Heat seal compositions

Abstract

Embodiments of the present disclosure are directed towards heat seal compositions including an ethylene methyl acrylate copolymer, ethylene acrylic acid copolymer, a base, and water.

Description

HEAT SEAL COMPOSITIONSField of Disclosure

[0001] Embodiments of the present disclosure are directed towards heat seal compositions.Background

[0002] Heat seal compositions can be utilized to adhere two substrates together for various end use applications. For instance, heat seal compositions can be exposed to a seal initiation temperature to adhere two substrates together. There exists a continuing need for new and / or improved heat seal compositions and / or heat seal substrates.Summary

[0003] The present disclosure provides various embodiments, including the following. In some embodiments, the present disclosure relates to a heat seal composition including an ethylene methyl acrylate copolymer; an ionomer of ethylene methacrylic acid copolymer; a base; and water.

[0004] The above summary of the present disclosure is not intended to describe each disclosed embodiment or every implementation of the present disclosure. The description that follows more particularly exemplifies illustrative embodiments. In several places throughout the application, guidance is provided through lists of examples, which examples can be used in various combinations. In each instance, the recited list serves only as a representative group and should not be interpreted as an exclusive list.Detailed Description

[0005] Heat seal compositions are disclosed herein. The heat seal compositions disclosed herein can advantageously be utilized to provide an improved heat seal bond strength, i.e., an increased heat seal bond strength, as compared to other heat seal compositions. An increased heat seal bond strength is desirable for a number of applications, such as medical packaging, food packaging and industrial applications, for instance.

[0006] The heat seal compositions disclosed herein can provide desirable adhesion for a number of different substrates. Additionally, the heat seal compositions disclosed herein can provide water resistance and a low seal initiation temperature.

[0007] The heat seal compositions disclosed herein include an ethylene methyl acrylate copolymer. The ethylene methyl acrylate copolymer includes compositional units derived from monomers, i.e., ethylene and methyl acrylate.

[0008] Embodiments provide that the ethylene methyl acrylate copolymer can have from 10 to 40 weight percent of constitutional units derived from methyl acrylate based upon a total weight of constitutional units derived from methyl acrylate and ethylene. All individual values and subranges from 10 to 40 weight percent are included; for example, the ethylene methyl acrylate copolymer can have from a lower limit of 10, 15, or 20 weight percent of constitutional units derived from methyl acrylate to an upper limit of 40, 35, or 30 weight percent of constitutional units derived from methyl acrylate based upon the total weight of constitutional units derived from methyl acrylate and ethylene.

[0009] Embodiments provide that the ethylene methyl acrylate copolymer can have from 60 to 90 weight percent of constitutional units derived from ethylene based upon a total weight of constitutional units derived from methyl acrylate and ethylene. All individual values and subranges from 60 to 90 weight percent are included; for example, the ethylene methyl acrylate copolymer can have from a lower limit of 60, 65, or 70 weight percent of constitutional units derived from ethylene to an upper limit of 90, 85, or 80 weight percent of constitutional units derived from ethylene based upon the total weight of constitutional units derived from methyl acrylate and ethylene.

[0010] The ethylene methyl acrylate copolymer can be prepared using known equipment, reaction conditions, and reaction components. The ethylene methyl acrylate copolymer can be obtained commercially. A commercial example of the ethylene methyl acrylate copolymer is ELVALOY AC 12024S from The Dow Chemical Company, among other ethylene methyl acrylate copolymers.

[0011] Embodiments provide that the ethylene methyl acrylate copolymer can have a melt index (I2) from 2 g / 10min to 400 g / 10min. All individual values and subranges from 5 to 35 g / 1 Omin are included; for example, the ethylene methyl acrylate copolymer can have an I2 from a lower limit of 2, 3, 5, 10, or 15 g / 1 Omin to an upper limit of 400, 300, 200, 100, 75, 50, 35, 30, or 25 g / 1 Omin. Melt index (I2) can be determined according to ASTM D1238.

[0012] Embodiments provide that the ethylene methyl acrylate copolymer can have a density from 0.900 g / cm3to 0.990 g / cm3. All individual values and subranges from 0.900 g / cm3to 0.990 g / cm3are included; for example, the ethylene methyl acrylate copolymercan have a density from a lower limit of 0.900, 0.910, 0.920, or 0.930 g / cm3to an upper limit of 0.990, 0.980, 0.970, or 0.960 g / cm3. Density can be determined according to ASTM D792.

[0013] Embodiments provide that the ethylene methyl acrylate copolymer can have a peak melting point (DSC) from 70 to 95 °C. All individual values and subranges from 70 to 95 °C are included; for example, the ethylene methyl acrylate copolymer can have a peak melting point from a lower limit of 70, 75, or 80 °C to an upper limit of 95, 93, or 90 °C. Peak melting point can be determined according to ASTM D3418.

[0014] The heat seal compositions disclosed herein can include The term "ionomer" as used herein refers to a polymer, e.g., a copolymer, comprising ionic groups that are carboxylate salts, such as ammonium carboxylates, alkali metal carboxylate salts, alkaline earth metal carboxylate salts, transition metal carboxylate salts, and / or combinations of such carboxylate salts. As defined herein, such polymers are typically prepared by partially or fully neutralizing, e.g., by reaction with a base, the carboxylic acid groups of a precursor or parent polymer, wherein the precursor or parent polymer is an acid copolymer. An example of an ionomer as used herein is a sodium ionomer, such as a copolymer of ethylene and methacrylic acid, wherein all or a portion of the carboxylic acid groups of the copolymerized methacrylic acid units are in the form of sodium carboxylate groups. An example of a mixed metal ionomer as used herein is a zinc / sodium ionomer (or zinc / sodium neutralized mixed ionomer), such as a copolymer of ethylene and methacrylic acid, wherein all or part of the carboxylic acid groups of the copolymerized methacrylic acid units are in the form of zinc and sodium carboxylates. One or more embodiments provide that the ionomer of ethylene methacrylic acid copolymer is a sodium ionomer of ethylene methacrylic acid copolymer.

[0015] Embodiments provide that the ionomer of ethylene methacrylic acid copolymer can have from 75 to 90 weight percent of constitutional units derived from ethylene based upon a total weight of constitutional units derived from ethylene and methacrylic acid. All individual values and subranges from 75 to 90 weight percent are included; for example, the ionomer of ethylene methacrylic acid copolymer can have from a lower limit of 75 or 80 weight percent of constitutional units derived from ethylene to an upper limit of 85 or 90 weight percent of constitutional units derived from ethylene based upon the total weight of constitutional units derived from ethylene and methacrylic acid.

[0016] Embodiments provide that the ionomer of ethylene methacrylic acid copolymer can have from 10 to 25 weight percent of constitutional units derived from methacrylicacid based upon a total weight of constitutional units derived from ethylene and methacrylic acid. All individual values and subranges from 10 to 25 weight percent are included; for example, the alkali metal ionomer of ethylene methacrylic acid copolymer can have from a lower limit of 10 or 15 weight percent of constitutional units derived from methacrylic acid to an upper limit of 20, or 25 weight percent of constitutional units derived from methacrylic acid based upon the total weight of constitutional units derived from ethylene and methacrylic acid.

[0017] The ionomer of ethylene methacrylic acid copolymer can be prepared using known equipment, reaction conditions, and reaction components. The ionomer of ethylene methacrylic acid copolymer can be obtained commercially. The ionomer of ethylene methacrylic acid copolymer can be prepared by in-situ neutralization during aqueous dispersion preparation.

[0018] Embodiments provide that the ionomer of ethylene methacrylic acid copolymer can have a melt index (I2) from 2 g / 10min to 400 g / 10min. All individual values and subranges from 2 to 400 g / 10min are included; for example, the ionomer of ethylene methacrylic acid copolymer can have an I2 from a lower limit of 2, 3, 5, 10, 25, 35, or 50 g / 1 Omin to an upper limit of 400, 300, 200, 150, or 100 g / 1 Omin. Melt index (I2) can be determined according to ASTM D1238.

[0019] Embodiments provide that the ionomer of ethylene methacrylic acid copolymer can have a density from 0.900 g / cm3to 0.990 g / cm3. All individual values and subranges from 0.900 g / cm3to 0.990 g / cm3are included; for example, the ionomer of ethylene methacrylic acid copolymer can have a density from a lower limit of 0.900, 0.910, 0.920, or 0.930 g / cm3to an upper limit of 0.990, 0.980, 0.970, or 0.960 g / cm3. Density can be determined according to ASTM D792.

[0020] Embodiments provide that the ionomer of ethylene methacrylic acid copolymer can have a peak melting point (DSC) from 50 to 100 °C. All individual values and subranges from 50 to 100 °C are included; for example, the alkali metal ionomer of ethylene methacrylic acid copolymer can have a peak melting point from a lower limit of 50, 60, 70, 75, or 80 °C to an upper limit of 100, 95, 93, or 90 °C. Melting point can be determined according to ASTM D3418.

[0021] The heat seal compositions disclosed herein include a base. The base can be an inorganic base, an organic base, or a combination thereof. Examples of the base include sodium hydroxide, potassium hydroxide, ammonium hydroxide, calciumhydroxide, dimethylethanolamine, and combinations thereof. One or more embodiments provide that the base is an inorganic base. One or more embodiments provide that the base is ammonium hydroxide.

[0022] The base can be utilized to provide that the heat seal composition has a pH from 8.0 to 11 .0. All individual values and subranges from 8.0 to 1 1 .0 are included; for example, the base can be utilized to provide that the heat seal composition has a pH from a lower limit of 8.0, 8.5, or 9.0 to an upper limit of 11 .0, 10.5, or 10.0. pH can be determined according to ASTM E70-19.

[0023] The heat seal compositions, which may be referred to as aqueous heat seal compositions, in contrast to solvent-based compositions. The heat seal compositions disclosed herein include water. As discussed further, different amounts of water can be utilized for various applications.

[0024] The heat seal compositions disclosed herein can include a tackifier. The tackifier can be a resin. Examples of the tackifier include petroleum-based tackifiers, terpene-based tackifiers, phenol-based tackifiers, ketone-based tackifiers, and the like including rosin-based tackifiers and rosin derivative tackifiers.

[0025] Examples of rosin-based tackifiers include a rosin such as gum rosin, wood rosin, tall oil rosin, a stabilized rosin (for example, a stabilized rosin obtained by disproportionating or hydrogenating the rosin), a polymerized rosin (for example, rosin multimers, typically dimers), modified rosins, e.g., unsaturated acid-modified rosin modified with an unsaturated acid such as maleic acid, fumaric acid, (meth) acrylic acid, etc. Examples of the rosin derivative tackifiers include esterified, including partially esterified, products of the rosin-based tackifiers (for example, rosin esters such as stabilized rosin ester and polymerized rosin ester), and phenol-modified products of the rosin-based resin (phenol-modified rosin), and esterified products thereof (phenol- modified rosin ester) and the like. Examples of the petroleum-based tackifiers include aliphatic petroleum resins, aromatic petroleum resins, copolymerized petroleum resins, alicyclic petroleum resins, and hydrides thereof. Examples of the terpene tackifiers include a-pinene resin, p-pinene resin, aromatic modified terpene resin, terpene phenol resin, and the like. Examples of the ketone-based tackifiers include ketone-based resins obtained by condensation of ketones (for example, aliphatic ketones such as methyl ethyl ketone, methyl isobutyl ketone, and acetophenone; alicyclic ketones such as cyclohexanone and methylcyclohexanone) and formaldehyde.

[0026] Embodiments provide that the ethylene methyl acrylate copolymer is 10 to 25 wt% of the heat seal composition based upon a total weight of the heat seal composition. All individual values and subranges from 10 to 25 wt% are included; for example, the ethylene methyl acrylate copolymer can be from a lower limit of 10, 12, or 15 wt% to an upper limit of 25, 22, or 20 wt% of the heat seal composition based upon the total weight of the heat seal composition.

[0027] Embodiments provide that the ionomer of ethylene methacrylic acid copolymer is 3 to 15 wt% of the heat seal composition based upon a total weight of the heat seal composition. All individual values and subranges from 3 to 15 wt% are included; for example, the ionomer of ethylene methacrylic acid copolymer can be from a lower limit of 3, 4, or 5 wt% to an upper limit of 15, 12, or 10 wt% of the heat seal composition based upon the total weight of the heat seal composition.

[0028] Embodiments provide that the base is 1 to 5 wt% of the heat seal composition based upon a total weight of the heat seal composition. All individual values and subranges from 1 to 5 wt% are included; for example, the base can be from a lower limit of 1 , 1 .5, or 2 wt% to an upper limit of 5, 4.5 or 4 wt% of the heat seal composition based upon the total weight of the heat seal composition.

[0029] Embodiments provide that the water is 35 to 90 wt% of the heat seal composition based upon a total weight of the heat seal composition. All individual values and subranges from 35 to 90 wt% are included; for example, the water can be from a lower limit of 35, 45, 55, or 60 wt% to an upper limit of 90, 85, 84, or 80 wt% of the heat seal composition based upon the total weight of the heat seal composition.

[0030] Embodiments provide that the tackifier, when utilized, is 1 to 15 wt% of the heat seal composition based upon a total weight of the heat seal composition. All individual values and subranges from 1 to 15 wt% are included; for example, the tackifier can be from a lower limit of 1 wt% to an upper limit of 15, 10, or 5 wt% of the heat seal composition based upon the total weight of the heat seal composition.

[0031] In some embodiments, the heat seal compositions of the present disclosure can include one or more additives including but not limited to, for example, catalysts plasticizers, rheology modifiers, adhesion promoters, antioxidants, fillers, colorants, surfactants, and combinations of two or more thereof. Different amounts of the one or more additives can be utilized for various applications.

[0032] As mentioned, the heat seal compositions disclosed herein can provide desirable adhesion for a number of different substrates. Examples of substrates includepolymeric films. Examples of polymeric films include polyethylene films, polypropylene films, polystyrene films, and polyvinyl chloride films. The substrate may be laminated, e.g., an aluminum laminated film.

[0033] One or more embodiments provide that a heat seal article can be made by utilizing a first substrate and a second substrate, with a heat seal coating therebetween. Embodiments provide that the heat seal coating is made by removing volatile components, e.g., water, from the heat seal composition, e.g. drying, and exposing the dried composition, as disclosed herein, to a seal initiation temperature. Known equipment, such as an oven, a Meyer bar, and / or a heat sealer, and components can be utilized to make the heat seal article. Heat sealing is a well-known process.

[0034] Embodiments provide that the heat seal composition, as disclosed herein, can be applied to a substrate, e.g., the first substrate, and then that substrate can be heat sealed to a second substrate. One or more embodiments provide that the first substrate and the second substrate are different film materials; for example, the first substrate can be an aluminum laminated film and the second substrate can be a polymeric film. One or more embodiments provide that the first substrate and the second substrate are a same film material.

[0035] Embodiments provide that various seal initiation temperatures can be utilized for different applications. Embodiments provide that the seal initiation temperature can be from 70 °C to 200 °C. All individual values and subranges from 70 °C to 200 °C are included; for example, the seal initiation temperature can be from a lower limit of 70, 75, 80, 85, or 90 °C to an upper limit of 200,195, 190, 185, or 180 °C.

[0036] Advantageously, the heat seal composition, as disclosed herein, can provide an improved, i.e., greater, heat seal bond strength at various seal initiation temperatures as compared to other compositions. An increased heat seal bond strength is desirable for a number of applications, such as medical packaging, food packaging and industrial applications, for instance.

[0037] Advantageously, the heat seal composition, as disclosed herein, can provide an improved, i.e., greater, heat seal bond strength for a number of materials. For instance, one or more embodiments provide that the heat seal composition can provide an improved, i.e., greater, heat seal bond strength when utilizing a HDPE film. As mentioned, an increased heat seal bond strength is desirable for a number of applications, such as medical packaging, food packaging and industrial applications, for instance.

[0038] Additionally, the heat seal compositions disclosed herein can provide water resistance, e.g., as evidenced by a Water Immersion test value of Pass. Water resistance is desirable for a number of applications.EXAMPLES

[0039] In the Examples, various terms and designations for materials are used including, for instance, the following:

[0040] Ethylene methyl acrylate copolymer (24 wt% methyl acrylate; melt index (I2) 20 g / 1 Omin; density 0.944 g / cm3; peak melting point 88 °C; ELVALOY AC 12024S, obtained from The Dow Chemical Company);

[0041] Ionomer of ethylene methacrylic acid copolymer (melt index (I2) 70 g / 1 Omin, obtained from The Dow Chemical Company);

[0042] Tackifier (partially esterified rosin; DYMEREX 9604; obtained from Eastman);

[0043] Base 1 (28 wt% Ammonia in water);

[0044] Base 2 (dimethylethanolamine);

[0045] Ethylene octene copolymer (ENGAGE 8407, melt index (I2) 30 g / 1 Omin; obtained from The Dow Chemical Company);

[0046] Ethylene vinyl acetate copolymer (ELVAX 2010W, melt index (I2) 400 g / 1 Omin; obtained from The Dow Chemical Company);

[0047] Ethylene methacrylic acid copolymer (NUCREL 960, melt index (I2) 60 g / 1 Omin; obtained from The Dow Chemical Company);

[0048] Ethylene acid copolymer (PRIMACOR 5980i, melt index (I2) 300 g / 1 Omin; obtained from SK Global);

[0049] Example 1 , a heat seal composition, was made as follows.

[0050] Ethylene acrylate copolymer, sodium ionomer of ethylene methacrylic acid copolymer, and tackifier were fed into a 25 mm diameter twin screw extruder using a controlled rate feeder; using the feed rate in grams / minute (g / min) as indicated in Table 1 . These components were forwarded through the extruder and melted to form a liquid melt material. The extruder temperature profile was ramped up to the temperature shown in the Polymer Melt Zone column of Table 1 . Water and base (28 wt% aqueous ammonium hydroxide) were mixed together and fed to the extruder at the rates indicated in Table 1 for neutralization at an initial water introduction site. Then dilution water was fed into the extruder at the rates indicated in Table 1 . The extruder temperature profilewas cooled to a temperature below 100 °C near the end of the extruder. The extruder speed (rpm) is reported in Table 1 . At the extruder outlet, a backpressure regulator was used to adjust the pressure inside the extruder barrel to a pressure adapted to reduce steam formation (the pressure was from approximately 2 MPa to 4 MPa). The aqueous dispersion exited from the extruder and was filtered first through a 200 micrometer (pm) filter to provide Example 1 .

[0051] Examples 2-3 and Comparative Example A were made as Example 1 , with any changes reported in Table 1 .Table 1

[0052] Weight percentages of the respective components of Examples 1 -3 and Comparative Example A are reported in Table 2.Table 2

[0053] A number of properties of Examples 1-3 and Comparative Example A are reported in Table 3.

[0054] pH was determined according to ASTM E70-19.

[0055] Viscosity was determined using an RV viscometer at 50 rpm using the appropriate spindle for the given viscosity (RV3).

[0056] V mean was determined using a COULTER LS-230 particle size analyzer (Beckman Coulter Corporation, Fullerton, CA).Table 3

[0057] A number of components were utilized to make heat seal articles.

[0058] Prelaminate (a substrate, 48 gauge polyester film (12 pm) laminated to 0.00035 inch aluminum foil).

[0059] HDPE film (a substrate, high density polyethylene film (50 pm)).

[0060] PET film (a substrate, polyester film, 92 Gauge (23 pm)).

[0061] CPP film (a substrate, cast polypropylene film, 3 mil (75 pm)).

[0062] Comparative Example B (organic solvent based grafted polymer dispersion; DEGACRYL 4147E; obtained from Evonik).

[0063] Comparative Example C (organic solvent based grafted polymer dispersion; DEGACRYL 4294; obtained from Evonik).

[0064] Comparative Example D (ammonia neutralized ethylene acrylic acid copolymer dispersion; ADCOTE 50C12; obtained from the Dow Chemical Company).

[0065] Comparative Example E (formulated ethylene vinyl acetate waterborne heat seal coating; ADCOTE 37JD 1198; obtained from the Dow Chemical Company).

[0066] Heat seal articles were prepared as follows. Examples (Ex.) 1 -3 and Comparative Examples (C. Ex.) A-E were respectively coated on the foil side of the prelaminate utilizing a Meyer bar to provide a coat weight from 3 to 4 Ib / ream. The coatings were then oven dried (90 °C) for 2 minutes for water removal before being heat sealed to a secondary substrate. The coated prelaminates were heat sealed to the secondary substrates utilizing a SENCROP 12ASL / 1 heater sealer at 162 °C, at 40 psi for 1 second. The upper jaw of the sealer was heated to the indicated temperature and the lower jaw was maintained at approximately 20 °C to 30 °C. Then heat seal bond strength was determined by utilizing an Instron tensile tester with a 200 N loading cell with 1 inch strips of the heat seal articles at a pulling rate of 12 inches / minute and a 0 preset distance. Heat seal bond strength is reported in Table 4.

[0067] Water immersion testing was conducted as follows. Examples (Ex.) 1 -3 and Comparative Examples (C. Ex.) A-E were respectively coated on the foil side of the prelaminate utilizing a Meyer bar to provide a coat weight from 3 to 4 Ib / ream. The coatings were then oven dried (90 °C) for 2 minutes for water removal before being stored at 23 °C and 50% relative humidity for 24 hours. Then, respective 3 inch x 3 inch portions were fully immersed in deionized water for 72 hours at 20 °C. Then, respective 3 inch x 3 inch portions were removed from the water and visually observed for any delamination, adhesion loss, or change in color. A "pass” grade was given if there was no observed delamination, adhesion loss, or change in color. Results are reported in Table 4.Table 4

[0068] The data of Table 6 show that each of Examples 1 -3 provide an improved, i.e., greater, heat seal bond strength utilizing the HDPE film, as compared to each of Comparative Examples A-E. A relatively greater heat seal bond strength utilizing the HDPE film is advantageous for a number of applications.

[0069] The data of T able 6 show that each of Examples 1 -3 provide a Water Immersion test value of Pass.

[0070] Seal initiation temperature testing was performed as follows. Examples 1 - 3 and Comparative Examples B-C were respectively coated on the foil side of the prelaminate utilizing a Meyer bar to provide a coat weight from 3 to 4 Ib / ream. The coatings were then oven dried (90 °C) for 2 minutes for water removal before being heat sealed to a secondary substrate. The coated prelaminates were heat sealed to respective secondary substrates (HDPE film) utilizing a SENCROP 12ASL / 1 heater sealer at various reported seal initiation temperatures, at 40 psi for 1 second. The upper jaw of the sealer was heated to the indicated temperature and the lower jaw was maintained at approximately 20 °C to 30°C. Then heat seal bond strength was determined by utilizing an Instron tensile tester with a 200 N loading cell with 1 inch strips of the heat seal articles at a pulling rate of 12 inches / minute and a 0 preset distance. Heat seal bond strength (an average of the Mean value obtained on three tested strips) is reported in Table 5.Table 5

[0071] The data of Table 5 show that each of Examples 1 -3 provided an improved, i.e., greater, heat seal bond strength at each reported seal initiation temperature as compared to each of Comparative Examples B-C. A relatively greater heat seal bond strength at various seal initiation temperatures is advantageous for a number of applications.

Claims

ClaimsWhat is claimed is:1 . A heat seal composition comprising: an ethylene methyl acrylate copolymer; an ethylene acrylic acid copolymer; a base; and water.

2. The heat seal composition of claim 1 , wherein the ethylene methyl acrylate copolymer has from 10 to 40 weight percent of constitutional units derived from methyl acrylate based upon a total weight of constitutional units derived from methyl acrylate and ethylene.

3. The heat seal composition of any one of claims 1 -2, wherein the ionomer of ethylene methacrylic acid copolymer has from 75 to 90 weight percent of constitutional units derived from ethylene based upon a total weight of constitutional units derived from ethylene and methacrylic acid.

4. The heat seal composition of any one of claims 1 -3, wherein the base is ammonium hydroxide.

5. The heat seal composition of any one of claims 1 -4, wherein the ethylene methyl acrylate copolymer is 10 to 25 wt% of the heat seal composition based upon a total weight of the heat seal composition, the ionomer of ethylene methacrylic acid copolymer is 3 to 15 wt% of the heat seal composition based upon the total weight of the heat seal composition, the base is 1 to 5 wt% of the heat seal composition based upon the total weight of the heat seal composition, and the water is 50 to 90 wt% of the heat seal composition based upon the total weight of the heat seal composition.

6. The heat seal composition of any one of claims 1 -5, comprising a tackifier.

7. The heat seal composition of claim 6, wherein the tackifier is a partially esterified rosin.

8. A heat seal article comprising: a first substrate; a second substrate; and a heat seal coating between the first substrate and the second substrate, wherein the heat seal coating is made by exposing the heat seal composition of any one of claims 1 -7 to a seal initiation temperature.

9. The heat seal article of claim 8, wherein the first substrate is an aluminum laminated film and the second substrate is a polymeric film.

10. The heat seal article of claim 9, wherein the polymeric film is a polyethylene film or a polypropylene film.

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