Packaging film composition

Abstract

A composition for producing an abrasion-resistant film comprising: (a) at least one ionomer of an acid copolymer; (b) at least one anti-slip additive; (c) at least one anti-blocking additive; (d) at least one chill roll release additive; and (e) optionally, one or more additives different from components (a) to (d); a process for producing the film composition; a monolayer abrasion-resistant film or a multilayer abrasion-resistant film, at least one layer of the monolayer film or the multilayer film comprising an abrasion-resistant film layer produced from the film composition; and a process for producing the monolayer film or the multilayer film.

Description

[Technical Field]

[0001] The present invention relates to a composition for producing a packaging film, more particularly, the present invention relates to a composition for producing an abrasion-resistant and scratch-resistant film for packaging containers used in food packaging. [Background technology]

[0002] Using recycled materials is considered to be better for the environment and reduce the waste of natural resources used in disposable products. Therefore, many industries desire to use recyclable materials in their products and / or product packaging to provide for the recycling of disposable products and the reduction of natural resources. In the packaging industry, the current structure of some containers for various food contact packaging applications is generally made from a combination of various materials, some of which are recyclable and some of which are not. Producing final food product packaging containers using non-recyclable materials makes it difficult, and in some cases impossible, to recycle the food packaging container after the container is disposed of. For example, packaging containers for packaging food products (e.g., bottles, bags, sachets, pouches such as pillow pouches, or cans such as composite cans) can include a multi-layer structure including several layers of different materials, such as a combination of paper, gas and / or moisture barrier materials, and polymer resin layers.

[0003] Typically, in the construction of containers for food packaging having a multilayer film structure, the innermost film layer of the container (i.e., the "film liner") comes into contact with the food product and is required to meet many important quality requirements, such as, for example, (1) high abrasion and scratch resistance, (2) extended shelf life of the packaged food product, and (3) excellent sealing performance.

[0004] To date, film liners used in food contact applications have been successfully made from ionomeric polymer resins based on copolymers of ethylene and methacrylic acid, such as SURLYN™ available from The Dow Chemical Company. Such film liners generally have several favorable properties, such as high abrasion resistance, scratch resistance, long shelf life, improved sealing performance, and recyclability, and have been used with some success in providing multilayer packaging films for food packaging. However, in some cases, it is desirable for the packaging industry to thin the film liners of multilayer packaging containers in order to conserve the amount of material used in manufacturing the packaging containers while maintaining the favorable properties mentioned above. Unfortunately, it has been found that thinning the inner layer (film liner) made from previously known ionomeric compositions significantly shortens the shelf life of food products in contact with the thinned film liner.

[0005] It would be desirable to provide alternative ionomer compositions that can be used to make abrasion and scratch resistant films, such as film liners for packaging applications, that can be thinned without compromising the abrasion, scratch, oil, and seasoning resistance of the thinned film liner and / or the shelf life of the packaged food product, in addition to allowing the film liner to be recyclable. Summary of the Invention

[0006] One general embodiment of the present invention relates to a polymer resin composition or formulation for use in producing abrasion- and scratch-resistant films (abbreviated herein as "ARF") for packaging applications. The polymer resin composition of the present invention comprises a combination of an ionomer and certain additives, which are used at unique levels such that ARF produced from resin compositions containing such additives advantageously have high levels of abrasion and scratch resistance in the presence of oils and seasonings. Additionally, a fabricated container / packaging product comprising an ARF layer of the present invention, such as a film liner for a container, can advantageously be thinned from 0% (no thinning) up to 80% in one general embodiment without adversely affecting the shelf life of food products in contact with the ARF. Furthermore, the fabricated container / packaging product of the present invention can be recyclable.

[0007] In one preferred embodiment of the present invention, the film composition comprises, for example: (a) at least one ionomer resin comprising 20% to 100% by weight of ethylene copolymerized with an acid (e.g., (meth)acrylic acid) group, containing selective ions of sodium, zinc, iron, magnesium, and having improved abrasion resistance, scratch resistance, chemical resistance, and resistance to oil, salt, and seasonings, and in one typical embodiment having a selective neutralized acid level of >5%, a selective free acid level of >7%, and a selective total acid level of >13%; (b) 0.5% to 5% by weight of at least one anti-slip additive in the form of a masterbatch material made from an ethylene (meth)acrylic acid copolymer, the at least one anti-slip additive having the following properties: a slow bloom rate of a long chain fatty acid amide or fatty amide; (c) 0.25% to 3% by weight of at least one antiblocking additive in the form of a masterbatch material made from ethylene (meth)acrylic acid copolymer as a carrier resin, the at least one antiblocking additive having the following characteristics: being a nonmigratory material, for example, a nonmigratory organic compound or an inorganic synthetic or natural mineral particle; (d) 0.1% to 3% by weight of at least one chill roll peeling additive in the form of a masterbatch material made from an ethylene (meth)acrylic acid copolymer as a carrier resin, the at least one chill roll peeling additive having the following properties: a fast bloom rate of long chain fatty acid amides and primary amides; and (e) Optionally, one or more other additives different from components (b) to (d).

[0008] In another embodiment, the present invention relates to a monolayer or multilayer film made from the above film composition.

[0009] In yet another embodiment, the present invention relates to a fabricated container packaging product having a multi-layer packaging structure comprising at least one inner ARF layer made from the above-described film composition.

[0010] In other embodiments, the present invention relates to processes for preparing the formulation, the ARF layer, and the multi-layer packaging structure. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view of a can of the present invention showing the different layers of the container wall. [Figure 2] 1 is a black and white image of a perspective front view of a prior art film sheet showing areas of the film sheet before the film sheet is subjected to an abrasion process. [Figure 3] 1 is a black and white image of a perspective front view of a prior art film sheet showing the worn and scratched areas of the film sheet after the film sheet has been subjected to an abrasion process. [Figure 4] 1 is a black and white image of a perspective front view of a film sheet of the present invention showing an area of the film sheet before the film sheet is subjected to an abrasion process. [Figure 5] 1 is a black and white image of a perspective front view of a film sheet of the present invention showing the worn and scratched areas of the film sheet after the film sheet has been subjected to an abrasion process. [Figure 6] 1 is a black and white image of a perspective front view of another prior art film sheet showing worn and scratched areas of the film sheet after the film sheet has been subjected to an abrasion process. [Figure 7] 7 is a black and white image of a perspective front view of another film sheet of the present invention, showing the worn and scratched areas of the film sheet after the film sheet has been subjected to an abrasion process. The film sheet of FIG. 7 can be compared to the film sheet of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] Reference will now be made in detail to embodiments of ARFs made from film compositions comprising ionomeric polymer resins based on copolymers of ethylene and (meth)acrylic acid. While ARFs can be used in food product packaging applications, it should be noted that they are merely exemplary, illustrative implementations of the embodiments disclosed herein. The embodiments are also applicable to other packaging technologies that desire the incorporation of film materials that (1) have high abrasion and scratch resistance, (2) can be thinned while maintaining their properties, (3) are recyclable, and (4) are resistant to oils, grease, and seasonings when present in and around the packaged food product.

[0013] The term "composition" refers to a mixture of materials that comprise the composition, as well as reaction products and decomposition products formed from the materials of the composition.

[0014] The term "recyclability," as used herein with respect to packaging articles containing paper as a recyclable material, refers to a property of the packaging article that allows the article to be processed through a paper recycling and repulping process to recover the paper from the packaging article and convert the recovered paper back into pulp. For example, in one embodiment, the paper recycling and repulping process includes: (1) shredding the paper-containing packaging article; (2) immersing the shredded article in an aqueous solution that breaks down the fibers and separates them into pulp; (3) filtering to separate the pulp from any debris, including plastic film; (4) recovering the separated pulp; and (5) converting the recovered pulp back into recycled paper products. As known to those skilled in the art, in one embodiment, one way to determine the recyclability of paper is by determining the pulp yield, i.e., how much reusable pulp is recovered during the repulping process.

[0015] As used herein, the term "polymer" refers to a polymeric compound prepared by polymerizing monomers, whether of the same or different types. Thus, the generic term "polymer" encompasses (1) the term homopolymer (used to refer to a polymer prepared by polymerizing only one type of monomer, with the understanding that trace amounts of impurities may be incorporated into the polymer structure), and (2) the term copolymer or interpolymer (used to refer to a polymer prepared by polymerizing two or more different monomers, with the understanding that trace amounts of impurities may be incorporated into the polymer structure). Trace amounts of impurities (e.g., catalyst residues) may be incorporated into and / or present within the polymer. The polymer may be a single polymer or a polymer blend.

[0016] The term "interpolymer" refers to a polymer prepared by polymerizing at least two different types of monomers. Thus, the generic term interpolymer includes copolymers and other polymers prepared by polymerizing more than two different types of monomers, such as terpolymers.

[0017] An "ionomer" is a copolymer of ethylene and an ethylenically unsaturated monocarboxylic acid having the carboxylic acid groups partially neutralized by a metal ion, such as sodium or zinc. Ionomers useful herein include those in which sufficient metal ions are present in the ionomer to neutralize 15% to 60% (neutralization rate) of the acid groups in the ionomer. Carboxylic acids include, for example, "(meth)acrylic acid." As used herein, "(meth)acrylic acid" refers to acrylic acid and / or methacrylic acid. Useful ionomers (or "partially neutralized ethylene acid copolymers") include those having, in one embodiment, at least 50% by weight of ethylene units, in another embodiment, 50% to 90% by weight of ethylene units, and in yet another embodiment, 80% to 90% by weight of ethylene units. Useful ionomers also include those having 1% to 20% by weight of acid units.

[0018] As used herein, the terms "comprising," "including," "having," and their derivatives are not intended to exclude the presence of any additional component, step, or procedure, whether specifically disclosed or not. For the avoidance of doubt, all compositions claimed through the use of the term "comprising" may include any additional additive, adjuvant, or compound, whether polymeric or otherwise, unless otherwise stated to the contrary. In contrast, the term "consisting essentially of" excludes from the scope of any succeeding description any other component, step, or procedure, except those that are not essential to operability. The term "consisting of" excludes any component, step, or procedure not specifically delineated or listed.

[0019] As used throughout this specification, the following abbreviations have the following meanings unless the context clearly dictates otherwise: "=" means "equal to," "<" means "less than," ">" means "greater than," "≦" means "less than or equal to," "≧" means "greater than or equal to," "I2" means "melt index for an application weight of 2.16 kilograms at 190 degrees Celsius," g = grams, mg = milligrams, pts = parts by weight, kg = kilogram, "kg / hr" = kilograms per hour, g / cc = grams per cubic centimeter, kg / m 3 = kilograms per cubic meter, g / mol = grams per mole, L = liter, mL = milliliter, g / L = grams per liter, Mw = mass molecular weight, Mn = number molecular weight, Mz = z-average molecular weight, m = meter, μm = micrometer, mm = millimeter, cm = centimeter, min = minute, s = second, mm / s 2= millimeters per second squared, mm / s = millimeters per second, ms = milliseconds, hr = hours, mm / min = millimeters per minute, m / s = meters per second, °C = degrees Celsius, °C / min = degrees Celsius per minute, mPa.s = millipascal-seconds, MPa = megapascals, kPa = kilopascals, Pa.s / m 2 = Pascal-seconds per square meter, N = Newton, cN = centinewton, rpm = revolutions per minute, mm 2 = square millimeters, g / 10min = grams per 10 minutes, J = joules, J / g = joules per gram, % = percent, eq% = equivalent percent, vol% = volume percent, and wt% = weight percent.

[0020] Unless otherwise specified, all percentages, parts, ratios, and other amounts are defined by weight. For example, all percentages set forth herein are weight percentages (wt %) unless otherwise indicated.

[0021] Temperatures are given in degrees Celsius (°C), and "ambient temperature" means 20°C to 25°C unless otherwise specified.

[0022] In a broad embodiment, the present invention relates to a resin formulation or composition useful for preparing food product packaging films, for example, comprising a combination, blend, or mixture of the following: (a) at least one ionomer of an acid copolymer; (b) at least one anti-slip additive (e.g., CONPOL™ 20S1); (c) at least one anti-blocking additive (e.g., CONPOL™ 13B); (d) at least one anti-blocking additive (e.g., CONPOL™ 5R); and (e) optionally, one or more additives different from components (b)-(d).

[0023] In some embodiments, the resin composition described above is advantageously used to make a film product, such as a monolayer film or a multilayer film. In one embodiment, the film product is incorporated into a multilayer structure (i.e., a structure including various different substrate layers) food product packaging container, in which the film product of the present invention is at least one of the substrate layers of the multilayer structure. The film product of the present invention may be a monolayer film or a multilayer film, and at least one layer of the at least one monolayer film or multilayer film includes at least one of the substrate layers of the multilayer structure that makes up the food product packaging container. In one embodiment, the film product of the present invention that makes up one of the substrates of the food product packaging container is a film liner that directly contacts the food product packaged in the food product packaging container.

[0024] Before a film product is made from the resin composition, the resin composition is first processed into pellets. For example, components (a) to (d) and optionally (e) that form the blend are melt-blended (e.g., mixed by melting through an extruder) to produce a melt-blended composition. The melt-blended composition is then conveyed from the extruder (e.g., a twin-screw extruder) through a strand die to a pelletizer to form pellets of the blended composition. Once formed, the pellets are then processed to produce a film product exhibiting the desired abrasion and scratch resistance.

[0025] In some embodiments, the film resin composition may comprise, for example, (a) at least one ionomer resin comprising 20% to 100% by weight of ethylene copolymerized with acid groups, such as (meth)acrylic acid groups, which has several advantages, including beneficial percent acid content, selective ion type, and lower ion concentration limits; (b) at least one anti-slip additive provided as a masterbatch material made from an ethylene (meth)acrylic acid copolymer and an anti-slip additive, wherein the content of the anti-slip additive in the masterbatch is 5% to 25% by weight based on the total concentration of one or more various anti-slip additives used in the masterbatch, for example, in one embodiment, the anti-slip additive may be a combination of CONPOL™ 5B10S1 and CONPOL™ S1, and the concentration of the anti-slip additive may be 10% for CONPOL™ 5B10S1 and 20% for CONPOL™ S1, and the at least one anti-slip additive has the following property: a slow bloom rate of long chain fatty amide or fatty amide; (c) at least one antiblocking additive provided as a masterbatch material made from an ethylene (meth)acrylic acid copolymer and an antiblocking additive, wherein the content of the antiblocking additive in the masterbatch is 3% to 25% by weight based on the total concentration of one or more various antiblocking additives used in the masterbatch; for example, in one embodiment, the antiblocking additive may be a combination of CONPOL™ 5B10S1 and CONPOL™ 20B, wherein the concentration of the antiblocking additive is 5% for CONPOL™ 5B10S1 and 20% for CONPOL™ 20B; and wherein the at least one antiblocking additive has the property of being a non-migratory material comprising a non-migratory organic or inorganic compound, a synthetic mineral, or a naturally occurring mineral particle; (d) at least one chill roll release additive provided as a masterbatch material made from an ethylene (meth)acrylic acid copolymer and a chill roll release additive, wherein the content of the chill roll release additive in the masterbatch is 3% to 10% by weight based on the total concentration of one or more various chill roll release additives used in the masterbatch, for example, in one embodiment, the chill roll release additive may be CONPOL™ 5R, and the concentration of the chill roll release additive may be 5% for CONPOL™ 5R, and the at least one chill roll release additive has the property of being a long chain fatty acid amide and a primary amide with a high bloom rate; (e) optionally, one or more other additives different from additive components (b) to (d); Includes.

[0026] In one general embodiment of the present invention, a film resin composition useful for preparing a film includes, for example, at least one ionomer resin. Examples of ionomer resins, component (a), useful for preparing the film composition of the present invention include, for example, one or more polyolefins having one or more acidic functional groups, where the acidic functional groups are neutralized with metal ions. Examples of the one or more acidic functional groups include, for example, carboxylic acids, maleic anhydride, fumaric acid, and the like, and mixtures thereof. Examples of metal ions include, for example, sodium, zinc, iron, magnesium, and the like, and mixtures thereof. An example of a preferred embodiment of the ionomer resin is ethylene copolymerized with an acid group, such as a (meth)acrylic acid group.

[0027] Illustrative examples of some commercially available ionomer resins useful in preparing the film compositions of the present invention include, for example, SURLYN™ resins (available from The Dow Chemical Company), Primacor™ IO (available from SK Global Chemical Co. Ltd. company), and mixtures thereof.

[0028] The ionomer resin, component (a), used in preparing the film composition can generally be present in the composition in an amount of from 20% to 100% by weight in one embodiment, from 30% to 100% by weight in another embodiment, and from 50% to 100% by weight in yet another embodiment, based on the total amount of components in the film composition. Below the aforementioned general ranges of ionomer resin, the abrasion and scratch resistance of the packaging film in the presence of oils / seasonings may be insufficient to provide the necessary protection for packaging applications.

[0029] In one general embodiment of the present invention, a film composition useful for preparing a film liner includes at least one anti-slip additive, component (b), for example, in the form of a masterbatch material made using an ethylene (meth)acrylic acid copolymer as the carrier resin.

[0030] The anti-slip additive, component (b), is available in pellet form, and multiple pellets are blended with the ionomer resin, component (a), to modify the surface properties of the resulting film article made from the film resin composition. For example, the anti-slip additive can bloom to the film surface over time and be used to change the coefficient of friction (COF) of the surface of a film made from the film composition. In some embodiments, the anti-slip additive can also reduce in-line blocking during film extrusion and offline film blocking during film roll unwinding.

[0031] Examples of anti-slip additives, component (b), useful in preparing the film compositions of the present invention include, for example, long-chain fatty acid amides, fatty amides, and mixtures thereof, which have a slow bloom rate. In a preferred embodiment, the anti-slip additives include, for example, oleyl palmitamide, erucamide, and mixtures thereof.

[0032] Illustrative of some commercially available anti-slip additives, component (b), useful in preparing the film compositions of the present invention include, for example, CONPOL™ (available from The Dow Chemical Company), Ampacet 10090 (available from Ampacet Corp), Crodamide ER™ (available from CRODA), and mixtures thereof.

[0033] The anti-slip additive used in preparing the film composition, component (b), can generally be present in the composition in an amount greater than 0.05 wt. % in one embodiment, greater than 0.05 wt. % to 6 wt. % in another embodiment, 0.1 wt. % to 5 wt. % in yet another embodiment, 0.1 wt. % to 3 wt. % in yet another embodiment, and 0.88 wt. % to 1.5 wt. % in yet another embodiment, based on the total amount of components in the film composition.

[0034] If the amount of anti-slip additive is less than the general range mentioned above, the COF of the film will be too high, resulting in slower packaging production output due to the high COF. Also, if the amount of anti-slip additive is less than the general range mentioned above, the abrasion and scratch resistance of the packaging film in the presence of oil / seasoning may be reduced, which may adversely affect the protection required for packaging applications. If the amount of anti-slip additive is more than the general range mentioned above, the anti-slip additive may plate out, which may cause film curling problems and may reduce the sealing performance of the film.

[0035] In one general embodiment of the present invention, a film composition useful for preparing a film liner includes at least one antiblocking additive, component (c), for example, in the form of a masterbatch material made using an ethylene (meth)acrylic acid copolymer as the carrier resin.

[0036] The anti-blocking additive, component (c), is available in pellet form, and multiple pellets are blended with the ionomer resin, component (a), to modify the surface properties of the resulting film article made from the film composition. For example, the anti-blocking additive can be used to modify the surface of a film made from the film composition to prevent bubble blocking, for example, when the film is produced on a blown film line as an inner layer. The anti-blocking additive also helps reduce the energy required to unwind a film roll. The anti-blocking additive also helps reduce the COF of the film. All of the above beneficial results of using the anti-blocking additive help increase the production output rate of the film.

[0037] Examples of the anti-blocking additive, component (c), useful for preparing the film composition of the present invention include, for example, diatomaceous earth (silicon dioxide), talc (magnesium silicate), synthetic silica (silicon dioxide), calcium carbonate, alumina-silicate ceramic, clay (aluminum silicate), mica (potassium aluminum silicate), stearyl erucamide, zinc stearate, silicone, glycerol monostearate, ethylene bis-stearamide, and mixtures thereof. In a preferred embodiment, the anti-blocking additive includes, for example, silicon dioxide, talc, and mixtures thereof.

[0038] Illustrative of some commercially available antiblocking additives, component (c), useful in preparing the film compositions of the present invention include, for example, CONPOL™ 13B, CONPOL™ 20B, CONPOL™ 5B10S1, and CONPOL™ 20T (all available from The Dow Chemical Company), as well as Crodamide BR (available from CRODA), and Ampacet 10063 (available from Ampacet Corp), and mixtures thereof.

[0039] The anti-blocking additive used in preparing the film composition, component (c), can generally be present in the composition in an amount greater than 0.05 wt. % in one embodiment, greater than 0.05 wt. % to 6 wt. % in another embodiment, greater than 0.1 wt. % to 5 wt. % in yet another embodiment, greater than 0.1 wt. % to 3 wt. % in yet another embodiment, and greater than 0.5 wt. % to 1 wt. % in yet another embodiment, based on the total amount of components in the film composition.

[0040] Amounts of the anti-blocking additive below the general ranges set forth above can make it difficult for line operators to unwind the resulting film, while amounts of the anti-blocking additive above the general ranges set forth above can increase the haze properties of the film and decrease the film's sealing ability.

[0041] In one general embodiment of the present invention, a film composition useful for preparing a film liner includes at least one chill roll release additive, component (d), for example, in the form of a masterbatch material made using an ethylene (meth)acrylic acid copolymer as the carrier resin.

[0042] The chill roll release additive, component (d), is available in pellet form, and multiple pellets are blended with the ionomer resin, component (a), to modify the surface properties of the resulting film article made from the film composition. For example, the chill roll release additive tends to migrate to the surface of the film between the film and the chill roll, and therefore the chill roll release additive can be used to modify the surface of the film made from the film composition to prevent the film from sticking to the chill roll.

[0043] Examples of chill roll release additives, component (d), useful in preparing the film composition of the present invention include, for example, long-chain fatty acid amides and primary amides that have a high bloom rate. In some embodiments, for example, the amides may be saturated or unsaturated and include oleyl (C18) to erucyl (C22) and mixtures thereof. In a preferred embodiment, the chill roll release additive includes, for example, oleamide, behenamide, and mixtures thereof.

[0044] Illustrative of some commercially available chill roll release additives, component (d), useful in preparing the film compositions of the present invention include, for example, CONPOL™ (available from The Dow Chemical Company), Ampacet™ (available from Ampacet Corp.), Crodamide (available from CRODA), and mixtures thereof.

[0045] The chill roll release additive, component (d), used in preparing the film composition may generally be present in the composition in an amount greater than 0.05 wt. % in one embodiment, from 0.05 wt. % to 6 wt. % in another embodiment, from 0.05 wt. % to 5 wt. % in yet another embodiment, from 0.1 wt. % to 2 wt. % in yet another embodiment, and from 0.15 wt. % to 1 wt. % in yet another embodiment, based on the total amount of components in the film composition.

[0046] Below the general ranges of chill roll release additive, the resulting film will stick to the chill roll until the film can break and the line operator will need to stop and restart the line. Above the general ranges of chill roll release additive, further improvement is minimal.

[0047] In another embodiment, the film composition of the present invention can include a wide variety of other optional additives. The additives combined with the composition of the present invention can be formulated to enable the performance of specified functions while maintaining the excellent benefits / properties of the composition. For example, the following additives can be blended into the compounded resin composition to form the film composition of the present invention, including: antioxidants, antifog agents, pigments, colorants, UV stabilizers, UV absorbers, processing aids, fillers, compatibilizers, other ionomer resins different from component (a), other anti-slip additives (migratory and non-migratory anti-slip additives) different from component (b), other anti-blocking additives different from component (c), other chill roll release additives different from component (d), and the like, as well as mixtures thereof.

[0048] When used in a film composition, optional additives can be present in the film composition in an amount generally less than 10 wt.% in one embodiment, less than 5 wt.% in another embodiment, less than 3 wt.% in yet another embodiment, and less than 1 wt.% in yet another embodiment. In other embodiments, optional additives can be added to the film composition in an amount generally ranging from 0 wt.% to less than 10 wt.% in one embodiment, from 0.1 wt.% to less than 10 wt.% in another embodiment, from 0.1 wt.% to less than 5 wt.% in yet another embodiment, from 0.1 wt.% to less than 3 wt.% in yet another embodiment, and from 0.1 wt.% to less than 1 wt.% in yet another embodiment, based on the total amount of components in the film composition.

[0049] In one broad embodiment of the present invention, a process for making a film resin composition includes, for example, mixing or blending the above-described components (a), (b), (c), and (d), as well as any desired optional component (e). Both dry-blending and melt-blending processes (compounding processes) known to those skilled in the art of polymer resin mixing can be used. For example, a dry-blending process, in one typical embodiment, involves mixing all polymer pellets together using either a tumble or ribbon blender or any equivalent dry blender. For example, a compounding (or melt-blending) process, in one typical embodiment, involves melt-mixing components (a), (b), (c), (d), and optionally (e) at a temperature of 80°C to 285°C in a mixing device known to those skilled in the art, such as a twin-screw extruder, a single-screw extruder, a continuous mixer, or a batch mixer, to form a homogeneous melt.

[0050] Some of the advantageous / beneficial properties of film compositions produced according to the aforementioned mixing or compounding processes can include, for example, the ease with which the film composition can be produced, i.e., the ease and more even (uniform or homogeneous) dispersion of the different components (a), (b), (c), (d), and optionally (e) of the composition, as well as improved processability of the composition, i.e., the ease with which the composition can be processed to produce food product packaging films.

[0051] As disclosed herein below, when an ARF is produced using the above composition, the film exhibits specifically improved properties such as one or more of the following: increased abrasion and scratch resistance in the presence of vegetable oils, salt, vinegar, spices, and other seasonings, while maintaining chemical resistance, sealant caulking properties, low heat seal initiation temperature, and high hot tack strength to meet other requirements of the target application.

[0052] It is hypothesized that the improved abrasion / scratch resistance properties in the presence of, but not limited to, vegetable oils, fats, or fatty substances found in foods and seasonings is due to the compositions of the present invention having a proportional increase in total acid content and neutralization rate compared to known films, which has been shown to result in increased chemical or food product resistance, toughness, and stiffness.

[0053] In some embodiments, the present invention relates to producing ARF from the above-described film compositions and pellets. The ARF is useful as an inner layer (or film liner) for incorporation into packaging containers used in food product packaging applications where the ARF layer contacts the food product. The ARF layer of the present invention has a good combination of properties, including high levels of abrasion and scratch resistance in the presence of oils and seasonings. The ARF layer of the present invention can be thinned by up to 80% in one typical embodiment without adversely affecting the shelf life of the food product in contact with the ARF layer, and container packaging products having the ARF layer of the present invention may be recyclable.

[0054] In some embodiments, the above film compositions can be processed into ARF components having an abrasion resistance rating value Y greater than 6.0 according to formula (I) below:

[0055]

number

[0056] Equation (I) can be used to help predict the abrasion resistance of an abraded film, as quantified by Y, based on key physical properties A, B, and C, which can be measured by standard ASTM methods. To develop equation (I), multiple linear regression was performed using software, and the input for the continuous response variable Y was determined by an experimental abrasion resistance evaluation method for each of the comparative examples and inventive examples. The software used was commercially available software, including JMP, a computer program for statistical analysis developed by JMP, a subsidiary of SAS Institute. The abrasion resistance evaluation method is described in detail in the Test Methods section, and the measured values for Y are presented in Table V for each example. The inputs for the categorical response variables A, B, and C are the measured physical properties of the comparative examples and inventive examples, and are also included in Table V. The coefficient of determination value R for equation (I) based on multiple linear regression is 2 (which can range from 0 to 1) is, for example, 0.975.

[0057] In some embodiments, the wear resistance rating value Y of the ARF component can be, for example, 6 or more to 9 in one embodiment, 6 or more to 8 in another embodiment, and 6 or more to 7 in yet another embodiment.

[0058] In one broad embodiment of the present invention, the film composition described above is used to make an ARF, such as a film liner. The film composition can be, for example, a resin formulation or composition that includes a combination, blend, or mixture of the following: (a) at least one ionomer of an acid copolymer, (b) at least one non-slip additive such as CONPOL™ 20S1, (c) at least one anti-blocking additive such as CONPOL™ 13B, (d) at least one chill roll release additive such as CONPOL™ 5R, and (e) optionally, one or more additives different from components (a) through (d).

[0059] The single layer ARF structure includes, for example, a film sheet of any desired length and width, having a thickness of, for example, 5 μm to 380 μm in one typical embodiment, 10 μm to 250 μm in another embodiment, and 10 μm to 100 μm in yet another embodiment.

[0060] In one broad embodiment of the present invention, the process for making the monolayer film includes using any conventional film-forming process, such as, for example, cast film processes, blown film processes, extrusion coating processes, and other processes and equipment known to those skilled in the art of film formation.

[0061] Some of the advantageous / beneficial properties of monolayer films produced according to the above-described process include, for example, improved performance in (1) tear strength in the cross direction (CD) of the film, (2) CD stress at break in the CD of the film using the test method set forth in ASTM D882, (3) MD stress at break in the machine direction (MD) of the film using the test method set forth in ASTM D882, and (4) static and dynamic COF between the sealant layer and the metal surface using the test method set forth in ASTM D1894. Furthermore, the increased total acid percentage and neutralization percentage of the film generally result in improved physical properties. Additionally, the film can advantageously exhibit superior sealing performance, such as improved hot tack, reduced heat seal initiation temperature, and improved caulking.

[0062] When the film compositions of the present invention are converted into monolayer films, the processed films of the present invention exhibit tear strength properties in the CD of the film of at least 1 gf / mil (0.4 N / mm) in one typical embodiment, at least 5 gf / mil (1.9 N / mm) in another embodiment, at least 10 gf / mil (3.9 N / mm) in yet another embodiment, and at least 15 gf / mil (5.8 N / mm) in yet another embodiment. In some embodiments, the processed films of the present invention exhibit CD tear strength properties, as measured by the test method set forth in ASTM D 1922, of from 1 gf / mil (0.4 N / mm) to 200 gf / mil (77 N / mm) in one typical embodiment, from 5 gf / mil (1.9 N / mm) to 150 gf / mil (58 N / mm) in another embodiment, from 10 gf / mil (3.9 N / mm) to 100 gf / mil (39 N / mm) in yet another embodiment, and from 10 gf / mil (3.9 N / mm) to 75 gf / mil (29 N / mm) in yet another embodiment. Values below the above typical ranges result in decreased abrasion resistance of the film, while values above the above typical ranges result in increased abrasion resistance.

[0063] The processed monolayer film also exhibits a CD break stress in the CD of the film of, in one typical embodiment, 7,000 psi (48.3 MPa) or less, in another embodiment, 5,000 psi (34.5 MPa) or less, and in yet another embodiment, 4,000 psi (27.6 MPa) or less. In some embodiments, the film exhibits a CD break stress of, in one typical embodiment, 500 psi (3.4 MPa) to 7,000 psi (48.3 MPa), in another embodiment, 500 psi (3.4 MPa) to 5,000 psi (34.5 MPa), and in yet another embodiment, 500 psi (3.4 MPa) to 4,000 psi (27.6 MPa), as measured by the test method set forth in ASTM D882. Below the typical ranges, the film cannot support tension during downstream processes, such as lamination or packaging converting processes. Above the typical ranges, abrasion resistance is reduced.

[0064] The processed monolayer film also exhibits an MD stress at break in the MD of the film of, in one typical embodiment, 1,000 psi (6.9 MPa) or greater, in another embodiment, 2,000 psi (13.8 MPa) or greater, and in yet another embodiment, 4,700 psi (32.4 MPa) or greater. In some embodiments, the film exhibits an MD stress at break of, in one embodiment, 1,000 psi (6.9 MPa) to 8,000 psi (55.2 MPa), in another embodiment, 2,000 psi (13.8 MPa) to 7,000 psi (48.3 MPa), and in yet another embodiment, 4,700 psi (32.4 MPa) to 6,000 psi (41.4 MPa), as measured by the test method set forth in ASTM D882. Stresses below the above typical ranges result in decreased abrasion resistance of the film, while stresses above the above typical ranges result in increased abrasion resistance.

[0065] Furthermore, the processed film exhibits a static and dynamic sealant-to-metal COF of 1 or less in one typical embodiment, 0.5 or less in another embodiment, and 0.35 or less in yet another embodiment. In some embodiments, the film exhibits a static and dynamic sealant-to-metal COF of 0.05 to 1.0 in one typical embodiment, 0.10 to 0.5 in another embodiment, and 0.10 to 0.35 in yet another embodiment, as measured by the test method set forth in ASTM D1894. Below the typical ranges, the low COF can cause the film to slip uncontrollably as it is pulled through the packaging machine, making film control difficult and reducing packaging efficiency. Above the typical ranges, the high COF can cause the film to stick at different points along the packaging line, similarly reducing packaging efficiency.

[0066] In addition to the monolayer film structure described above, in some embodiments, the ARF can include two or more film layers combined together to form an ARF used in food product packaging applications. For example, the ARF can be made from two, three, five, seven, nine, or more layers. In one embodiment, the ARF includes a two-layer film structure including (1) an outer skin layer and (2) an inner ARF layer coextruded with the outer skin layer. For example, the two-layer film structure can be referred to as an A / B film structure, where the A layer is the outer skin layer and the B layer is the inner ARF layer. The inner ARF layer B contacts the food product packaged in a packaging article such as a can or canister. The outer skin layer A can be made of the same material as the inner ARF layer B, or the two layers A and B can be made of different materials.

[0067] In another embodiment, the ARF may be a three-layer film structure including an outer skin layer, an adhesion-promoting tie layer, and an inner film liner layer. For example, a three-layer ARF may be referred to as an A / B / C film structure, where layer A is the outermost skin layer, layer B is the tie layer, and layer C is the innermost ARF layer. Tie layer B is disposed between outer layer A and ARF layer C. Outer layer A and tie layer B can be made of the same or different material as ARF layer C. Inner ARF layer C contacts a food product packaged in a package containing inner ARF layer C.

[0068] In other embodiments, the multilayer ARF of the present invention can be made with any number of layers greater than three using processes and equipment readily apparent to those skilled in the art of film fabrication, provided that at least one layer of the multilayer film member is an ARF layer made from the film composition of the present invention. For example, the innermost layer (or film liner) of a package can be the ARF layer that contacts the food product packaged within the package. The ARF layer advantageously has an appropriate balance of properties such as abrasion / scratch resistance, thinness, and recyclability.

[0069] For the various multilayer film components described above, the other layers (i.e., layers not counting the inner film liner layer of the present invention) can be formed of any material known in the art for use in multilayer films. Thus, for example, in one embodiment, the outer skin layer A of the two-layer structure described above can be formed, for example, from polyethylene (homopolymer or copolymer), which can be, for example, VLDPE, LDPE, LLDPE, MDPE, HDPE, and mixtures thereof, as well as other polyethylenes known in the art. In another embodiment, for example, the outer skin layer A can be formed from polyethylene (homopolymer or copolymer), a non-polyethylene polymer, such as polypropylene, or a blend of polyethylene and a non-polyethylene polymer.

[0070] Some illustrative examples of commercially available materials useful for the outer skin layer(s) A of the films of the present invention include, for example, DOWLEX™ 2045G, DOWLEX™ NG 5045P, DOWLEX™ 2645G, DOWEX™ 2049G, DOWLEX™ 2038.68G, DMDA-6200 NT 7, DMDA-6400 NT 7, DOWLEX™ GM 8070G, LDPE 611A, AGILITY™ 2000, AGILITY™ 1023, LDPE™ 150E, 310E (all available from The Dow Chemical Company); Enable™ 2703 and Enable™ 3505 (both available from ExxonMobil); Lutenex™ BE0400 (available from LG Chem); and mixtures thereof.

[0071] The various resin polymer materials described above can have various density and melt index properties. For example, in one preferred embodiment, the outer skin layer A can be made of LDPE resin, which in one typical embodiment has a density of 0.915 g / cc to 0.928 g / cc, and in one typical embodiment has a melt index I2 of 0.10 g / 10 min to 30 g / 10 min.

[0072] When used in the multilayer film of the present invention, the thickness of the outer skin layer A can be, for example, 2 μm to 380 μm in one typical embodiment, 7 μm to 260 μm in another embodiment, and 7 μm to 100 μm in yet another embodiment.

[0073] In multilayer film structures, one or more of Layers B as adhesion-promoting tie layers can include, for example, methylene-acrylic acid copolymers, ethylene-vinyl acetate copolymers, and mixtures thereof, such as the NUCREL™ series of copolymers available from The Dow Chemical Company.

[0074] When used in the multilayer film of the present invention, the thickness of the tie layer B can be, for example, 2 μm to 380 μm in one typical embodiment, 7 μm to 260 μm in another embodiment, and 7 μm to 100 μm in yet another embodiment.

[0075] The film compositions for producing the ARF layer C of the present invention are described above in connection with monolayer film structures; i.e., the ARF layer C can be made from a film resin formulation or composition comprising a combination, blend, or mixture of the following: (a) at least one ionomer of an acid copolymer; (b) at least one non-slip additive such as CONPOL™ 20S1; (c) at least one anti-blocking additive such as CONPOL™ 13B; (d) at least one chill roll release additive such as CONPOL™ 5R; and (e) optionally, one or more additives different from components (a)-(d) as desired.

[0076] Once the ARF layer is prepared, it is attached to other layers by coextrusion or lamination, as is well known to those skilled in the art of film making.

[0077] When used in the multilayer film of the present invention, the thickness of the ARF layer is, for example, 2 μm to 380 μm in one typical embodiment, 7 μm to 260 μm in another embodiment, and 7 μm to 100 μm in yet another embodiment.

[0078] The density of the ARF layer is generally between 0.900 g / cc and 0.980 g / cc in one embodiment, between 0.920 g / cc and 0.980 g / cc in another embodiment, and between 0.935 g / cc and 0.980 g / cc in yet another embodiment.

[0079] The melt index of the ARF layer is generally from 0.5 g / 10 min to 50 g / 10 min in one embodiment, from 1 g / 10 min to 30 g / 10 min in another embodiment, and from 2 g / 10 min to 15 g / 10 min in yet another embodiment.

[0080] In one broad embodiment of the present invention, the process for making the multilayer film includes using any conventional film-forming process, such as, for example, cast film processes, blown film processes, extrusion coating processes, and other processes and equipment known to those skilled in the art of film formation.

[0081] As described above, some of the advantageous properties exhibited by ARF products produced from film compositions using the above-described process of the present invention include, for example, (1) the ARF advantageously exhibits high levels of abrasion and scratch resistance in the presence of oil and seasonings, (2) processed container packaging products comprising the ARF of the present invention can be thinned by up to 80% without adversely affecting the shelf life of food products that come into contact with the ARF, and (3) processed container packaging products comprising the ARF of the present invention can be manufactured such that the processed container packaging products can be recyclable.

[0082] In some embodiments, processed container packaging products comprising the ARF of the present invention may be thinned by up to 80% in one embodiment, up to 70% in another embodiment, up to 60% in yet another embodiment, and up to 50% in yet another embodiment. In other embodiments, processed container packaging products comprising the ARF of the present invention may be thinned by 0% (no thinning) to up to 80% in one typical embodiment, 5% to up to 70% in another embodiment, 5% to up to 60% in yet another embodiment, and 5% to up to 50% in yet another embodiment. In some embodiments, for example, processed container packaging products comprising the ARF of the present invention may be thinned by 10% to up to 80% in one embodiment, 10% to up to 70% in another embodiment, 10% to up to 60% in yet another embodiment, and 10% to up to 50% in yet another embodiment. In other embodiments, processed container packaging products comprising the ARF of the present invention may be thinned by 20% to up to 80% in one embodiment, 20% to up to 70% in another embodiment, 20% to up to 60% in yet another embodiment, and 20% to up to 50% in yet another embodiment.

[0083] Without being limited to the following theory, it is theorized that by balancing (1) neutralizing the ionomer and increasing the free acid, (2) selecting the appropriate ion for neutralization, and (3) reducing the COF of the film, a suitable fabricated container packaging product comprising the ARF of the present invention can be made that has the appropriate beneficial properties required for the film to be suitable for use in packaging applications.

[0084] When an entire film product has several layers, and at least one layer is an ARF layer of the present invention, the overall ARF has several advantageous properties. For example, the entire film made from multiple layers exhibits improved properties such as abrasion resistance, scratch resistance, and oil resistance. And, based on the COF of the resulting film product, the film can provide high sealant performance as well as excellent machinability.

[0085] The ARF of the present invention prepared as described above can be used, for example, in food product packaging applications. For example, a packaging container for packaging food products (e.g., a bottle, a bag, a sachet, a pouch such as a pillow pouch, or a can such as a composite can) can include a multi-layer structure including several layers of different materials, such as a combination of paper, gas and / or moisture barrier material, and a polymer resin layer, and at least one of the layers including the resin layer is an ARF layer of the present invention.

[0086] As mentioned above, containers, such as rigid containers for packaging food, may have a multilayer film structure, with the innermost film layer (i.e., "film liner") of the container being an ARF layer. Because the ARF layer typically comes into direct contact with the food product, it is necessary for the ARF layer to have sufficiently high abrasion and scratch resistance to maintain an adequate shelf life of the packaged food product, especially when the food product contains sharp edges that can abrade and scratch the inside of the rigid container during handling and transportation. By way of example, food products that can be packaged in a rigid container having an ARF layer as a film liner of the present invention include, but are not limited to, food products with rough, sharp edges that can abrade or scratch the film liner, such as nuts, grains, trail mixes, and pretzels.

[0087] 1, a multilayer structure including an ARF layer of the present invention is shown. For example, the multilayer structure may be a rigid container package, generally designated by reference numeral 10. Generally, the rigid container package 10 is made of mixed materials, i.e., several layers of a variety of different substrates such as paper, plastic, metal, etc.

[0088] Referring again to FIG. 1 , a multi-substrate structure 10 of the present invention is shown made from various substrates including, for example, a paper layer 11, an LDPE polymer or other polymer resin layer 12, and an ARF layer 13. The resulting multi-substrate structure 10, such as a rigid container having an ARF layer of the present invention, is made from paper and plastic, advantageously rendering the rigid container 10 recyclable. In some embodiments, other substrates (not shown), such as a gas and / or moisture barrier substrate or a different plastic substrate, can be used as one of the layers of the rigid container (multi-layer structure 10). In some embodiments of the present invention, the ARF layer 13 of the present invention exhibits improved abrasion, scratch, oil, and condiment resistance when used as a film liner in a rigid container 10 in which, for example, an abrasive food product is packaged. In the above example, the film liner of the rigid container exhibits improved abrasion, scratch, oil, and condiment resistance while maintaining the required shelf life of the food product, even when the ARF layer 13 of the present invention is thinned to form a thinner layer. [Example]

[0089] The following Inventive Example (Inv. Ex.) and Comparative Example (Comp. Ex.) (collectively "Examples") are presented herein to further illustrate features of the present invention, but are not intended to be construed, either explicitly or implicitly, as limiting the scope of the claims. Inventive Examples are identified by Arabic numerals, and Comparative Examples are designated by alphabetic letters. The following experiments analyzed the performance of embodiments of the compositions described herein. Unless otherwise indicated, all parts and percentages are by weight based on total weight.

[0090] Abbreviation and name Various terms, abbreviations, names, and raw materials used in the examples and comparative examples of the present invention are explained below. "EMAA" stands for ethylene methacrylic acid.

[0091] "EAA" stands for ethylene-acrylic acid.

[0092] "SBR" is a suffix used herein to indicate the addition of "slip (S)", "antiblock (B)", and "chill roll release (R)" additives to the formulation.

[0093] "iBA" stands for isobutyl acrylate.

[0094] raw materials The ingredients / raw materials used in the examples are described below. SURLYN™ is a series of ionomeric polymer resin products available from The Dow Chemical Company.

[0095] CONPOL™ is a series of additives used in the above-mentioned polymer resin products, including, for example, anti-slip additives, anti-blocking additives, and chill roll release additives, available from The Dow Chemical Company.

[0096] Resin formulation for ARF General Procedure for Preparing ARF Formulations Samples of the ARF resin formulations (film compositions) described in Table I were prepared by dry blending various polymer pellets of components (a), (b), (c), (d), and optionally (e) using a dry blender such as either a tumble blender or a ribbon blender.

[0097] [Table 1] Notes for Table II: (1) "Masterbatch 1" is an antiblocking masterbatch with an antiblocking additive and 13% silicon dioxide, and the carrier resin is ethylene-methacrylic acid. (2)"Masterbatch 2" is a chill roll release masterbatch containing 5% Amide 1 where the carrier resin is ethylene-methacrylic acid. (3) "Masterbatch 3" is a slip masterbatch containing 20% Amide 2 where the carrier resin is ethylene-methacrylic acid.

[0098] film General procedure for preparing ARF After preparing samples of the resin formulations (film compositions) listed in Table I, various ARF samples listed in Table II were manufactured using the formulations listed in Table I. The film compositions were processed into ARF specimens according to the following general procedure.

[0099] The ARF samples used in the examples were cast films, and the ARF was manufactured using a cast film process. All ARF samples had a monolayer film structure. The total thickness of each sample film was 50.8 μm.

[0100] The film samples were cast using a laboratory scale cast film line manufactured by COLLIN and equipped with a single 30 mm extruder. The film production parameters / conditions were as follows: (1) Gauge = 2 mil (50.8 μm) (2) Die gap = 20 mils (0.508 mm) (3) Die size = 10 inches (250 mm) (4) Air gap = 0.75 inches (19.05 mm) (4) Screw speed = 42 rpm (5) Melt pressure = 35 MPa (6) Output = 5 kg / hour (7) Line speed = 0.112 m / s (8) Drawdown ratio = 10:1 (9) Cooling roll temperature = 18°C (10) Film width after inline slitting = 9 inches (228.6 mm) (11) Melting temperature = 203°C (12) The extruder temperature profile for the various zones was as set forth in the following table.

[0101] [Table 2]

[0102] Test Method Transverse and machine direction average breaking stress Generally, the mean stress-at-break test is performed according to the procedure described in ASTM D882. While the film is pulled under uniaxial tension at a strain rate of 20 inches / minute (8.47 mm / second), a tensile force-displacement curve is measured with the machine direction or transverse direction of the film parallel to the direction of displacement. A stress-strain curve is calculated from the measured force-displacement curve, and the stress at the point where the film breaks (breaks) is taken as the break stress. More specifically, the following method is used to determine the tensile properties of thin plastic sheets according to the procedure described in ASTM D882.

[0103] Tensile testing is used to measure the properties of films when tested under uniaxial stretching. The films to be tested are conditioned at 23°C (+ / - 2°C) and 50% RH + / - 10% according to ASTM standards for at least 40 hours after film production. The standard test conditions are 23°C (+ / - 2°C) and 50% RH + / - 10% according to the procedure described in ASTM D882.

[0104] Tensile test strips are cut from the sheet in the machine direction (MD) and cross direction (CD), if applicable. The cut strips are 1 inch (25.4 mm) wide by approximately 8 inches (203.2 mm) long. For standard tensile testing, the test strip sample is loaded into a tensile test frame using line grip jaws (flat rubber on one side of the jaw, line grip on the other) set at a gauge length (distance from line grip to line grip) of 2 inches (50.8 mm). The test sample is then strained at a crosshead speed of 20 inches / minute (8.47 mm / second). From the resulting load-displacement curve, the yield strength and yield strain, tensile strength and tensile strength at break, strain at break, and energy to break can be determined. Strain is calculated using the crosshead extension divided by the original gauge length (2 inches) (50.8 mm). Stress is reported as engineering stress or nominal stress and is the load divided by the original cross-sectional area.

[0105] Average normalized Elmendorf tear strength in the transverse direction The force (grams) required to propagate a tear across a film specimen is measured using a modified Pro-Tear Electronic Elmendorf Tear Tester. Acting by gravity, the pendulum swings through an arc, tearing the specimen from a pre-cut slit. The tear propagates in the transverse direction.

[0106] The Elmendorf tear test uses an Elmendorf-type tear tester to determine the average force to propagate a tear through a specified length of plastic film or non-rigid sheet after the tear has been initiated.

[0107] The film is conditioned for at least 40 hours after film production at 23°C (+ / - 2°C) and 50% RH (+ / - 10%) according to ASTM standards. Standard test conditions are 23°C (+ / - 2°C) and 50% RH (+ / - 10%) according to ASTM standards.

[0108] The force (grams) required to propagate a tear across a film or sheeting specimen is measured using a precisely calibrated pendulum device. Acting on gravity, the pendulum swings through an arc, tearing the specimen from a pre-cut slit. The specimen is held on one side by the pendulum and on the other side by a fixture. The energy loss by the pendulum is indicated by a pointer or by an electronic balance. The balance reading is a function of the force required to tear the specimen. The specimens used are "constant radius geometry" as specified in D1922. Tests are typically performed on specimens cut from both the MD and CD directions. Prior to testing, the specimen thickness is measured at the center of the specimen. A total of 15 specimens per direction (MD and CD) are tested, and the average tear strength is reported. Specimens torn at angles greater than 60° from the vertical are described as "diagonal" tears; such tears should be noted, but the strength value is included in the average strength calculation.

[0109] Static (dynamic) friction coefficient (sealant to metal) Generally, static and dynamic coefficient of friction tests are based on the procedure set forth in ASTM D1894. A tensile frame with a COF attachment is used to generate data. A plastic film is secured to a flat surface and placed in contact with a flat, weighted metal surface. The metal strip is displaced at a constant rate across the surface of the plastic film, and the force required to displace the metal strip is used to calculate the static and dynamic coefficient of friction. Data reported are average static and dynamic energy. Testing is performed only at 23°C. More specifically, the following method is used to determine the static and dynamic coefficient of friction of plastic films and sheeting according to the procedure set forth in ASTM 1894.

[0110] The test described in ASTM D 1894 is used to measure the static and dynamic coefficient of friction of plastic films / sheets. The coefficient of friction (COF) can be tested for different surface pairs: film to film (inside-inside, outside-outside, or inside-outside) or film to metal (inside-metal or outside-metal).

[0111] The film samples to be tested are conditioned for at least 40 hours in an environment of 23°C (+ / - 2°C) and 50% RH (+ / - 10%) according to ASTM standards. The standard test conditions are 23°C (+ / - 2°C) and 50% RH (+ / - 10%) according to ASTM standards.

[0112] The test is performed using an INSTRON 5564 Universal Testing Machine. A specimen of the film sample is cut to 3 inches by 6 inches (76.2 mm by 152.4 mm) and an AB-type sled measuring 2.5 inches by 2.5 inches (63.5 mm by 63.5 mm) square and weighing 195 g is used. The sample is wrapped snugly around the sled, with the machine direction (MD) aligned parallel to the direction of travel. This is aided by the use of double-sided tape pre-attached to the top surface of the sled. Ensure that the film surface being tested is wrinkle-free. A COF measurement fixture consisting of a rigid plate with a low-friction pulley is attached to the fixed base of the instrument. A metal plate is then placed on the aforementioned rigid plate and used as the plane against which the sled is driven. The crosshead is then driven over a distance of 3 inches (76.2 mm) at a rate of 6 inches per minute (2.54 mm per second). The force at which the sample begins to move (the initial peak in the load-displacement data) is the static force (F S The average load calculated between the 1 / 2 inch (12.7 mm) and 3 inch (76.2 mm) travel is called the dynamic force (F K ) Static COF, μ S is the static force (F S ) to the normal force (=sled weight, W). Similarly, the dynamic COF, μ K is the dynamic force (F K ) to the normal force. Five specimens from the same film roll (sample) are tested. Each specimen is tested once. After testing each of the five specimens, the average test result is reported.

[0113] Total Acid Level The total acid level is the initial weight percent of ethylene acid acid functionality incorporated into the copolymer.

[0114] % Neutralized Acid Ionomers are produced by adding salt to ethylene acid copolymers during the compounding process. The neutralization percentage of the ionomer is determined by the ratio of the mole percentage of salt added to the mole percentage of acid functionality in the ethylene acid copolymer. The weight percent of neutralized acid in the ionomer is determined by the product of the neutralization percentage and the initial weight percent of acid functionality in the ethylene acid copolymer.

[0115] Free Acid Levels The weight percent of free acid is obtained by the difference between the initial weight percent of acid functionality of the ethylene acid copolymer and the weight percent of neutralized acid.

[0116] Average abrasion resistance rating in the presence of oil and seasoning For the purpose of evaluating the abrasion resistance of ARF, monolayer film samples of ARF are subjected to an abrasion procedure using a shaker table process. A cast film process is used to produce monolayer film samples with a thickness of 2 mils (0.0508 mm). To determine the average abrasion resistance rating for each monolayer film sample, each monolayer film sample is first cut into a 210 mm x 297 mm sheet with the machine direction of the cast film parallel to the 297 mm long edge. Three film specimens are cut from each sample film roll. A 5.5 oz (155.9 g) cylindrical can with a lid is used to contain an abrasive food product, which also includes seasonings and oils on the surface of the food product. The abrasive food contents of the cylindrical can are emptied and cleaned. Each sheet sample is rolled into a cylinder and inserted into the emptied and cleaned cylindrical can so that the film lines the inside of the can. The abrasive, seasoned, oily food product is then carefully reinserted into the can to prevent damage to the food product. The cylindrical can lid is replaced and secured to the top of the cylindrical can. The cylindrical can containing the abrasive food product is placed on a shaker table and shaken vertically at ambient temperature at a frequency of 5 Hz and a displacement of 0.7 inches (17.78 mm) for 24 hours. Following the shaker table process, the film is removed from the cylindrical can, washed, and photographed.

[0117] Images of each monolayer film sample were taken before and after the film sample was processed through the abrasion procedure described above. The assembly for obtaining the images of the film samples (for imaging the film to reveal abraded and scratched areas of the film) included an optical camera and a circularly polarized lens in combination with a white backlight for the film and a linearly polarized film to increase contrast in the abraded and scratched areas of the film and reduce glare.

[0118] Referring to FIG. 2, a black-and-white image of a prior art single (monolayer) film sheet is shown, generally designated by reference numeral 20. Film sheet 20 is made using a known ionomer, for example, a copolymer of ethylene and methacrylic acid, such as SURLYN™ available from The Dow Chemical Company. The image of film sheet 20 in FIG. 2 is the film sheet before it is subjected to an abrasion process. In FIG. 2, three regions (areas or sections) of the film sheet are shown, generally indicated by dotted circles 21, 22, and 23 on film sheet 20. In FIG. 2, film sheet 20 does not contain any abrasion in regions 21, 22, and 23. After film sheet 20 is subjected to the abrasion process, an abraded film sheet is formed, as shown in FIG. 3, having various abrasions and scratches present on the surface of the film sheet.

[0119] Referring to Figure 3, a black and white image of a prior art single (monolayer) film sheet (from Figure 2) is shown after the film sheet has been subjected to an abrasion process, indicated generally by reference numeral 30. Referring again to Figure 3, film sheet 30 is shown after abrasion with some abrasion and / or scratches generally located in the abrasion and scratch areas indicated generally by dotted circles 31, 32, and 33 on film sheet 30. The abrasion and / or scratches on film sheet 30 shown in Figure 3 may be indicated by black or white areas, such as those indicated by reference numerals 34, 35, and 36, located within areas 31, 32, and 33, respectively.

[0120] Referring to Figure 4, there is shown a black and white image of a single (monolayer) film sheet of the present invention, generally designated by reference numeral 40, made using a composition comprising an ionomer of the present invention. The image of film sheet 40 in Figure 4 is the film sheet before the film sheet is subjected to an abrasion process. In Figure 4, three regions, generally designated by dotted circles 41, 42, and 43, of film sheet 40 are shown. In Figure 4, film sheet 40 does not contain any abrasion in regions 41 and 42 of film sheet 40. After film sheet 40 is subjected to the abrasion process, an abraded film sheet is formed having various abrasions and scratches present on the surface of the film sheet, as shown in Figure 6.

[0121] Referring to FIG. 5, a black-and-white image of a single (single-layer) film sheet of the present invention is shown after the film sheet (from FIG. 4) has been subjected to an abrasion process, generally designated by reference numeral 50. Referring again to FIG. 5, the abraded film sheet 50 is shown having abrasions and / or scratches. The abrasions and / or scratches in FIG. 5 are generally located within the abrasion and scratch areas generally designated by dotted circles 51, 52, and 53 on the film sheet 50. The abrasions and / or scratches on the film sheet 50 shown in FIG. 5 may be indicated by black or white areas, such as those designated by reference numerals 54, 55, and 56, located within areas 51, 52, and 53, respectively. The abraded film sheet 50 shown in FIG. 5 has less abrasions and / or scratches compared to the abraded film sheet 30 shown in FIG. 3.

[0122] The images shown in Figures 2-5 are prepared to determine the amount of abrasion / scratching that occurs on the surface of the film sheet 5 of the present invention compared to a conventional film after the film is subjected to an abrasion process. The abrasion and scratch areas of the film sheet are also used to evaluate the abrasion resistance of the film.

[0123] Abrasion resistance evaluation method A rating system for determining an abrasion resistance rating Y for each film is used to semi-quantitatively compare the films to one another based on the appearance of abrasion and scratch areas on each film. The following system utilizing formula (II) is used for the abrasion resistance rating Y: Y=m1×A1+m2×A2+m3×A3+m4×A4+m5×A5 Formula (II); (In formula (II), m n is a multiplier that describes the severity of wear for n=1, 2, 3, 4, or 5, and A n is the severity level m n (The rating factor A corresponds to the % of the total area worn having a value of 0.01). Tables II and III show the above rating system and the coefficients A used in formula (II). n and m n Please write down each of the following. n and A n To aid in the determination of m, a 1 cm x 1 cm square grid was superimposed on each film image, and squares that overlapped any areas of wear were outlined to indicate the presence of wear. The area within each outlined square was assigned a value m based on the severity of wear. n The guidelines used for this evaluation are shown in Table III. n To determine the value of each m n The total areas of the outlined squares corresponding to the were summed and divided by the total area of the image.

[0124] [Table 3]

[0125] [Table 4]

[0126] Test results The results for the properties of each film composition tested are listed in Table IV.

[0127] [Table 5] Notes for Table IV: * "NC" stands for "not calculated" since this composition is a blend of terpolymer resin and ionomer 3. ** "NC" stands for "not calculated" since the base resin is a terpolymer resin containing 10% total acid and 10% iBA. *** "NC" stands for "not calculated" since this composition is a blend of terpolymer resin and ionomer 8. (1) "iBA" stands for "isobutyl acrylate." This composition is not an ionomer.

[0128] The properties and performance results of each ARF tested are listed in Table V.

[0129] [Table 6] Notes for Table V: (1) "SBR" indicates the addition of anti-slip, anti-blocking, and chill roll release additives. (2) The terpolymer resin is not an ionomer. (3) Terpolymers are not ionomers, so "NA" stands for "not applicable."

[0130] Discussion of results As shown in Table II, the ARF of Inventive Example 2 has good properties and good performance. For example, the abrasion resistance rating (Y) is one of the useful performance indicators. The higher the Y, the better the performance. As shown in Table II, Inventive Example 2 has the highest Y, which indicates that Inventive Example 2 has the highest abrasion and resistance performance in the presence of oil / fat and seasonings compared to the other comparative examples. Other physical properties of the film are correlated to Y based on formula (I). The relationship defined by a linear equation shows the importance of each physical property value to the abrasion resistance rating.

[0131] The abrasion resistance rating is an important performance indicator of the film; the higher the abrasion resistance rating, the better the abrasion resistance performance of the film. The abrasion resistance rating was highest for the ARF of Inventive Example 2, indicating that Inventive Example 2 has the highest abrasion and resistance performance in the presence of oil / fat and seasoning compared to the Comparative Example. Other physical properties of the ARF are correlated to the abrasion resistance rating based on Equation (1). The relationship defined by the linear equation, Equation (1), shows the importance of each physical property value to the abrasion resistance rating.

Claims

1. A composition for producing an abrasion-resistant film, comprising: (a) at least one ionomer of an ethylene (meth)acrylic acid copolymer; (b) at least one anti-slip additive; (c) at least one antiblocking additive; (d) at least one chill roll release additive; (e) optionally one or more additives different from components (a) to (d); Including, 1. The composition of claim 1, wherein said at least one ionomer of ethylene (meth)acrylic acid copolymer, component (a), is a sodium-based ionomer of at least one ethylene acid copolymer having (i) a neutralized acid content greater than 7 weight percent, (ii) a free acid content greater than 9 weight percent, and (iii) a total acid content greater than 16 weight percent.

2. 10. The composition of claim 1, wherein the at least one anti-slip additive, component (b), is added to the composition as a masterbatch comprising the anti-slip additive and an ethylene-(meth)acrylic acid carrier resin; the at least one anti-blocking additive, component (c), is added to the composition as a masterbatch comprising the anti-blocking additive and an ethylene-(meth)acrylic acid carrier resin; and the at least one chill roll release additive, component (d), is added to the composition as a masterbatch comprising the chill roll release additive and an ethylene-(meth)acrylic acid carrier resin.

3. 10. The composition of claim 1, wherein the at least one anti-slip additive, component (b), is an oleyl palmitamide additive; the at least one anti-blocking additive, component (c), is a silicon dioxide additive; and the at least one chill roll release additive, component (d), is a behenamide additive.

4. The composition comprises a compound of the following formula (I): [Equation 1] 10. The composition of claim 1, which is fabricated into a film member having an abrasion resistance rating value Y greater than 6.0 according to the formula: where Y is an abrasion resistance rating greater than 6.0, A is the average tensile stress at break in the transverse direction of said film member, B is the average tensile stress at break in the machine direction of said film member, and C is the average normalized Elmendorf tear in the transverse direction of said film member.

5. 10. The composition of claim 1, wherein the concentration of the at least one acid copolymer ionomer, component (a), of the composition is from 20 weight percent to 100 weight percent; the concentration of the at least one non-slip additive, component (b), of the composition is greater than 0.05 weight percent; the concentration of the at least one anti-blocking additive, component (b), of the composition is greater than 0.05 weight percent; and the concentration of the at least one chill roll release additive, component (d), of the composition is greater than 0.05 weight percent.

6. 10. The composition of claim 1, wherein the composition, when processed into a film, provides a film exhibiting one or more of the following properties: a tear strength in the CD of 0.4 N / mm or greater; a CD break stress in the CD of 48.3 MPa or less and a MD break stress in the MD of 6.9 MPa or greater, using the test method set forth in ASTM D882; and static and dynamic coefficients of friction between the sealant and metal of 0.35 or less, using the test method set forth in ASTM D1894.

7. 1. A process for producing a composition for producing a film, comprising: (a) at least one acid copolymer ionomer; (b) at least one non-slip additive; (c) at least one anti-blocking additive; (d) at least one chill roll release additive; and (e) optionally one or more additives different from components (a)-(d). A process comprising mixing

8. 10. An abrasion-resistant film comprising at least one monolayer film or at least one multilayer film, wherein the at least one monolayer film or the at least one multilayer film comprises at least one layer comprising a film made from the film composition of claim 1.

9. 10. The film of claim 8, wherein the film exhibits at least one or more of the following properties: a tear strength in the CD of 0.4 N / mm or greater; a CD break stress in the CD of 48.3 MPa or less and a CD break stress in the MD of 6.9 MPa or greater, using the test method set forth in ASTM D882; and a static and dynamic coefficient of friction between the sealant and metal of 0.35 or less, using the test method set forth in ASTM D1894.

10. The process comprises: (I) (a) at least one ionomer of an acid copolymer; (b) at least one non-slip additive; (c) at least one anti-blocking additive; and (d) at least one chill roll release additive. (e) optionally one or more additives different from components (a) to (d); and mixing the (II) forming at least one monolayer film or at least one multilayer film from the film mixture of step (I); 9. The process for producing a film of claim 8, comprising:

11. 10. An article or package comprising an article or package made from the film of claim 8.

12. 12. The article or package of claim 11, wherein the article or package is a food product packaging container comprising a multi-layer structure, the multi-layer structure comprising at least one layer comprising a film made from the film composition of claim 1, the film having (i) sufficient abrasion and scratch resistance and (ii) sufficient resistance to oils and seasonings to avoid environmental stress cracking such that the film liner can be in contact with abrasive, seasoned, oily food products without adversely affecting the abrasion and scratch resistance of the film liner.

Images