination.
Many modifications and other embodiments of the invention set forth herein will readily occur to one skilled in the art to which the invention pertain having the benefit of the teachings presented in the foregoing descriptions and the associateddrawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
,CLAIMS:We claim:
1. A multi-layered metallized biaxially oriented polypropylene (BOPP) film (10, 20, 30), comprising of:
an inner layer (11, 21, 31);
a plurality of tie layer (12, 22, 32, 14, 24, 34);
a core layer (13, 23, 33);
a treated layer (15, 25, 35); and
an outer layer (16, 26, 36);
wherein,
said plurality of tie layer is having an intermediate layer (12, 22, 32) and an adhesive layer (14, 24, 34);
said BOPP film (10, 20, 30) exhibits gauge reduction with a thickness in a range of 6-7 microns to provide barrier for air, water or moisture; and
said BOPP film (10, 20, 30) exhibits haze in a range of 1.8-3.2% and gloss in a range of 89-91 GU.
2. The multi-layered metallized BOPP film as claimed in claim 1, wherein said inner layer (11, 21, 31) is a heat seal layer having a thickness ranging from 0.7-0.9 microns is made up of 90-98% copolymer and 2-10% additive.
3. The multi-layered metallized BOPP film as claimed in claim 1, wherein said plurality of tie layer (12, 22, 32, 14, 24, 34) having a thickness ranging from 0.7-0.9 microns is made up of 100% of homopolymer or additive or compatibilizer.
4. The multi-layered metallized BOPP film as claimed in claim 1, wherein said core layer (13, 23, 33) having a thickness ranging from 3-5 microns is made up of homopolymer or additive.
5. The multi-layered metallized BOPP film as claimed in claim 1, wherein said treated layer (15, 25, 35) having thickness ranging from 0.7 to 1.5 microns is made up of 90-100% of terpolymer or 90-100% of copolymer and 0-10% of additive or ethylene vinyl alcohol (EVOH) or homopolymer.
6. The multi-layered metallized BOPP film as claimed in claim 1, wherein said outer layer (16, 26, 36) is a metallized layer having a metal deposited with optical density (OD) ranging from 2.6 to 2.8.
7. The multi-layered metallized BOPP film as claimed in claim 1, wherein said BOPP film (10) exhibits barrier against air having oxygen transmission rate (OTR) ranging from 0.14 to 0.2 cc/m2/day.
8. The multi-layered metallized BOPP film as claimed in claim 1, wherein said BOPP film (10) exhibits barrier against moisture or water having water vapour transmission rate (WVTR) ranging from 0.1 to 0.2 g/m2/day.
9. The multi-layered metallized BOPP film as claimed in claim 1, wherein said BOPP film (10) exhibits tensile strength in a range of 1186-1300 kg/cm2 for machine direction (MD) and a range of 2323-2500 kg/cm2 for transverse direction (TD).
10. The multi-layered metallized BOPP film as claimed in claim 1, wherein said BOPP film (10) exhibits % shrinkage of 3-4.5 for MD and 2.0 for TD at a temperature of 120°C for a time period of 5 minutes.