PACKAGING TRAY WITH CAPPING LAYER

Abstract

The present invention is directed to rigid or semi-rigid trays having a bulk layer comprising a crystalline aromatic polyester and a capping layer which is in direct contact with the bulk layer. The capping layer comprises a copolymer having a first structural repeating unit of ethylene and a second structural repeating unit selected from the following: (i) an acrylate-based moiety: fit) at least 12% by weight relative to the total weight of the copolymer of vinyl acetate; and (iii) an anhydride or carboxylic acid. It has been discovered that the bulk layer and the capping layer of the present invention can be readily co-extruded together and have sufficient bond strength to each other despite their chemical dissimilarity. In some preferred embodiments, the capping layer acts as a heat seal layer and is formulated to heat seal to conventional polyolefin-based lidstock.

Claims

1. A tray comprising: a bulk layer comprising a crystalline aromatic polyester; and a capping layer in direct contact with the bulk layer; wherein the capping layer comprises a copolymer comprising at least a first structural repeating unit of ethylene and a second structural repeating unit selected from the following: i) an acrylate-based moiety; ii) at least 12% by weight relative to the total weight of the copolymer of vinyl acetate; and iii) an anhydride or carboxylic acid.

2. The tray according to claim 1, wherein the crystalline aromatic polyester is selected from the group consisting of polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate; polyethylene-2,6-naphthalate, polytrimethylene-2,6-naphthalate, polybutylene-2,6-naphthalate, polyhexamethylene-2,6-naphthalate, polyethylene isophthalate, polytrimethylene isophthalate, polybutylene isophthalate, polyhexamethylene isophthalate, poly-1,4-cyclohexane-dimethanol terephthalate, and polybutylene adipate terephthalate and derivatives thereof.

3. The tray according to claim 1, wherein the crystalline aromatic polyester is polyethylene terephthalate.

4. The tray according to claim 1, wherein the acrylate-based moiety is selected from the group consisting of butyl acrylate, ethyl acrylate, ethyl methacrylate, methyl acrylate, methyl methacrylate, 2-ethylhexyl acrylate, glycidyl methacrylate, and blends thereof.

5. The tray according to claim 4, wherein the acrylate-based moiety is methyl acrylate.

6. The tray according to claim 5, wherein the methyl acrylate is at least 21% by weight relative to the total weight of the copolymer.

7. The tray according to claim 1, wherein the carboxylic acid is selected from the group consisting of acrylic acid, methacrylic acid, -ethylacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, and endo-cis-bicyclo[2,2,1]-hepto-5-ene-2,3-dicarboxylic acid.

8. The tray according to claim 1, wherein the anhydride is maleic anhydride or a derivative thereof.

9. The tray according to claim 1, wherein the capping layer is a monolayer.

10. The tray according to claim 1, wherein the capping layer is a multilayer film.

11. The tray according to claim 1, wherein the capping layer comprises a copolymer comprising a third structural repeating unit.

12. The tray according to claim 11, wherein the third structural repeating unit is a different structural repeating unit than the second structural repeating unit.

13. The tray according to claim 12, wherein the second structural repeating unit is methyl acrylate and the third structural repeating unit is maleic anhydride.

14. The tray according to claim 13, wherein the methyl acrylate is about 24% by weight relative to the total weight of the copolymer and the maleic anhydride is about 0.1% by weight relative to the total weight of the copolymer.

15. The tray according to claim 11, wherein the second structural repeating unit is vinyl acetate and the third structural repeating unit is maleic anhydride.

16. The tray according to claim 15, wherein the vinyl acetate is at least about 9.5% by weight relative to the total weight of the copolymer and the maleic anhydride is at least about 0.1% by weight relative to the total weight of the copolymer.

17. The tray according to claim 11, wherein the second structural repeating unit is methyl acrylate and the third structural repeating unit is glycidyl methacrylate.

18. The tray according to claim 17, wherein the methyl acrylate is about 24% by weight relative to the total weight of the copolymer and the glycidyl methacrylate is about 8% by weight relative to the total weight of the copolymer.

19. The tray according to claim 1, wherein the bulk layer and the capping layer has a bond strength of at least about 450 grams/inch.

20. The tray according to claim 1, wherein the bulk layer and the capping layer has a bond strength of at least about 1,000 grams/inch.

21. The tray according to claim 1, wherein the bulk layer comprises a crystalline aromatic polyester having between 20% and 40% crystallinity.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Further features and advantages of the present invention will become apparent from the following detailed description, taken in combination with the appended drawings, in which:

[0014] FIG. 1 illustrates a schematic of one embodiment of a tray according to the present invention.

[0015] FIG. 2 illustrates a schematic cross-sectional view of one embodiment of a tray according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0016] The present inventions now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the inventions are shown. Indeed, these inventions may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.

[0017] One preferred embodiment of tray 10 of the present invention is illustrated in FIG. 1. It should be understood that tray 10 may be of any shape desired, such as, for example, rectangular, square, and circular or polygon depending on both functional and aesthetic requirements. It will be appreciated that tray 10 is thermoformed to any depth as desired depending upon type and amount of food or non-food product to be packaged. It should also be appreciated that tray 10 may be configured to include two or more recessed areas (not shown) depending again on both functional and aesthetic requirements of a particular packaging application. In some preferred embodiments, tray 10 includes a sealing flange 20 extending around the periphery of a recessed cavity 30 to facilitate the sealing of a lidding film 40 to enclose a food product 50 as is shown in FIG. 1.

[0018] Referring now more particularly to FIG. 2 of the drawings, a preferred embodiment of tray 10 embodying the present invention is shown. Tray 10 includes a bulk layer 11 comprising a crystalline aromatic polyester and a capping layer 12 which is in direct contact with bulk layer 11. In some preferred embodiments, capping layer 12 is a monolayer film. In other preferred embodiments, capping layer 12 is a multilayer film.

[0019] In some preferred embodiments, bulk layer 11 comprises an aromatic polyester having between 20% and 40% crystallinity. Such crystalline aromatic polyester may include, but are not limited to, polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate; polyethylene-2,6-naphthalate, polytrimethylene-2,6-naphthalate, polybutylene-2,6-naphthalate, polyhexamethylene-2,6-naphthalate, polyethylene isophthalate, polytrimethylene isophthalate, polybutylene isophthalate, polyhexamethylene isophthalate, poly-1,4-cyclohexane-dimethanol terephthalate, and polybutylene adipate terephthalate and derivatives thereof. In one preferred embodiment, bulk layer 11 comprises crystalline polyethylene terephthalate. It is also contemplated that additives such as, but not limited to, anti-oxidants, anti-static and anti-block agents, impact modifiers, nucleating agents, recycled PET, inorganic fillers, and other polymeric materials may be included in the bulk layer at concentrations typically known in the art to improve the extrusion process and layer properties of the final sheet. In the various embodiments of the invention, it is preferred that the bulk layer 11 makes up between 50% and 99% of the thickness of the tray. In other preferred embodiments, the bulk layer 11 has a thickness of between about 15 mil (381 micron) and about 50 mil (1270 micron). In particularly preferred compositions, bulk layer 11 includes between about 85% and 100% by weight of a crystalline polyethylene terephthalate and between 0% and 15% by weight of an additive mixture of impact modifiers, nucleating agents for recycled PET. In other particularly preferred compositions, bulk layer 11 may include mixtures described in U.S. Pat. No. 6,077,904, the disclosure of which is incorporated herein by reference in its entirety. For example, bulk layer 11 may include between about 60% and 99% by weight of a crystalline polyethylene terephthalate which functions as the base polymer, between about 1% and 15% by weight of additive mixture including an impact modifier from the group consisting of polymers of ethylene-methyl acrylate, ethylene-butyl acrylate, ethylene-ethyl acrylate, ethylene-vinyl acetate, ethylene-maleic acid, polypropylene, polybutadiene, polymethyl methacrylate-polycarbonate shell core modifier and paramethylstyrene, a compatibilizer which functions to improve the surface properties between the polyethylene terephthalate and the impact modifier and a nucleating agent, and between about 0% and 40% by weight of recycled PET.

[0020] The capping layer 12 includes a copolymer having at least a first structurally distinct repeating unit of ethylene and a second structurally distinct repeating unit selected from the following: (i) an acrylate-based moiety; (ii) at least 12% by weight relative to the total weight of the copolymer of vinyl acetate; and (iii) an anhydride or carboxylic acid. In some preferred embodiments, the capping layer 12 is a monolayer film. In other preferred embodiments, capping layer 12 is a multilayer film coextruded with bulk layer 11 where the layer in direct contact with bulk layer 11 comprises a copolymer having at least a first structurally distinct repeating unit of ethylene and a second structurally distinct repeating unit selected from the following: (i) an acrylate-based moiety; (ii) at least 12% by weight relative to the total weight of the copolymer of vinyl acetate; and (iii) an anhydride or carboxylic acid.

[0021] In some preferred embodiments, the capping layer 12 comprises an ethylene copolymer which includes a second structural repeating unit of an acrylate-based moiety. The acrylate-based moiety may include, but is not limited to any selected from the group consisting of butyl acrylate, ethyl acrylate, ethyl methacrylate, methyl acrylate, methyl methacrylate, 2-ethylhexyl acrylate, glycidyl methacrylate, and blends thereof. In other preferred embodiments, the acrylate-based moiety is methyl acrylate. Such embodiments may include at least 21% by weight relative to the total weight of the copolymer of the methyl acrylate structural repeating unit.

[0022] In other preferred embodiments, the capping layer 12 comprises an ethylene copolymer which includes a second structural repeating unit of a carboxylic acid moiety. The carboxylic acid may include, but is not limited to any selected from the group consisting of acrylic acid, methacrylic acid, -ethylacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, and endo-cis-bicyclo[2,2,1]-hepto-5-ene-2,3-dicarboxylic acid.

[0023] In other preferred embodiments, the capping layer 12 comprises an ethylene copolymer which includes a second structural repeating unit of an anhydride moiety. The anhydride may include, but is not limited to any cyclic and/or linear anhydride known in the art. Useful examples of cyclic anhydrides include itaconic anhydride and maleic anhydride and alkyl substituted derivatives thereof. Other non-limiting examples of cyclic anhydrides are those derived from monomers selected from the group consisting of allyl succinic anhydride, isobutenyl succinic anhydride, butenyl succinic anhydride, octenyl succinic anhydride, nonenyl succinic anhydride, dodecenyl succinic anhydride, tetradecenyl succinic anhydride, n-hexadecenyl succinic anhydride, iso-hexadecenyl succinic anhydride, n-octadecenyl succinic anhydride, iso-octadecenyl succinic anhydride, and n-triacontenyl succinic anhydride. In some preferred embodiments, the anhydride structural repeating unit is maleic anhydride.

[0024] Capping layer 12 may also comprise a copolymer having at least a first structurally distinct repeating unit of ethylene, a second structurally distinct repeating unit and a third structurally distinct repeating units. The second and third structural repeating units may include any acrylate-based moiety, vinyl acetate, anhydride or carboxylic acid as described above. For example, in some preferred embodiments, the capping layer 12 comprises a terpolymer having a first structural repeating unit of ethylene, a second structural repeating unit and a third structural repeating unit which is different than the second structural repeating unit. In some preferred embodiments, the second structural repeating unit includes methyl acrylate and the third structural repeating unit includes maleic anhydride. In a particularly preferred embodiment, the methyl acrylate is about 24% by weight relative to the total weight of the copolymer and the maleic anhydride is about 0.1% by weight relative to the total weight of the copolymer. In other preferred embodiments, the capping layer 12 includes a terpolymer where the first structural repeating unit is ethylene, the second structural repeating unit is vinyl acetate and the third structural repeating unit is maleic anhydride. In a particularly preferred embodiment, the vinyl acetate is at least about 9.5% by weight relative to the total weight of the copolymer and the maleic anhydride is at least about 0.1% by weight relative to the total weight of the copolymer. In still further preferred embodiments, the capping layer 12 comprises a terpolymer having a first structural repeating unit of ethylene, the second structural repeating unit of methyl acrylate and the third structural repeating unit of glycidyl methacrylate. In a particularly preferred embodiment, the methyl acrylate is about 24% by weight relative to the total weight of the copolymer and the glycidyl methacrylate is about 8% by weight relative to the total weight of the copolymer.

WORKING EXAMPLES

[0025] In the following Examples 1-13 and Comparative Examples 1-3, there is described various embodiments of a tray 10 having a two-layer structure as illustrated in FIGS. 1-2. In all these examples, the bulk layer 11 and capping layer 12 were co-extruded into a sheet form using single-screw laboratory extruders (LabTech Engineering Company, Ltd. Thailand) In all these examples, the thickness of the bulk layer was about 8 mil (203 micron) and the thickness of the capping layer was about 3 mil (76 micron).

Example 1

[0026] Example 1 is one preferred embodiment of tray 10 of the present invention having a structure and layer compositions as described below. Reported below is the layer composition relative to the total weight of the layer. [0027] Layer 11: 86 wt.-% of a crystalline polyethylene terephthalate (CPET)-LASER+C9921 (DAK Americas LLC, Charlotte, N.C., USA) and 14 wt.-% of an additive mixture. [0028] Layer 12: 100 wt.-% of an ethylene methyl acrylate copolymer having a methyl acrylate content of 21.5 wt.-%, a density of 0.943 g/cm.sup.3 and a melt index of 0.4 g/10 min-EMAC SP2202 (Westlake Chemical Company, Houston, Tex., USA).

Example 2

[0029] Example 2 is another preferred embodiment of tray 10 of the present invention having a structure and layer compositions as described below. Reported below is the layer composition relative to the total weight of the layer. [0030] Layer 11: 86 wt.-% of a crystalline polyethylene terephthalate (CPET)-LASER+C9921 (DAK Americas LLC, Charlotte, N.C., USA) and 14 wt.-% of an additive mixture. [0031] Layer 12: 100 wt.-% of an ethylene methyl acrylate copolymer having a methyl acrylate content of 20 wt.-%, a density of 0.942 g/cm.sup.3 and a melt index of 8 g/10 min-DuPont Elvaloy AC 1820 (E.I. du Pont de Nemours and Company, Wilmington, Del., USA).

Example 3

[0032] Example 3 is another preferred embodiment of tray 10 of the present invention having a structure and layer compositions as described below. Reported below is the layer composition relative to the total weight of the layer. [0033] Layer 11: 86 wt.-% of a crystalline polyethylene terephthalate (CPET)-LASER+C9921 (DAK Americas LLC, Charlotte, N.C., USA) and 14 wt.-% of an additive mixture. [0034] Layer 12: 100 wt.-% of an ethylene vinyl acetate copolymer having a vinyl acetate content of 28 wt.-%, a density of 0.95 g/cm.sup.3 and a melt index of 6 g/10 min-DuPont Elvax 3175 (E.I. du Pont de Nemours and Company, Wilmington, Del., USA).

Example 4

[0035] Example 4 is another preferred embodiment of tray 10 of the present invention having a structure and layer compositions as described below. Reported below is the layer composition relative to the total weight of the layer. [0036] Layer 11: 86 wt.-% of a crystalline polyethylene terephthalate (CPET)-LASER+C9921 (DAK Americas LLC, Charlotte, N.C., USA) and 14 wt.-% of an additive mixture, [0037] Layer 12: 100 wt.-% of an ethylene vinyl acetate copolymer having a vinyl acetate content of 18 wt.-%, a density of 0.94 g/cm.sup.3 and a melt index of 30 g/10 min-DuPont Elvax 3176 (E.I. du Pont de Nemours and Company, Wilmington, Del., USA).

Example 5

[0038] Example 5 is another preferred embodiment of tray 10 of the present invention having a structure and layer compositions as described below. Reported below is the layer composition relative to the total weight of the layer. [0039] Layer 11: 86 wt.-% of a crystalline polyethylene terephthalate (CPET)-LASER+C9921 (DAK Americas LLC, Charlotte, N.C., USA) and 14 wt.-% of an additive mixture. [0040] Layer 12: 100 wt.-% of an ethylene vinyl acetate copolymer having a vinyl acetate content of 12 wt.-%, a density of 0.93 g/cm.sup.3 and a melt index of 0.35 g/10 min-DuPont Elvax 3135XZ (E.I. du Pont de Nemours and Company, Wilmington, Del., USA).

Example 6

[0041] Example 6 is another preferred embodiment of tray 10 of the present invention having a structure and layer compositions as described below. Reported below is the layer composition relative to the total weight of the layer. [0042] Layer 11: 86 wt.-% of a crystalline polyethylene terephthalate (CPET)-LASER+C9921 (DAK Americas LLC, Charlotte, N.C., USA) and 14 wt.-% of an additive mixture. [0043] Layer 12: 100 wt.-% of an ethylene-based anhydride grafted copolymer elastomer having a density of 0.89 g/cm.sup.3 and a melt index of 7.2 g/10 min-ADMER SE810 (Mitsui Chemicals America, Inc. of Rye Brook, N.Y., USA).

Example 7

[0044] Example 7 is another preferred embodiment of tray 10 of the present invention having a structure and layer compositions as described below. Reported below is the layer composition relative to the total weight of the layer. [0045] Layer 11: 86 wt.-% of a crystalline polyethylene terephthalate (CPET).-LASER+C9921 (DAK Americas LLC, Charlotte, N.C., USA) and 14 wt-% of an additive mixture. [0046] Layer 12: 100 wt.-% of an ethylene-based anhydride grafted copolymer elastomer having a density of 0.89 g/cm.sup.3 and a melt index of 2.6 g/10 min-ADMER SF755A (Mitsui Chemicals America, Inc. of Rye Brook, N.Y., USA).

Example 8

[0047] Example 8 is another preferred embodiment of tray 10 of the present invention having a structure and layer compositions as described below. Reported below is the layer composition relative to the total weight of the layer [0048] Layer 11: 86 wt.-% of a crystalline polyethylene terephthalate (CPET)-LASER+C9921 (DAK Americas LLC, Charlotte, N.C., USA) and 14 wt.-% of an additive mixture. [0049] Layer 12: 100 wt.-% of an anhydride modified linear low density polyethylene copolymer having a density of 0.918 g/cm.sup.3 and a melt index of 8.0 g/10 min-Westlake TYMAX GT4300 (Westlake Chemical Corporation, Houston, Tex., USA).

Example 9

[0050] Example 9 is another preferred embodiment of tray 10 of the present invention having a structure and layer compositions as described below. Reported below is the layer composition relative to the total weight of the layer. [0051] Layer 11: 86 wt.-% of a crystalline polyethylene terephthalate (CPET)-LASER+C9921 (DAK Americas LLC, Charlotte, N.C., USA) and 14 wt.-% of an additive mixture. [0052] Layer 12: 100 wt.-% of an anhydride modified linear low density polyethylene copolymer having a density of 0.91 g/cm.sup.3 and a melt index of 2.7 g/10 min-DuPont Bynel 41E710 (E.I. du Pont de Nemours and Company, Wilmington, Del., USA).

Example 10

[0053] Example 10 is another preferred embodiment of tray 10 of the present invention having a structure and layer compositions as described below. Reported below is the layer composition relative to the total weight of the layer. [0054] Layer 11: 86 wt.-% of a crystalline polyethylene terephthalate (CPET)-LASER+C9921 (DAK Americas LLC, Charlotte, N.C., USA) and 14 wt.-% of an additive mixture. [0055] Layer 12: 100 wt.-% of an anhydride modified acrylate terpolymer having a methyl acrylate content of 24 wt.-%, a density of 0.943 g/cm.sup.3 and a melt index of 2.7 g/10 min-TYMAX GT7058 (Westlake Chemical Corporation, Houston, Tex., USA).

Example 11

[0056] Example 11 is another preferred embodiment of tray 10 of the present invention having a structure and layer compositions as described below. Reported below is the layer composition relative to the total weight of the layer. [0057] Layer 11: 86 wt.-% of a crystalline polyethylene terephthalate (CPET)-LASER+C9921 (DAK Americas LLC, Charlotte, N.C., USA) and 14 wt.-% of an additive mixture. [0058] Layer 12: 100 wt.-% of an anhydride modified ethylene vinyl acetate terpolymer having density of 0.95 g/cm.sup.3 and a melt index of 6.7 g/10 min-DuPont Bynel 1123 (E.I. du Pont de Nemours and Company, Wilmington, Del., USA).

Example 12

[0059] Example 12 is another preferred embodiment of tray 10 of the present invention having a structure and layer compositions as described below. Reported below is the layer composition relative to the total weight of the layer. [0060] Layer 11: 86 wt.-% of a crystalline polyethylene terephthalate (CPET)-LASER+C9921 (DAK Americas LLC, Charlotte, N.C., USA) and 14 wt.-% of an additive mixture. [0061] Layer 12: 100 wt.-% of an anhydride modified ethylene vinyl acetate terpolymer having density of 0.94 g/cm.sup.3 and a melt index of 0.85 g/10 min-DuPont Bynel 3930 (E.I. du Pont de Nemours and Company, Wilmington, Del., USA).

Example 13

[0062] Example 13 is another preferred embodiment of tray 10 of the present invention having a structure and layer compositions as described below. Reported below is the layer composition relative to the total weight of the layer. [0063] Layer 11: 86 wt.-% of a crystalline polyethylene terephthalate (CPET)-LASER+C9921 (DAK Americas LLC, Charlotte, N.C., USA) and 14 wt.-% of an additive mixture, [0064] Layer 12: 100 wt.-% of an ethylene glycidyl methacrylate terpolymer having a methyl acrylate content of 24 wt.-%, a glycidyl methacrylate content of 8 wt.-%, a density of 0.94 g/cm.sup.3 and a melt index of 6 g/10 min-LOTADER AX8900 (Arkema, Colombes, France).

Comparative Example 1

[0065] Comparative Example 1 is an embodiment of a tray having a structure and layer compositions as described below. Reported below is the layer composition relative to the total weight of the layer. [0066] Layer 11: 86 wt.-% of a crystalline polyethylene terephthalate (CPET)-LASER+C9921 (DAK Americas LLC, Charlotte, N.C., USA) and 14 wt.-% of an additive mixture. [0067] Layer 12: 100 wt.-% of an ethylene vinyl acetate copolymer (EVA) having a 10% vinyl acetate content, a melt index of 0.3 g/10 min-DuPont Elvax 3129-1 (E.I. du Pont de Nemours and Company, Wilmington, Del., USA).

Comparative Example 2

[0068] Comparative Example 2 is an embodiment of a tray having a structure and layer compositions as described below. Reported below is the layer composition relative to the total weight of the layer. [0069] Layer 11: 86 wt.-% of a crystalline polyethylene terephthalate (CPET)-LASER+C9921 (DAK Americas LLC, Charlotte, N.C., USA) and 14 wt.-% of an additive mixture. [0070] Layer 12: 100 wt.-% of an ethylene vinyl acetate copolymer (EVA) having a 4% vinyl acetate content, a melt index of 1.0 g/10 min-Petrothene NA340 (LyondellBasell Industries, Houston, Tex., USA).

Comparative Example 3

[0071] Comparative Example 3 is an embodiment of a tray having a structure and layer compositions as described below. Reported below is the layer composition relative to the total weight of the layer. [0072] Layer 11: 86 wt.-% of a crystalline polyethylene terephthalate (CPET)-LASER+C9921 (DAK Americas LLC, Charlotte, N.C., USA) and 14 wt-% of an additive mixture. [0073] Layer 12: 90 wt.-% of an ethylene vinyl acetate copolymer (EVA) having a 10% vinyl acetate content, a melt index of 0.3 g/10 min-DuPont Elvax 3129-1 (E.I. du Pont de Nemours and Company, Wilmington, Del., USA)+10 wt.-% of a polypropylene (PP)-Total 3576 (Total Petrochemicals USA, La Porte, Tex., USA).

Bond Strength Between Bulk and Capping Layers

[0074] Specimens for testing bond strength between the bulk layer and the capping layer of each of the above examples were prepared by first heat sealing each example to a two-layer support substrate of 75-gauge OPET/3-mil EVA with capping layer (layer 12) of each example being heat sealed to the EVA layer of the support substrate. The heat sealing parameters were 300 F. (149 C.) under a pressure of 40 psi for a dwell time of 1 second. Next, the specimens were cut to roughly 1-inch wide by 4-inch long pieces and an end section of the bulk layer and capping layer with the two-layer support substrate were secured to an Instron Pull Tester Model No. 5967 (Norwood, Mass. USA). Each specimen was pulled apart at a 180 angle at a rate of 12 in/min while the average force (gram/inch) to separate the bulk layer from the capping layer of the specimen was measured at room temperature (23 C.) in accordance with ASTM Test Method F-904. The results are reported in TABLE 1 below.

TABLE-US-00001 TABLE 1 Bond Strength Between Bulk and Capping Layers Average Bond Sample Strength (g/in) Example 1 1757 Example 2 6062 Example 3 3100 Example 4 2998 Example 5 1199 Example 6 .sup.>8000.sup. Example 7 3435 Example 8 1873 Example 9 450 Example 10 3100 Example 11 3203 Example 12 2028 Example 13 6646 Comparative 60 Example 1 Comparative 7 Example 2 Comparative 15 Example 3 .sup.Indicates destructive failure of the film.

[0075] It should be evident to one of ordinary skill in the art that based on the above results the bond strength between a bulk layer of crystalline PET and a capping layer comprising a copolymer having a first structural repeating unit of ethylene and a second structural repeating unit selected from the following: (i) an acrylate-based moiety; (ii) at least 12% by weight relative to the total weight of the copolymer of vinyl acetate; and (iii) an anhydride or carboxylic acid may be controlled to provide a bond strength value within a range of between 450 g/in and 8000 g/in. and thus, readily adjusted to meet the needs of a particular application by selective formulation of the capping layer composition.

[0076] The above description and examples illustrate certain embodiments of the present invention and are not to be interpreted as limiting. Selection of particular embodiments, combinations thereof, modifications, and adaptations of the various embodiments, conditions and parameters normally encountered in the art will be apparent to those skilled in the art and are deemed to be within the spirit and scope of the present invention.