Patent Application
20050254731
The present invention generally relates to thermoplastic handle bags suitable for storing and transporting medium to heavy loads, e.g., frozen foods such as chickens, turkeys, and the like comprising an easy-open feature, and more particularly, to thermoplastic handle bags having an easy-open feature adapted for the removal of large or bulky medium to heavy loads contained therein.
Thermoplastic bags having a handle opening and/or an easy-open feature which support heavy granulated items such as salt pellets, pet food, fertilizer, etc. are known in the art. U.S. Pat. No. 6,231,232 to Warr is directed to synthetic bags primarily for granulated contents which are capable of carrying loads of from 10 to 50 pounds and which include a hand-insertion slit below the top seal of the bag that may serve as a handle. U.S. Pat. Nos. 5,482,376 and 5,601,369, both to Moseley et al. also disclose bags adapted to hold pourable contents from 20 to 150 pounds. These bags include a handle which is either attached or formed from the bag and further disclose a curved line of perforations in the corner portion of the bag which permits easy opening of the bag. U.S. Pat. Nos. 5,482,376 and 5,601,369 both to Warr further disclose thermoplastic bags designed for heavy-duty applications which include a die-cut handle opening similar to that described in U.S. Pat. No. 6,231,232 and an easy-open feature which comprises a line of perforations which extends from the top edge to the side edge at the corner of the bag. While these bags are capable of carrying medium to heavy load and are easy to open, they are not suitable for large or bulky items contained therein which require a different means of removal from the package.
It is also known in the art that flexible bags may include both a handle and an opening zone in the side of the package which facilitates in the removal of bulky items contained therein. U.S. Pat. No. 4,966,286 to Muckenfuhs; U.S. Pat. No. 5,036,978 to Frank et al. and U.S. Pat. No. 5,054,619 to Muckenfuhs describe thermoplastic packages which are suitable for storing and transporting compressed flexible articles, such as disposable absorbent products, e.g., diapers, bandages, sanitary napkins and the like. These packages have a carrying handle and an easy-open feature which consists of one or more arcuate lines of weakness in a side panel or gusset of the bag. While these bags allow for easy removal of relatively bulky contents, they will neither separately support medium to heavy loads nor will the perforated tear lines of the easy-open feature resist tearing or bursting during transportation or storage of medium to heavy loads.
The present invention provides flexible bags that resists tearing or bursting during the storage and transportation of medium to heavy duty loads which may range in weight from about five pounds to about fifty pounds or more. The present invention also provides flexible bags formed from thermoplastic films which include a handle opening and an easy-open feature. The present invention further provides flexible bags suitable for supporting medium to heavy duty loads which include an easy-open feature suitable for removing large or bulky items contained therein.
Accordingly, one aspect of the present invention is directed to flexible bags for medium to heavy duty packaging applications which have a body formed from a thermoplastic film having an inner surface and an outer surface relative to the bag. Preferably, the flexible bags include a body formed from a thermoplastic film having an unrestrained linear thermal shrinkage in both the machine direction and the transverse direction of between 0-10% at 85° C. as measured in accordance with ASTM D-2732-96, which is hereby incorporated, in its entirety, by reference thereto. Preferably, the thermoplastic film has a minimum tensile strength at break in the machine direction of at least 3000 psi (2×107 N/m2) as measure at a rate of 12 inch/min. (30.5 cm/min.) in accordance with ASTM D-882, which is hereby incorporated, in its entirety, by reference thereto. Preferably, the thermoplastic film has a maximum elongation at break in the machine direction of between 0-150% as measure at a rate of 12 inch/min. (30.5 cm/min.) in accordance with ASTM D-882, which is hereby incorporated, in its entirety, by reference thereto. Preferably, the film has a total thickness of from about 2.0 to 7.0 mils (0.005 to 0.018 cm). Although the thermoplastic film may be a monolayer film or a multilayer film, preferably the film is a multilayer film. Preferably, the film is a multilayer film comprising at least a first polymer layer, a second polymer layer, and a third polymer layer. The first polymer layer of the thermoplastic multilayer film comprises a material selected from the group consisting of polyester, polyamide, polyolefin or blends thereof, preferably, a material selected from the group consisting of polyester terephthalate, polyamide, polypropylene or blends thereof, and most preferably, either a biaxially-oriented polyester terephthalate or a biaxially-oriented polyamide. The second polymer layer of the thermoplastic multilayer film comprises an adhesive material. The third polymer layer of the thermoplastic multilayer film comprises a sealant material. Preferably, the second polymer layer is directly adhered to the first and third polymer layer. For certain packaging applications, it may be beneficial to include the three-layer thermoplastic film as a substructure in a larger multilayer flexible film in forming the body of a bag. In such a configuration, the larger multilayer film incorporating three-layer structure as a substructure may advantageously possess properties and benefits resulting from the three-layer structure as discussed herein, but may also possess additional properties and benefits arising from the additional layers. Larger multilayer film structures which incorporate three-layer structure as a substructure may have at least one additional layer adhered to this substructure by various methods known to those skilled in the art which include thermal lamination, adhesive lamination, coextrusion coating, coextrusion lamination.
The present invention is also directed to bags which include a first panel and a second panel where each of the panels have a perimeter which includes a first peripheral side edge and an opposing second peripheral side edge, connected by a peripheral top edge and an opposing peripheral bottom edge. The body also includes a plurality of seals which joins the first panel to the second panel. In one embodiment of the present invention, the plurality of seals include a first side seal, a first top seal and an opposing bottom seal. The first side seal, first top seal and opposing bottom seal can be connected together to form a seal perimeter between the first and second panels. Alternatively, the plurality of seals may further include a first side seal and an opposing second side seal, a first top seal and an opposing bottom seal. In this regard, the first side seal and opposing second side seal, the first top seal and opposing bottom seal can be connected together to form a seal perimeter. In another embodiment, the plurality of seals may still further include a first side seal and an opposing second side seal, a first top seal, a second top seal and an opposing bottom seal. Preferably, the second top seal is parallel with the first top seal and positioned below the handle opening of the bag extending transversely across the bag from the first peripheral side edge to the second peripheral side edge. In this particular embodiment, the first side seal and opposing second side seal, the second top seal and opposing bottom seal can be connected together to form a seal perimeter. The body of the bags are provided with a receptacle cavity which is formed between the first and second panels and defined by the seal perimeter. While the flexible bags of the present invention need not necessarily include side gussets, for some applications it may be beneficial to include at least one of: a first side gusset and a second side gusset, a bottom gusset, or a first side gusset, a second side gusset and a bottom gusset.
As a second aspect, the present invention is directed to flexible bags for medium to heavy duty packaging applications which include an integral handle opening. The integral handle opening is disposed in a pre-determined area below the peripheral top edge and extends transversely across the bag from a first peripheral side edge to a second peripheral side edge. The integral handle opening may be formed in the first and second panels of the body of the bag as either a hole, slit, cut and the like. Preferably, the pre-determined area in the first panel and the second panel is a reinforced portion of the body of the bag.
As a third aspect, the present invention is directed to flexible bags for medium to heavy duty packaging applications having an easy-open feature adapted such that large and/or bulky items may be easily removed from the receptacle cavity of the bag. Examples of large or bulky items include, but are not limited to, fresh or frozen meat and poultry, such as turkey, chicken, duck and the like. The easy-open feature extends longitudinally from the peripheral top edge to the peripheral bottom edge in either the first panel or the second panel and is positioned adjacent to either the first peripheral side edge or the second peripheral side edge of the body of the bag.
In one embodiment of the invention, the easy-open feature may include at least one line of structural weakness in either the inner surface or the outer surface of the thermoplastic film. Preferably, the at least one line of structural weakness further includes a tear-initiation feature. A tear-initiation feature may be formed as a cut, notch or surface-roughening area and the like, in the external surface of film positioned above the at least one line of structural weakness. In this regard, the bag can be easily opened by a relatively weak manual force at the tear-initiation feature and in combination with the at least one line of structural weakness obviating the need to cut the bag with a knife, scissors or any other sharp implement.
Alternatively, the easy-open feature may be provided as a reclosable fastener attached to the inner surface of the thermoplastic film forming the body of the bag. Suitable reclosable fastener, in general, are known and are taught, for example, in U.S. Pat. Nos. 5,063,644; 5,301,394; 5,442,837; 5,964,532; 6,409,384; 6,439,770; 6,524,002; 6,527,444; 6,609,827; 6,616,333; 6,632,021; 6,663,283; 6,666,580; 6,679,027; and U.S. patent application Nos. 2002/0097923; and 2002/0196987, each of which is incorporated by reference herein.
Preferably, the reclosable fastener comprises a first interlocking member and a second interlocking member. Preferably, the first and second interlocking members each have an attachment flange for securing each member to the inner surface of the thermoplastic film forming the body of the bag. Preferably, the reclosable fastener further comprises a slider device which facilitates the manual operation of the fastener by engaging and dis-engaging the first interlocking member with the second interlocking member.
In another embodiment, the easy-open feature may include a combination of both the at least one line of structural weakness in either the inner surface or the outer surface of the thermoplastic film and the reclosable fastener attached to the inner surface of the thermoplastic film.
The present invention is also directed to flexible bags for medium to heavy duty packaging applications which further comprises at least one removable thermoplastic inner package disposed within and separate from the bag. Preferably, the at least one removable thermoplastic inner package comprises a freezer storage package.
As used herein, the term “multilayer” refers to a plurality of layers in a single film structure generally in the form of a sheet or web which can be made from a polymer material or a non-polymer material bonded together by any conventional means known in the art, i.e., coextrusion, extrusion coating, and lamination, vacuum vapor deposition coating, solvent coating, emulsion coating, or suspension coating or combination of one or more thereof. The multilayer film of the present invention may include as many layers as desired, preferably, at least three polymer layers.
As used herein, the phrase “thermoplastic” refers to a polymer or polymer mixture that softens when exposed to heat and returns to its original condition when cooled to room temperature. In general, thermoplastic materials include, but are not limited too, synthetic polymers such as polyamides, polyolefins, polyalkyl acrylates, polyesters, ethylene/vinyl alcohol copolymers, and the like. Thermoplastic materials may also include any synthetic polymer that are cross-linked by either radiation or chemical reaction during a manufacturing process operation.
As used herein, the term “polymer” refers to the product of a polymerization reaction, and is inclusive of homopolymers, copolymers, terpolymers, etc. In general, the layers of a film can consist essentially of a single polymer, or can have still additional polymers together therewith, i.e., blended therewith.
As used herein, the term “copolymer” refers to polymers formed by the polymerization of reaction of at least two different monomers. For example, the term “copolymer” includes the co-polymerization reaction product of ethylene and an α-olefin, such as 1-hexene. The term “copolymer” is also inclusive of, for example, the co-polymerization of a mixture of ethylene, propylene, 1-propene, 1-butene, 1-hexene, and 1-octene. As used herein, a copolymer identified in terms of a plurality of monomers, e.g., “propylene/ethylene copolymer”, refers to a copolymer in which either monomer may copolymerize in a higher weight or molar percent than the other monomer or monomers. However, the first listed monomer preferably polymerizes in a higher weight percent than the second listed monomer.
As used herein, the term “extrusion” refers to the process of forming continuous shapes by forcing a molten polymeric material through a die, followed by cooling.
As used herein, the term “coextrusion” refers to the process by which the outputs of tow or more extruders are brought smoothly together in a feed block, to form a multilayer molten mixture that is fed to a die to produce a layered extrudate. Coextrusion can be employed in film blowing, sheet and flat film extrusion, blow molding, and extrusion coating.
As used herein, the term “biaxially-oriented” refers to a polymer web which forms a film structure in which the web has been elongated in two directions at elevated temperatures followed by being “set” in the elongated configuration by cooling the material while substantially retaining the elongated dimensions. This combination of elongation at elevated temperature followed by cooling causes an alignment of the polymer chains to a more parallel configuration, thereby improving the mechanical properties of the polymer web. Upon subsequently heating of certain unrestrained, unannealed, biaxially-oriented sheet of polymer to its orientation temperature, heat-shrinkage may be produced. Following orientation, the biaxially-oriented polymer web is preferably cooled and then heated to an elevated temperature, most preferably to an elevated temperature which is above the glass transition temperature and below the crystalline melting point of the polymer. This reheating step, which may be referred to as annealing or heat setting, is performed in order to provide a polymer web of uniform flat width. In accordance with the present invention, the biaxially-oriented polymer web may be used to form a film layer is heated to an elevated temperature in order to provide a packaging film with an unrestrained linear thermal shrinkage in the machine direction of between 0-10% at 85° C. as measured in accordance with ASTM D-2732-96 test method, which is incorporated herein by reference.
As used herein, the terms “joins” or “joining” are used in its broad sense to mean either two formerly separate sheets connected together, or integrally formed by, for example, folding over a film or laminate to define an edge.
As used herein, the phrase “machine direction” refers to a direction “along the length” of the film, i.e., in the longitudinal direction the film is formed during extrusion. In contrast, the “transverse direction” refers to the direction across the film or perpendicular to the machine direction.
As used herein, terminology employing a “/” with respect to the chemical identity of a copolymer (e.g., polyvinylidene chloride/methyl acrylate copolymer), identifies the comonomers which are copolymerized to produce the copolymer.
As used herein, the term “polyester” refers to homopolymers or copolymers having an ester linkage between monomer units which may be formed, for example, by condensation polymerization reactions between a dicarboxylic acid and a glycol. The dicarboxylic acid may be linear or aliphatic, i.e., oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and the like; or may be aromatic or alkyl substituted aromatic, i.e., various isomers of phthalic acid, such as paraphthalic acid (or terephthalic acid), isophthalic acid and naphthalic acid. Specific examples of alkyl substituted aromatic acids include the various isomers of dimethylphthalic acid, such as dimethylisophthalic acid, dimethylorthophthalic acid, dimethylterephthalic acid, the various isomers of diethylphthalic acid, such as diethylisophthalic acid, diethylorthophthalic acid, the various isomers of dimethylnaphthalic acid, such as 2,6-dimethylnaphthalic acid and 2,5-dimethylnaphthalic acid, and the various isomers of diethylnaphthalic acid. The glycols may be straight-chained or branched. Specific examples include ethylene glycol, propylene glycol, trimethylene glycol, 1,4-butane diol, neopentyl glycol and the like. In one example a preferred embodiment of this invention, the first layer comprises polyethylene terephthalate copolymer and most preferable, biaxially-oriented polyethylene terephthalate copolymer.
As used herein, the term “adhesive” refers to a polymer material serving a primary purpose or function of adhering two surfaces to one another. In the present invention, the adhesive may adhere one film layer surface to another film layer surface or one area of a film layer surface to another area of the same film layer surface. The adhesive may comprise any polymer, copolymer or blend of polymers having a polar group thereon, or any other polymer, homopolymer, copolymer or blend of polymers including modified and unmodified polymers, e.g., grafted copolymers, which provide sufficient interlayer adhesion to adjacent layers comprising otherwise nonadhering polymers. Adhesive compositions of the present invention may include, but are not limited to, modified and unmodified polyolefins, preferably polyethylene, such as for example, low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, and modified and unmodified copolymers of ethylene with one or more alpha-olefins (α-olefins) such as butene-1, hexene-1, octene-1, or the like as a comonomer.
As used herein, the term “polyolefin” refers to homopolymers, copolymers, including e.g. bipolymers, terpolymers, etc., having a methylene linkage between monomer units which may be formed by any method known to those skill in the art. Suitable examples of polyolefins include polyethylene, low density polyethylene, linear low density polyethylene, very low density polyethylene, ultra low density polyethylene, medium density polyethylene, high density polyethylene, polyethylenes comprising ethylene/α-olefin which are copolymers of ethylene with one or more alpha-olefins (α-olefins) such as butene-1, hexene-1, octene-1, or the like as a comonomer, linear low density polyethylene, very low density polyethylene, ultra low density polyethylene, ethylene/propylene copolymers, polypropylene, propylene/ethylene copolymer, polyisoprene, polybutylene, polybutene, poly-3-methylbutene-1, poly-4-methylpentene-1, ionomers and the like.
As used herein, the phrase “ethylene/α-olefin” refers to a modified or unmodified copolymer produced by the co-polymerization of ethylene and any one or more α-olefin. The α-olefin in the present invention may have between 3-20 pendant carbon atoms. The co-polymerization of ethylene and an α-olefin may be produced by heterogeneous catalysis, i.e., co-polymerization reactions with Ziegler-Natta catalysis systems, for example, metal halides activated by an organometallic catalyst, i.e., titanium chloride, optionally containing magnesium chloride, complexed to trialkyl aluminum and may be found in patents such as U.S. Pat. No. 4,302,565 to Goeke, et al. and U.S. Pat. No. 4,302,566 to Karol, et al., both of which are hereby incorporated, in their entireties, by reference thereto.
As used herein, the term “modified” refers to a chemical derivative, e.g., one having any form of anhydride functionality, such as anhydride of maleic acid, crotonic acid, citraconic acid, itaconic acid, fumaric acid, etc., whether grafted onto a polymer, copolymerized with a polymer, or blended with one or more polymers, and is also inclusive of derivatives of such functionalities, such as acids, esters, and metal salts derived therefrom.
As used herein, the term “polyamide” refers to homopolymers, copolymers, or terpolymers having an amide linkage between monomer units which may be formed by any method known to those skill in the art. Useful polyamide homopolymers include nylon 6 (polycaprolactam), nylon 11 (polyundecanolactam), nylon 12 (polylauryllactam), and the like. Other useful polyamide homopolymers also include nylon 4,2 (polytetramethylene ethylenediamide), nylon 4,6 (polytetramethylene adipamide), nylon 6,6 (polyhexamethylene adipamide), nylon 6,9 (polyhexamethylene azelamide), nylon 6,10 (polyhexamethylene sebacamide), nylon 6,12 (polyhexamethylene dodecanediamide), nylon 7,7 (polyheptamethylene pimelamide), nylon 8,8 (polyoctamethylene suberamide), nylon 9,9 (polynonamethylene azelamide), nylon 10,9 (polydecamethylene azelamide), nylon 12,12 (polydodecamethylene dodecanediamide), and the like. Useful polyamide copolymers include nylon 6,6/6 copolymer (polyhexamethylene adipamide/caprolactam copolymer), nylon 6/6,6 copolymer (polycaprolactam/hexamethylene adipamide copolymer), nylon 6,2/6,2 copolymer (polyhexamethylene ethylenediamide/hexamethylene ethylenediamide copolymer), nylon 6,6/6,9/6 copolymer (polyhexamethylene adipamide/hexamethylene azelaiamide/caprolactam copolymer), as well as other nylons which are not particularly delineated here.
As used herein, the term “sealant” refers to a layer which is heat sealable to itself, i.e., be capable of fusion bonding by conventional indirect heating means which generate sufficient heat on at least one film contact surface for conduction to the contiguous film contact surface and formation of a bond interface therebetween without loss of the film integrity. Advantageously, the bond interface must be sufficiently thermally stable to prevent gas or liquid leakage therethrough. Suitable examples of sealants for the present invention include, but are not limited to, polyolefins, including polyethylenes, polypropylenes, polybutylenes, ionomers, ethylene/α-olefin copolymers and blends thereof.
As used herein, the term “surface-roughened” refers to dimples, indentations, scratches, bores, holes, perforations, and the like, on an external surface of a film. It will be recognized by those skilled in the art, that the dimples, indentations, scratches, bores, holes, perforations, and the like may have a random or regular repeating arrangement. Generally, a predetermined portion (less than the entire area) of a surface of the film is treated in order to provide a surface-roughened portion. The surface-roughened portion may be formed by mechanical means, e.g., subjecting the external surface of the film layer to knurling by a roller formed with a plurality of circumferentially extending projections as described, for example, in U.S. Pat. Nos. 4,543,279 and 4,778,058, which are incorporated herein by reference. Alternatively, non-mechanical methods may be used which include corona discharge, plasma discharge, ultrasonic wave, and optical ablation.
The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, 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 be thorough and complete and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.
Referring now to
Body 11 further comprises an inner receptacle cavity 19 (not shown) which is formed between first panel 14a and opposing second panel 14b and defined by a seal perimeter 18, and an integral handle opening 20 which extends transversely across the bag 10 from the first peripheral side edges 16a to the second side edges 16b. Integral handle opening 20 may be fabricated, for example, by slitting or die cutting into first panel 14a and second panel 14b at the same time such that the slit or cut in first panel 14a is in registration with the slit or cut in second panel 14b. Body 11 also includes an easy-open feature 21 which extends longitudinally from the first top seal 17b to opposing bottom seal 17c and is disposed adjacent to peripheral side edge 16a of the first panel 14a. Easy-open feature 21, by way of example, is depicted as being at least one line of structural weakness 21a in the first panel 14a and may be formed in either the inner surface 13a (See
Formation of the at least one line of structural weakness 21a may be accomplished by methods disclosed in U.S. Pat. Nos. 3,626,143; 3,909,582; 4,778,058; 4,834,245; 5,001,325; 5,613,779; 5,630,308; and 6,427,420, which are hereby incorporated by reference. These methods include e.g., forming grooves, scores, scratches, cuts, slits or surface roughening e.g., with a laser, by corona or plasma discharge, by contact with a rough surface roller or roughened surface such as sand paper, emery paper, or by cutting devices or blades. For example, the at least one line of structural weakness may be provided by any of the methods disclosed in the aforementioned documents, such as using a cutting device to form the at least one line of structural weakness in a first moving web or layer followed by lamination of the first moving web or layer to a second moving web or layer with or without tear-initiation features or the like. It will be appreciated that at least one line of structural weaknesses 21a may be provided in a variety of shapes including curves or sinusoidal and may also be provided either continuously or intermittently along the inner surface 13a (See
Referring now to
Turning now to
Thermoplastic film 12 has an unrestrained linear thermal shrinkage in both the machine direction and the transverse direction of between 0-10% at 85° C. as measured in accordance with ASTM D-2732-96, a minimum tensile strength at break in the machine direction of at least 3000 psi (2×107 N/m2) as measured at a rate of 12 inch/min. (30.5 cm/min.) in accordance with ASTM D-882, and a maximum elongation at break in the machine direction of between 0-150% as measured at a rate of 12 inch/min. (30.5 cm/min.) in accordance with ASTM D-882. Preferably, thermoplastic film 12 has a total thickness of between 2.0-7.0 mils (0.005-0.018 cm).
Unless otherwise noted, the physical properties and performance characteristics reported herein were measured by test procedures similar to the following methods.
Many modifications and other embodiments of the invention will come to mind to one skilled in the art to which this invention pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. 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.
