Films with Improved Easy Open Properties Calvin W. Beddingfield, Simpsonville, SC, James E. Pelkie, Simpsonville, SC, Daniel A.

Dorroh, Greenville, SC, Frank M. Hofmeister, Simpsonville, SC

SPECIFICATION

BACKGROUND OF THE INVENTION [0001] The present invention is in the field of food packaging. More particularly, the present invention is in the field of easy open food packaging.

[0002] Certain food products, most commonly, meat products are often packaged in food packages known as chub packages. For example, ground beef and other comminuted food products are available in grocery stores in a chub package in various sizes. These packages are generally produced using a vertical form fill seal (VFFS) process, in which a tube is formed from a flat sheet of roll stock film. The tube is formed vertically and longitudinally sealed with a vertical sealing bar. The bottom of the tube is then sealed with a metal clip applied to the bottom of the tube. The food product is pumped into the open end of the tube, and the top is sealed with another metal clip to produce a chub package. The chub package resembles a semi-rigid tube with the tubular film forming a skin tight layer of film around the food product. Package sizes may range from 1 to 20 pounds, depending on the intended mode of distribution. Commercially available films currently used in chub packaging applications are the HS 3000, HS 3000W, HS 3500, and BSC 6000 produced by Cryovac, Inc., a subsidiary of Sealed Air Corporation. U.S. Pat. No. 4,909,726 (Bekele), incorporated herein by reference in its entirety, discloses films useful in packaging ground meat in chub packages. [0003] During the VFFS process the chub package undergoes relatively high

temperatures and pressure during the sealing process. Thus, packaging film used for chub packaging must have sufficient heat resistance to withstand relatively high temperatures and pressures. Known chub packages often have a strong seal to prevent unintended opening of the chub during the VFFS process and transport of the final chub package which contains the food product. In order to open a chub package, common practice is to use a knife, scissors or other cutting device. This practice requires a cutting device and adds a risk of injury from the cutting device. Therefore, it is desired for an improved easy open chub package. The easy open chub package would be able to withstand relatively high temperatures and pressures, but also provide a way to open the chub package without the use of cutting devices.

SUMMARY OF THE INVENTION

[0004] The present invention is directed to a film for use in chub packaging. In some embodiments, the film may have a first peelable layer with less than 8% of polybutylene, a second peelable layer with less than 8% of polybutylene, and at least one sealant layer.

The film may have an average peel initiation force greater than 0.5 kg-force. The film may have a variation of the average peel initiation force of less than 50%.

[0005] In other embodiments, the film may have a first peelable layer comprising less than 8% of polybutylene, a second peelable layer comprising less than 8% of polybutylene, and at least one sealant layer. The film may have an average peel initiation force greater than 0.5 kg-force. The film may have a difference between the maximum and minimum value for peel initiation force of less than 75%.

[0006] The invention is also directed to a method for producing a film. The method may include extruding resins in an extrusion die to create a mixture of molten resins. The method may also include filling the die with air thereby causing the mixture of molten resins to expand into the shape of a tube. In some embodiments, the method may further include collapsing the tube so that the inside surface of the tube adheres to itself to form a film.

[0007] The invention is also directed to a chub package made from a film. The film may have a first peelable layer comprising less than 8% of polybutylene, a second peelable layer comprising less than 8% of polybutylene, and at least one sealant layer. The film may have an average peel initiation force greater than 0.5 kg-force. The film may also have a variation of the average peel initiation force of less than 50%.

[0008] The invention is also directed to a chub package made from a film. The film may have a first peelable layer comprising less than 8% of polybutylene, a second peelable layer comprising less than 8% of polybutylene, and at least one sealant layer. The film may have an average peel initiation force greater than 0.5 kg-force. The film may also have a difference between the maximum and minimum value for peel initiation force of less than 75%.

BRIEF DESCRIPTION OF THE DRAWING [0009] Fig. 1 illustrates a schematic cross-sectional view of an embodiment of the present invention;

[0010] Fig. 2 illustrates a schematic cross-sectional view of a multilayer film;

[0011] Fig. 3 illustrates a schematic cross-sectional view of a tubular lay-flat film;

[0012] Figs. 4A and 4B are graphs showing load versus time for samples 1 :5 and 1 .

[0013] Figs. 5A and 5B are graphs showing load versus time for samples 2:5 and 2.

[0014] Figs. 6A and 6B are graphs showing load versus time for samples 3:5 and 3.

DETAILED DESCRIPTION OF THE INVENTION

[0015] The invention discloses a film for use in chub packaging. This film has an easy open feature where the film has two peelable layers present in a multilayer film. The film has an average peel initiation force greater than 0.5 kg-force (kgf). The film also has low variation in the average peel initiation force.

[0016] While the following terms are believed to be well understood by one of ordinary skill in the art, the following definitions are set forth to facilitate explanation of the presently disclosed subject matter. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which the presently disclosed subject matter belongs.

[0017] Following long standing patent law convention, the terms "a", "an", and "the" refer to "one or more" when used in the subject application, including the claims. Thus, for example, reference to "a formulation" includes a plurality of such formulations, and so forth.

[0018] Unless indicated otherwise, all numbers expressing quantities of components, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about." Accordingly, unless indicated to the contrary, the numerical parameters set forth in the instant specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the presently disclosed subject matter.

[0019] As used herein, the term "about", when referring to a value or to an amount of mass, weight, time, volume, concentration, percentage, and the like can encompass variations of, and in some embodiments, ±20%, in some embodiments ±10%, in some embodiments ±5%, in some embodiments ±1 %, in some embodiments ±0.5%, and in some embodiments ±0.1 %, ±0.01 %, from the specified amount, as such variations are appropriated in the disclosed package and methods.

[0020] As used herein, the term "polymer" refers to the product of a polymerization reaction, and is inclusive of homopolymers, copolymers, terpolymers, tetrapolymers, etc. [0021] As used herein, the term "copolymer" refers to a polymer formed by the

polymerization reaction of at least two different monomers and is inclusive of random copolymers, block copolymers, graft copolymers, etc.

[0022] As used herein, the term "(meth)acrylic acid" refers to an acrylic acid and/or methacrylic acid. An ethylene/(meth)acrylic acid copolymer is a copolymer of ethylene with an α,β ethylenically unsaturated monocarboxylic acidic monomer selected from acrylic acid and methacrylic acid. The copolymer typically contains from about 4% to about 18% by weight of acrylic or methacrylic acid units. The copolymer can also contain, copolymerized therein, an alkyl(meth)acrylate, such as n-butyl acrylate or methacrylate or isobutyl acrylate or methacrylate. The term "EAA" is generally used to indicate a copolymer of ethylene and acrylic acid, whereas the term ΈΜΑΑ" generally refers to a copolymer of ethylene and methacrylic acid. Useful ethylene/(meth)acrylic acid copolymers are commercially available from DuPont under the trademark Nucrel®, e.g., Nucrel® 1202, Nucrel® 1302 or under the trademark Elvaloy®, e.g., Elvaloy® 1214AC or from Dow Chemicals under the trademark Primacor®, e.g. , Primacor® 1410.

[0023] As used herein, the term "ionomer" refers to a neutralized ethylene/(meth)acrylic acid copolymer. Ionomer is a copolymer of ethylene and acrylic and/or methacrylic acid having the carboxylic acid neutralized by a metal ion, such as zinc, or preferably, sodium. Typically, neutralized ethylene/(meth)acrylic acid copolymers include at least 60% by weight, preferably at least 70% by weight and more preferably 80% by weight of ethylene units. Useful neutralized ethylene/(meth)acrylic acid copolymers include those in which sufficient metal ion is present to neutralize from about 15% to about 60% of the acid groups of the polymer. Useful neutralized ethylene/(meth)acrylic acid copolymers are commercially available from DuPont under the trademark Surlyn®, e.g., Surlyn® 1601 , Surlyn® 1650, Surlyn® 1650SB, Surlyn® 1652, Surlyn® 1901 , Surlyn®2601 or from ExxonMobil under the trademark lotek®, e.g. , lotek® 31 10.

[0024] As used herein, the term "peelable", as applied to polymer blends, refers to a polymer blend of at least two components selected in such a way that the internal cohesive forces holding together the blend are overcome during opening of the package. The term "peelable", as applied to a film layer, refers to a layer with a frangible polymer blend. The internal cohesive forces of a peelable layer are lower than a heat-seal formed between the sealant layer of the multilayer film of the invention when sealed to itself or another sealant layer. The term "peelable" also includes the term "frangible".

[0025] While the foregoing written description of the invention enables one of ordinary skill to make and use what is considered presently to be the best mode thereof, those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The invention should therefore not be limited by the above described embodiment, method, and examples, but by all embodiments and methods within the scope and spirit of the invention as claimed.

Films

[0026] The invention disclosed is directed to a film for use in chub packaging. The film may have at least one peelable layer. The film may have a first peelable layer. The first peelable layer may have less than 15% polybutylene. In some embodiments, the first peelable layer may have less than 8% polybutylene. In other embodiments, the first peelable layer may have 5% polybutylene. The first peelable layer may have a polymer blend. The polymer blend may have an ionomer, ethyl vinyl acetate copolymer and polybutylene. In some embodiments, the polymer blend of an ionomer, ethyl vinyl acetate (EVA) copolymer and polybutylene may be at a weight ratio range of 15: 10: 1 to 10:5: 1 , respectively. The polymer blend of an ionomer, ethyl vinyl acetate (EVA) copolymer and polybutylene may be at a weight ratio of 15: 10: 1 , 15: 1 1 : 1 , 15:9:1 , 15:8:1 , 15:6: 1 , 14: 11 :1 , 14: 10:1 , 14:9: 1 , 14:8: 1 , 14:6:1 , 13: 10:1 , 13:8:1 , 13:6: 1 , 12: 15: 1 , 1 1 : 10: 1 , 10:5: 1 , or any range between any of these values. In other embodiments, the polymer blend of an ionomer, EVA copolymer and polybutylene may be at a weight ratio range of 13:6: 1 , respectively. The ionomer may be a neutralized ethylene/(meth)acrylic acid copolymer. In some embodiments, the ionomer may be Surlyn® 1650SB from DuPont. The EVA copolymer may be a modified-EVA copolymer In some embodiments, the EVA copolymer may be Elvax 650q from DuPont. The polybutylene may be PB8640M from LyondellBasell. In some embodiments the polymer blend may be 65% ionomer, 30% EVA copolymer and 5% polybutylene.

[0027] The film may have a second peelable layer. The second peelable layer may have less than 15% polybutylene. In some embodiments, the second peelable layer may have less than 8% polybutylene. In other embodiments, the second peelable layer may each have 5% polybutylene. The second peelable layer may be the same formulation as the first peelable layer. The second peelable layer may have a polymer blend. In some embodiments the polymer blend may be 65% ionomer, 30% EVA copolymer and 5% polybutylene. In some embodiments, the first and the second peelable layer may have a polymer blend of an ionomer, an ethylene vinyl acetate copolymer and a polybutylene. The polymer blend of the first and the second peelable layer may be at a weight ratio range of 15: 10: 1 to 10:5: 1 . The polymer blend of an ionomer, ethyl vinyl acetate (EVA) copolymer and polybutylene may be at a weight ratio of 15: 10:1 , 15:1 1 : 1 , 15:9:1 , 15:8: 1 , 15:6: 1 , 14:1 1 : 1 , 14: 10: 1 , 14:9: 1 , 14:8:1 , 14:6:1 , 13: 10:1 , 13:8:1 , 13:6: 1 , 12:15: 1 , 11 : 10: 1 , 10:5: 1 , or any range between any of these values. In other embodiments, the polymer blend of an ionomer, EVA copolymer and polybutylene may be at a weight ratio range of 13:6: 1 , respectively. In other embodiments, the first and the second peelable layer may each have a polymer blend with 65% ionomer, 30% EVA copolymer and 5% polybutylene. The first and the second peelable layer may have 15% polybutylene, 14% polybutylene, 13% polybutylene, 12% polybutylene, 1 1 % polybutylene, 10% polybutylene, 8% polybutylene, 6% polybutylene, 5% polybutylene, 4% polybutylene, 3% polybutylene, 2% polybutylene, or any range between any of these values.

[0028] The first and second peelable layer may each have a thickness of less than 1 mil. In some embodiments the first and second peelable layer may each have a thickness of less than 0.5 mils. In other embodiments, the first and second peelable layer may each have a thickness of less than 0.25 mils. The first and second peelable layer may each have a thickness of 0.25 mils, 0.2 mils, 0.15 mils, 0.14 mils, 0.138 mils, 0.13 mils, 0.12 mils, 0.1 1 mils, 0.10 mils, 0.08 mils, 0.05 mils, or any range between any of these values. The first and second peelable layer may have a thickness of 0.138 mils.

[0029] The film may have at least one sealant layer. The film may have a plurality of sealant layers. The at least one sealant layer may be adhesively laminated. The sealant layer may be a self-weldable layer and may be from a multilayer layer film that has a peelable layer and a sealant layer.

[0030] The sealant layer may have a thickness of less than 1 mil. In some embodiments the sealant layer may have a thickness of less than 0.5 mils. In other embodiments, the sealant layer may have a thickness of less than 0.25 mils. The sealant layer may have a thickness of 0.25 mils, 0.2 mils, 0.15 mils, 0.14 mils, 0.13 mils, 0.12 mils, 0.1 1 mils, 0.10 mils, 0.092 mils, 0.09 mils, 0.08 mils, 0.05 mils, or any range between any of these values. The sealant layer may have a thickness of 0.092 mils.

[0031] In some embodiments, the at least one sealant layer may be a polyethylene. The at least one sealant layer may be a blend of polyethylenes. In some embodiments, the at least one sealant layer may be a blend of low density polyethylene (LDPE) and linear low density polyethylene (LLDPE). In some embodiments, the at least one sealant layer may be a blend of LLDPE and LDPE at a weight ratio of 10:90 to 90:10. The at least one sealant layer may be a blend of 10% LLDPE and 90% LDPE, 20% LLDPE and 80% LDPE, 30% LLDPE and 70% LDPE, 40% LLDPE and 60% LDPE, 50% LLDPE and 50% LDPE, 60% LLDPE and 40% LDPE, 70% LLDPE and 30% LDPE, 80% LLDPE and 20% LDPE, 90% LLDPE and 10% LDPE, or any range between any of these values. In other embodiments, the at least one sealant layer may be a blend of 90% LLDPE and 10% LDPE The at least one sealant layer may be a first sealant layer and a second sealant layer.

[0032] The film may have at least one tie layer. The at least one tie layer may be EVA. In some embodiments, the at least one tie layer may be at least one modified-EVA copolymer. In other embodiments, the at least one tie layer may be maleic-anhydride- modified EVA copolymer. In further embodiments, the at least one tie layer may be a modified LLDPE. The at least one tie layer may have a modified ethylene vinyl acetate copolymer and a modified LLDPE. The at least one tie layer may be maleic-anhydride grafted LLDPE. In some embodiments, the at least one tie layer may be a first tie layer self-welded to a second tie layer.

[0033] The at least one tie layer may have a thickness of less than 1 mil. In some embodiments the at least one tie layer may have a thickness of less than 0.5 mils. In other embodiments, the at least one tie layer may have a thickness of less than 0.25 mils. The at least one tie layer may have a thickness of 0.25 mils, 0.2 mils, 0.15 mils, 0.14 mils, 0.13 mils, 0.12 mils, 0.1 15 mils, 0.1 1 mils, 0.10 mils, 0.09 mils, 0.08 mils, 0.05 mils, or any range between any of these values. The at least one tie layer may have a thickness of 0.1 15 mils.

[0034] The film may have at least one core layer. The at least one core layer may have a polyamide. The film may have 1 core layer. In some embodiments, the film may have 2 core layers. In other embodiments, the film may have 3 core layers. The film may have 4 core layers. The film may have 5 core layers. The at least one core layer may have hydrolyzed ethylene/vinyl acetate copolymer (EVOH/EVAL), polyamides, blends of EVOH and polyamides, PVDC or combinations thereof. The at least one core layer may have a polyamide. The polyamide may be a nylon. The nylon may be nylon 6, nylon 6/12, nylon 6/6, nylon 6/66, nylon 6/69, or combinations thereof. In some embodiments, the nylon may be nylon 6. In other embodiments, the film may have one core layer, wherein the core layer has a blend of nylon 6, hydrolyzed ethylene/vinyl acetate copolymer

(EVOH/EVAL). In further embodiments, the film may have 3 core layers, wherein the first core layer is nylon 6, the second core layer is an EVOH/EVAL, and the third core layer is nylon 6. These core layers act as barrier layers in the film. The EVOH/EVAL may have between 30-40 mole% ethylene.

[0035] The at least one core layer may have a thickness of less than 1 mil. In some embodiments the at least one core layer may have a thickness of less than 0.5 mils. In other embodiments, the at least one core layer may have a thickness of less than 0.25 mils. The at least one core layer may have a thickness of 0.25 mils, 0.2 mils, 0.15 mils, 0.14 mils, 0.13 mils, 0.125 mils, 0.12 mils, 0.1 15 mils, 0.1 1 mils, 0.10 mils, 0.09 mils, 0.084 mils, 0.08 mils, 0.05 mils, or any range between any of these values. In some embodiments, the at least one core layer may have a thickness of 0.125 mils. In other embodiments, the at least one core layer may have a thickness of 0.084 mils. In further embodiments, the at least one core layer may be 3 layers wherein the first core layer is nylon 6 and has a thickness of 0.125 mils, the second core layer is a hydrolyzed ethylene/vinyl acetate copolymer having between 30-40 mole% ethylene and has a thickness of 0.084 mils, and the third core layer is nylon 6 and has a thickness of 0.125 mils.

[0036] In some embodiments, the film may have at least one additional layer. The at least one additional layer may be a second tie layer. The second tie layer may be EVA. In some embodiments, the second tie layer may be at least one modified-EVA copolymer. In other embodiments, the second tie layer may be maleic-anhydride-modified EVA copolymer. The second tie layer may have a modified-EVA copolymer and maleic- anhydride-modified EVA copolymer. In further embodiments, the second tie layer may be a modified LLDPE. The second tie layer may be maleic-anhydride grafted LLDPE.

[0037] The at least one additional layer may be at least one bulk layer. The at least one additional layer may be a second tie layer and a bulk layer. The bulk layer may be may be a polyethylene. The bulk layer may be a blend of polyethylenes. In some

embodiments, the bulk layer may be a blend of very low density polyethylene (VLDPE) and LLDPE. The LLDPE may have a colorant. The colorant may be white. In some embodiments, the bulk layer may be a blend of VLDPE and LLDPE with a white colorant. The bulk layer may be a blend of VLDPE and LLDPE at a weight ratio of 80:20 to 20:80. The bulk layer may be a blend of 80% VLDPE and 20% LLDPE, 70% VLDPE and 30% LLDPE, 60% VLDPE and 40% LLDPE, 50% VLDPE and 50% LLDPE, 40% VLDPE and 60% LLDPE, 30% VLDPE and 70% LLDPE, 20% VLDPE and 80% LLDPE, or any range between any of these values. In other embodiments, the bulk layer may be a blend of 60% VLDPE and 40% LLDPE with a white colorant. The at least one additional layer may be a second tie layer that is maleic-anhydride-modified EVA copolymer and a bulk layer that is a blend of 60% VLDPE and 40% LLDPE with a white colorant.

[0038] The at least one additional layer may have a thickness of less than 1 mil. In some embodiments the at least one additional layer may have a thickness of less than 0.5 mils. The at least one additional layer may have a thickness of 0.5 mils, 0.4 mils, 0.357 mils, 0.25 mils, 0.2 mils, 0.15 mils, 0.14 mils, 0.13 mils, 0.125 mils, 0.12 mils, 0.1 15 mils, 0.1 1 mils, 0.10 mils, 0.09 mils, 0.084 mils, 0.08 mils, 0.05 mils, or any range between any of these values. In some embodiments, the at least one additional layer may have a thickness of 0.357 mils. In other embodiments, the at least one additional layer may have a thickness of 0.1 15 mils. The at least one additional layer may be a second tie layer with a thickness of 0.1 15 mils and a bulk layer with a thickness of 0.357 mils.

[0039] The film may be a multilayer film. FIG. 1 is a cross-sectional view of an

embodiment of a multilayer film 1 having a sealant layer 20, a peelable layer 25, a bulk layer 30, a second tie layer 35, 3 core layers 40, 45, 50, and a tie layer 55. The multilayer film 1 may be extruded as a tubular film and once the multilayer film 1 is collapsed, the tie layer 55 will self-weld to itself and create a 15 layer film. The film may be a lay-flat tubular film. The film may be an extruded lay-flat tubular film. As seen in FIG. 2, the lay-flat tubular film 2 may have a sealant layer 20, a peelable layer 25, a bulk layer 30, a second tie layer 35, 3 core layers 40, 45, 50, and a tie layer 55. The tie layer 55 self-welds at the interface 33. The interface 33 represents the point of contact between the two tie layers 55, 55 when the tubular film is collapsed and the other layers 20, 25, 30, 35, 40, 45, and 50 are on both sides of the self-welded tie layers 55 and the interface 33. All layers are adhered together during an extrusion process. The layers may be adhered together by a lamination process. The lamination process could be performed by extrusion coating, thermal lamination, adhesive lamination, or any other lamination process well known in the art. The lamination would be a complete lamination between the entire areas of the layers. For example, the lamination would not be a partial lamination where the layers had areas of no lamination and areas of lamination. [0040] The film may have a peel initiation force and a peel strength. The peel initiation force is the initial force that it takes to begin peeling open the film. The peel strength is the measure of the average force over a specified distance of the film during peeling. Testing for the peel initiation force and peel strength were done according to ASTM F88, which is incorporated here in its entirety by reference. The peel strength may be determined using a seal strength test on an Instron 5543. In some embodiments, samples of the lay-flat tubular film as a chub package may be prepared using a vertical form fill and seal process. Testing may also be done on the film when prepared as a chub package and may be filled with comminuted food, such as ground beef.

[0041] The film may have an average peel initiation force greater than 0.5 kg-force (kgf).

The average peel initiation force may be determined using ASTM F88. The film may have an average peel initiation force greater than 0.6 kgf. An average peel initiation force may be determined by testing multiple samples of the film for each sample's peel initiation force and then obtaining an average peel initiation force of all samples tested. The film may have less than 50% variation in the average peel initiation force. In some embodiments, the film may have less than 75% variation in the maximum and minimum value for peel initiation force. In other embodiments, the film may have less than 50% variation in the maximum and minimum value for peel initiation force. In further embodiments, the film may have less than 30% variation in the maximum and minimum value for peel initiation force. The film may have less than 20% variation in the maximum and minimum value for peel initiation force. The film may have 4% variation in the maximum and minimum value for peel initiation force. The film may have a peel strength less than 1 kgf. In some embodiments, the film may have a peel strength less than 0.75 kgf.

[0042] An embodiment of the film before it is a lay-flat tubular film, may have a thickness of 3 mils or less. For example, in FIG. 1 , the film may have a thickness of 3 mils or less. In some embodiments, the film as shown in FIG. 1 , may have a thickness of 1 mil to 3 mils. In other embodiments, the film as shown in FIG. 1 , may have a thickness of 1 mil to 2 mils In further embodiments, the film as shown in FIG. 1 may have a thickness of 1 mil to 1.5 mils. The film as shown in FIG. 1 may have a thickness of 1 .15 mils.

[0043] The film may have a peel tab at the seal after the vertical form fill seal process. The peel tab may be created by a wider film around the fold of the film when making the chub package. The fold of the film may be a fin seal, a lap seal or any other seal known in the art. In some embodiments, the ends of the film may need to extend past the seal.

METHODS OF MAKING A FILM

[0044] The invention is also directed to a method for producing a film. The method may include providing a multiple layer co-extrusion die. The method may also include extruding resins in an extrusion die to create a mixture of molten resins. The method may further include filling the die with air thereby causing the mixture of molten resins to expand into the shape of a tube. In some embodiments, the tube may be cooled. In some embodiments, the method may further include collapsing the tube so that the inside surface of the tube adheres to itself to form a film. The inside surface of the tube may be at least one tie layer. The at least one tie layer may be self-weldable.

[0045] The invention is also directed to a chub package made from a film. The film may have a first peelable layer comprising less than 8% of polybutylene, a second peelable layer comprising less than 8% of polybutylene, and a sealant layer. The chub package may have an average peel initiation force greater than 0.5 kgf. The peel initiation force may be determined using an Instrom test. In some embodiments, the chub package may have the variation of the average peel initiation force of less than 50%. The chub package may have a difference between the maximum and minimum value for peel initiation force of less than 75%.

[0046] The chub package may be made from a film that is a tubular lay-flat film and at least one tie layer is a self-weldable layer. The chub package may have a thickness of 1 mil to 3 mils. In some embodiments, the chub package may have a thickness of 2.3 mils.

In some embodiments, the chub package may have a thickness of 1 mil to 2 mils. In other embodiments, the chub package may have a thickness of 1 mil to 1 .5 mil. [0047] The chub package may have at least 1 sealant layer after the first and the second sealant layer are heat sealed to each other. In some embodiments, the seal may be made with hot air, often called a hot air seal. The seal may be made with ultrasonic sealing, impulse sealing, hot air sealing, hot-jaw sealing, or combinations thereof. As shown in FIG. 3, the chub package may have a sealant layer 6 attached to the first peelable layer 3 and to the second peelable layer 9. The sealant layer 6 may have a first peelable layer 3 on one side and a second peelable layer 9 on a second side.

EXAMPLES

EXAMPLE 1

[0048] Three samples of extruded lay-flat tubular film were prepared for use as chub packaging. The formulation of the prepared samples 1 -3 are listed in Table 1 below. Sample 1 and sample 3 had the peelable layer (layer 7 and 9) next to the sealant layer (layer 8) and are referred to as "easy open tearout" films, while sample 2 has the peelable layer in layer 7 and a peelable layer in layer 8 and is referred to as an "easy open sealant" film.

Table 1

Maleic anhydride-modified Maleic anhydride-modified Maleic anhydride-modified ethylene/vinyl acetate ethylene/vinyl acetate ethylene/vinyl acetate

12 copolymer copolymer copolymer

60% VLDPE, 40% White 60% VLDPE, 40% White 60% VLDPE, 40% White

13 color concentrate color concentrate color concentrate

65% lonomer of ethylene 65% lonomer of ethylene 65% lonomer of ethylene acid copolymer, 30% acid copolymer, 30% acid copolymer, 30% Ethylene/vinyl acetate Ethylene/vinyl acetate Ethylene/vinyl acetate copolymer, and 5% copolymer, and 5% copolymer, and 10%

14 Polybutylene Polybutylene Polybutylene

58.5% lonomer of ethylene

acid copolymer, 27%

Ethylene/vinyl acetate

copolymer, 4.5%

10% Silica in LDPE and Polybutylene, and 10% 10% Silica in LDPE and

15 90% LLDPE Silica in LDPE 90% LLDPE

[0049] All the samples were tested for peel strength using an internal standard seal

strength test on an Instron 5543. The samples were prepared using a vertical form fill and seal machine. Samples 1 and 3 were evaluated using test 1 and test 2, while sample 2 was only evaluated using test 1 . One inch peels of empty tubular film were tested for each sample (n=10). The seal from packages filled with ground beef were also evaluated. An additional sample, sample 4 was tested with the ground beef inside the chub package as a comparison sample. Sample 4 was a partially adhesive laminated chub package.

Peel strengths for samples 1 -4 are in Table 2 below.

Table 2

[0050] Sample 1 was initially aggressive to break, then easy to open with tubing. The 1 pound at test 2 for sample 1 with a small peel tab appeared to be easier to open and the 5 pounds at test 2 for sample 1 was initially aggressive to break, then easy to open.

Sample 3 was initially aggressive to break, then easy to open with tubing. The 1 pound at test 2 for sample 3 had a small peel tab and appeared to be easier to open. The 5 pounds at test 2 for sample 3 was initially aggressive to break, then easy to open.

[0051] The Instron peels for the ground beef chubs for samples 1 (1 .5-1 .7) and 3 (1 .1 ) were both less than sample 4's peel strength (2.0). Samples 1 and 3 had lower peel strengths, but also had acceptable objective peels.

[0052] Overall, the quantitative peel strengths appeared to match the objective peel strengths. In conclusion, it was determined to perform further testing for sample 1 and 3. Sample 2 had an easy initial peel and was very easy to open in the chub package. It was determined to discontinue further testing of sample 2 because the initial peel was too easy and that the easy open sealant film was not optimal.

Example 2

[0053] A shipping test was performed where 10 cases of ground beef chubs (1 and 5- pound chubs) using samples 1 and 2 were shipped from 1 location to another in a refrigerated truck for 3 days for a total travel distance of approximately 800 miles. The chub packages were observed to determine if any leaks were present as a result of the shipping. Chub packages that have leaks present were defined as leakers during testing. Sample 1 had no leakers in the 1 pound chub packages shipped, but had 2 leakers in the 5 pound chub packages shipped. Both leakers were due to wrinkles/channels in the seal area of the chub package. Sample 3 had no leakers in the 1 pound chub package with no tab and 1 leaker in the 1 pound chub package with peel tab shipped. After visual inspection, it appeared that the peel tab had been stretched before shipping and resulted in the leak. Sample 3 had no leakers in the 5 pound chub packages shipped. The results of the shipping test are seen below in Table 3.

Table 3

Example 3

[0054] Sample 1 and 3 were further tested under freezing conditions and using a shaker table to simulate trucking distribution conditions. Both 1 and 5 pound chub packages using samples 1 and 3 were tested. The chub packages were then placed in the freezer for 3 days and a vibration analysis was performed using a Lansmont vibration system according to ASTM 4169, and shaken for 1 hour (0.52 Grms at 48 hours). The chub packages were allowed to thaw for 3 days. There were no leakers in either 1 or 5 pound chub packages for both sample 1 and 3. The results are seen in Table 4 below.

Table 4

[0055] In conclusion, it was determined that both sample 1 and sample 3 performed well in both shipping tests in both the 1 and 5 pound chub package sizes.

Example 4

[0056] Samples 1 -3 were further tested in a comparative test where each sample was tested for peel strength as a lay-flat tubular film and then compared against a multilayer film that only had 1 side of the tubular film (layers 1 -8) of the sample adhered to sample 5. This comparative evaluates the peel strength of a 1 -sided peelable multilayer film against a 2-sided multilayer lay-flat tubular film. The 1 -sided peelable multilayer film would have layers 1 -8 of sample 1 adhered to sample 5 (sample 1 :5), layers 1 -8 of sample 2 adhered to sample 5 (sample 2: 5), and layers 1 -8 of sample 3 adhered to sample 5 (sample 3:5). Samples 1 : 5, 2:5 and 3: 5 had a total of 14 layers where the tie layer (maleic anhydride- modified ethylene/vinyl acetate copolymer) from samples 1 -3 collapses on itself at the same tie layer in sample 5. All samples were tested for peel strength using an internal standard seal strength test on an Instron 5543. One inch peels of empty tubular film were tested for each sample (n=4) and the average peel initiation force was determined for each sample. The formulation for sample 5 is below in Table 5.

Table 5

[0057] Peel strengths for samples 1 :5 and 1 are shown, respectively, in FIGS. 4A and 4B. Both figures have a sample size of 4 (n-4) for each sample. The variation in peel strength over time was not significantly different when comparing sample 1 :5 to sample 1 .

However, it was shown that the variation in initial peel initiation force for sample 1 was more consistent than sample 1 :5. The variation in initial peel initiation force for sample 1 :5 was 103%, but only 21 % for sample 1. The average peel initiation force for sample 1 was 0.66 kgf. The average peel initiation force for sample 1 :5 was 0.41 kgf, but sample 1 :5 had a very large variation. Also, the difference between the maximum value and minimum value for peel initiation force for 1 -4 of sample 1 :5 was 274%, but for 1 -4 of sample 1 , the difference was only 14%. This difference is significantly lower for the 2-sided peelable multilayer tubular film.

[0058] Peel strengths for samples 2:5 and 2 are shown, respectively, in FIGS. 5A and 5B. Both figures have a sample size of 4 (n=4) for each sample. It can be seen that the variation in peel strength over time was not significantly different when comparing sample 2:5 to sample 2. It was also determined that the variation in peel initiation force for sample 2 was not more consistent than sample 2:5.

[0059] Peel strengths for samples 3:5 and 3 are shown, respectively, in FIGS. 6A and 6B. Both figures have a sample size of 4 (n=4) for each sample. It can be seen that the variation in peel strength over time was not significantly different when comparing sample 3:5 to sample 3. It was also determined that the variation in peel initiation force for sample 3 was not more consistent than sample 3:5.

[0060] In conclusion, it was determined that a 2-sided peelable lay-flat tubular film, specifically, sample 1 , had significantly more consistency in the peel initiation force than the 1 -sided peelable multilayer film, sample 1 :5.