Field of the Invention [0001] A multilayer polyolefin film for adhering to synthetic fabric.

Background of the Invention

[0002] In recent years, automobiles oftentimes include inflatable head airbags having a curtain design, in addition to the traditional airbags. Inflatable airbags typically comprise nylon or another synthetic fabric with a thin barrier layer covering the fabric. The barrier layer can be bonded to the fabric with an adhesive coating, but preferably the barrier layer is part of a multilayer film including a barrier layer and an adhesive layer.

[0003] Manufacturers of existing multilayer films oftentimes include polypropylene in the barrier layer because polypropylene is easily extrudable. An example of a multilayer film including polypropylene is disclosed in U.S. Patent No. 4,588,648, assigned to American Can Company. In airbag applications, barrier layers typically include extrudable polymer resins or polyolefins. An example of a vehicle airbag having a barrier layer including polyolefins is disclosed in U.S. Patent No. 5,302,432, assigned to Asahi Kasei Kogyo Kabushiki Kaisha. [0004] The composition of the barrier layer in a multilayer film has a significant impact on the permeability, thickness, flexibility, strength, melting point, adhesive properties, overall performance, and production cost of the multilayer film. However, the desired physical properties of the multilayer film are different for each unique application, which makes the specific composition of the barrier layer difficult to formulate. For example, multilayer films useful for automotive interior trim applications are generally not adequate for airbag applications. The composition must also be manufactured according to cost restraints, which are different for each application and often change from year to year.

[0005] Barrier layers used for inflatable airbag applications should yield a film having a low permeability to provide an airtight seal over the fabric, while maintaining enough flexibility to assist in the folding and unfolding of the airbag. The barrier layer should also have a high melting temperature to prevent blocking of the film laminate to itself when the airbag is in its rolled-up position and when the vehicle is exposed to high temperatures, which can be as high as 100° C, and so that the film can be laminated onto nylon, or another type of fabric without forming pinholes.

[0006] Many existing multilayer films having a polyolefin barrier layer are not preferable for inflatable airbag applications because they are either costly to manufacture, their permeabilities are too high, their peel strengths are too low, or their melting temperature is too low. There remains a great need for a cost effective film for adhering to synthetic fabrics having an improved barrier layer with low permeability, adequate flexibility, high peel strength and high melting temperature.

SUMMARY OF THE INVENTION

[0007] The subject invention provides a multi-layer polyolefin film comprising a barrier layer and an adhesive layer for adhering to synthetic fabric, such as nylon, polyester, polyethylene, polypropylene, aramide, or another fibrous fabric used in airbag applications. The barrier layer includes a first ungrafted polyolefin having a flexural modulus (1% secant) less than about 385 MPa, using the ISO 178 method. The barrier layer also includes a second ungrafted polyolefin having a melting point greater than about 140° C. The first ungrafted polyolefin typically includes a copolymer of ethylene and at least one C3 to ClO alpha olefin, such as a propylene-ethylene copolymer. The first ungrafted polyolefin typically comprises from about 3 weight percent (wt%) to about 45 wt% of the barrier layer. The second ungrafted polyolefin may be a polypropylene polymer comprising from about 55 wt% to about 95 wt% of the barrier layer. [0008] The subject invention provides an improved polyolefin film having low permeability, high flexibility, high peel strength and high melting temperature. The permeability of the subject invention is typically about .02 cm ³ /sec/cm ² and the peel strength from the synthetic fabric is typically about 100 N/m or higher. In addition, the barrier layer has a high melting point, which allows the film to be laminated onto the fabric without forming pinholes. The polyolefin film provides good hydrolytic and UV stability. Also, polyolefins allow high levels of additives or fillers, such as an Mg(OH) ₂ flame retardant, to be added to the film. [0009] These physical properties make the polyolefin film ideal for inflatable airbag applications, especially those having a curtain design. The film can be used in other automotive airbag applications, such as first impact airbags and knee airbags, located in front of either the driver or passenger. The film can also be used in motorcycle airbags, rucksack avalanche airbags, tarpaulins, sails, parachutes, clothing, and architectural fabrics.

[0010] The subject invention also provides a polyolefin film having a long storage life.

The film has a melting temperature greater than 105° C, and therefore temperature control and ventilation is not required for storage of the film at temperatures under 70° C. The storage costs of the subject invention are significantly less than existing silicone coating raw materials, which must be stored in sealed containers, away from moisture, and in a ventilated area under 35° C. Also, unlike silicone coatings, which typically have storage limitations of about 15 months, and a life of about only 24 hours when mixed, the film of the subject invention can be stored up to about three years. [0011] The inventive film can be produced with cost effective raw materials and extrusion processes so that the total production costs are generally lower than prior art films. The polyolefins used in the subject invention are less expensive than TPU, copolyesters, and other exotic materials used in many existing films. Also, the polyolefin film of the subject invention does not require mixing and curing chemistry in a chemical plant. The multi-layer film, including the barrier layer and adhesive layer, can be applied to the synthetic fabric in one step. Thus, the barrier layer can prevent excessive penetration of the adhesive layer into the fabric and prevent blocking between layers of the fabric. Films including separate barrier layers require multi-step manufacturing processes and do not provide this anti-blocking benefit. Also, the polyolefin film of the subject invention can be produced, transported, and stored without expensive packaging, such as drums, that must be returned to a supplier.

[0012] When appropriate precautions are taken, the polyolefin film can also be efficiently recycled. Unlike existing silicone coatings, which must be stripped of the silicone prior to reuse, the film of the subject invention can be recycled without expensive stripping or other preparation. Further, unlike existing TPU films laminated to nylon, which typically form an unstable compound that cannot be re-used, the film of the subject invention, including the polyolefin barrier layer, enables a stable, versatile, and re-usable compound when laminated to nylon.

DETAILED DESCRIPTION OF THE INVENTION

[0013] The polyolefin film includes a barrier layer and an adhesive layer for adhering to synthetic fabric, such as nylon, polyester, polyethylene, polypropylene, aramide (such as KEVLAR), or another fibrous fabric for inflatable airbag applications. The barrier layer includes a first ungrafted polyolefin having a flexural modulus (1% secant) less than about 500 MPa, and most preferably less than about 385 MPa, using the ISO 178 method. The first polyolefin is added to reduce the stiffness and the flexural modulus of the barrier layer. Therefore, the preferred first polyolefins should have low flexural moduli (1% secant), typically from about 5 MPa to about 500 MPa, using the ISO 178 method. The first polyolefin is typically an ethylene copolymer, most preferably a polypropylene-ethylene copolymer, such as a VERSIFY™ propylene based plastomer or elastomers, available from the Dow Chemical Company. Other first polyolefins preferably include, but are not limited to copolymers of ethylene and at least one C3 to ClO alpha olefin, such as ethylene-butene copolymers and ethylene-octene random or block copolymers. However, other polyolefins, such as propylene having a flexural modulus less than about 500 MPa can be used instead of a propylene-ethylene copolymer. The first polyolefin preferably has a density from about .850 g/cm ³ to about .900 g/cm ³ , tested using the ISO 1183 method. It typically has a melting index from about 1.0 g/10 minutes to about 25.0 g/10 minutes at 230 ⁰ C and 2.16 kg force, tested using the ISO 1133 method. The first polyolefin preferably comprises from about 3 wt% to about 45 wt% of the barrier layer, and most preferably about 20 wt%.

[0014] The second ungrafted polyolefin of the barrier layer has a melting temperature greater than about 140° C, tested using the ISO 306/A test method. The second polyolefin is added to increase the melting temperature of the barrier layer. Therefore, the preferred second polyolefins should have relatively high melting temperatures, preferably from about 145° C to about 165° C. The most preferred second polyolefins are typically polypropylene impact copolymers, such as INSPIRE 114, available from the Dow Chemical Company. However, polypropylene random copolymers or homopolypropylene or other polyolefins having a melting temperature greater than about 140° C can be used. The second polyolefin preferably has a melt index from about 0.5 g/10 minutes to about 5.0 g/10 minutes at 230° C and 2.16 kg force, a flexural modulus (1% secant) from about 1100 MPa to about 1700 MPa, tested using the ISO 178 method, and a density of about .900 g/cm ³ . These physical properties are tested using the same ISO methods as the first polyolefin. The second polyolefin preferably comprises from about 55 wt% to about 97 wt% of the barrier layer, and most preferably about 80 wt%. [0015] The barrier layer preferably includes two polyolefins, as described above, but can include a different number of polyolefins. The barrier layer preferably comprises from about 15 % to about 60 % of the film thickness. The barrier layer, including the first and second polyolefins, preferably has a melting temperature greater than 105° C, tested using the ASTM D 3418 method. The barrier layer polymer blend typically has a melt flow rate less than about 20 g/min, tested using the ASTM D 1238 method. The barrier layer can also include one or more additives. The possible additives include, but are not limited to, polymer stabilizing additives for preventing polymer degradation, ultra violet (UV) stabilizing additives for preventing UV degradation, and anti-block additives for preventing the polymers from adhering to one another and to processing equipment. The additives of the barrier layer can also include a flame retardant additive, a pigment for coloring the film and a lubricant.

[0016] The polyolefin film also comprises an adhesive layer. The adhesive layer typically includes at least one polyolefin, and preferably at least one grafted polyolefin which includes maleic anhydride (MAH grafted polyolefin). The polyolefin chosen for the MAH grafted polyolefin preferably has a melting temperature greater than about 105 ⁰ C or lower than about 85 ° C. A preferred MAH grafted polyolefin is an ethylene-octene block copolymer grafted with about .8 wt% MAH. The ethylene-octene block copolymer can be prepared by grafting an INFUSE 9807 ethylene-octene block copolymer, available from the Dow Chemical Company, and having a melt index of about 15.0 g/10 minutes at 190 ⁰ C and 2.16 kg force, a hard segment content of about 15 wt%, and a density of about .866 g/cm ³ . Other suitable MAH grafted polyolefins preferably include, but are not limited to, copolymers of ethylene and at least one C3 to ClO alpha-olefin, such as ethylene-octene block copolymers, ethylene-octene random copolymers, and ethylene-butene random copolymers.

[0017] The adhesive layer preferably has a maleic anhydride surface concentration (c _m ) from about .025 g/m ² to about .250 g/m ² . The maleic anhydride surface concentration (c _m ) is calculated according to the surface concentration equation c _m = /m x Λ x /α x yOf x t _f Equation 1 wherein f _m is the weight fraction of the maleic anhydride in the grafted polyolefins, f _g is the weight fraction of the grafted polyolefins in the adhesive layer, f _a is the weight fraction of the adhesive layer in the film, pf is the density of the film and t _f is the total thickness of the film. [0018] The adhesive layer of the film can alternatively comprise a polyesteramide based coating (PEA coating) adhered to the synthetic fabric by extrusion coating, and the barrier layer can be laminated onto the PEA coating. The PEA coating can also be applied as a one layer co- extrusion system. PEA coatings can be used as barrier layers of films adhering to synthetic fabric, and in this case, the PEA coating of the adhesive layer can include a barrier function. [0019] The PEA coating includes a single layer comprising a group of multiple bis-amide units containing polyester or polyether-esters. Preferably, the bis-amide units comprise from about 40 wt% to about 85 wt% of the PEA coating, and most preferably from about 50 wt% to about 60 wt% of the PEA coating. The PEA coating has melting temperature greater than about 125° C, depending on the bis-amide content of the coating. The melting temperature of greater than about 125° C prevents blocking or sticking. The PEA coating has a thickness from about 5 microns to about 100 microns, and most preferably from about 10 microns to about 25 microns. The viscosity of the PEA coating should be as low as possible to provide easy application to the synthetic fabric, but high enough to prevent leaking through the synthetic fabric. The material modulus and thickness of the PEA coating should also be as low as possible to further prevent blocking or sticking. An example of the PEA coating includes polybutylene adipate containing 1,2 etane di-amide units, prepared by a polycondensation reaction disclosed in U.S. Patent No. 6,172,167.

[0020] The adhesive layer including the PEA coating is preferably adhered to the synthetic fabric by a hot melt direct extrusion process. Nylon 6, 6, or polyesters can be used as the synthetic fabric when the PEA coating is used as the adhesive layer. After the hot melt PEA coating is applied to the synthetic fabric, the barrier layer can be laminated onto the PEA coating. When the adhesive layer includes the PEA coating, the barrier layer should have a melting temperature significantly higher than the hot PEA coating, but with sufficient chemical affinity to the PEA coating to achieve complete adhesion.

[0021] The PEA coating adheres well to synthetic fabric, especially nylon. The bis- amid4e units provide compatibility and hydrogen bonds to the synthetic fabric, preferably Nylon 6,6 or polyester when the PEA coating penetrates the fabric surface and closes the fabric pores. An additional adhesive layer is not required to adhere the PEA coating to the synthetic fabric. The PEA coating allows the polyolefin film to maintain excellent flexibility and low air permeability at minimum thickness and base weight. The high viscosity and thus high flow of the hot PEA coating makes the coating extremely suitable for use with the extrusion coating process to impregnate the synthetic fabric. The PEA coating also has a low coefficient of friction and provides resistance to blocking and sticking to itself. [0022] The polyolefin film should have a total film thickness from about 25 microns to about 100 microns, and most preferably about 50 microns. The film preferably has a permeability from about .015 cm ³ /sec/cm ² to about .400 cm ³ /sec/cm ² , and most preferably less than about .100 cm ³ /sec/cm ² . The film may be separated or peeled from the fabric by applying a strong force. The film may exhibit a peel failure mode being adhesive or cohesive, depending on the specific composition of the barrier layer and adhesive layer. When the peel failure mode of the film from the synthetic fabric is adhesive, the peel strength is preferably greater than about 100 N/m at 23° C. The permeability and peel strength are tested using the methods disclosed in Table 1. The film preferably has a tensile modulus (1% secant) in the machine direction (MD) from about 100 MPa to about 500 MPa, tested using the ASTM D 882 method. [0023] In an alternative embodiment, the polyolefin film includes at least one additional layer, for example a tie layer or a recycle layer between the barrier layer and adhesive layer. The most preferred tie layers comprise an olefin having a density less than about .920 g/cm . For excellent bonding to the adhesive layer and the barrier layer, the preferred tie layers comprise either linear low density polyethylene, ultra low density polyethylene, or metallocene based polyethylene. The preferred recycle layers may comprise these same olefins combined with excess material from the adhesive layer and barrier layer. The tie layers and recycle layers may reduce the manufacturing costs of the film.

[0024] The polyolefin film can be prepared by extrusion processes known in the field. A pelletized form of the barrier layer blend can be prepared by a twin screw extruder. Next, the multi-layer film can be prepared by a blown or cast film extrusion process. The multi-layer film can then be laminated onto fabric, for example nylon 6, 6, polyester, polyethylene, polypropylene, or aramide (such as KEVLAR), with a fusing machine. An advantage of using polyester over nylon is the lower cost of the polyester fibers. However, for the same fiber tenacity, polyester fibers have a smaller diameter fiber than nylon 6,6, which leads to a looser weave at the same strength. The inventive film is superior to the traditional silicone coating in retaining the gas content in the airbag. In addition, the MAH of the adhesive layer can form polar bonds with the polyester, ensuring high peel strengths of the film to the polyester fabric. Specific Embodiments

[0025] The following examples are given as particular embodiments of the invention and to demonstrate the practice and advantages thereof. The examples are given by way of illustration and are not intended to limit the specification or the claims in any manner.

Example 1

[0026] The barrier layer includes a resin blend comprising a first ungrafted polyolefin being a commercial propylene-ethylene copolymer, such as VERSIFY 2000, available from the Dow Chemical Company. The first polyolefin has a flexural modulus (1% secant) of about 385 MPa, tested using the ISO 178 method. The first polyolefin has a melt index of about 2.0 g/10 minutes at 230 ⁰ C and 2.16 kg force, tested using the ISO 1133 method, and a density of about .888 g/cm ³ , tested using the ISO 1183 method. The first polyolefin is added to reduce the flexural modulus of the barrier layer and it accounts for 20 wt% of the barrier layer. [0027] The resin blend further comprises a second ungrafted polyolefin being a commercial polypropylene impact copolymer having a melting temperature of about 160° C, such as INSPIRE 114, available from the Dow Chemical Company. The melting temperature is tested using the ISO 306/A test method. The second polyolefin has a flexural modulus (1% secant) of about 1480 MPa, tested using the ISO 178 method, a melt index of about 0.5 g/10 minutes at 230 ⁰ C and 2.16 kg force, and a density of about .900 g/cm ³ , tested using the same ISO methods as the first polyolefin. The second polyolefin is added to increase the melting temperature of the barrier layer and it accounts for 80 wt% of the barrier layer. [0028] The barrier layer is prepared by a twin screw extruder having two weight loss feeders and eight heating zones, such as a WP-ZSK 25, available from Werner and Pfleider. The first polyolefin is fed into one weight loss feeder and the second polyolefin is fed into the other weight loss feeder. The extruder speed is about 500 rpm. The first heating zone is about 170 ⁰ C, the second heating zone is about 175° C, the third heating zone is about 180 ⁰ C, the fourth heating zone is about 185° C, the fifth heating zone is about 190 ⁰ C, the sixth heating zone is about 195° C, the seventh heating zone is about 200° C and the eighth heating zone is about 210° C. The barrier layer can be extruded as a strand and pelletized to form compound pellets upon exiting the extruder.

[0029] Next, a two layer polyolefin film being about 50.8 microns thick and including the barrier layer is prepared on a small blown film extrusion line, such as a DS 075 HM extruder, available from Davis Standard. The extrusion line has three extruders each having an 18 inch length and a ³ A inch diameter (L/D 24:1). Each extruder includes a die having a 2 inch die diameter and a .333 inch die gap. The extruders have three controlled heating zones and the dies have two heating zones. The three extruders operate simultaneously and have a nip speed of about 10.7 ft/min.

[0030] Extruder 1 accounts for the pelletized barrier layer, as described above, comprising 30 % of the film. Extruder 1 operates at a speed of 75 rpm and a pressure of 2095 psi. The melting temperature of the barrier layer in Extruder 2 is about 202° C. The three controlled heating zones are at 188° C, 193° C, and 204 ⁰ C and both die heating zones are at 204° C. [0031] Extruders 2 and 3 account for the adhesive layer comprising 70 % of the film.

Each extruder accounts for 35 % of the film and contains a pelletized form of the adhesive layer. Extruder 2 operates at a speed of 79 rpm and a pressure of 2380 psi. The three controlled heating zones are at 188° C, 193° C, and 204 ⁰ C and both die heating zones are at 204 ⁰ C. Extruder 3 operates at a speed of 79 rpm and a pressure of 2100 psi. The three controlled heating zones and die heating zones are the same as Extruder 2. The adhesive layer has a calculated MAH surface concentration of about .051 g/m ² .

[0032] The density of the overall polyolefin film is about .903 g/cm ³ , tested using the

ASTM D792 method. The film preferably has a tensile modulus (1% secant) in the Machine Direction (MD) of about 360 MPa, tested using the ASTM D882 method.

[0033] The polyolefin film can also be prepared as a dry blend of pellets so that pre- compounding is not required. The film can be laminated onto commercially available synthetic fabric, such as Nylon Style 28147-7726, available from Safety Components Inc. The lamination process occurs on a fusing machine, such as an Astex Model 3024, available from Advanced Innovation Technologies LLC. The lamination process includes cutting a sample of the film, placing the film onto the fabric and then placing them between two fluropolymer coated glass release sheets. The glass sheets are placed between two heated moving belts of the fusing machine with a 30 second dwell time and 30 psi gauge pressure. The film and fabric in the glass sheets are heated to temperatures between 160° C and 177° C. The finished film is then prepared for testing. Table 1 provides an overview of testing details for the finished polyolefin film. Table 2 provides testing results for the examples. Example 2

[0034] The barrier layer includes a resin blend comprising a first ungrafted polyolefin being a commercial ethylene-butene copolymer, such as ENR 7467, available from the Dow Chemical Company. The first polyolefin has a flexural modulus (1% secant) of about 4.1 MPa, tested using the ASTM D 790 method. The first polyolefin has a melt index of about 1.2 g/10 minutes at 190 ⁰ C and 2.16 kg force, tested using the ASTM D 1238 method. It has a density of about .862 g/cm ³ , tested using the ASTM D 792 method. The first polyolefin is added to reduce the flexural modulus of the barrier layer and it accounts for 20 wt% of the barrier layer. [0035] The resin blend further comprises a second ungrafted polyolefin being a commercial polypropylene impact copolymer having a melting temperature of about 160° C, such as INSPIRE 114, available from the Dow Chemical Company. The second polyolefin has a melt index of about 0.5 g/10 minutes at 230 ⁰ C and 2.16 kg force, a flexural modulus (1% secant) of about 1480 MPa, tested using the ISO 178 method, and a density of about .900 g/cm ³ . The physical properties of the second polyolefin are tested using the ISO test methods disclosed in Example 1. The second polyolefin is added to increase the melting temperature of the barrier layer and it accounts for 80 wt% of the barrier layer.

[0036] The barrier layer is prepared by a twin screw extruder, as described in Example 1.

Next, a two layer polyolefin film being about 53 microns thick and including the barrier layer is prepared on a small blown film extrusion line, such as a DS 075 HM extruder, as described in Example 1. Extruder 1 accounts for the pelletized barrier layer, as described above, comprising 30 % of the film. Extruder 1 operates at a speed of 75 rpm and a pressure of 1995 psi. The melting temperature of the barrier layer in Extruder 1 is about 202° C. The three controlled heating zones are at 188° C, 193° C, and 204 ⁰ C and both die heating zones are at 204 ⁰ C. [0037] Extruders 2 and 3 account for the adhesive layer comprising 70 % of the film.

Each extruder accounts for 35 % of the film and contains a pelletized form of the adhesive layer. Extruder 2 operates at a speed of 79 rpm and a pressure of 2400 psi. The three controlled heating zones are at 188° C, 193° C, and 204 ⁰ C and both die heating zones are at 204 ⁰ C. Extruder 3 operates at a speed of 79 rpm and a pressure of 2100 psi. The three controlled heating zones and die heating zones are the same as Extruder 2. The melt temperature of the adhesive layer in Extruder 3 is about 202° C. The adhesive layer has a calculated MAH surface concentration of about .053 g/m ² .

[0038] The density of the overall polyolefin film is about .893 g/cm ³ , tested using the

ASTM D792 method. The film preferably has a tensile modulus (1% secant) in the Machine Direction (MD) of about 270 MPa, tested using the ASTM D882 method.

[0039] The film is bonded to commercial fabric on a fusing machine, as described in

Example 1. The finished film is then prepared for testing. Table 1 provides an overview of testing details for the finished film. Table 2 provides testing results for the examples.

Example 3

[0040] The barrier layer includes a resin blend comprising a first ungrafted polyolefin being a developmental ethylene-octene block copolymer such as INFUSE D9007.10, available from the Dow Chemical Company. The first polyolefin has a melt index of about 0.5 g/10 minutes at 190 ⁰ C and 2.16 kg force and a density of about .866 g/cm ³ . The physical properties of the first polyolefin are tested using the ASTM test methods disclosed in Example 2. The first polyolefin is added to reduce the flexural modulus of the barrier layer and it accounts for 20 wt% of the barrier layer. [0041] The resin blend further comprises a second ungrafted polyolefin being a commercial polypropylene impact copolymer having a melting temperature of about 160° C, such as INSPIRE 114, available from the Dow Chemical Company. The second polyolefin has a melt index of about 0.5 g/10 minutes at 230 ⁰ C and 2.16 kg force, a flexural modulus (1% secant) of about 1480 MPa, tested using the ISO 178 method, and a density of about .900 g/cm ³ . The physical properties of the second polyolefin are tested using the ISO test methods disclosed in Example 1. The second polyolefin is added to increase the melting temperature of the barrier layer and it accounts for 80 wt% of the barrier layer.

[0042] The barrier layer is prepared by a twin screw extruder, as described in Example 1.

Next, a two layer polyolefin film being about 54 microns thick and including the barrier layer is prepared on a small blown film extrusion line, such as a DS 075 HM extruder, as described in Example 1. Extruder 1 accounts for the pelletized barrier layer, as described above, comprising 30 % of the film. Extruder 1 operates at a speed of 75 rpm and a pressure of 1200 psi. The melting temperature of the barrier layer in Extruder 1 is about 202° C. The three controlled heating zones are at 188° C, 193° C, and 204 ⁰ C and both die heating zones are at 204 ⁰ C. [0043] Extruders 2 and 3 account for the adhesive layer comprising 70 % of the film.

Each extruder accounts for 35 % of the film and contains a pelletized form of the adhesive layer. Extruder 2 operates at a speed of 79 rpm and a pressure of 2425 psi. The three controlled heating zones are at 188° C, 193° C, and 204 ⁰ C and both die heating zones are at 204 ⁰ C. Extruder 3 operates at a speed of 79 rpm and a pressure of 2130 psi. The three controlled heating zones and die heating zones are the same as Extruder 2. The melt temperature of the adhesive layer in Extruder 3 is about 202° C. The adhesive layer has a MAH surface concentration of about .054 g/m ² . [0044] The density of the overall polyolefin film is about .893 g/cm ³ , tested using the

ASTM D792 method. The film preferably has a tensile modulus (1% secant) in the Machine Direction (MD) of about 190 MPa, tested using the ASTM D882 method.

[0045] The film is bonded to commercial fabric on a fusing machine, as described in

Example 1. The finished film is then prepared for testing. Table 1 provides an overview of testing details for the finished film. Table 2 provides testing results for the examples.

Example 4

[0046] The barrier layer includes a resin blend comprising a first ungrafted polyolefin being a commercial propylene-ethylene copolymer, such as VERSIFY 2000, available from the Dow Chemical Company. The first polyolefin has a flexural modulus (1% secant) of about 385 MPa, tested using the ISO 178 method. The first polyolefin has a melt index of about 2.0 g/10 minutes at 230 ⁰ C and 2.16 kg force and a density of about .888 g/cm ³ . The physical properties are tested using the ISO test methods disclosed in Example 1. The first polyolefin is added to reduce the flexural modulus of the barrier layer and it accounts for 40 wt% of the barrier layer. [0047] The resin blend further comprises a second ungrafted polyolefin being a commercial polypropylene impact copolymer having a melting temperature of about 160° C, such as INSPIRE 114, available from the Dow Chemical Company. The second polyolefin has a melting index of about 0.5 g/10 minutes at 230 ⁰ C and 2.16 kg force, a flexural modulus (1% secant) of about 1480 MPa, tested using the ISO 178 method, and a density of about .900 g/cm . The physical properties of the second polyolefin are tested using the ISO test methods disclosed in Example 1. The second polyolefin is added to increase the melting temperature of the barrier layer and it accounts for 60 wt% of the barrier layer. [0048] The barrier layer is prepared by a twin screw extruder, as described in Example 1.

Next, a two layer polyolefin film being about 54 microns thick and including the barrier layer is prepared on a small blown film extrusion line, such as a DS 075 HM extruder, as described in Example 1. Extruder 1 accounts for the pelletized barrier layer, as described above, comprising 30 % of the film. Extruder 1 operates at a speed of 75 rpm and a pressure of 2130 psi. The melt temperature of the barrier layer in Extruder 1 is about 202° C. The three controlled heating zones are at 188° C, 193° C, and 204 ⁰ C and both die heating zones are at 204 ⁰ C.

[0049] Extruders 2 and 3 account for the adhesive layer comprising 70 % of the film.

Each extruder accounts for 35 % of the lamination film and contains a pelletized form of the adhesive layer. Extruder 2 operates at a speed of 79 rpm and a pressure of 2435 psi. The three controlled heating zones are at 188° C, 193° C, and 204 ⁰ C and both die heating zones are at 204° C. Extruder 3 operates at a speed of 79 rpm and a pressure of 2135 psi. The three controlled heating zones and die heating zones are the same as Extruder 2. The adhesive layer has a MAH surface concentration of about .054 g/m ² .

[0050] The density of the overall polyolefin film is about .894 g/cm ³ , tested using the

ASTM D792 method. The film preferably has a tensile modulus (1% secant) in the Machine Direction (MD) of about 150 MPa, tested using the ASTM D882 method.

[0051] The film is bonded to commercial fabric on a fusing machine, as described in

Example 1. The finished film is then prepared for testing. Table 1 provides an overview of testing details for the finished film. Table 2 provides testing results for the examples. TABLE 1

TABLE 2

[0052] Obviously, many modifications and variations of the present invention are possible in light of the above teachings and may be practiced otherwise than as specifically described while within the scope of the appended claims. These antecedent recitations should be interpreted to cover any combination in which the inventive novelty exercises its utility.