Multilayer film and tear open package

Abstract

A multilayer film providing good opening in a heat sealed area of a package via a laser scored disrupted path is disclosed. The multilayer film includes a first protection layer, a score receptive layer, and a sealing layer. The first protection layer includes a melting temperature TMP1. The score receptive layer includes a melting temperature TMR and a laser sensitive component. The sealing layer is located at a surface of the multilayer film and includes a melting temperature TMS. The first protection layer is located between the score receptive layer and the sealing layer. The melting temperature TMS of the sealing layer is at least 20°C lower than melting temperature TMP1 of the first protection layer. Further, each of the first protection layer, the score receptive layer, and the sealing layer includes greater than 50% polyolefin, by weight.

Description

[0001] MULTILAYER FILM AND TEAR OPEN PACKAGE

[0002] TECHNICAL FIELD

[0003] The present application relates generally to a multilayer film, a method of producing the multilayer film, a package including the multilayer film, and a method of producing a tear open package.

[0004] BACKGROUND

[0005] There is an increasing global demand for plastic waste reduction and sustainable packaging. Therefore, recyclability may be a highly desirable property of films that are used for packaging purposes. Films having a mono-polyolefin structure may provide a recycling-ready alternative to traditional packaging films which may include, for example, PET / PE, OPA / PE, or similar structures and a gas barrier layer, such as metallized BOPET and aluminum foil.

[0006] Furthermore, easy opening of a package may be a functionality desired by end consumers to easily access packaged content without requiring use of cutting tools, such as scissors, to open the package. A tear open package is one example of packages that provide such easy opening.

[0007] Tear open packages may be formed from films that can be scored to provide a line of weakness along which the package can be torn to access packaged content. However, tear open packages formed from conventional recyclable films having a mono-polyolefin structure may fail to tear along the line of weakness. Specifically, during heat sealing of the conventional recyclable films to form tear open packages therefrom, the scores present in a heat sealing area may fill up and close, which may cause difficulty in, or in some cases prevent, tearing of the tear open packages along the line of weakness.

[0008] SUMMARY

[0009] A multilayer film has been developed. The multilayer film includes a score receptive layer that may be laser scored to provide a disrupted path (i.e., a line of weakness). The multilayer film further includes a sealing layer that may be heat sealed to itself or another component to form a package. The multilayer film further includes a first protection layer located between the score receptive layer and the sealing layer. The first protection layer may protect the disrupted path of the score receptive layer during heat sealing of the sealing layer. As a result, the disrupted path may be preserved during formation of the package from the multilayer film. The multilayer film may therefore be suitable for forming tear open packages that can be manually opened without use of cutting tools, such as scissors. Moreover, the multilayer film includes a high polyolefin content, and therefore may be recyclable.

[0010] One embodiment of the present disclosure is a multilayer film. The multilayer film includes a first protection layer including a melting temperature TMP1 . The multilayer film further includes a score receptive layer including a melting temperature TMR. The score receptive layer further includes a laser sensitive component. The multilayer film further includes a sealing layer located at a surface of the multilayer film. The sealing layer includes a melting temperature TMS. The first protection layer is located between the score receptive layer and the sealing layer. The melting temperature TMS of the sealing layer is at least 20°C lower than the melting temperature TMP1 of the first protection layer. Each of the first protection layer, the score receptive layer, and the sealing layer includes greater than 50% polyolefin, by weight.

[0011] The score receptive layer may be scored using a laser. The score receptive layer may therefore include a disrupted path made by laser scoring. As the melting temperature TMS (and the heat seal initiation temperature) of the sealing layer is lower than the melting temperature TMP1 of the first protection layer, the sealing layer may be heat sealed at a lower temperature than the melting temperature TMP1 of the first protection layer. Consequently, the first protection layer may not melt during heat sealing of the sealing layer, thereby protecting the disrupted path of the score receptive layer during heat sealing. Specifically, the first protection layer may prevent closing of the disrupted path due to the heat sealing, which may otherwise occur in absence of the first protection layer. For example, in absence of the first protection layer, during heat sealing, the sealing layer may melt, fill, and close the disrupted path, thereby compromising the functionality of the disrupted path (i.e., may prevent easy tearing along the disrupted path). The multilayer film may preserve the disrupted path during the heat sealing of the sealing layer. Consequently, the multilayer film may be suitable to form tear open packages. Specifically, the multilayer film may be suitable to form tear open packages that include a laser scored opening feature (i.e., a disrupted path in the score receptive layer) that is located at least partially within a heat sealed portion of a package.

[0012] Furthermore, the multilayer film may provide an optimal heat-sealing temperature range, that is, a temperature range greater than the heat seal initiation temperature of the sealing layer and less than the melting temperature TMP1 of the first protection layer.

[0013] Moreover, the multilayer film may be recyclable due to high polyolefin content. As a result, the multilayer film may be recyclable in a recycling stream. In some embodiments, the multilayer film may be recyclable in a polyethylene recycling stream. In some other embodiments, the multilayer film may be recyclable in a polypropylene recycling stream. Therefore, the multilayer film may be environmentally friendly.

[0014] In some embodiments, each of the first protection layer and the sealing layer has a polymeric content greater than 80% polyethylene, by weight.

[0015] In some embodiments, the multilayer film has a polyethylene content greater than 80%, by weight, or a polypropylene content greater than 80%, by weight.

[0016] In some embodiments, the melting temperature TMS of the sealing layer is at least 25°C lower than the melting temperature TMP1 of the first protection layer.

[0017] In some embodiments, the melting temperature TMS of the sealing layer is at least 30°C lower than the melting temperature TMP1 of the first protection layer.

[0018] In some embodiments, the melting temperature TMS of the sealing layer is at least 20°C lower than the melting temperature TMR of the score receptive layer.

[0019] In some embodiments, the multilayer film further includes a second protection layer including a melting temperature TMP2. The second protection layer further includes greater than 50% polyolefin, by weight. The score receptive layer is located between the first protection layer and the second protection layer. The melting temperature TMP2 of the second protection layer is at least 20°C higher than the melting temperature TMS of the sealing layer.

[0020] In some embodiments, the melting temperature TMP2 of the second protection layer is equal to or greater than the melting temperature TMR of the score receptive layer.

[0021] The second protection layer may further protect the disrupted path of the score receptive layer during the heat sealing of the sealing layer.

[0022] In some embodiments, the multilayer film has a polymeric content including greater than 80% polyolefin, by weight. In some embodiments, the multilayer film has a polymeric content including greater than 90% polyolefin, by weight.

[0023] In some embodiments, the multilayer film has a polymeric content including greater than 95% polyolefin, by weight.

[0024] In some embodiments, the sealing layer includes a heat seal initiation temperature less than or equal to 100°C, as measured by ASTM F2029.

[0025] Therefore, the sealing layer may be heat sealed at a temperature lower than the melting temperature of the first protection layer, and in some embodiments, lower than the melting temperature TMR of the score receptive layer.

[0026] Another embodiment of the present disclosure is a multilayer film. The multilayer film includes a first protection layer including a melting temperature TMP1 greater than or equal to 125°C. The multilayer film further includes a score receptive layer including a melting temperature TMR. The score receptive layer further includes a laser sensitive component. The multilayer film further includes a sealing layer located at a surface of the multilayer film. The sealing layer includes a melting temperature TMS less than or equal to 100°C. The first protection layer is located between the score receptive layer and the sealing layer. The multilayer film has a polymeric content including greater than 80% polyethylene, by weight.

[0027] The score receptive layer may include a disrupted path. The disrupted path may be made by laser scoring. As the melting temperature TMS of the sealing layer is lower than the melting temperature TMP1 of the first protection layer, the sealing layer may be heat sealed at a lower temperature than the melting temperature TMP1 of the first protection layer. Consequently, the first protection layer may not melt during heat sealing of the sealing layer, thereby protecting the disrupted path of the score receptive layer during heat sealing. The multilayer film may preserve the disrupted path during the heat sealing of the sealing layer. Consequently, the multilayer film may be suitable to form tear open packages. Moreover, the multilayer film may be recyclable in a polyethylene recycling stream due to a high polyethylene content.

[0028] In some embodiments, each of the first protection layer and the sealing layer includes a polyethylene content greater than 80%, by weight.

[0029] In some embodiments, the score receptive layer is directly adjacent to the first protection layer.

[0030] In some embodiments, the first protection layer is free of the laser sensitive component. In some embodiments, the first protection layer includes a high-density polyethylene polymer.

[0031] In some embodiments, the multilayer film further includes a second protection layer including a melting temperature TMP2 greater than or equal to 125°C. The score receptive layer is located between the first protection layer and the second protection layer. The score receptive layer is directly adjacent to the second protection layer. The second protection layer may further protect the disrupted path of the score receptive layer during the heat sealing of the sealing layer.

[0032] In some embodiments, the second protection layer is free of the laser sensitive component.

[0033] In some embodiments, the second protection layer includes a high-density polyethylene polymer.

[0034] In some embodiments, the multilayer film is free of ethylene vinyl acetate copolymers.

[0035] In some embodiments, the laser sensitive component is inorganic particles or EVOH. The laser receptive layer may include one or more laser sensitive components. The laser receptive layer may include up to 50 wt.% of inorganic particles as laser sensitive components. The laser receptive layer may include up to 100% EVOH as the laser sensitive component.

[0036] In some embodiments, the multilayer film further includes an oriented polyethylene film. Advantageously, the oriented polyethylene film may provide toughness and / or abuse resistance to the multilayer film.

[0037] In some embodiments, the score receptive layer further includes a disrupted path. The disrupted path may be formed by laser scoring. The disrupted path may be a line of weakness. A package formed from the multilayer film may be opened by tearing the package along the disrupted path. The disrupted path may therefore allow opening of the package without use of cutting tools, such as scissors. Advantageously, the disrupted path may be protected by the first protection layer, and in some embodiments, the second protection layer during heat sealing of the sealing layer.

[0038] Another embodiment of the present disclosure is a package. The package includes the multilayer film including the disrupted path. The package further includes one or more heat sealed areas including a connection between the sealing layer of the multilayer film and another component. At least one of the one or more heat sealed areas overlaps the disrupted path. The disrupted path (i.e., the gap formed by laser scoring) may be preserved during formation of the one or more heat sealed areas. That is, the disrupted path present at the one or more heat sealed areas may not close during formation of the one or more heat sealed areas. Consequently, the package may be torn along the disrupted path, providing easy access to packaged content without use of cutting tools, such as scissors.

[0039] Another embodiment of the present disclosure is a method of producing a multilayer film. The method includes simultaneously co-extruding a first protection layer, a score receptive layer, and a sealing layer to produce an intermediate film. The method further includes creating a disrupted path in the score receptive layer of the intermediate film with a laser to form the multilayer film. The sealing layer is located at a surface of the multilayer film. The first protection layer is located between the score receptive layer and the sealing layer. The first protection layer includes a melting temperature TMP1. The score receptive layer includes a melting temperature TMR. The score receptive layer further includes a laser sensitive component. The sealing layer includes a melting temperature TMS. The melting temperature TMS of the sealing layer is at least 20°C lower than the melting temperature TMP1 of the first protection layer. The multilayer film has a polymeric content including greater than 80% polyolefin, by weight.

[0040] In some embodiments, the method further includes laminating the multilayer film to a polyethylene film.

[0041] In some embodiments, the first protection layer is in direct contact with each of the score receptive layer and the sealing layer.

[0042] Another embodiment of the present disclosure is a method of producing a tear open package. The method includes producing the multilayer film. The method further includes heat sealing the multilayer film to another component to form a heat sealed area. The heat sealed area includes a connection between the sealing layer of the multilayer film and the another component. The heat sealed area overlaps the disrupted path.

[0043] There are several aspects of the present subject matter which may be embodied separately or together. These aspects may be employed alone or in combination with other aspects of the subject matter described herein, and the description of these aspects together is not intended to preclude the use of these aspects separately or the claiming of such aspects separately or in different combinations. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The disclosure may be more completely understood in consideration of the following detailed description of various embodiments of the disclosure in connection with the accompanying drawings, in which:

[0045] FIG. 1 is a schematic cross-sectional view of a multilayer film in accordance with an embodiment of the present disclosure;

[0046] FIG. 2 is schematic cross-sectional view of a multilayer film in accordance with another embodiment of the present disclosure;

[0047] FIG. 3 is a schematic cross-sectional view of a multilayer film in accordance with another embodiment of the present disclosure;

[0048] FIG. 4A is a schematic cross-sectional view of a multilayer film in accordance with an embodiment of the present disclosure;

[0049] FIG. 4B is a schematic top view of the multilayer film of FIG. 4A;

[0050] FIG. 5A is a schematic top view of a package in accordance with an embodiment of the present disclosure;

[0051] FIG. 5B is a schematic top view of a package partially torn off along the score in accordance with an embodiment of the present disclosure;

[0052] FIG. 6 is a flowchart depicting steps of a method of producing a multilayer film in accordance with an embodiment of the present disclosure; and

[0053] FIG. 7 is a flowchart depicting steps of a method of producing a tear open package in accordance with an embodiment of the present disclosure.

[0054] The figures are not necessarily to scale. Like numbers used in the figures refer to like components. It will be understood, however, that the use of a number to refer to a component in a given figure is not intended to limit the component in another figure labeled with the same number.

[0055] DETAILED DESCRIPTION

[0056] The present application describes a multilayer film. The multilayer film includes a first protection layer including a melting temperature TMP1. The multilayer film further includes a score receptive layer including a melting temperature TMR. The score receptive layer includes a laser sensitive component. The multilayer film further includes a sealing layer located at a surface of the multilayer film. The sealing layer includes a melting temperature TMS. The first protection layer is located between the score receptive layer and the sealing layer. The melting temperature TMS of the sealing layer is at least 20°C lower than the melting temperature TMP1 of the first protection layer. Each of the first protection layer, the score receptive layer, and the sealing layer includes greater than 50% polyolefin, by weight.

[0057] The score receptive layer may be scored using a laser. The score receptive layer may therefore include a disrupted path made by laser scoring. As the melting temperature TMS (and the heat seal initiation temperature) of the sealing layer is lower than the melting temperature TMP1 of the first protection layer, the sealing layer may be heat sealed at a lower temperature than the melting temperature TMP1 of the first protection layer. Consequently, the first protection layer may not melt during heat sealing of the sealing layer, thereby protecting the disrupted path of the score receptive layer during heat sealing. Specifically, the first protection layer may prevent closing of the disrupted path due to the heat sealing, which may otherwise occur in absence of the first protection layer. For example, in absence of the first protection layer, during heat sealing, the sealing layer may melt, fill, and close the disrupted path, thereby compromising the functionality of the disrupted path. Additionally, in absence of the first protection layer, during heat sealing the score receptive layer may melt, fill (i.e., flow into) and close the disrupted path, thereby compromising the functionality of the opening feature. In the absence of the first protection layer, during heat sealing an adjacent layer may melt, fill and close the disrupted path of the score receptive layer. The multilayer film may preserve the disrupted path during the heat sealing of the sealing layer. Consequently, the multilayer film may be suitable to form tear open packages that rely on laser scoring in the area of heat seals.

[0058] Furthermore, the multilayer film may provide an optimal heat-sealing temperature range, that is, a temperature greater than the heat seal initiation temperature of the sealing layer and less than the melting temperature TMP1 of the first protection layer.

[0059] Moreover, the multilayer film may be recyclable due to high polyolefin content. As a result, the multilayer film may be recyclable in a recycling stream. In some embodiments, the multilayer film may be recyclable in a polyethylene recycling stream. In some other embodiments, the multilayer film may be recyclable in a polypropylene recycling stream. Therefore, the multilayer film may be environmentally friendly.

[0060] As used herein, the term “film” refers to a material with a very high ratio of a length or a width to a thickness. A film has two major surfaces defined by a length and a width. Films typically have good flexibility and can be used for a wide variety of applications, including flexible packaging. Films may also have thickness and / or material composition such that they are flexible, semi-rigid, or rigid. Films may be described as monolayer or multilayer.

[0061] As used herein, the term “layer” refers to a thickness of material that may be homogeneous or heterogenous. Layers may be of any type of material including polymeric, cellulosic, and metallic, or a blend thereof. A layer may include a single polymer-type or a blend of polymers and may be accompanied by additives. A given layer may be combined or connected to other layers to form films. A layer may be either partially or fully continuous as compared to adjacent layers or the film. A given layer may be partially or fully coextensive with adjacent layers. A layer may contain sub-layers.

[0062] The term “exterior surface” refers to a surface of a layer or multilayer film that does not have contact with another film or layer surface prior to forming a package. An exterior surface may be in contact with another component upon formation of a package (i.e. , attached to an exterior surface of another component by heat sealing).

[0063] As used herein, layers or films that are “in direct contact with” or “are directly adjacent to” each other have no intervening layer or film between them.

[0064] As used herein, the term “polyolefin” refers generally to polyethylene and polypropylene polymers.

[0065] As used herein, the terms “polyethylene” and “polyethylene polymer” refers to polymers that include an ethylene linkage. Polyethylenes may be homopolymers, copolymers, or interpolymers. Polyethylene copolymers or interpolymers may include other types of polymers (i.e., non-polyethylene polymers). Polyethylenes may have functional groups incorporated by grafting or other means. Polyethylenes include, but are not limited to, low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), ultra-low density polyethylene (ULDPE), and high-density polyethylene (HDPE).

[0066] As used herein, the term “high-density polyethylene” or “HDPE” refers to homopolymers of ethylene which have densities from about 0.960 gram per cubic centimeter (g / cm3) to about 0.970 g / cm3, as well as copolymers of ethylene and an alpha-olefin (usually 1 -butene or 1 -hexene) which have densities from about 0.940 g / cm3to about 0.958 g / cm3. HDPE includes high molecular weight “polyethylenes.” As used herein, the term “low-density polyethylene” or “LDPE” refers to branched homopolymers of ethylene having densities from about 0.915 g / cm3to about 0.930 g / cm3, as well as copolymers of ethylene containing polar groups resulting from copolymerization (such as with vinyl acetate or ethyl acrylate).

[0067] As used herein, the term “mLLDPE” refers to metallocene low linear density polyethylene. Metallocene LLDPE is a form of linear low-density polyethylene which is produced using a metallocene catalyst.

[0068] As used herein, the terms “polypropylene” and “polypropylene polymer” refer to polymers that are derived from monomers of propylene. Polypropylenes may be homopolymers, copolymers, or interpolymers. Polypropylene copolymers or interpolymers may include other types of polymers (i.e., non-polypropylene polymers). Propylene linkage can be represented by the general formula: [CH2 — CH(CHs)]n. Polypropylenes may have functional groups incorporated by grafting or other means. Polypropylenes include, but are not limited to, propylene-ethylene copolymers, ethylene-propylene copolymers, and maleic anhydride grafted polypropylenes (MAHgPP).

[0069] As used herein, the terms “ethylene / vinyl alcohol copolymer” or “EVOH” refers to polymerized ethylene vinyl alcohol. Ethylene / vinyl alcohol copolymers include saponified (or hydrolyzed) ethylene / vinyl acrylate copolymers and refer to a vinyl alcohol copolymer having an ethylene comonomer prepared by, for example, hydrolysis of vinyl acrylate copolymers or by chemical reactions with vinyl alcohol. As discussed herein, EVOH is a polyethylene. In some embodiments of the multilayer film, EVOH is limited to less than 10% or less than 5% of the overall weight of the multilayer film. Some embodiments of the multilayer film are free from EVOH.

[0070] As used herein, the term “polyamide” or “PA” refers to homopolymers or copolymers having an amide linkage between monomer units. Some embodiments of the multilayer film are free from polyamide.

[0071] As used herein, the term “polyethylene terephthalate” or “PET” refers to a homopolymer of polyethylene terephthalate or a copolymer thereof. Some embodiments of the multilayer film are free from polyethylene terephthalate.

[0072] As used herein, the term “ethylene vinyl acetate” or “EVA” refers to copolymers comprised of repeating units of ethylene and vinyl acetate. Ethylene vinyl acetate copolymers may be represented by the general formula: [(CH2 — CH2)n — (CH2 — CH(COO)(CH3)]n. As used herein, the term “oriented” refers to a monolayer or multilayer film, sheet, or web which has been elongated in at least one of a machine direction or a transverse / cross direction. Non-limiting examples of such procedures include the single bubble blown film extrusion process with in-line machine direction orientation and the slot case sheet extrusion process with subsequent stretching, for example, by tentering, to provide orientation. Another example of such procedure is the double bubble process or triple bubble process Transverse direction orientation may be accomplished by inflation, radially expanding the heated film tube. Machine direction orientation may be accomplished by the use of nip rolls rotating at different speeds, pulling, or drawing the film tube in the machine direction. The 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 film, sheet, web, package, or otherwise. Heat-shrinkage may be reduced if the oriented article is annealed or heat-set by heating to an elevated temperature, preferably to an elevated temperature which is above the glass transition temperature and below the crystalline melting point of the polymer comprising the article. This reheating / annealing / heat-setting step also provides a polymeric web of uniform flat width. The polymeric web may be annealed (i.e., heated to an elevated temperature) either in-line with (and subsequent to) or off-line from (in a separate process) the orientation process. As used herein, the prefix “O,” when used in conjunction with a material, means that a layer or film of the material is oriented in either the machine direction and / or the transverse direction. For example, “OPE” refers to a layer of film oriented in the machine direction and / or the transverse direction and including polyethylene. The prefix “MDO,” when used in conjunction with a material, means that a layer or film of the material is oriented only in the machine direction. For example, “MDOPE” refers to a layer or film oriented in the machine direction and including polyethylene. The prefix “BO,” when used in conjunction with a material, means that a layer or film of the material is biaxially oriented. For example, “BOPE” refers to a layer or film that is biaxially oriented and includes polyethylene.

[0073] As used herein, the term “disrupted path” refers to a line of weakness. Specifically, the term “disrupted path” refers to a continuous or non-continuous series of holes, vents, slits, slots, perforations, notches, punctures, orifices, openings, inlets, channels, etc., through a layer of a film. A continuous or non-continuous disrupted path may follow a straight line or a curved line. A disrupted path may be a full or partial gap in the continuity of the layer. The gap created by the disrupted path may extend from the first surface of a layer to the second surface of the layer (i.e., throughout the entire thickness of the layer). Alternatively, the depth of a disrupted path may extend from about 50% to about 95% of the thickness of a layer. The terms “disrupted path” and “line of weakness” can be interchangeably used herein.

[0074] As used herein, the term “laser scoring” refers to cutting, scoring, and / or perforating a layer or film using a laser to create a disrupted path.

[0075] As used herein, the term “printed indicia” refers to a marking, image, text, and / or symbol located on the surface of a film, sheet, or web. The printed indicia can be placed on the surface by any suitable means (e.g., ink printing, laser printing, etc.). The indicia can include, e.g., a printed message or instructions, list of ingredients (active and inactive), weight of product, manufacturer name and address, manufacturer trademark, etc.

[0076] As used herein, the term “extrusion process” refers to the process of forming continuous shapes by forcing a molten plastic material through a die, followed by cooling and solidification.

[0077] As used herein, the term “co-extruding” refers to a process of forming an extrudate including more than one distinct and different polymeric melt composition, such as in a multilayer configuration, in which each distinct and different polymeric melt composition may define a distinct and individual layer of the extrudate.

[0078] As used herein, the term “sealing layer” refers to a layer, or layers, involved in the sealing of a film: to itself; to another film layer of the same film or another film; and / or to another article which is not a film. In general, the sealing layer is a surface layer, i.e., an exterior or an interior layer of any suitable thickness, that provides for the sealing of the film to itself or another layer.

[0079] As used herein, the term “heat seal initiation temperature” refers to the minimum temperature at which a prescribed heat seal achieves a seal strength of 5.25 N / 15mm. Heat seal initiation temperature may be measured by ASTM F2029.

[0080] As used herein, the term “melting temperature” refers to the temperature at which a polymer transitions from a crystalline state (i.e., relatively solid) to a viscous flow state (i.e., relatively liquid). In other words, melting temperature is the temperature at which the material of the layer flows or begins to flow. As discussed above, a layer may include a single polymer-type or a blend of polymers and may be accompanied by additives. The melting temperature of a layer may therefore be defined as a function of all its components. The melting temperature of a layer can be measured by hot stage microscopy. The melting temperature of a layer may also be estimated by evaluating raw materials in the blend of a particular layer. For example, if a layer contains 60% of HDPE “A” and 40% of additive “B,” a 60 / 40 melt blended sample of the layer may be made and tested via differential scanning calorimetry (DSC) or other techniques.

[0081] As used herein, melting temperature of a layer is measured by hot stage microscopy. A sample of the film structure to be tested is placed on a cold surface (typically -50°C) and surrounded by water, which then freezes to ice. The sample is then cut with a microtome (i.e. , by Reichert&Jung) in the designated area, exposing a cross sectional view. The resulting cross section of the film is placed on a microscope slide and covered with a glass cover slip. A microscope (i.e., an Olympus BX51 ) equipped with a hot stage (i.e., Linkam, LTS350) is used to view the sample during heating. The sample is heated up at a rate of 10°C / min. As the anticipated melting point of the polymer is reached, images are captured at intervals of 5°C. The melting point of a layer is clearly noted when there is a visible change in the layer.

[0082] FIG. 1 shows a schematic cross-sectional view of a multilayer film 100 in accordance with an embodiment of the present disclosure.

[0083] Multilayer film 100 includes a score receptive layer 102. Score receptive layer 102 includes a first major surface 102A and a second major surface 102B opposite to first major surface 102A.

[0084] Score receptive layer 102 further includes a laser sensitive component. The laser sensitive component may facilitate scoring of score receptive layer 102 using a laser (i.e., laser scoring). In some embodiments, score receptive layer 102 may include a disrupted path (not shown in FIG. 1 ) forming a gap therein. The disrupted path may be formed by laser scoring. Specifically, the disrupted path may be formed by laser scoring. Multilayer film 100 may be easily torn along the disrupted path. As will be discussed later, multilayer film 100 including the disrupted path may be used to form tear open packages.

[0085] Typically, polyolefins are not receptive to the wavelength of industrial lasers (e.g., CO2 lasers), so scoring without a laser sensitive component is challenging. The laser sensitive component may be polymeric, such as polyester, polyamide, EVOH, etc., or inorganic. Specifically, in some embodiments, the laser sensitive component may be inorganic particles or EVOH. The laser receptive layer may include one or more laser receptive components. The inorganic particles may include, for example, titanium dioxide (TiC ), wollastonite, mica, talc, magnesium silicates, kieselguhr, and other inorganic pigments. If inorganic particles are used as the laser sensitive component, they may be present in the laser receptive layer at a level up to about 50%, by weight. If EVOH or another polymer is used as the laser sensitive component, they may be present at a level of more than 50%, more than 75%, more than 90% or 100%, by weight.

[0086] Multilayer film 100 further includes a sealing layer 106. Sealing layer 106 includes a first major surface 106A and a second major surface 106B opposite to first major surface 106A. Sealing layer 106 is located at a surface 121 of multilayer film 100. Surface 121 may be an exterior surface of multilayer film 100. Second major surface 106B of sealing layer 106 may correspond to surface 121 of multilayer film 100.

[0087] Multilayer film 100 further includes a first protection layer 104. First protection layer 104 includes a first major surface 104A and a second major surface 104B opposite to first major surface 104A. First protection layer 104 is located between score receptive layer 102 and sealing layer 106. In some embodiments, score receptive layer 102 may be directly adjacent to first protection layer 104.

[0088] In some embodiments, first protection layer 104 may be in direct contact with each of score receptive layer 102 and sealing layer 106. Specifically, in the illustrated embodiment of FIG. 1 , first major surface 104A of first protection layer 104 is in direct contact with second major surface 102B of score receptive layer 102, and second major surface 104B of first protection layer 104 is in direct contact with first major surface 106A of sealing layer 106. In other embodiments of the multilayer film there may be one or more additional layers between the score receptive layer 102 and the first protection layer 104. In other embodiments of the multilayer film there may be one or more additional layers between the first protection layer 104 and the sealing layer 106.

[0089] Further, in the illustrated embodiment of FIG. 1 , score receptive layer 102 is located at a surface 122 of multilayer film 100. Surface 122 may be an exterior surface of multilayer film 100 opposite to surface 121. First major surface 102A of score receptive layer 102 may correspond to surface 122 of multilayer film 100. In other embodiments, first major surface 102A is adjacent to an additional layer and is not at the surface of the multilayer film. First protection layer 104 includes a melting temperature TMP1. Further, score receptive layer 102 includes a melting temperature TMR. Moreover, sealing layer 106 includes a melting temperature TMS.

[0090] The melting temperature TMS of sealing layer 106 is at least 20°C lower than the melting temperature TMP1 of first protection layer 104. In some embodiments, the melting temperature TMS of sealing layer 106 may be at least 25°C lower than the melting temperature TMP1 of first protection layer 104. In some embodiments, the melting temperature TMS of sealing layer 106 may be at least 30°C lower than the melting temperature TMP1 of first protection layer 104.

[0091] Moreover, in some embodiments, the melting temperature TMS of sealing layer 106 may be at least 20°C lower than the melting temperature TMR of score receptive layer 102. In some embodiments, the melting temperature TMS of sealing layer 106 may be at least 25°C lower than the melting temperature TMR of score receptive layer 102. In some embodiments, the melting temperature TMS of sealing layer 106 may be at least 30°C lower than the melting temperature TMR of score receptive layer 102.

[0092] More specifically, in some embodiments, the melting temperature TMP1 of first protection layer 104 may be greater than or equal to 125°C. Further, in some embodiments, the melting temperature TMR of score receptive layer 102 may be greater than or equal to 125°C. Moreover, in some embodiments, the melting temperature TMS of sealing layer 106 may be less than or equal to 100°C. Consequently, sealing layer 106 may include a heat seal initiation temperature less than or equal to 100°C, as measured by ASTM F2029. Sealing layer 106 may be heat sealed to itself or another component to form a package from multilayer film 100. The temperature of the sealing equipment used to form the heat seal of the package may be in a range to raise the sealing layer 106 above the heat seal initiation temperature (i.e., above TMS or above 100°C) and prevent the protection layer 104 from reaching TMP1 (i.e., below 125°C).

[0093] As discussed above, score receptive layer 102 may include a disrupted path. As the melting temperature TMS (and the heat seal initiation temperature) of sealing layer 106 is lower than the melting temperature TMP1 of first protection layer 104, sealing layer 106 may be heat sealed at a lower temperature than the melting temperature TMP1 of first protection layer 104. Consequently, first protection layer 104 may not melt during heat sealing of sealing layer 106, thereby protecting the disrupted path of score receptive layer 102 during heat sealing. Specifically, first protection layer 104 may prevent closing of the disrupted path due to the heat sealing, which may otherwise occur in absence of first protection layer 104. For example, in absence of first protection layer 104, during heat sealing, sealing layer 106 may melt, fill, and close the disrupted path, thereby compromising the functionality of the disrupted path (i.e., prevent easy tearing along the disrupted path). Multilayer film 100 may preserve the disrupted path during the heat sealing of sealing layer 106. Consequently, multilayer film 100 may be suitable to form tear open packages that include a scored opening feature within a heat sealed area.

[0094] Furthermore, multilayer film 100 may provide an optimal heat-sealing temperature range, that is, a temperature range greater than the heat seal initiation temperature of sealing layer 106 and less than the melting temperature TMP1 of first protection layer 104.

[0095] Each of first protection layer 104, score receptive layer 102, and sealing layer 106 includes greater than 50% polyolefin, by weight. In other words, first protection layer 104 includes greater than 50% polyolefin, by weight of first protection layer 104; score receptive layer 102 includes greater than 50% polyolefin, by weight of score receptive layer 102; and sealing layer 106 includes greater than 50% polyolefin, by weight of sealing layer 106.

[0096] Specifically, in some embodiments, first protection layer 104 may include greater than 50% polyethylene, by weight of first protection layer 104; score receptive layer 102 may include greater than 50% polyethylene, by weight of score receptive layer 102; and sealing layer 106 may include greater than 50% polyethylene, by weight of sealing layer 106.

[0097] In some other embodiments, first protection layer 104 may include greater than 50% polypropylene, by weight of first protection layer 104; score receptive layer 102 may include greater than 50% polypropylene, by weight of score receptive layer 102; and sealing layer 106 may include greater than 50% polypropylene, by weight of sealing layer 106.

[0098] In some embodiments, each of first protection layer 104 and sealing layer 106 may include a polymeric content greater than 80% polyethylene, by weight. In other words, first protection layer 104 may include a polymeric content greater than 80% polyethylene, by weight of first protection layer 104; and sealing layer 106 may include a polymeric content greater than 80% polyethylene, by weight of sealing layer 106. In some embodiments, each of first protection layer 104 and sealing layer 106 may include a polyethylene content greater than 80%, by weight. In other words, first protection layer 104 may include a polyethylene content greater than 80%, by weight of first protection layer 104; and sealing layer 106 may include a polyethylene content greater than 80%, by weight of sealing layer 106.

[0099] In some embodiments, score receptive layer 102 may include a low-density polyethylene polymer. In some embodiments, score receptive layer 102 may include a high-density polyethylene polymer. In some embodiments, score receptive layer 102 may include a blend including a low-density polyethylene polymer and a high-density polyethylene polymer.

[0100] In some embodiments, first protection layer 104 may include a low-density polyethylene polymer. In some embodiments, first protection layer 104 may include a high-density polyethylene polymer. In some embodiments, first protection layer 104 may include a blend including a low-density polyethylene polymer and a high-density polyethylene polymer. In some embodiments, first protection layer 104 may be free of the laser sensitive component.

[0101] Multilayer film 100 may have a polymeric content including greater than 80% polyolefin, by weight. That is, multilayer film 100 may have a polymeric content including greater than 80% polyethylene, by weight, or greater than 80% polypropylene, by weight. In some embodiments, multilayer film 100 may have a polymeric content including greater than 90% polyolefin, by weight. In some embodiments, multilayer film 100 may have a polymeric content including greater than 95% polyolefin, by weight. The polymeric content does not include any inorganic content.

[0102] In some embodiments, multilayer film 100 may include a polyethylene content greater than 80%, by weight, or a polypropylene content greater than 80%, by weight. Specifically, in some embodiments, multilayer film 100 may include a polyethylene content greater than 80%, by weight. In some other embodiments, multilayer film 100 may include a polypropylene content greater than 80%, by weight. In some embodiments, multilayer film 100 may be free of ethylene vinyl acetate (EVA) copolymers. That is, each layer of multilayer film 100 may be free of EVA copolymers.

[0103] Multilayer film 100 may be recyclable due to high polyolefin content. As a result, multilayer film 100 may be recyclable in a recycling stream. In some embodiments, multilayer film 100 may be recyclable in a polyethylene recycling stream. In some other embodiments, multilayer film 100 may be recyclable in a polypropylene recycling stream. Therefore, multilayer film 100 may be environmentally friendly.

[0104] The high levels of polyolefin (i.e., polyethylene and / or polypropylene) in the multilayer film and the layers therein provides for ease of recycling. However, in designing multilayer films with high levels of polyolefin, sealing layers having relatively low heat seal initiation temperatures (i.e., less than 100°C) becomes necessary so that packages can be formed by heat sealing without marring, shrinking or other visual defects due to high sealing temperatures. The high polyolefin content has a relatively low heat resistance, thus necessitating low heat seal temperature requirements. Since the sealing layers are then designed with lower melting temperatures, they have a tendency to easily melt and flow into any gaps that may have been formed for tearing purposes. Therefore, multilayer films with high polyolefin content, needing to be heat sealed at low temperatures, benefit from the structures as defined herein.

[0105] FIG. 2 shows a schematic cross-sectional view of a multilayer film 200 in accordance with another embodiment of the present disclosure. Multilayer film 200 is substantially similar to multilayer film 100 of FIG. 1 , with like elements designated by like reference characters. However, multilayer film 200 includes one or more additional layers as compared to multilayer film 100.

[0106] Specifically, in the illustrated embodiment of FIG. 2, multilayer film 200 includes a second protection layer 108. Second protection layer 108 includes a first major surface 108A and a second major surface 108B opposite to first major surface 108A.

[0107] In the illustrated embodiment of FIG. 2, score receptive layer 102 is located between first protection layer 104 and second protection layer 108. Further, score receptive layer 102 is directly adjacent to second protection layer 108. In the illustrated embodiment of FIG. 2, score receptive layer 102 is directly adjacent to each of first protection layer 104 and second protection layer 108. Specifically, in the illustrated embodiment of FIG. 2, first major surface 102A of score receptive layer 102 is in direct contact with second major surface 108B of second protection layer 108, and second major surface 102B of score receptive layer 102 is in direct contact with first major surface 104A of first protection layer 104.

[0108] Sealing layer 106 is located at a surface 221 of multilayer film 200. Surface 221 may be an exterior surface of multilayer film 200. Second major surface 106B of sealing layer 106 may correspond to surface 221 of multilayer film 200. Furthermore, in the illustrated embodiment of FIG. 2, second protection layer 108 is located at a surface 222 of multilayer film 200. Surface 222 may be an exterior surface of multilayer film 200 opposite to surface 221 . First major surface 108A of second protection layer 108 may correspond to surface 222 of multilayer film 200.

[0109] Second protection layer 108 may include greater than 50% polyolefin, by weight. In some embodiments, second protection layer 108 may include greater than 80% polyethylene, by weight. In some embodiments, second protection layer 108 may include greater than 80% polypropylene, by weight.

[0110] In some embodiments, second protection layer 108 may include a low-density polyethylene polymer. In some embodiments, second protection layer 108 may include a high-density polyethylene polymer. In some embodiments, second protection layer 108 may include a blend including a high-density polyethylene polymer and a low- density polyethylene polymer. In some embodiments, second protection layer 108 may be free of the laser sensitive component.

[0111] Second protection layer 108 may include a melting temperature TMP2. The melting temperature TMP2 of second protection layer 108 may be at least 20°C higher than the melting temperature TMS of sealing layer 106. In some embodiments, the melting temperature TMP2 of second protection layer 108 may be at least 25°C higher than the melting temperature TMS of sealing layer 106. In some embodiments, the melting temperature TMP2 of second protection layer 108 may be at least 30°C higher than the melting temperature TMS of sealing layer 106.

[0112] In some embodiments, the melting temperature TMP2 of second protection layer 108 may be equal to or greater than the melting temperature TMR of score receptive layer 102. In some embodiments, the melting temperature TMP2 of second protection layer 108 may be greater than or equal to 125°C.

[0113] FIG. 3 shows a schematic cross-sectional view of a multilayer film 300 in accordance with another embodiment of the present disclosure. Multilayer film 300 is substantially similar to multilayer film 200 of FIG. 2, with like elements designated by like reference characters. However, multilayer film 300 includes one or more additional layers or films as compared to multilayer film 200.

[0114] Specifically, in the illustrated embodiment of FIG. 3, multilayer film 300 includes an oriented polyethylene film 110. Oriented polyethylene film 1 10 may be machine direction oriented or biaxially oriented. In other words, oriented polyethylene film 110 may be MDOPE or BOPE. Oriented polyethylene film 110 includes a first major surface 110A and a second major surface 11 OB opposite to first major surface 110A. In the illustrated embodiment of FIG. 3, oriented polyethylene film 1 10 is directly adjacent to second protection layer 108. Specifically, in the illustrated embodiment of FIG. 3, second major surface 1 1 OB of oriented polyethylene film 1 10 is in direct contact with first major surface 108A of second protection layer 108. In such embodiments, oriented polyethylene film 110 may be laminated to second protection layer 108 by adhesive or extrusion lamination (not shown).

[0115] Further, in the illustrated embodiment of FIG. 3, sealing layer 106 is located at a surface 321 of multilayer film 300. Surface 321 may be an exterior surface of multilayer film 300. Second major surface 106B of sealing layer 106 may correspond to surface 321 of multilayer film 300. Furthermore, oriented polyethylene film 1 10 is located at a surface 322 of multilayer film 300. Surface 322 may be an exterior surface of multilayer film 200 opposite to surface 321 . First major surface 1 10A of oriented polyethylene film 1 10 may correspond to surface 322 of multilayer film 300.

[0116] Surface 322 of multilayer film 300 may be an exterior surface of a package formed from multilayer film 300. As a result, surface 322 may be subject to handling and abuse, for example, from equipment during packaging, and from rubbing against other packages, shipping containers, and storage shelves during transport and storage. Advantageously, oriented polyethylene film 110 may provide desirable properties, such as toughness and abuse resistance, to multilayer film 300.

[0117] In some embodiments, multilayer film 300 may be devoid of second protection layer 108. In such embodiments, oriented polyethylene film 110 may be directly adjacent to score receptive layer 102. More specifically, in such embodiments, second major surface 110B of oriented polyethylene film 1 10 may be in direct contact with first major surface 102A of score receptive layer 102. Moreover, in such embodiments, oriented polyethylene film 1 10 may be laminated to score receptive layer 102 by adhesive or extrusion lamination.

[0118] Furthermore, some embodiments may include additional layers. For example, a multilayer film may be similar to multilayer film 300, with the exceptions that the film is devoid of second protection layer 108 (as discussed) but includes a different layer in the noted position of layer 108. Alternatively, multilayer film 300 may be as shown in FIG.3, and further include an additional layer located between the second protection layer 108 and the oriented polyethylene film 110. Such a layer may have functionality to enhance lamination bonds.

[0119] In some embodiments, oriented polyethylene film 110 may further include printed indicia (not shown). The printed indicia may be printed on first major surface 1 10A and / or second major surface 110B of oriented polyethylene film 1 10.

[0120] FIGS. 4A and 4B show a multilayer film 400 in accordance with another embodiment of the present disclosure. Specifically, FIG. 4A illustrates a schematic cross-sectional view of multilayer film 400 and FIG. 4B illustrates a schematic top view of multilayer film 400. Multilayer film 400 is substantially similar to multilayer film 200 of FIG. 2, with like elements designated by like reference characters. However, score receptive layer of 102 of multilayer film 400 has a different configuration than that of multilayer film 200.

[0121] Referring to FIGS. 4A and 4B, in some embodiments, score receptive layer 102 includes a disrupted path 410 (schematically shown by hatching in FIG. 4B). Disrupted path 410 may be continuous or discontinuous. The disrupted path may be formed by laser scoring. Specifically, the laser sensitive component of score receptive layer 102 may allow laser scoring of score receptive layer 102 to form disrupted path 410.

[0122] Disrupted path 410 may be configured such that multilayer film 400 remains intact, secure, and unbroken during package fabrication, distribution, and storage, and also easily tears along disrupted path 410 when it is desired to open a package made from multilayer film 400. The package made from multilayer film 400 may be manually opened without use of scissors or other cutting tools by tearing the package along disrupted path 410. Disrupted path 410 may be linear with respect to the schematic top view as shown in FIG. 4B or it may be curved or shaped in any other configuration.

[0123] FIGS. 5A and 5B show schematic front views of a package 500 in accordance with an embodiment of the present disclosure.

[0124] Referring to FIGS. 4A, 5A and 5B, package 500 includes multilayer film 400. In other words, package 500 may be formed from multilayer film 400. Specifically, sealing layer 106 (shown in FIG. 4A) of multilayer film 400 may be heat sealed to another component to form package 500. More specifically, package 500 may include one or more heat sealed areas 510 (depicted by hatching in FIGS. 5A and 5B) including a connection between sealing layer 106 of multilayer film 400 and the another component. The another component may be, for example, another packaging film (such as multilayer film 400). In some embodiments, sealing layer 106 of one multilayer film 400 may be heat sealed with sealing layer 106 of another multilayer film 400 to form package 500, such that disrupted path 410 of one multilayer film 400 is aligned with disrupted path 410 of another multilayer film 400. Furthermore, package 500 may be of any suitable type, for example, a gusseted pouch, a stand-up pouch, a pillow pouch, etc.

[0125] Package 500 may include a tearable portion 530 to permit access to packaged content of package 500. Tearable portion 530 may be defined by disrupted path 410 of multilayer film 400. Tearable portion 530 may be torn along disrupted path 410 to access the packaged content. Therefore, package 500 may be interchangeably referred to as “tear open package 500.” In some embodiments, the disrupted path 410 may be configured such that the tearable portion 530 can be completely removed from the package 500.

[0126] At least one of one or more heat sealed areas 510 may overlap disrupted path 410. Specifically, at least one of the one or more heat sealed areas 510 may overlap disrupted path 410 at an overlapping portion 520. Advantageously, at least one of the one or more heat sealed areas 510 may not hinder opening of package 500 by tearing at the disrupted path 410. Specifically, disrupted path 410 (i.e., plurality of scores) may remain intact during formation of at least one of one or more heat sealed areas 510. Therefore, tearable portion 530 may be torn along disrupted path 410, particularly along disrupted path 410 at overlapping portion 520. In some cases, the tear may initiate from overlapping portion 520.

[0127] FIG. 6 shows a method 600 of producing a multilayer film (e.g., multilayer film 400 of FIGS. 4A and 4B) in accordance with an embodiment of the present disclosure. Method 600 will be described with further reference to FIGS. 1 , 4A, and 4B.

[0128] At step 602, method 600 includes simultaneously co-extruding a first protection layer, a score receptive layer, and a sealing layer to produce an intermediate film. The sealing layer is located at a surface of the multilayer film and the first protection layer is located between the score receptive layer and the sealing layer. The first protection layer includes a melting temperature TMP1. The score receptive layer includes a melting temperature TMR. The score receptive layer further includes a laser sensitive component. The sealing layer includes a melting temperature TMS. The melting temperature TMS of the sealing layer is at least 20°C lower than the melting temperature TMP1 of the first protection layer. The multilayer film has a polymeric content including greater than 80% polyolefin, by weight. For example, method 600 may include simultaneously co-extruding first protection layer 104, score receptive layer 102, and sealing layer 106 to produce the intermediate film (e.g., the multilayer film 100 of FIG. 1 ).

[0129] At step 604, method 600 further includes creating a disrupted path in the score receptive layer of the intermediate film with a laser to form the multilayer film. For example, method 600 may include creating disrupted path 410 (see FIGS. 4A and 4B) in score receptive layer 102 with a laser to form multilayer film 400.

[0130] In some embodiments, disrupted path may include a plurality of scores. Specifically, in some embodiments, creating the disrupted path in the score receptive layer of the intermediate film with the laser may include forming a plurality of scores using the laser. For example, disrupted path 410 may include a plurality of scores. The plurality of scores may be formed by laser scoring.

[0131] In some embodiments, the first protection layer is in direct contact with each of the score receptive layer and the sealing layer. For example, as shown in FIG. 1 , first protection layer 104 may be in direct contact with each of score receptive layer 102 and the sealing layer 106.

[0132] In some embodiments, method 600 further includes laminating the intermediate film to a polyethylene film. In some embodiments, the polyethylene may be oriented. The intermediate film may be laminated to the polyethylene film by any suitable lamination process, such as, for example, adhesive lamination and extrusion lamination. Referring to FIG. 3, for example, method 600 may include laminating the intermediate film to oriented polyethylene film 1 10.

[0133] FIG. 7 shows a flowchart depicting various steps of a method 700 of producing a tear open package (e.g., the package 500 of FIG. 5) in accordance with an embodiment of the present disclosure. Method 700 will be described with further reference to FIGS. 4A-5B.

[0134] At step 702, method 700 includes producing a multilayer film according to method 600 of FIG. 6. For example, method 700 may include producing multilayer film 400.

[0135] At step 704, method 700 further includes heat sealing the multilayer film to another component to form a heat sealed area including a connection between the sealing layer of the multilayer film and the another component. The heat sealed area overlaps the disrupted path. For example, method 700 may include heat sealing multilayer film 400 to the another component to form one or more heat sealed areas 510 including connection between sealing layer 106 of multilayer film 400 and the another component.

[0136] Tear open package 500 produced using method 700 may tear along disrupted path 410, particularly along disrupted path 410 located at one or more heat sealed areas 510. Further, tear open package 500 may be recyclable.

[0137] Examples

[0138] The following illustrative examples are merely meant to exemplify the present invention and are not intended to limit or otherwise define the scope of the present disclosure.

[0139] In the following examples, the layers and the composition of the layers are described. Some layers include minor amounts (i.e. , less than 5% or less than 3%) of standard extrusion additives such as antiblock, slip or processing aid which are not noted in the formula. For a given layer, the percentages of constituents listed are with respect to the total weight of the layer minus these additives. Further, Tm refers to the melting temperature of the constituent.

[0140] The melting temperature (Tm) is noted for some of the layer components as they were obtained from technical data sheets for the polymers. The melt temperature of the layers as obtained by hot stage microscopy testing is discussed in the Experimental Results section. However, please note that these are not the melting temperature of the layer. The melting temperature of the layers is further discussed in the experimental results below.

[0141] Example 1 : A multilayer film having the following structure (the layers connected in this order) was developed:

[0142] -25 microns - HDPE-rich MDOPE;

[0143] -3.5 microns - Polyurethane adhesive;

[0144] -20 microns - 54% LDPE (Tm: 1 10°C) + 33% HOPE (Tm: 131 °C) + 13% white masterbatch (based on LDPE carrier);

[0145] -12 microns - 67% LDPE (Tm: 1 10°C) + 33% HDPE (Tm: 131 °C) [second protection layer] (100% polyolefin, by weight); -38 microns - 58% LDPE (Tm: 110°C) + 36% HDPE (Tm: 131 °C) + 6% laser receptive component in a PE carrier [score receptive layer] (layer is 98.8% polyolefin, by weight);

[0146] -12 microns - 67% LDPE (Tm: 110°C) + 33% HDPE (Tm: 131°C) [first protection layer] (100% polyolefin, by weight); and

[0147] -28 microns - 65% ethylene plastomer (Tm: 73°C) + 35% ethylene plastomer (Tm: 97°C) [sealing layer] (100% polyolefin, by weight).

[0148] Example 2: Another multilayer film having the following structure was developed:

[0149] -25 microns - HDPE-rich MDOPE ;

[0150] -3.5 microns - Polyurethane adhesive;

[0151] -32 microns - 67% LDPE (Tm: 110°C) + 33% HDPE (Tm: 131 °C) [second protection layer] (100% polyolefin, by weight);

[0152] -38 microns - 52% LDPE (Tm: 110°C) + 32% HDPE (Tm: 131 °C) + 16% white masterbatch (LDPE carrier with TiO2, TiO2 functions as laser receptive component) [score receptive layer] (layer is 88.8% polyolefin, by weight);

[0153] -12 microns - 67% LDPE (Tm: 110°C) + 33% HDPE (Tm: 131 °C) [first protection layer] (100% polyolefin, by weight); and

[0154] -28 microns - 65% ethylene plastomer (Tm: 73°C) + 35% ethylene plastomer (Tm: 97°C) [sealing layer] (100% polyolefin, by weight).

[0155] Comparative Example: A comparative multilayer film having the following structure was selected:

[0156] -25 microns - HDPE rich MDOPE;

[0157] -2 microns - Polyurethane adhesive;

[0158] -41 microns - 60% LPDE (Tm: 110°C) + 40% LLDPE (Tm: 123°C);

[0159] -98 microns - 50% plastomer (Tm: 100°C) + 29% LDPE with laser sensitive component (Tm: 1 10°C), 9% white masterbatch (LDPE carrier with TiO2, TiO2 functions as laser receptive component) and 12% regrind [score receptive layer]; and -41 microns — 100% plastomer (Tm: 100°C) [sealing layer].

[0160] (Note: the regrind listed in the composition of the Comparative Example was a post-industrial blend of plastomer, white masterbatch, and other polyethylene materials.) Experimental Results

[0161] Scoring / Tearing Tests

[0162] The multilayer films of Examples 1 and 2 and the Comparative Example were scored using a CO2 laser. Specifically, a disrupted path (i.e., a score) was formed on the score receptive layer of the multilayer films. Example 1 film was scored using an approximate laser power of 20W and a line speed of 35 m / min. Example 2 film was scored using an approximate laser power of 65W and a line speed of 180 m / min. Comparative Example film was scored using an approximate laser power of 20W and a line speed of 35 m / min.

[0163] Prior to forming packages from the multilayer films (i.e., before subjecting the films to heat sealing), the multilayer films of Examples 1 and 2 and the Comparative Example tore similarly along the disrupted path. Each sample tore cleanly and easily.

[0164] Subsequently, experiments were conducted on the multilayer films to determine the effect of heat and heat sealing on the scores formed using the laser. In a set of experiments, the multilayer films of Examples 1 and 2 and the Comparative Example were formed into respective packages by heat sealing as shown in Fig. 5A. Specifically, two samples of each of the multilayer films and the comparative multilayer film were heat sealed together such that the disrupted paths of the two samples aligned with each other, the heat seals located at the edge of the films and the disrupted path passing through the heat seal area.

[0165] The package formed from the Comparative Example even at the lowest sealing temperature failed to tear along the disrupted path in the heat sealed area, which prevented tear initiation. It was concluded that the tear initiation was prevented due to closing of the scores as a result of the heating experienced during heat sealing.

[0166] In contrast, the packages formed from the multilayer films of Examples 1 and 2 in the range of 100-120°C tore along the disrupted path in the heat-sealed area with an opening force that corresponds to the opening force of the two unsealed scored film layers. At a packaging formation temperature of 130°C, the opening force increased by 3-4 times compared to unsealed single-layer. Therefore, it was concluded that the multilayer films of Examples 1 and 2 were suitable for forming tear open packages and sealing process didn’t close scored area in the operating temperature window of 100-120°C, while higher temperatures destroyed the protective layers and prevented good opening initiation. Melt Temperature of Lavers

[0167] A set of experiments were performed on the multilayer films of Examples 1 and 2 and the Comparative Example film using hot stage microscopy in order to understand 1 ) the melt temperatures of the layers and 2) the behavior of the layers under heated conditions.

[0168] The multilayer film of the Comparative Example was heated to temperatures above 100°C and observed. At these temperatures, the layers melted and flowed into the scores formed on the score receptive layer at maximum 1 15°C. Upon reaching the relatively low melting temperature of the sealing and score receptive layers, the scores were filled in with melted polymer, effectively rendering the score as useless, even without application of additional pressure.

[0169] The multilayer films of Examples 1 and 2 were heated to 130°C and observed. It was observed that the sealing layer of each of the multilayer films started melting at 95°C. Similarly, the first protection layer, the second protection layer and the score receptive layer each started melting at 130°C. It was further observed that the first protection layer of each of the multilayer films prevented closure of the scores formed on the score receptive layer, up to 130°C. Based on this result, it was concluded that the multilayer films of Examples 1 and 2 can maintain the scores during heat sealing of the sealing layer, which the Comparative Example film failed to do.

[0170] Each and every document cited in this present application, including any cross referenced, is incorporated in this present application in its entirety by this reference, unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any embodiment disclosed in this present application or that it alone, or in any combination with any other reference or references, teaches, suggests, or discloses any such embodiment. Further, to the extent that any meaning or definition of a term in this present application conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this present application governs.

[0171] Unless otherwise indicated, all numbers expressing sizes, amounts, ranges, limits, and physical and other properties used in the present application are to be understood as being preceded in all instances of the term “about.” Accordingly, unless expressly indicated to the contrary, the numerical parameters set forth in the present application are approximations that can vary depending on the desired properties sought to be obtained by a person of ordinary skill in the art without undue experimentation using the teachings disclosed in the present application.

[0172] As used in the present application, the singular forms “a,” “an,” and “the” encompass embodiments having plural referents, unless the context clearly dictates otherwise. As used in the present application, the term “or” is generally employed in its sense including “and / or”, “unless” the context clearly dictates otherwise.

[0173] Spatially related terms, including, but not limited to, “lower,” “upper,” “beneath,” “below,” “above,” “bottom,” and “top,” if used in the present application, are used for ease of description to describe spatial relationships of an element(s) to another. Such spatially related terms encompass different orientations of the device in use or operation, in addition to the particular orientations depicted in the figures and described in the present application. For example, if an object depicted in the drawings is turned over or flipped over, elements previously described as below, or beneath other elements would then be above those other elements.

[0174] The drawings show some but not all embodiments. The elements depicted in the drawings are illustrative and not necessarily to scale, and the same (or similar) reference numbers denote the same (or similar) features throughout the drawings.

[0175] The description, examples, embodiments, and drawings disclosed are illustrative only and should not be interpreted as limiting. The present invention includes the description, examples, embodiments, and drawings disclosed; but it is not limited to such description, examples, embodiments, or drawings. As briefly described above, the reader should assume that features of one disclosed embodiment can also be applied to all other disclosed embodiments, unless expressly indicated to the contrary. Modifications and other embodiments will be apparent to a person of ordinary skill in the packaging arts, and all such modifications and other embodiments are intended and deemed to be within the scope of the present invention.

Claims

CLAIMSWhat is claimed is:

1. A multilayer film comprising: a first protection layer comprising a melting temperature TMP1 , a score receptive layer comprising a melting temperature TMR, the score receptive layer further comprising a laser sensitive component, and a sealing layer located at a surface of the multilayer film and comprising a melting temperature TMS, wherein: the first protection layer is located between the score receptive layer and the sealing layer, the melting temperature TMS of the sealing layer is at least 20°C lower than the melting temperature TMP1 of the first protection layer, and each of the first protection layer, the score receptive layer, and the sealing layer comprises greater than 50% polyolefin, by weight.

2. The multilayer film according to claim 1 , wherein each of the first protection layer and the sealing layer has a polymeric content greater than 80% polyethylene, by weight.

3. The multilayer film according to claim 1 , wherein the multilayer film has a polyethylene content greater than 80%, by weight, or a polypropylene content greater than 80%, by weight.

4. The multilayer film according to any of claims 1 -3, wherein the melting temperature TMS of the sealing layer is at least 25°C lower than the melting temperature TMP1 of the first protection layer.

5. The multilayer film according to any of claims 1 -4, wherein the melting temperature TMS of the sealing layer is at least 30°C lower than the melting temperature TMP1 of the first protection layer.

6. The multilayer film according to any of claims 1 -5, wherein the melting temperature TMS of the sealing layer is at least 20°C lower than the melting temperature TMR of the score receptive layer.

7. The multilayer film according to any of claims 1 -6, further comprising a second protection layer comprising a melting temperature TMP2, wherein: the second protection layer comprises greater than 50% polyolefin, by weight, the score receptive layer is located between the first protection layer and the second protection layer, and the melting temperature TMP2 of the second protection layer is at least 20°C higher than the melting temperature TMS of the sealing layer.

8. The multilayer film according to claim 7, wherein the melting temperature TMP2 of the second protection layer is equal to or greater than the melting temperature TMR of the score receptive layer.

9. The multilayer film according to any previous claim, wherein the multilayer film has a polymeric content including greater than 80% polyolefin, by weight.

10. The multilayer film according to any previous claim, wherein the multilayer film has a polymeric content including greater than 90% polyolefin, by weight.11 . The multilayer film according to any previous claim, wherein the multilayer film has a polymeric content including greater than 95% polyolefin, by weight.

12. The multilayer film according to any previous claim, wherein the sealing layer comprises a heat seal initiation temperature less than or equal to 100°C, as measured by ASTM F2029.

13. A multilayer film comprising: a first protection layer comprising a melting temperature TMP1 greater than or equal to 125°C, a score receptive layer comprising a melting temperature TMR, the score receptive layer further comprising a laser sensitive component, anda sealing layer located at a surface of the multilayer film and comprising a melting temperature TMS less than or equal to 100°C, wherein: the first protection layer is located between the score receptive layer and the sealing layer, and the multilayer film has a polymeric content including greater than 80% polyethylene, by weight.

14. The multilayer film according to claim 13, wherein each of the first protection layer and the sealing layer comprises a polyethylene content greater than 80%, by weight.

15. The multilayer film according to any previous claim, wherein the score receptive layer is directly adjacent to the first protection layer.

16. The multilayer film according to any previous claim, wherein the first protection layer is free of a laser sensitive component.

17. The multilayer film according to any previous claim, wherein the first protection layer comprises a high-density polyethylene polymer.

18. The multilayer film according to any of claims 13-17, further comprising a second protection layer comprising a melting temperature TMP2 greater than or equal to 125°C, wherein the score receptive layer is located between the first protection layer and the second protection layer, and wherein the score receptive layer is directly adjacent to the second protection layer.

19. The multilayer film according to claim 18, wherein the second protection layer is free of a laser sensitive component.

20. The multilayer film according to any previous claim, wherein the second protection layer comprises a high-density polyethylene polymer.21 . The multilayer film according to any previous claim, wherein the multilayer film is free of ethylene vinyl acetate copolymers.

22. The multilayer film according to any previous claim, wherein the laser sensitive component is inorganic particles or EVOH.

23. The multilayer film according to any previous claim, further comprising an oriented polyethylene film.

24. The multilayer film according to any previous claim, wherein the score receptive layer further comprises a disrupted path.

25. A package comprising: the multilayer film according to claim 24, and one or more heat sealed areas comprising a connection between the sealing layer of the multilayer film and another component, wherein at least one of the one or more heat sealed areas overlaps the disrupted path.

26. A method of producing a multilayer film, the method comprising: i) simultaneously co-extruding a first protection layer, a score receptive layer, and a sealing layer to produce an intermediate film; and ii) creating a disrupted path in the score receptive layer of the intermediate film with a laser to form the multilayer film; wherein: the sealing layer is located at a surface of the multilayer film and the first protection layer is located between the score receptive layer and the sealing layer; the first protection layer comprises a melting temperature TMP1 , the score receptive layer comprises a melting temperature TMR, the score receptive layer further comprises a laser sensitive component, the sealing layer comprises a melting temperature TMS, and the melting temperature TMS of the sealing layer is at least 20°C lower than the melting temperature TMP1 of the first protection layer, andthe multilayer film has a polymeric content including greater than 80% polyolefin, by weight.

27. The method according to claim 26, further comprising laminating the intermediate film to a polyethylene film.

28. The method according to claim 26 or 27, wherein the first protection layer is in direct contact with each of the score receptive layer and the sealing layer.

29. A method of producing a tear open package, the method comprising: i) producing the multilayer film according to claim 26, ii) heat sealing the multilayer film to another component to form a heat sealed area comprising a connection between the sealing layer of the multilayer film and the another component, wherein the heat sealed area overlaps the disrupted path.

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